Didaktorikh Diatribh

Panepisthmio Patrwn Poluteqnikh Sqolh Tmhma Hlektrologwn Mhqanikwn kai Teqnologiac Upologistwn Tomeac Thlepikoinwniwn kai Teqnologiac Plhroforiac Ergasthrio Asurmathc Thlepikoinwniac Teqnikèc BeltistopoÐhshc thc Poiìthtac twn Pareqomènwn Uphresi n (QoS) me 'Elegqo KrÐsimwn Hlektrik n kai Hlektromagnhtik n Paramètrwn sta SÔgqrona AsÔrmata Thlepikoinwniakˆ Sust mata Didaktorikh Diatribh tou IWANNH G. FRAIMH DIPLWMATOUQOU HLEKTROLOGOU MHQANIKOU KAI TEQNOLOGIAS UPOLOGISTWN Epiblèpwn: Kwtsìpouloc A. StaÔroc Kajhght c PanepisthmÐou Patr n Arijmìc Diatrib c: 293 Ergasthrio Asurmathc Thlepikoinwniac Pˆtra, IoÔnioc 2012

Panepist mio Patr n, Poluteqnik Sqol Tm ma Hlektrolìgwn Mhqanik n kai TeqnologÐac Upologist n Tomèac Thlepikoinwni n kai TeqnologÐac PlhroforÐac Ergast rio AsÔrmathc ThlepikoinwnÐac (Upograf )... Fraimhc Iwannhc tou Gewrgiou DiplwmatoÔqoc Hlektrolìgoc Mhqanikìc kai TeqnologÐac Upologist n Thl.:++306942843558 Email: ifraimhs@ece.upatras.gr c 2012 All rights reserved {H ègkrish thc paroôsac DD apì to Tm ma Hlektrolìgwn Mhqanik n kai TeqnologÐac Upologist n thc Poluteqnik c Sqol c tou PanepisthmÐou Patr n den upodhl nei apodoq twn apìyewn kai twn sumperasmˆtwn tou suggrafèa} (N. 5343/1932, ˆrjro 202, par. 2)

Panepist mio Patr n, Poluteqnik Sqol Tm ma Hlektrolìgwn Mhqanik n kai TeqnologÐac Upologist n Tomèac Thlepikoinwni n kai TeqnologÐac PlhroforÐac Ergast rio AsÔrmathc ThlepikoinwnÐac Copyright c All rights reserved FraÐmhc Iwˆnnhc tou GewrgÐou. Me epifôlaxh pantìc dikai matoc. ApagoreÔetai h antigraf, apoj keush kai dianom thc paroôsac ergasðac, ex olokl rou tm matoc aut c, gia emporikì skopì. Epitrèpetai h anatôpwsh, apoj keush kai dianom gia skopì mh kerdoskopikì, ekpaideutik c ereunhtik c fôshc, upì thn proôpìjesh na anafèretai h phg proèleushc kai na diathreðtai to parìn m numa. Erwt mata pou aforoôn sth qr sh thc ergasðac gia kerdoskopikì skopì prèpei na apeujônontai proc to suggrafèa. Gia th suggraf thc DD qrhsimopoi jhke to prìgramma L A TEX, en h metˆfrash twn teqnik n ìrwn ègine sômfwna me to lexikì [1]. Ta graf mata ta opoða emperièqontai dhmiourg jhkan me to logismikì MS VISIO 2007 kai h prosomoðwsh twn algorðjmwn kai ta sq mata me to Matlab R2007b.

SÔntomo Biografikì ShmeÐwma O Iwˆnnhc G. FraÐmhc genn jhke sthn Pˆtra stic 30 IounÐou 1982. ApofoÐthse apì to EniaÐo LÔkeio EuhnoqwrÐou ton IoÔnio tou 2000 kai ton Okt brio tou Ðdiou ètouc eis - qjh sto Tm ma Hlektrolìgwn Mhqanik n kai TeqnologÐac Upologist n thc Poluteqnik c Sqol c tou PanepisthmÐou Patr n apì to opoðo apofoðthse to Noèmbrio tou 2005. Apì ton Dekèmbrio tou 2005 mèqri s mera eðnai metaptuqiakìc foitht c sto EAT tou tm matoc Hlektrolìgwn Mhqanik n kai TeqnologÐac Upologist n tou PanepisthmÐou Patr n kai olok rwse tic spoudèc tou gia thn apìkthsh DidaktorikoÔ Dipl matoc. Wc metaptuqiakìc foitht c tou EAT kai sto plaðsio tou epikourikoô tou èrgou, tan upeôjunoc gia thn kajod ghsh kai thn epðbleyh foitht n kai prosèfere epikourik bo - jeia stic ergasthriakèc ask seic twn majhmˆtwn <<Diˆdosh kumˆtwn kai jewrða kerai n>> kai <<Sust mata eureðac ekpomp c >>. Epiplèon prosèfere epikourikì èrgo se diplwmatikèc ergasðec proptuqiak n foitht n pou dienerg jhkan sta plaðsia tou EAT kai dðdaxe sto earinì sqoleðo << WiCoNeT 2009>>. EpÐshc o I. G. FraÐmhc eðnai krit c se diejn periodikˆ (IEEE Communications Letters, IEEE Tansactions on Vehicular Technology), kaj c kai se diejn sunèdria (IEEE International Symposium on Personal, Indoor and Mobile Radio Communications). Katˆ th diˆrkeia twn metaptuqiak n spoud n tou èqei ergasteð ston OTE, sto KUPES tou tm matoc Hlektrolìgwn Mhqanik n kai TeqnologÐac Upologist n tou PanepisthmÐou Patr n kai sthn BKP tou Ðdiou PanepisthmÐou. Ta kôria ereunhtikˆ tou endiafèronta perilambˆnoun asôrmata dðktua kai diaqeðrish radiopìrwn sta asôrmata kuyelwtˆ dðktua me kôria èmfash sto QoS twn qrhst n. 1

EuqaristÐec H paroôsa DD pragmatopoi jhke sto EAT tou Tm matoc Hlektrolìgwn Mhqanik n kai TeqnologÐac Upologist n thc Poluteqnik c Sqol c tou PanepisthmÐou Patr n, upì thn epðbleyh kai kajod ghsh tou Kajhght kai Dieujunt tou EAT k. StaÔro Kwtsìpoulo ton opoðo euqarist idiaðtera gia thn sunergˆsia pou eðqame ìla autˆ ta qrìnia kaj c epðshc gia thn polôtimh sumbol tou sthn apoperˆtwsh thc paroôsac DD. EpÐshc ja jela na euqarist sw ìlo to didaktikì, ereunhtikì, dioikhtikì kai foithtèc pou apasqoloôntai kai apasqol jhkan sto EAT gia ìlec tic wraðec stigmèc pou perˆsame mazð. IdiaÐtera euqarist ton Didˆktora tou PanepisthmÐou Patr n k. BasÐlh Papouts gia thn epoikodomhtik kai euqˆristh sunergasða pou eðqame mèsa apì thn opoða proèkuyan arketèc dhmosieumènec ergasðec se diejn periodikˆ kai sunèdria. Tèloc, ofeðlw èna megˆlo euqarist stouc goneðc mou Gi rgo kai Basilik kaj c kai sthn upìloiph oikogèneiˆ mou oi opoðoi mou sumparastˆjhkan se ìla ta probl mata pou anèkuyan ìla autˆ ta qrìnia kai bo jhsan me ìlec touc tic dunˆmeic sthn prospajeiˆ olokl rwshc twn spoud n mou. 2

PerÐlhyh Ta sôgqrona asôrmata thlepikoinwniakˆ sust mata anamènetai na parèqoun uphresðec uyhloô rujmoô metˆdoshc dedomènwn se poluˆrijmouc qr stec me diˆforec apait seic se poiìthta uphresðac (QoS). Apì thn ˆllh meriˆ, oi pìroi tou sust matoc ìpwc eðnai to diajèsimo fˆsma suqnot twn kai h ekpempìmenh isqôc den eðnai aperiìristoi kai epomènwc anazhtoôntai teqnikèc kai politikèc diaqeðrishc twn diajèsimwn pìrwn ste na beltiwjeð kai na diasfalisteð to apaitoômeno epðpedo QoS twn qrhst n, qwrðc epiplèon kìstoc gia to sôsthma. E c t ra plhj ra teqnik n diaqeðrishc twn diajèsimwn radiopìrwn gia thn beltðwsh tou QoS èqei protajeð, ìmwc h megˆlh pleioyhfða aut n eðte èqei estiasteð se sust mata me ènan pompì kai pollaploôc dèktec qwrðc na upologðzei thn Ôparxh omokanalik n parembol n, eðte parablèpei teqnologðec pou enisqôoun shmantikˆ to QoS ìpwc h poluekpomp kai h teqnologða MIMO. Shmei netai ìti h parousða twn omokanalik n parembol n eðnai èntonh se polukuyelwtˆ dðktua me shmantikì antðktupo sto epðpedo QoS twn qrhst n. Skopìc thc paroôsac DD eðnai h prìtash nèwn kai apodotik n teqnik n gia thn beltðwsh tou QoS twn qrhst n elègqontac parˆllhla krðsimec hlektrikèc kai hlektromagnhtikèc paramètrouc ìpwc eðnai h ekpempìmenh isqôc kai to diajèsimo eôroc z nhc antðstoiqa. Wc paramètroi tou QoS jewroôntai to eôroc z nhc, o rujmìc metˆdoshc dedomènwn kai to BER. H apìdosh thc kˆje teqnik c apotup netai se deðktec ìpwc h pijanìthta parabðashc tou QoS, h dikaiosônh tou sust matoc (deðkthc Jain) kai h qwrhtikìthta tou sust matoc. To Kefˆlaio 1 dðnei mia sôntomh perigraf thc exèlixhc twn asôrmatwn thlepikoinwniak n diktôwn ìpwc epðshc kai perigraf twn basik n teqnik n pollapl c prìsbashc twn asôrmatwn susthmˆtwn pˆnw stic opoðec basðsthkan oi nèec teqnikèc pou anaptôqjhkan sthn paroôsa DD. Epiplèon perigrˆfontai ta kðnhtra pou od ghsan sthn prìtash thc kˆje teqnik c kaj c epðshc kai h suneisforˆ thc kˆje mðac. Tèloc parèqontai o dhmosieôseic pou proèkuyan katˆ thn enasqìlhsh me ta zht mata thc DD. Sto Kefˆlaio 2 proteðnetai ènac algìrijmoc anˆjeshc twn radiopìrwn gia sust mata OFDMA ta opoða axiopoioôn thn teqnologða MIMO. Aforˆ sust mata pou metadðdoun tìso me monoekpomp ìso kai me poluekpomp kai parousiˆzei qamhl upologistik poluplokìthta. To elˆqisto epðpedo QoS thc kˆje omˆdac qrhst n diasfalðzetai mèsw dèsmeushc eôrouc z nhc apokleistikˆ gia kˆje mða omˆda. H beltistopoðhsh tou QoS pou prosfèrei h teqnik apotup netai sthn olik qwrhtikìthta tou sust matoc se sôgkrish me ˆllec teqnikèc, sthn dikaiosônh tou sust matoc kai sthn katanom twn radiopìrwn se kˆje omˆda qrhst n. 3

4 PerÐlhyh Sto Kefˆlaio 3 anaptôssetai mða teqnik diaqeðrishc twn radiopìrwn gia dðktua OFDMA me skopì th beltistopoðhsh tou QoS twn qrhst n. JewreÐtai to Ðdio elˆqisto epðpedo rujmoô metˆdoshc dedomènwn kai BER gia qr stec pou an koun sthn Ðdia klˆsh uphresðac kai mèsw qamhl c poluplokìthtac epanalhptikoô algorðjmou epitugqˆnetai mikrìterh pijanìthta parabðashc tou QoS kai megalôteroc rujmìc metˆdoshc twn dedomènwn sta ˆkra thc kuyèlhc sqetikˆ me ˆllec statikèc teqnikèc pou protˆjhkan prìsfata kai efarmìzontai se dðktua OFDMA. To Kefˆlaio 4 proteðnei ènan dunamikì epanalhptikì algìrijmo o opoðoc ìqi mìno jewreð elˆqisto epðpedo rujmoô metˆdoshc kai sugkekrimèno BER gia qr stec pou an koun sthn Ðdia klˆsh allˆ epðshc sunupologðzei kai thn katˆstash stic ourèc anamon c twn qrhst n sto SB. O algìrijmoc emfanðzei qamhlìterh pijanìthta parabðashc tou QoS, enisqumèno rujmì metˆdoshc dedomènwn sta ˆkra thc kuyèlhc kai kalôtero deðkth dikaiosônhc se sqèsh me ˆllec dhmofileðc teqnikèc gia polukuyelwtˆ sust mata OFDMA. Sto Kefˆlaio 5 anaptôssetai dunamik teqnik apofug c twn omokanalik n parembol n gia sust mata OFDMA. ApaiteÐtai sunergasða metaxô twn geitonik n pomp n kai ta ofèlh thc teqnik c aut c eðnai o beltiwmènoc rujmìc metˆdoshc dedomènwn kaj c kai o beltiwmènoc deðkthc dikaiosônhc gia touc qr stec thc diaqwristik c epifˆneiac thc kuyèlhc se sqèsh me ˆllec statikèc teqnikèc. MporeÐ na efarmosteð tìso sthn katerqìmenh zeôxh susthmˆtwn OFDMA pou parèqoun uphresðec periorismènou eôrouc z nhc (Narrow band services), ìso kai sthn anerqìmenh zeôxh susthmˆtwn OFDMA. Sto Kefˆlaio 6 proteðnetai mða teqnik gia thn metˆdosh dedomènwn poluekpomp c se polukuyelwtì dðktuo CDMA. O proteinìmenoc mhqanismìc se kˆje perðodo anˆjeshc kanali n epilègei na metad sei se kˆje omˆda qrhst n pou apaiteð to Ðdio perieqìmeno eðte me afierwmèna kanˆlia eðte me koinì kanˆli èqontac wc krit rio thn ligìterh apaitoômenh isqô. Sthn perðptwsh pou oi qr stec brðskontai sta ìria thc kuyèlhc kai o SB adunateð na parèqei to apaitoômeno QoS, tìte èna mèroc thc apaitoômenhc isqôoc parèqetai apì geitonikì SB. Wc parˆmetroc tou QoS jewreðtai o rujmìc metˆdoshc dedomènwn kai h enèrgeia se kˆje bit proc thn parembol. Sto Parˆrthma Aþ parousiˆzontai oi klasikèc teqnikèc epanaqrhsimopoðhshc fˆsmatoc kai pio sugkekrimèna oi teqnikèc Reuse-1 kai Reuse-3 oi opoðec eðnai polô basikèc gia polukuyelwtˆ sust mata kai apotèlesan thn bˆsh gia thn anˆptuxh apodotikìterwn teqnik n. Sto Parˆrthma Bþ parousiˆzetai h teqnik thc klasmatik c epanaqrhsimopoðhshc fˆsmatoc (FFR) pou skopìc thc eðnai h beltðwsh twn qrhst n sta ìria thc kuyèlhc kai parousðazei dôo ekdoqèc: thn pia epanaqrhsimopoðhsh fˆsmatoc (SFR) kai thn merik e- panaqrhsimopoðhsh fˆsmatoc (PFR). Tèloc sto Parˆrthma Gþ dðnetai h polukuyelwt dom pou qrhsimopoi jhke wc to montèlo tou sust matoc gia tic diˆforec teqnikèc pou protˆjhkan sthn paroôsa DD kaj c epðshc kai oi exis seic gia ton upologismì twn apwlei n diˆdoshc tou s matoc.

PerÐlhyh 5 Lèxeic Kleidiˆ PoluplexÐa me Orjogwnik DiaÐresh Suqnìthtac, Poiìthta UphresÐac, Pollapl Prìsbash me Orjogwnik DiaÐresh Suqnìthtac, Pollaplèc EÐsodoi Pollaplèc 'Exodoi, Pollapl Prìsbash me DiaÐresh Q rou, Katanom Radiopìrwn, DiaqeÐrish Radiopìrwn, Pallapl Prìsbash me DiaÐresh K dika, DeÐkthc DikaiosÔnhc.

Abstract Modern wireless communication networks and systems are expected to provide high data rate services to nymerous wireless users with diverse quality of service (QoS) requirements. On the other hand, system resources like transmission power and available bandwidth are limited and therefore new tecniques and policies of resource management are needed in order to improve the users QoS without additional cost. Great number of resource management techniques aiming at QoS improvement has been proposed so far. But the vast majority focuses on single cell systems without considering co-channel interference, whose presence is intense in multi-cell systems and has a serious impact on QoS or overlooks technologies which can enhance users QoS like MIMO technology and multicasting. This doctoral thesis aims at proposing new efficient techniques for QoS improvement while controling critical electrical and electromagnetic system parameters like the transmission power and bandwidth. The data rate, the required bandwidth and bit error rate (BER) are considered as QoS parameters for users. The technique efficiency is reflected to indices like the QoS violation probability, the Jain s fairness index and the cell capacity. Chapter 1 gives a brief description of wireless systems evolution, while also describes basic multiple access techniques of wireless systems which are the base for new technique proposed in this doctoral thesis. Moreover, the motives behind each one of the proposed techniques and the contribution of each technique are described. This chapter also provides the list of the produced papers. In Chapter 2, a radio resource allocation algorithm is proposed for OFDMA systems which exploit MIMO technology. Unicast and multicast transmission modes are considered while also the algorithm shows low computational complexity. The minimum QoS level of each multicast group is assured through bandwidth reservation. The QoS improvement that the proposed technique offers is depicted in system capacity in comparison with other unicast schemes, in the system fairness and subcarrier distribution. In Chapter 3, a resource management technique is developed for OFDMA networks which aims at improving users QoS. The same minimum level of data rate and BER are considered for users pairtaining to the same service class. The proposed technique is able to provide lower QoS violation probability, higher data rate for cell-edge users compared to other techniques used for multi-cell OFDMA systems. Chapter 4 proposes a dynamic iterative algorithm which not only considers minimum 6

Abstract 7 data rate and targer BER for users but also users queue buffers are considered. proposed algorithm provides lower QoS violation probability, enhanced cell-edge data rate and higher fairness index than other popular techniques for multi-cell OFDMA systems. In Chapter 5, a dynamic interference avoidance scheme for OFDMA systems is proposed. BS Coordination is needed and the outcomes of the proposed technique are the improved data rate and fairness index for users near cell boundary in comparison with other widely used schemes for multi-cell systems. In Chapter 6, a technique for multicast transmission in a CDMA system is proposed. The proposed scheme in every desicion time interval chooses to transmit to users demanding the same content either with dedicated channels or either with a common channel. The channel type depends on power consumption and the less power consuming mode is preferred without QoS degradation. In case BS power is not enough in order to provide the required QoS, then neighboring BSs can assit cell-edge users. The data rate and the energy per bit to interference ratio. In Appendix A, traditional frequency reuse schemes are given and particularly the Reuse-1 scheme and Reuse-e scheme which are the basis for new frequency reuse techniques. Appendix B The provides the fractional frequency reuse scheme which aims at enhancing cell edge users performance and includes two variants: the soft frequency reuse and the partial frequency reuse. Finally, Appendix Γ provides the multi-cellular structure which is used as system model for various techniques which are introduced in this doctoral thesis as well as the equations for the calculation of path-losses. Keywords Orthogonal Frequency Division Multiplexing, Orthogonal Frequency Division Multiple Access, Multiple Input Multiple Output, Quality of Service, Cell-Edge Data Rate, Space Division Multiple Access, Radio Resource Allocation, Radio Resource Management

Perieqìmena SÔntomo Biografikì ShmeÐwma 1 EuqaristÐec 2 PerÐlhyh 3 Abstract 6 Perieqìmena 11 Katˆlogoc Sqhmˆtwn 13 Katˆlogoc Pinˆkwn 14 PÐnakac Majhmatik n Sumbìlwn 15 AkrwnÔmia 16 Metafrˆseic Xènwn 'Orwn 19 1 Eisagwg 22 1.1 JematologÐa kai MejodologÐa thc DD..................... 22 1.2 H Exèlixh twn AsÔrmatwn Thlepikoinwniak n Susthmˆtwn.......... 23 1.3 Basikèc Teqnikèc Anˆjeshc Radiopìrwn.................... 24 1.4 Episthmonikˆ KÐnhtra kai Suneisforˆ...................... 25 1.5 Episthmonikèc DhmosieÔseic........................... 28 1.5.1 Diejn Periodikˆ............................. 29 1.5.2 Diejn Sunèdria............................. 29 1.5.3 Ellhnikˆ Sunèdria............................ 30 1.5.4 Anaforèc TrÐtwn sto Dhmosieumèno Ereunhtikì 'Ergo........ 30 BibliografÐa 33 8

Perieqìmena 9 2 Diasfˆlish tou QoS me Egguhmèno EÔroc Z nhc stouc Qr stec se Sust mata Poluekpomp c teqnologðac MIMO-OFDMA 38 2.1 PerÐlhyh...................................... 38 2.2 Eisagwg..................................... 39 2.3 Montèlo tou Sust matoc kai DiatÔpwsh tou Probl matoc.......... 42 2.4 Proteinìmenoc Algìrijmoc Katanom c twn Radiopìrwn............ 45 2.5 Anˆlush thc Emplekìmenhc Poluplokìthtac.................. 47 2.6 Montèla Prosomoi sewn kai Parˆmetroi.................... 48 2.7 Apotelèsmata twn Prosomoi sewn....................... 50 2.7.1 Rujmìc Metˆdoshc Dedomènwn kai DikaiosÔnh gia Diˆforec Timèc tou SNR.................................. 50 2.7.2 Rujmìc Metˆdoshc Dedomènwn kai antðstoiqh DikaiosÔnh gia diˆforec timèc BER............................... 51 2.7.3 Apìdosh se Epikoinwniakì Peribˆllon me Pollaplˆ MGs...... 52 2.7.4 Katanom eôrouc z nhc......................... 53 2.8 Sumperˆsmata................................... 55 BibliografÐa 56 3 UlopoÐhsh AlgorÐjmou me Egguhmèno EpÐpedo RujmoÔ Metˆdoshc twn Dedomènwn kai tou BER stouc Qr stec Polukuyelwt n Susthmˆtwn OFDMA 68 3.1 PerÐlhyh...................................... 68 3.2 Eisagwg..................................... 69 3.3 Montèlo tou Sust matoc kai DiatÔpwsh tou Probl matoc.......... 70 3.3.1 Perigraf tou sust matoc........................ 70 3.3.2 Majhmatik diatôpwsh tou probl matoc................ 71 3.4 Proteinìmenh Teqnik Katanom c twn Radiopìrwn............... 72 3.5 Anˆlush thc Upologistik c Poluplokìthtac................. 74 3.6 Parˆmetroi twn Prosomoi sewn......................... 75 3.7 Apotelèsmata twn Prosomoi sewn....................... 75 3.8 Sumperˆsmata................................... 78 BibliografÐa 79 4 BeltÐwsh tou QoS se Sust mata OFDMA: Qr stec me Elˆqistec ApaÐthseic QoS kai Periorismì stic Ourèc Anamon c 82 4.1 PerÐlhyh...................................... 82 4.2 Eisagwg..................................... 82 4.3 Montèlo tou Sust matoc kai DiatÔpwsh tou Probl matoc.......... 85 4.3.1 Montèlo tou Sust matoc........................ 85 4.3.2 Montèla kanalioô kai rujmoô metˆdoshc twn dedomènwn....... 85

10 Perieqìmena 4.3.3 Majhmatik diatôpwsh tou probl matoc................ 86 4.4 Proteinìmenh Teqnik Katanom c twn Radiopìrwn............... 87 4.5 Anˆlush thc Upologistik c Poluplokìthtac................. 88 4.6 Parˆmetroi twn Prosomoi sewn......................... 89 4.7 Apotelèsmata twn Prosomoi sewn....................... 90 4.8 Sumperˆsmata................................... 94 BibliografÐa 94 5 Teqnik Apofug c twn Omokanalik n Parembol n gia th BeltÐwsh tou QoS sta 'Oria thc Kuyèlhc DiktÔwn OFDMA 100 5.1 PerÐlhyh...................................... 100 5.2 Eisagwg..................................... 101 5.3 Montèlo tou Sust matoc kai DiatÔpwsh tou Probl matoc.......... 102 5.4 Proteinìmenh Teqnik Apofug c twn Omokanalik n Parembol n...... 104 5.5 Parˆmetroi twn Prosomoi sewn......................... 106 5.6 Apotelèsmata twn Prosomoi sewn....................... 106 5.7 Sumperˆsmata................................... 107 BibliografÐa 107 6 Teqnik Elègqou thc IsqÔoc gia thn Diasfˆlish tou QoS se Sust mata Poluekpomp c CDMA 117 6.1 PerÐlhyh...................................... 117 6.2 Eisagwg..................................... 117 6.3 Montèlo tou Sust matoc kai DiatÔpwsh tou Probl matoc.......... 119 6.4 Proteinìmenh Teqnik DiaqeÐrishc twn Radiopìrwn.............. 120 6.5 Parˆmetroi twn Prosomoi sewn......................... 121 6.6 Apotelèsmata twn Prosomoi sewn....................... 121 6.7 Sumperˆsmata................................... 125 BibliografÐa 126 7 EpÐlogoc 129 7.1 Sumperˆsmata................................... 129 7.2 Mellontikèc Epektˆseic............................. 130 Aþ Teqnikèc N-ostoÔ BajmoÔ EpanaqrhsimopoÐhshc twn Suqnot twn131 Bþ Teqnik thc Klasmatik c EpanaqrhsimopoÐhshc twn Suqnot twn (FFR) 132 Bþ.1 'Hpia EpanaqrhsimopoÐhsh Suqnot twn..................... 132 Bþ.2 Merik EpanaqrhsimopoÐhsh Suqnot twn.................... 133

Perieqìmena 11 Gþ Kuyelwt Dom DiktÔou kai Exis seic gia ton Upologismì twn Apwlei n Diˆdoshc 134

Katˆlogoc Sqhmˆtwn 2.1 Omˆdec qrhst n pou apaitoôn to Ðdia dedomèna................. 40 2.2 Genikì diˆgramma enìc thlepikoinwniakoô sust matoc MIMO......... 41 2.3 Fasmatik apìdosh tou sust matoc gia diˆforec timèc tou mèsou SNR.... 51 2.4 DikaiosÔnh tou sust matoc gia diˆforec timèc tou mèsou SNR......... 52 2.5 H fasmatik apìdosh tou sust matoc gia diˆforec timèc tou BER...... 53 2.6 H dikaiosônh tou sust matoc gia diˆforec timèc tou BER........... 54 2.7 Fasmatik apìdosh sust matoc kai pollaplˆ MGs............... 55 2.8 DikaiosÔnh tou sust matoc kai pollaplˆ MGs................. 56 2.9 Sunolik fasmatik apìdosh gia diˆforec timèc tou mèsou SNR ìpou den upˆrqei diaforˆ stic ap leiec diˆdoshc metaxô twn MGs............ 57 2.10 DikaiosÔnh gia diˆforec timèc tou mèsou SNR ìpou ìpou den upˆrqei diaforˆ stic ap leiec diˆdoshc metaxô twn MGs..................... 58 2.11 Fasmatik apìdosh kai mèsh tim SNR, ìpou upˆrqei 5 db diaforˆ stic ap leiec diˆdoshc metaxô twn dôo MGs..................... 59 2.12 DikaiosÔnh kai mèsh tim SNR, ìpou upˆrqei 5 db diaforˆ stic ap leiec diˆdoshc metaxô twn dôo MGs........................... 60 2.13 Fasmatik apìdosh kˆje MG kai mèsh tim tou SNR qwrðc diaforˆ sthn tim twn apwlei n diˆdoshc metaxô twn MGs..................... 61 2.14 Fasmatik apìdosh kˆje MG kai mèsh tim tou SNR me diaforˆ 5 db sthn tim twn apwlei n diˆdoshc metaxô twn MGs.................. 62 2.15 Katanom eôrouc z nhc qwrðc diaforˆ sthn tim twn apwlei n diˆdoshc metaxô twn MGs................................... 63 2.16 Katanom eôrouc z nhc me diaforˆ 5 db sthn tim twn apwlei n diˆdoshc metaxô twn MGs.................................. 64 3.1 Ajroistik sunˆrthsh katanom c (cdf) mèsou rujmoô metˆdoshc dedomènwn qr sth....................................... 76 3.2 Megèjunsh thc qamhlìterhc ourˆc thc ASK (cdf) tou mèsou rujmoô metˆdoshc dedomènwn qr sth............................. 77 3.3 Pijanìthta parabðashc tou egguhmènou epipèdou QoS twn qrhst n...... 78 12

Katˆlogoc Sqhmˆtwn 13 4.1 Ajroistik sunˆrthsh katanom c (cdf) tou mèsou rujmoô metˆdoshc dedomènwn gia K = 30 qr stec anˆ kuyèlh....................... 90 4.2 Ajroistik sunˆrthsh katanom c (cdf) tou mèsou rujmoô metˆdoshc dedomènwn gia K = 65 qr stec anˆ kuyèlh....................... 91 4.3 Megèjunsh thc Ajroistik c sunˆrthshc katanom c (cdf) tou mèsou rujmoô metˆdoshc dedomènwn gia K = 30 qr stec anˆ kuyèlh............. 92 4.4 Megèjunsh thc Ajroistik c sunˆrthshc katanom c (cdf) tou mèsou rujmoô metˆdoshc dedomènwn gia K = 65 qr stec anˆ kuyèlh............. 93 4.5 Pijanìthta parabðashc tou QoS gia K = 30 qr stec anˆ kuyèlh....... 94 4.6 Pijanìthta parabðashc tou QoS gia K = 65 qr stec anˆ kuyèlh....... 95 4.7 O deðkthc dikaiosônhc tou sust matoc gia K = 30 qr stec anˆ kuyèlh.... 96 4.8 O deðkthc dikaiosônhc tou sust matoc gia K = 65 qr stec anˆ kuyèlh.... 97 5.1 Rujmìc metˆdoshc dedomènwn stouc CEUs me Ðdio arijmì qrhst n stic kuyèlec.108 5.2 Rujmìc metˆdoshc dedomènwn stouc CEUs me ligìterouc qr stec stic geitonikèc kuyèlec.................................... 109 5.3 DikaiosÔnh tou sust matoc stouc CEUs gia diˆforec timèc tou mèsou SNR me K = 60 qr stec se kˆje kuyèlh........................ 110 5.4 DikaiosÔnh tou sust matoc stouc CEUs gia diˆforec timèc tou mèsou SNR me ligìterouc qr stec stic geitonikèc kuyèlec.................. 111 5.5 DikaiosÔnh tou sust matoc stouc CEUs me Ðdio arijmì qrhst n stic kuyèlec.112 5.6 DikaiosÔnh tou sust matoc stouc CEUs me ligìterouc qr stec stic geitonikèc kuyèlec.................................... 113 6.1 Ekpempìmenh isqôc gia uphresða 64 Kbps kai d/d 0 = 0.9 apìstash qrhst n apì ton SB..................................... 122 6.2 Ekpempìmenh isqôc gia uphresða 128 Kbps kai d/d 0 = 0.9 apìstash qrhst n apì ton SB..................................... 123 6.3 Ekpempìmenh isqôc gia uphresða 64 Kbps kai d/d 0 = 0.97 apìstash qrhst n apì ton SB..................................... 124 6.4 Ekpempìmenh isqôc gia uphresða 128 Kbps kai d/d 0 = 0.97 apìstash qrhst n apì ton SB.................................. 125 Aþ.1 Klasikèc teqnikèc epanaqrhsimopoðhshc fˆsmatoc............... 131 Bþ.1 Teqnikèc klasmatik c epanaqrhsimopoðhshc fˆsmatoc............. 132 Gþ.1 Kuyelwt dom diktôou.............................. 135

Katˆlogoc Pinˆkwn 2.1 Algìrijmoc.................................... 46 2.2 Poluplokìthta algorðjmwn........................... 48 2.3 Parˆmetroi arqik n sunjhk n prosomoi sewn................. 49 3.1 Upologistik poluplokìthta teqnik n..................... 75 3.2 SÔgkrish Teqnik n................................ 77 6.1 Ekpempìmenh isqôc gia metˆdosh mèsw FACH................. 120 6.2 Parˆmetroi prosomoðwshc............................ 122 6.3 Senˆrio A..................................... 124 6.4 Senˆrio B..................................... 125 14

PÐnakac Majhmatik n Sumbìlwn SÔmbolo ShmasÐa x Diˆnusma st lh/gramm X PÐnakac X SÔnolo F ASK σ 2 Sundiasporˆ {} Kenì sônolo Arijmìc stoiqeðwn sunìlou Σ 'Ajroisma Pollaplasiasmìc max Mègisto min Elˆqisto arg 'Orisma MegalÔterh akèraia tim pou eðnai mikrìter tou ( ) + max(0, ) O( ) Poluplokìthta 15

AkrwnÔmia i) EllhnikoÐ 'Oroi ASK BKP DD EAT EETT HPA KUPES OTE SB Ajroistik Sunˆrthsh Katˆnomhc Biblioj kh kai Kèntro Plhrofìrhshc Didaktorik Diatrib Ergast rio AsÔrmathc ThlepikoinwnÐac Ejnik Epitrop Thlepikoinwni n kai TaqudromeÐwn Hnwmènec PoliteÐec Amerik c Kèntro Upologistik n kai Epikoinwniak n Susthmˆtwn Organismìc Thlepikoinwni n Ellˆdac Stajmìc Bˆshc 16

AkrwnÔmia 17 ii) AgglikoÐ 'Oroi ACM AMPS AWGN BER BILP BWA CCI CCU CDF (cdf) CDMA CEU CR CSI DCH DVB-T EDGE E-TACS E-UTRA FACH FDD FDMA FFR FM GPRS GSM HAP ICI IEEE i.i.d. IMTS IP IS ISI ISDN LCRA LTE MAC MG MIMO Adaprive Coding and Modulation Advanced Mobile Phone System Additive White Gaussian Noise Bit Error Rate Binary Integer Linear Programming Broadband Wireless Access Co-Channel Interference Cell-Center User Cumulative Distribution Function Code Division Multiple Access Cell-Edge User Cognitive Radio Channel State Information Dedicated Channel Digital Video Broadcasting-Terrestial Enhanced Data rate for GSM European Total Access Communication System Enhanced-Universal Terrestial Radio Access Forward Access Channel Frequency Division Duplex Frequency Division Multiple Access Fractional Frequency Reuse Frequency Modulation General Packet Radio Service Global System for Mobile High Altitude Platform Intracell Interference Institute of Electrical and Electronic Engineers independent identically distributed Improved Mobile Telephone Service Internet Protocol Interim Standard Intersymbol Interference Integrated Services Digital Network Low Complexity Resource Allocation Long Term Evolution Medium Access Control Multicast Group Multiple Input Multiple Output

18 AkrwnÔmia MISO MU NTT OFDM OFDMA OSI PFR PFS PSD QAM QoE QoS RB RNC RRA RRM SDMA SFR SIMO SINR SISO SNR SMS TDD TDMA TD-SCDMA TV UMTS WCDMA WiMAX WLAN WMAN WRAN 3G 3GPP Multiple Input Single Output Memeber User Nippon Telegraph and Telephone Orthogonal Frequency Division Multiplexing Orthogonal Frequency Division Multiple Access Open Systems Interconnection Partial Frequency Reuse Proportional Fair Scheduler Power Spectral Density Quadrature Amplitude Modulation Quality of Experience Quality of Service Resource Block Radio Network Controller Radio Resource Allocation Radio Resource Management Space Division Multiple Access Soft Frequency Reuse Single Input Multiple Output Signal to Interference plus Noise Ratio Single Input Single Output Signal to Noise Ratio Short Message Service Time Division Duplex Time Division Multiple Access Time Division-Sychronous CDMA television Universal Mobile Telecommunications System Wideband CDMA Worldwide Interoperability Microwave Access Wireless Local Area Network Wireless Metropolitan Area Network Wireless Regional Area Network Third Generation Third Generation Partnership Project

Metafrˆseic Xènwn 'Orwn Metˆfrash ajroistik sunˆrthsh katanom c anˆdrash anˆjesh radiopìrwn analogikˆ dðkaioc qronoprogrammatist c apokleistikì kanˆli apolab kanalioô apolab sugkanˆlwshc ap leia diadrom c asôrmato kanˆli bajiˆ diˆleiyh gnwsiak radioepikoinwnða dedomèna dèkthc dikaiosônh diˆleiyh diamìrfwsh pollapl n ferìntwn diamìrfwsh suqnìthtac diasumbolik parembol diaforismìc diaforismìc pollapl n qrhst n diaforismìc q rou diaqeðrish radiopìrwn emprosjìforo kanˆli prìsbashc epanaqrhsimopoðhsh euruzwnikìc endo-kuyelwt perembol epilektik wc proc th suqnìthta diˆleiyh epðpedh diˆleiyh elegkt rac radiodiktôou euretikìc euruzwnik asôrmath prìsbash Agglikìc ìroc cumulative distribution function feedback radio resource allocation proportionally fair scheduler dedicated channel channel gain trunking gain path loss wireless channel deep fade cognitive radio data receiver fairness fading multicarrier modulation frequency moduation intersymbol interference diversity multiuser diversity spatial diversity radio resource management forward access channel reuse broadband intra-cell interference frequency selective fading flat fading radio network controller heuristic broanband wireless access 19

20 Metafrˆseic Xènwn 'Orwn eôroc z nhc bandwidth epanalhptikìc iterative epðbaro overhead idiokanˆli eigenchannel idiotim eigenvalue kanonistikìc forèac regulatory body katanemhmènoc algìrijmoc distributed algorithm kataqwrht c buffer kelð, kôttaro, kuyèlh cell klasmatik epanaqrhsimopoðhsh suqnìthtac fractional frequency reuse monoekpomp unicast omˆda poluekpomp c multicast group omokanalik parembol co-channel interference ourˆ anamon c queue parembol interference poluplexða me orjogwnik orthogonal frequency diaðresh suqnìthtac division multiplexing pollapl prìsbash orthogonal frequency orjogwnik c diaðreshc suqnìthtac division multiple access pollapl prìsbash space division diaðreshc q rou multiple access pollapl prìsbash code division diaðreshc k dika multiple access pollapl prìsbash time division diaðreshc qrìnou multiple access pollapl prìsbash frequency division diaðreshc suqnìthtac multiple access sust mata pollapl n eisìdwn multiple input multiple pollapl n exìdwn output systems poluekpomp multicast poluplokìthta complexity poluqrhstikì peribˆllon multiuser environment pompìc transmitter prìtupo standard prìtupo sugkritik c axiolìghshc, prìtupo arikreisðac benchmark prwtìkollo Ðnternet internet ptotocol radiodiepaf air interface rooj keush, reumˆtwsh streaming shmatodosða signaling skðash shadowing

Metafrˆseic Xènwn 'Orwn 21 sôgkroush sôsthma pollapl n kerai n sôsthma pollapl n ferìntwn sust mata apl c eisìdou apl c exìdou sôsthma pollapl c ekpomp c sôsthma pollapl n ferous n teqnologða fasmatik c exˆplwshc thlediˆskeyh trðthc geniˆc upoforèac fasmatik apìdosh fèmtokuyèlh qr sthc -mèloc omˆdac poluekpomp c qr sthc sthn diaqwristik epifˆneia, ˆkra, ìria kuyèlhc qr sthc sto kèntro thc kuyèlhc qronojurðda qronoprogrammatist c qwrik poluplexða qwrhtikìthta collision multiple antenna system multicarrier system single input single output systems multicast system multicarrier system spread spectrum technology videoconference third generation subcarrier spectral efficiency femtocell member multicast user cell-edge user cell-center user time slot scheduler spatial multiplexing capacity

Kefˆlaio 1 Eisagwg Se autì to Kefˆlaio perigrˆfetai to ereunhtikì antikeðmeno pou pragmateôetai h DD kai h mejodologða pou akolouj jhke. EpÐshc dðnetai mia sôntomh perigraf thc exèlixhc twn asôrmatwn susthmˆtwn e c s mera kai twn basik n teqnik n anˆjeshc radiopìrwn pˆnw stic opoðec basðzontai nèec teqnikèc beltistopoðhshc tou QoS. Sth sunèqeia perigrˆfontai ta kðnhtra pou od ghsan sthn anˆptuxh tou kˆje Kefˆlaiou thc DD kaj c epðshc kai h suneisforˆ tou kˆje KefalaÐou kaj c epðshc kai oi episthmonikèc dhmosieôseic pou proèkuyan apì thn enasqìlhsh me ta zht mata thc DD. 1.1 JematologÐa kai MejodologÐa thc DD H paroôsa DD diapragmateôetai teqnikèc gia thn beltistopoðhsh tou QoS sta sôgqrona thlepikoinwniakˆ sust mata pou wc teqnologða pollapl c prìsbashc èqoun thn prìsbash OFDMA kai thn prìsbash CDMA kai elègqoun parˆllhla krðsimec hlektrikèc paramètrouc ìpwc h ekpempìmenh isqôc kaj c epðshc kai hlektromagnhtikèc ìpwc eðnai to diajèsimo fˆsma suqnot twn. Oi teqnikèc pou anaptôssontai sthn paroôsa DD aforoôn epanalhptikoôc algìrijmouc diaqeðrishc twn diajèsimwn radiopìrwn pou efarmìzontai kurðwc sthn katerqìmenh zeôxh twn asôrmatwn susthmˆtwn. Wc parˆmetroi tou QoS jewroôntai: to elˆqisto epðpedo rujmoô metˆdoshc twn dedomènwn, to BER kai h elˆqisth posìthta radiopìrwn se kˆje qr sth. H axiolìghsh twn teqnik n pou proteðnontai gðnetai mèsw deikt n thc apìdoshc touc, oi opoðoi eðnai: h pijanìthta parabðashc tou QoS, o deðkthc dikaiosônhc tou Jain, o rujmìc metˆdoshc dedomènwn twn qrhst n sth diaqwristik epifˆneia thc kuyèlhc kai h qwrhtikìthta thc kuyèlhc. Gia thn exagwg twn deikt n aut n eðnai aparaðthta statistikˆ dedomèna ta opoða sullègontai mèsa apì megˆlo arijmì prosomoi sewn. Gia sust mata poluekpomp c teqnologðac MIMO-OFDMA to prìblhma diaqeðrishc twn diajèsimwn radiopìrwn epilôetai me ènan upobèltisto algìrijmo grammik c poluplokìthtac ìpou wc parˆmetroc QoS jewreðtai o elˆqistoc arijmìc radiopìrwn stouc qr stec kai to BER. DeÐktec thc apìdos c tou apoteloôn o sunolikìc rujmìc metˆdoshc twn dedomènwn kai o deðkthc dikaiosônhc tou sust matoc ta opoða exˆgontai se sunˆrthsh me ˆllec paramètrouc ìpwc eðnai h mèsh tim tou SNR, o arijmìc twn MGs kai to BER. 22

1.2 H Exèlixh twn AsÔrmatwn Thlepikoinwniak n Susthmˆtwn 23 Sthn teqnik pou proteðnetai gia ta polukuyelwtˆ sust mata OFDMA, wc parˆmetroi tou QoS jewroôntai to BER kai o elˆqistoc rujmìc metˆdoshc dedomènwn. H apìdos tou axiologeðtai mèsw prosomoi sewn, apì thn pijanìthta parabðash touc QoS kai to rujmì metˆdoshc dedomènwn sta ìria thc kuyèlhc se sôgkrish me tic apodìseic ˆllwn teqnik n katˆllhlwn gia polukuyelwtˆ sust mata OFDMA. Gia polukuyelwtˆ sust mata ìpou upˆrqei periorismìc stic ourèc anamon c twn qrhst n, o algìrijmoc pou diereunˆtai perilambˆnei autì ton periorismì sthn diadikasða anˆjeshc twn radiopìrwn jewr ntac wc paramètrouc tou QoS, ton elˆqisto rujmì metˆdoshc dedomènwn kai to BER. H apodos tou, metˆ apì megˆlo arijmì prosomoi sewn tou sust - matoc apotup netai sthn pijanìthta parabðashc tou QoS, sth dikaiosônh tou sust matoc kai ton rujmì metˆdoshc dedomènwn sta ˆkra thc kuyèlhc. Gia ta sust mata OFDMA me periorismèno arijmì radiopìrwn diajèsimo ston kˆje qr sth, to prìblhma thc enðsqushc tou rujmoô metˆdoshc dedomènwn sta ˆkra thc kuyèlhc epilôetai me epanalhptikì algìrijmo kai h apìdos tou axiologeðtai mèsw sôgkris c tou rujmoô metˆdoshc dedomènwn kai tou deðkth dikaiosônhc twn qrhst n sta ˆkra thc kuyèlhc thc proteinìmenhc teqnik c, me ton rujmì metˆdoshc sta ˆkra thc kuyèlhc kai ton deðkth dikaiosônhc ˆllwn teqnik n pou efarmìzontai sta dðktua OFDMA. Tèloc, gia ta sust mata poluekpomp c teqnologðac CDMA, h teqnik pou proteðnetai axiopoieð tìso th metˆdosh me apokleistikˆ afierwmèna kanˆlia ìso kai th metˆdosh me koinˆ kanˆlia kaj c epðshc kai th sunergasða metaxô geitonik n SB kata thn metˆdosh me apokleistikˆ afierwmèna kanˆlia gia touc qr stec sta ìria thc kuyèlhc. Wc parˆmetroi tou QoS jewroôntai o rujmìc metˆdoshc dedomènwn kai h enèrgeia se kˆje bit proc thn parembol kai h apìdos tou axiologeðtai mèsw prosomoðwshc. DeÐkthc apìdoshc jewreðtai h qwrhtikìthta thc kuyèlhc. 1.2 H Exèlixh twn AsÔrmatwn Thlepikoinwniak n Susthmˆtwn Lìgw thc exèlixhc twn teqnik n yhfiak c epexergasðac shmˆtoc kai twn eureðac klðmakac oloklhrwmènwn kuklwmˆtwn, ta asôrmata thlepikoinwniakˆ dðktua brðskontai se megˆlh anˆptuxh ta teleutaða qrìnia. Ta kuyelwtˆ dðktua kai ta asôrmata topikˆ dðktua (WLAN) eðnai oi pio epituqhmènec efarmogèc asôrmathc diktôwshc stic mèrec mac. H ènnoia twn asôrmatwn kuyelwt n susthmˆtwn genn jhke to 1970 sta ergast ria Bell stic HPA. To pr to asôrmato kuyelwtì dðktuo, gnwstì kai wc Advanced Mobile Phone System (AMPS), anaptôqjhke stic HPA sta 1980, uiojetìntac thn teqnologða thc diamìrfwshc suqnìthtac (FM) kai thn pollapl prìsbash diaðreshc suqnìthtac (FDMA). OmoÐwc sthn Eur ph anaptôqjhke to European Total Access Communication System (E- TACS). Par' ìla autˆ, lìgw thc periorismènhc qwrhtikìthtˆc touc, antiskatastˆjhkan apì ta kuyelwtˆ dðktua deôterhc geniˆc (2G) sta 1990. TrÐa prìtupa upˆrqoun gia autˆ ta dðktua, to Interim Standard (IS-95), to IS-136 stic HPA kai to Global System for Mobile (GSM) sthn Eur ph. Autˆ ta prìtupa qrhsimopoioôntai eurèwc akìmh kai s mera

24 Kefˆlaio 1. Eisagwg gia thn paroq basik n uphresi n fwn c. Oi enisqumènec ekdìseic aut n twn protôpwn me uyhlìterouc rujmoôc metˆdoshc gnwstˆ kai wc IS-95 High Data Rate, IS-136 High Speed gia ta IS-95 kai IS-136 kai ta General Packet Radio Service (GPRS) kai Enhanced Data rate for GSM (EDGE) gia to GSM. Autˆ ta beltiwmèna 2G sust mata, anafèrontai wc 2.5G sust mata [2]. Ta teleutaða qrìnia, ta trðthc geniˆc 3G kuyelwtˆ sust mata èqoun topojethjeð pagkosmðwc, kaj c ta sust mata pèran twn 3G pou uiojetoôn pollaplèc eisìdouc pollaplèc èxodouc (MIMO) kai to OFDMA fusikì epðpedo brðskontai se anˆptuxh. 'Omoia ta 2G sust mata, ta 3G apoteloôntai apì trða pagkìsmia prìtupa, to Wideband Code Division Multiple access (WCDMA), to CDMA2000 kai to Time Division-Sychronous CDMA (TD-SCDMA) [2]. Eidikìtera, ta prìtupa WCDMA Frequency Division Duplex (FDD) kai Time Division Duplex (TDD) èqoun uiojethjeð apì Eur ph kai KÐna antðstoiqa, en to CDMA2000 apì HPA kai Korèa. Epiplèon ta Long Term Evolution towards the Fourth Generation (4G) kuyelwtˆ sust mata brðskontai se anˆptuxh se pagkìsmio epðpedo. EpÐshc axiopoi ntac prohgmènec MIMO-OFDMA teqnikèc, sust mata Worldwide Inter-operability for Microwave Access (WiMAX) [3] qrhsimpopoioôntai se arketèc q rec wc mhtropolitikˆ euruzwnikˆ dðktua. Prìsfata èna prìtupo jemeli jhke basismèno se teqnikèc gnwsiak c radioepikoinwnðac (Cognitive Radio (CR)). Mia trèqousa CR efarmog eðnai to Wireless Regional Area Network (WRAN) pou antistoiqeð sto IEEE 802.20 prìtupo [4]. 1.3 Basikèc Teqnikèc Anˆjeshc Radiopìrwn Arketèc sumbatikèc teqnikèc anˆjeshc radiopìrwn gia thn diasfˆlish kai th beltðwsh tou apaitoômenou epipèdou poiìthtac uphresðac (QoS) èqoun axioipoihjeð apì ta asôrmata epikoinwniakˆ dðktua. Autèc oi teqnikèc perikleðoun strathgikèc kai algìrijmouc gia ton èlegqo thc ekpempìmenhc isqôoc, thn anˆjesh eôrouc z nhc kai ton èlegqo laj n [5]. H mèjodoc pollapl c prìsbashc eðnai polô basik gia thn pragmatopoðhsh teqnik n anˆjeshc kai diaqeðrishc twn diajèsimwn radiopìrwn. H pollapl prìsbash diaðreshc qrìnou (TDMA), eðnai mða sumbatik teqnik ìpou epitrèpei se arketoôc qr stec na moirˆzontai to Ðdio eôroc suqnìthtwn ekpèmpontac ta s matˆ touc se diaforetikèc qronojurðdec (time slots). Eidikìtera, diaforetikoð qr stec ekpèmpoun diadoqikˆ, o ènac metˆ ton ˆllo, me ton kˆje qr sth na qrhsimopoieð thn dik tou qronojurðda. H pollapl prìsbash me diaðresh suqnìthtac (FDMA), eðnai mða ˆllh jemeli dhc teqnik prìsbashc h opoða katamerðzei to eôroc z nhc se kanˆlia. Pio sugkekrimèna h teqnik FDMA anajètei se kˆje qr sth mða h parapˆnw mpˆntec suqnot twn gia metˆdosh [6]. Ektìc twn TDMA kai FDMA, h pollapl prìsbash me diaðresh k dika (CDMA) dðnei th dunatìthta se pollaploôc pompoôc na metadðdoun tautìqrona pˆnw apì èna koinì kanˆli. Gia na poluplèxei katˆllhla diaforetikoôc qr stec, h CDMA qrhsimpoieð thn teqnologða fasmatik c exˆplwshc kai yeudotuqaðouc k dikec [5]. H CDMA eðnai h mèjodoc prìsbashc twn 3G susthmˆtwn ìpwc to UMTS. EpÐshc, ekmetalleôontac thn parousða pollap n

1.4 Episthmonikˆ KÐnhtra kai Suneisforˆ 25 kerai n h teqnik thc pollapl c prìsbashc me diaðresh q rou (SDMA) eðnai ikan na belti sei shmantikˆ se sqèsh me ta sust mata mon c keraðac [6]. Epiplèon, h SDMA dhmiourgeð parˆllhla qwrikˆ kanˆlia gia na belti sei th qwrhtikìthta mèsw qwrik c polôplexhc diaforismoô. Tèloc mða polô shmantik teqnik anˆjeshc pìrwn eðnai h pollapl prìsbash orjogwnik c diaðreshc suqnìthtac (OFDMA). EÐnai h èkdosh thc poluplexðac me orjogwnik diaðresh suqnìthtac (OFDM) gia prìsbash sto diajèsimo fˆsma apì polloôc qr stec. H OFDM eðnai mða teqnik diamìrfwshc pollapl n ferìntwn (upoferìntwn) kai basðzetai sthn idèa diamelismoô enìc uyhloô rujmoô metˆdoshc se mikrìterouc kajènac apì touc o- poðouc metadðdetai me diaforetikì fèron s ma. H OFDMA epitrèpei se polloôc qr stec na metadðdoun dedomèna tautìqrona se diaforetikoôc upoforeðc [7]. Me thn OFDMA dðnetai h dunatìthta anˆptuxhc èxupnwn mhqanism n katanom c suqnotht n anajètontac kˆje forˆ upoforeðc se qr stec gia touc den brðskontai se bajeiˆ diˆleiyh, sumbˆllontac se megalôterouc rujmoôc metˆdoshc sto sôsthma [8]. H OFDMA èqei uiojethjeð apì uyhl c taqôthtac asôrmata epikoinwniakˆ sust mata ìpwc h epðgeia yhfiak binteoekpomp DVB- T, ta stajerˆ kai kinhtikˆ dðktua mhtropolitik c perioq c (IEEE 802.16 kai IEEE 802.16e) [3] kai thn exeligmènh pagkìsmia epðgeia radioprìsbash E-UTRA [9]. 1.4 Episthmonikˆ KÐnhtra kai Suneisforˆ Ta sôgqrona asôrmata sust mata anamènetai na exuphrhtèsoun megˆlo arijmì qrhst n me diˆforec apait seic QoS. H prìklhsh thc diasfˆlishc twn apait sewn twn qrhst n proèrqetai apì to gegonìc ìti oi dôo shmantikìteroi pìroi twn epikoinwniak n susthmˆtwn, to diajèsimo fˆsma kai h ekpempìmenh isqôc eðnai periorismènoi. Epomènwc eðnai epibeblhmènh h anˆptuxh teqnik n kai strathgik n gia thn sunet diaqeðrish twn diajèsimwn pìrwn kai ikanopoðhsh twn apait sewn QoS twn qrhst n. Sth bibliografða arketèc eðnai oi ergasðec kai oi melètec pou proteðnoun teqnikèc kai politikèc diaqeðrishc twn pìrwn tou sust matoc gia thn beltðwsh kai th diasfˆlish tou QoS. Arqikˆ eðqe dojeð megˆlh èmfash sthn prospˆjeia beltðwshc thc olik c qwrhtikìthtac twn asôrmatwn epikoinwniak n susthmˆtwn, ìmwc sthn sunèqeia apedeðqjhke wc mh epark c deðkthc gia to QoS, kaj c h Ôparxh qrhst n me diaforetikèc sunj kec kanalioô kai apait seic se eôroc z nhc den mporoôsan na apotupwjoôn sthn metrik aut. Epomènwc parˆmetroi ìpwc h elˆqisth apaðthsh rujmoô metˆdoshc dedomènwn, h elˆqisth apaðthsh se eôroc z nhc, to BER kai deðktec ìpwc h dikaiosônh tou sust matoc jewr jhkan pio katˆllhlec sthn prospˆjeia emperistatwmènou prosdiorismoô tou QoS twn qrhst n. E- pðshc, shmantik parˆmetroc apoteleð h upologistik poluplokìthta twn teqnik n aut n, h opoða eðnai ènac deðkthc thc duskolðac epðteuxhc enìc algorðjmou teqnik c. Akìmh, h Ôparxh teqnologi n ìpwc h teqnologða MIMO kai mejìdwn metˆdoshc plhroforðac san thn poluekpomp (multicasting) pou èqoun agnohjeð apì pollèc teqnikèc wc t ra sthn diejn bibliografða, ìpwc epðshc kai h mh exètash thc omokanalik c parembol c sthn anˆptuxh kai axiolìghsh twn teqnik n aut n, apotèlesan kðnhtro gia thn prìtash kai melèth ne n te-

26 Kefˆlaio 1. Eisagwg qnik n sthn paroôsa DD. Sto upìloipo thc enìthtac, perigrˆfontai ta eidikìtera kðnhtra gia kˆje mða teqnik pou melet jhke sthn DD. Gia sust mata me mon keraða se pompì kai dèktec (SISO), èqei protajeð kai ekponhjeð wc t ra megˆloc arijmìc teqnik n kai episthmonik n ergasi n [15]. To epðpedo QoS twn qrhst n belti netai eðte lambˆnontac wc krit rio aplˆ ton sunolikì rujmì metˆdoshc ì- pwc stic ergasðec [16], [17], eðte ikanopoi ntac tautìqrona krit ria analogik c dikaiosônhc stouc rujmoôc metˆdoshc twn qrhst n ìpwc sta sq mata twn ergasi n [18], [19]. Sth sunèqeia melet jhkan kai protˆjhkan teqnikèc me Ôparxh pollapl n kerai n eðte mìno ston pompì [20], eðte se pompì kai dèktec [21], [22], ste na prokôyoun akìma megalôteroi rujmoð metˆdoshc dðnontac th dunatìthta gia peraitèrw enðsqush tou QoS twn qrhst n. EpÐshc, mða akìmh shmantik kainotomða pou mporeð na belti sei kai ˆllo to QoS ìtan oi qr stec apaitoôn to Ðdio perieqìmeno eðnai h poluekpomp gia thn opoða dienerg jhkan melètec tìso gia ta dðktua CDMA [23], ìso kai gia ta dðktua OFDMA [24]. Par' ìla autˆ, lìgw thc elleipoôc èreunac e c t ra se sust mata multicast pou kˆnoun qr sh thc teqnologðac MIMO, upˆrqei èna arketˆ megˆlo pedðo gia anˆptuxh kai beltðwsh ìpwc shmei netai se prìsfath èreuna gia sust mata multicast me teqnologða OFDMA [25]. Epomènwc, h sônjesh twn parapˆnw kainotomi n gia thn dhmiourgða miac nèac teqnik c pou ja belti nei to QoS twn qrhst n apotelèse shmantikì kðnhtro gia to Kefˆlaio 2, ìpou gia kˆje qr sth exasfalðzetai èna tm ma tou diajèsimou eôrouc z nhc wc parˆmetroc thc elˆqisthc poiìthtac uphresðac (QoS) [26]. An kai eðnai arketèc oi teqnikèc pou upˆrqoun sthn bibliografða gia thn beltðwsh tou QoS, par' ìla autˆ sto sqediasmì praktik n diktôwn, oi teqnikèc autèc ja prèpei na dokimˆzontai se polukuyelwtì peribˆllon ìpou oi omokanalikèc parembolèc upologðzontai sthn exagwg sumperasmˆtwn ìpwc upogrammðzetai kai se prìsfath melèth [27]. Oi strathgikèc pou jètoun wc stìqo thn megistopoi sh tou olikoô rujmoô metˆdoshc ìpwc sthn episthmonik ergasða [14] parameloôn touc qr stec sta ìria thc kuyèlhc pou lìgw mh eunoðk n sunjhk n kanalioô den suneisfèroun arketˆ sto sunolikì rujmì metˆdoshc. Apì thn ˆllh meriˆ, teqnikèc pou qeirðzontai pio eunoðkˆ autoôc touc qr stec me strathgikèc apofug c twn parembol n ìpwc stic episthmonikèc ergasðec [10], [27], den stoqeôoun se sugkekrimèna elˆqista epðpeda QoS pou Ðswc eðnai aparaðthta gia thn ikanopoihtik metˆdosh miac uphresðac. Akìmh autèc oi teqnikèc emfanðzoun auxhmènh poluplokìthta [27]. Epomènwc, h prìtash teqnik c pou ja beltðwne to QoS ìlwn twn qrhst n anexart twc thc jèshc touc sthn kuyèlh me qamhl upologistik poluplokìthta apotelèse to jemèlio tou KefalaÐou 3 [28]. Shmei netai ìti h teqnik tou KefalaÐou 3 basðzetai ston analogikì dðkaio qronoprogrammatist (PFS) gia thn anˆjesh twn radiopìrwn, o opoðoc apoteleð mia eurèwc apodekt lôsh gia sumbibasmì metaxô sunolikoô rujmoô metˆdoshc kai dikaiosônhc tou sust matoc pou apoteloôn deðktec tou QoS. Akìmh o PFS apoteleð isodônamo thc lôshc tou probl matoc thc jewrðac paignðwn tou Nash gia thn anˆjesh radiopìrwn sta asôrmata dðktua ìpwc tekmhri netai se prìsfath èreuna pou aforˆ thn anˆjesh radiopìrwn se dðktua OFDMA [29]. Akìmh se pl joc ergasi n [15] ìpwc kai sto Kefˆlaio 3, h katˆstash stic ourèc

1.4 Episthmonikˆ KÐnhtra kai Suneisforˆ 27 anamon c twn qrhst n ston SB den exetˆzontai me apotèlesma thn lanjasmènh diaqeðrish twn pìrwn tou sust matoc. Opìte h prìtash teqnik n beltðwshc tou QoS me sunupologismì thc kðnhshc stic ourèc anamon c twn qrhst n proseggðzei perissìtero ta pragmatikˆ sust mata [30]. To Kefˆlaio 4 loipìn sthrðzetai pˆnw se aut th filosofða kai parˆllhla axiopoieð ton PFS. Sta kuyelwtˆ sust mata mða ˆllh kathgorða teqnik n beltðwshc tou QoS twn qrhst n apoteloôn oi algìrijmoi kai oi mhqanismoð apofug c twn omokanalik n parembol n ìpwc stic episthmonikèc ergasðec [10], [11], [14], [27], oi opoðec kathgoriopoioôntai se statikèc [10], [11] kai dunamikèc [14], [27]. Oi dunamikèc uperteroôn ènanti twn statik n kaj c apodðdoun megalôterouc rujmoôc metˆdoshc stouc qr stec kai eðnai pio euèliktec stic metabolèc thc kinhtikìthtac twn qrhst n qwrðc epðshc na qreiˆzontai prìtero sqediasmì sthn katanom twn suqnot twn. Oi teqnikèc apofug c jorôbou suntonismoô parembol c pou èqoun anaptuqjeð prìsfata qrhsimopoioôn ìlouc sqedìn ìlouc touc diajèsimouc radiopìrouc. Apì thn ˆllh meriˆ, teleutaða èqei anaptuqjeð h tˆsh proc ta <<Prˆsina DÐktua>> [31], ìpou h exoikonìmhsh thc ekpempìmenhc isqôoc eðnai prwtarqikìc stìqoc. To montèlo uphresðac ìpou se kˆje qr sth kataqwreðtai sugkekrimènoc arijmìc radiopìrwn (narrowband services) isqôoc, ìpwc sthn episthmonik ergasða [33], bohjˆ se aut thn kateôjunsh ìpwc epðshc kai sthn anerqìmenh zeôxh twn asôrmatwn susthmˆtwn eðnai periorismènoc o arijmìc twn radiopìrwn pou mporeð na anatejeð se kˆje qr sth. Epomènwc, jewr ntac tètoiou tôpou montèla uphresðac, gðnetai eôkola antilhptì ìti se kˆje kuyèlh miac polukuyelwt c thlepikoinwniak c dom c kˆpoiec suqnìthtec den qrhsimopoioôntai kai sunep c h anˆptuxh miac dunamik c teqnik c apofug c twn parembol n ja mporoôse na kˆnei apodotikìterh th leitourgða tou sust matoc. Tèloc, oi parembolèc ìpwc tonðsthke kai sta Kefˆlaia 2, 3 pl ttoun kuri c touc qr stec pou brðskontai sta ìria thc kuyèlhc kai ˆra h enðsqush tou QoS aut n twn qrhst n gðnetai epitaktik diìti oi qrhstèc pou an koun se mia sugkekrimènh klˆsh ja prèpei na èqoun an ìqi to Ðdio toulˆqiston parapl sio epðpedo QoS anexˆrthta thc gewgrafik c jèshc touc [27]. ExaitÐac loipìn thc dunatìthtac anˆptuxhc dunamik c teqnik c gia thn enðsqush tou QoS qrhst n sta ˆkra thc kuyèlhc gia ta montèla uphresðac pou anafèrjhkan, proèkuye to Kefˆlaio 4 [12], [34]. Ektìc ìmwc apì ta sust mata basismèna sthn teqnologða OFDMA, den ja mporoôsame na agno soume ta sust mata 3G pou basðzontai sthn teqnologða CDMA. Se autˆ ta sust mata gia to montèlo uphresi n poluekpomp c, dðnetai h dunatìthta qr shc eðte apokleistikˆ afierwmènwn kanali n ìpou h apaitoômenh isqôc exartˆtai apì ton arijmì kai th jèsh twn qrhst n, eðte koinoô kanalioô ìpou h isqôc exartˆtai apì to posostì kˆluyhc thc kuyèlhc [35], [36]. Opìte h qr sh tou tôpou kanali n me krit rio thn ligìtero apaitoômenh isqô ja mporoôse eðte na aux sei thn qwrhtikìthta tou sust matoc eðte na elatt sei thn ekpempìmenh isqô. Lìgw thc periorismènhc diajèsimhc isqôc eðnai pijanì na mhn mporeð o SB na parèqei to apaitoômeno QoS se oloôc touc qr stec. H dunatìthta ìmwc sunergasðac sthn metˆdosh kai l yh dedomènwn geitonik n SB gia qr stec pou brðskontai sta ìria thc kuyèlhc [37], [38] eðnai efikt kai h enswmatws thc se mia strathgik diaqeðrishc thc ekpempìmenhc isqôoc gia uphresðec poluekpomp c apotèlese kðnhtro gia thn prosèggish autoô

28 Kefˆlaio 1. Eisagwg to probl matoc sto Kefˆlaio 6 Parousiˆzontac parapˆnw loipìn ta kðnhtra gia thn suggraf thc paroôshc DD, o skopìc thc sunoptikˆ eðnai h episthmonikˆ emperistatwmènh prìtash nèwn teqnik n diaqeðrishc twn radiopìrwn gia thn beltðwsh tou QoS twn qrhst n asurmˆtwn diktôwn pou basðzontai stic teqnologðec prìsbashc tou radiofˆsmatoc OFDMA kai CDMA. Gia thn ulopoðhsh aut n twn teqnik n jewroôntai wc parˆmetroi tou QoS, o rujmìc metˆdoshc dedomènwn ston kˆje qr sth, to eôroc z nhc kˆje qr sth kai to BER. Akìmh shmantikìc deðkth apoteleð h dikaiosônh tou sust matoc [39]. Ta apotelèsmata pou ja parousiastoôn sthn paroôsa DD suneisfèroun sthn anˆptuxh algorðjmwn gia sust mata MIMO-OFDMA me uphresðec poluekpomp c, polukuyelwtˆ sust mata OFDMA kai sust mata poluekpomp c CDMA. EpÐshc, oi teqnikèc pou proteðnontai mporoôn na apotelèsoun th bˆsh gia thn anˆptuxh algorðjmwn se dðktua pou uposthrðzontai me anametadìtec [40], se femtokuyelikˆ sust mata [41] ìpwc kai se dðktua me gnwsiak radioepikoinwnða [42]. Eidikìtera h suneisforˆ thc DD eðnai: ProteÐnetai qamhl c upologistik c poluplokìthtac algìrijmoc o opoðoc axiopoieð thn parousða pollapl n kerai n se pompì kai dèktec ìpwc thn mèjodo metˆdoshc thc poluekpomp c kai exasfalðzei eôroc z nhc gia kˆje ènan apì touc qr stec. ProteÐnetai algìrijmoc gia polukuyelwtˆ sust mata OFDMA me antikeimenikì skopì thn ikanopoðhsh twn apait sewn se QoS twn qrhst n anexˆrthta thc jèshc touc sthn kuyèlh kai thn qamhl uplogistik poluplokìthta. EpekteÐnetai o algìrijmoc gia ta dðktua OFDMA, jewr ntac peperasmènec ourèc anamon c qrhst n stouc SB kai skopì thn thn ikanopoðhsh twn apait sewn QoS twn qrhst n kai thn dikaiosônh tou sust matoc. ProteÐnetai dunamikìc algìrijmoc apofug c twn omokanalik n parembol n gia thn enðsqush tou QoS twn qrhst n sth diaqwristik epifˆneia thc kuyèlhc. ProteÐnetai teqnik diaqeðrishc thc isqôoc gia thn exasfˆlish twn apait sewn QoS twn qrhst n se poluekpomp me sunergasða geitonik n SB gia sust mata CDMA. Shmei netai ìti h èreuna pou ekpon jhke se aut thn DD estiˆsthke sto fusikì epðpedo kai sto epðpedo elègqou prìsbashc mèsou MAC se mia poluepðpedh dom sust matoc sômfwna me to montèlo tou OSI. 1.5 Episthmonikèc DhmosieÔseic H enasqìlhsh me ta diˆfora zht mata thc episthmonik c perioq c pou pragmateôetai h paroôsa DD od ghsan sthn dhmosðeush ergasi n se diejn episthmonikˆ periodikˆ kai sunèdria me kritèc.

1.5 Episthmonikèc DhmosieÔseic 29 1.5.1 Diejn Periodikˆ 1. I. G. Fraimis, and S. A. Kotsopoulos QoS-Based Proportional Fair Allocation Algorithm for OFDMA Wireless Cellular Systems, IEEE Commun. Let., vol. 15, no. 10, pp. 1091-1093, Aug. 2011. 2. I. G. Fraimis, and S. A. Kotsopoulos, A Low-Complexity Resource Allocation Algorithm for MIMO-OFDMA with Spectrum-Guarantee Provisioning, Intern. J. of Digit. Multimed. Broadcast., Hindawi 2012. 3. V. D. Papoutsis, I. G. Fraimis and S. A. Kotsopoulos, A Novel Fairness-Aware Resource Allocation Scheme in Multiuser SISO-OFDMA Downlink, Intern, J. of Veh. Tech., Hindawi Corp., vol. 2010, Article ID 432762, 10 pages, 2010. doi:10.1155/2010/432762. 4. V. D. Papoutsis, I. G. Fraimis, and S. A. Kotsopoulos, User selection and resource allocation algorithm with fairness in MISO-OFDMA IEEE Commun. Let., vol. 14, no. 5, pp. 411-413 May 2010. 5. V. D. Papoutsis, I. G. Fraimis, and S. A. Kotsopoulos, Fairness-aware user selection and resource allocation in MISO-OFDMA European Trans. on Telecommun., John Wiley & Sons Ltd., vol. 21, no. 6, pp. 568-574 Oct. 2010. 6. I. G. Fraimis, and S. A. Kotsopoulos, Fair Radio Resource Allocation for MIMO OFDM-based Multicast Systems, Wirelss Personal Communications, Springer- Verlang, accepted for publication. 7. I. G. Fraimis, and S. A. Kotsopoulos, Queue-aware Resource Allocation Algorithm for Multi-Cell OFDMA Systems, Wirelss Personal Communications, Springer- Verlang, under review. 1.5.2 Diejn Sunèdria 1. I. G. Fraimis, V. D. Papoutsis, and S. A. Kotsopoulos, A Decentralized Subchannel Allocation Scheme with Inter-cell Interference Coordination (ICIC) for Multi-Cell OFDMA Systems, in Proc. IEEE Global Commun. Conf. (Globecom), Miami USA, Dec. 2010. 2. I. G. Fraimis, V. D. Papoutsis, and S. A. Kotsopoulos, A distributed radio resource allocation algorithm with interference coordination for multi-cell OFDMA systems, in Proc. IEEE Pers. Indoor and Mob. Radio Commun. Conf. (PIMRC), pp. 1354-1359, Instanbul, Turkey Sept. 2010. 3. I. G. Fraimis, and S. A. Kotsopoulos, A Low-Complexity Resource Allocation Algorithm for OFDMA-based Cellular Networks with QoS Provisioning: A Cross-Layer

30 Kefˆlaio 1. Eisagwg Design Approach, in Proc. IEEE Wireless Commun. Netw. Conf. (WCNC), Paris, France, Apr. 2012. 4. V. D. Papoutsis, I. G. Fraimis, S. A. Kotsopoulos, Fairness-aware resource allocation for the SISO downlink over frequency-selective channels, in Proc. IEEE Wireless Commun. Netw. Conf. (WCNC), NSW Austalia, Apr. 2010. 5. V. D. Papoutsis, I. G. Fraimis and S. A. Kotsopoulos, Resource allocation algorithm for MIMO-OFDMA systems with minimum resources guarantee, in Proc. IEEE Intern. Conf. on Electronics, Cicuits and Systems (ICECS), Athens Greece, Dec. 2010. 6. V. D. Papoutsis, I. G. Fraimis and S. A. Kotsopoulos, Efficient Resource Allocation for Spatial Multiuser Access in MISO-OFDMA systems, in Proc. Intern. ICST Conf. on Broadband Commun., Networks and Systems, Athens Greece, Oct. 2010. 7. I. G. Fraimis, V. D. Papoutsis, K. Ioannou, and S. A. Kotsopoulos, Power efficient eadio bearer selection for MBMS users in soft handover status, in Proc. IEEE Pers. Indoor and Mob. Radio Commun. Conf. (PIMRC), pp. 2571-2575, Tokyo, Japan Sept. 2009. 1.5.3 Ellhnikˆ Sunèdria 1. B. D. Papouts c, I. G. FraÐmhc, S. A. Kwtsìpouloc, << DÐkaih diaqeðrish radiopìrwn sthn katerqìmenh zeôxh asurmˆtwn susthmˆtwn mèsw kanali n epilektik n stic suqnìthtec,>> 13o Sunèdrio thc 'Enwshc Ell nwn Fusik n, Pˆtra Mˆrtioc 2010. 2. I. G. Fraimis, K. Ioannou, and S. A. Kotsopoulos, An adaptive channel management scheme for multi-layer cellular networks, A Panhellenic Conference in Electronics and Telecommunications, Patras March 2009. 1.5.4 Anaforèc TrÐtwn sto Dhmosieumèno Ereunhtikì 'Ergo 1. Anaforèc sthn ergasða << V. D. Papoutsis, I. G. Fraimis, and S. A. Kotsopoulos, User selection and resource allocation algorithm with fairness in MISO-OFDMA IEEE Commun. Let., vol. 14, no. 5, pp. 411-413 May 2010.>> Lu, W., Ji, F., Yu, H.: A general resource allocation algorithm with fairness for SDMA/MISO/OFDMA systems, IEEE Communications Letters 15 (10), art. no. 6012542, pp. 1072-1074, 2011 Luo, W.Y., Jin, L., Huang, K.Z., Zhong, Z.: User selection and resource allocation for secure multiuser MISO-OFDMA systems, Electronics Letters 47 (15), pp. 884-886, 2011

1.5 Episthmonikèc DhmosieÔseic 31 Basturk, I., Ozbek, B.: Fair resource allocation for multi-user MISO-OFDMA systems, 2011 IEEE 19th Signal Processing and Communications Applications Conference, SIU 2011, art. no. 5929699, pp. 506-509, 2011 Luo, W.Y., Jin, L., Liu, S.P., Zhang, L.Z.: Wireless physical layer security model and resource allocation algorithm in MISO-OFDMA, Electronics Letters 47 (6), pp. 414-416, 2011 Moon, J.-M., Cho, D.-H.: Efficient cell-clustering algorithm for inter-cluster interference mitigation in network MIMO systems, IEEE Communications Letters 15 (3), art. no. 5704846, pp. 326-328, 2011 Meng-gu Tsai: Resource Allocation Algorithms for MIMO-OFDM Systems with Imperfect Channel Knowledge, Master of Science Thesis, Student Number: 985203008, Advisor: Yung-Fang Chen, Department of Communication Engineering, National Central University, Taiwan (Republic of China), Date of Defense: 11/7/2011 Wen-ting Luo: Resource Allocation in Multiuser MIMO-OFDM Systems with MMSE Precoding, Master s Thesis, Advisor: Yung-fang Chen, Department of Communication Engineering, National Central University, Jhongli City, Taoyuan County 32001, Taiwan, Date of Defense: 2011-07-11, 2011 Bai, Z., Badic, B., Iwelski, S., Scholand, T., Balraj, R., Bruck, G. and Jung, P.: On the equivalence of MMSE and IRC receiver in MU-MIMO systems, IEEE Communication Letters, 15(2), art.no. 6051403, pp.1288-1290, 2011 Derrick Wing Kwan Ng, Ernest S.Lo and Robert Schober: Energy Efficient Resource Allocation in OFDMA Systems with Large Numbers of Base Station Antennas, IEEE International Conference on Communications, Ottawa, Canada, 2012 (appeard in the site: www.ece.ubc.ca/.../large a ntennas T W ). 2. Anaforèc sthn ergasða << V. D. Papoutsis, I. G. Fraimis, and S. A. Kotsopoulos, Fairness-aware user selection and resource allocation in MISO-OFDMA European Trans. on Telecommun., John Wiley & Sons Ltd., vol. 21, no. 6, pp. 568-574 Oct. 2010.>> Lu, W., Ji, F., Yu, H.: A general resource allocation algorithm with fairness for SDMA/MISO/OFDMA systems, IEEE Communications Letters 15 (10), art. no. 6012542, pp. 1072-1074, 2011 Mina A.A. Sokar, Khaled M.F. Elsayed: A dynamic radio resource management scheme for the IEEE 802.16 band-adaptive modulation and coding mode with proportional rate constraints, European Transactions on Telecommunications, DOI: 10.1002/ett.1529, 9 Dec 2011 3. Anaforèc sthn ergasða << V. D. Papoutsis, I. G. Fraimis and S. A. Kotsopoulos, A Novel Fairness-Aware Resource Allocation Scheme in Multiuser SISO-OFDMA

32 Kefˆlaio 1. Eisagwg Downlink, Intern, J. of Veh. Tech., Hindawi Corp., vol. 2010, Article ID 432762, 10 pages, 2010. doi:10.1155/2010/432762.>> W. Ben Hassen, M. Affif, F.Khelifa and A. Samet: A new approach for Sub- Channels Assignment in Downlink Fourth Generation Mobile Systems, Journal of Computer Science 7(9): 2368-1374, 2011 4. Anaforèc sthn ergasða <<I. G. Fraimis, V. D. Papoutsis, and S. A. Kotsopoulos, A Decentralized Subchannel Allocation Scheme with Inter-cell Interference Coordination (ICIC) for Multi-Cell OFDMA Systems, in Proc. IEEE Global Commun. Conf. (Globecom), Miami USA, Dec. 2010.>> Heba Eid: Inter-Cell and Intra-cell Interference Coordination in Cellular Network with Highly-Sectored Base Stations, Master of Applied Science in Electrical and Computer Engineering, Thesis Supervisor: Professor Halim Yanikomeroglu, Department of Systems and Computer Engineering, Ottawa-Carleton Institute for Electrical and Computer Engineering, May 2011 Norshidah Katiram, Norsheila Fisal, Sharifah Kamilah Syed Yusof, Siti Marwangi Mohamad Maharum, Aimi Syamimi Ab Ghafar and Faiz Asraf Saparudin: Inter-Cell Interference Mitigation and Coordination in CoMP Systems, in book A.Abd Manaf et al. (Eds): ICIEIS 2011, Part III, CCIS 253, pp. 654-665, 2011, Springer - Verlag Berlin Heidelberg 2011 G. Cao, Da-cheng Yang, X. Zhang, and Xiao-yue Zhu, A joint resource allocation and power control algorithm for heterogeneous network The Journal of China Universities of Posts and Telecommunications, vol. 18 (2), pp. 17-22, Dec. 2011 5. Anaforèc sthn ergasða <<I. G. Fraimis, V. D. Papoutsis, and S. A. Kotsopoulos, A distributed radio resource allocation algorithm with interference coordination for multi-cell OFDMA systems, in Proc. IEEE Pers. Indoor and Mob. Radio Commun. Conf. (PIMRC), pp. 1354-1359, Instanbul, Turkey Sept. 2010.>> Di Piazza, F.I., Mangione, and S., Tinnirello, I.: Maximizing network capacity in an heterogeneous macro-micro cellular scenario, Proceedings - IEEE Symposium on Computers and Communications, art. no. 5983927, pp. 735-740, 2011 Su Yi, Gang Wang, and Yong Xia, QoS-Enabled Dynamic Resource Management in Multi-Cell OFDMA-Based Systems,Vehicular Technology Conference (VTC Spring), 2011 IEEE 73rd,pp. 1-5 S. Wesemann,W. Rave, and G. Fettwies, Decentralized intercell interference coordination for fair resource allocation in large-scale networks, Smart Antennas (WSA) International ITG Workshop on, pp. 201-208, Dresden Germany March 2012

1.5 Episthmonikèc DhmosieÔseic 33 6. Anaforèc sthn ergasða << V. D. Papoutsis, I. G. Fraimis, S. A. Kotsopoulos, Fairnessaware resource allocation for the SISO downlink over frequency-selective channels, in Proc. IEEE Wireless Commun. Netw. Conf. (WCNC), NSW Austalia, Apr. 2010.>> Xiaopeng Huang, and V. B. Lawrence. Bandwidth-efficient Bit and Power Loading for Underwater Acoustic OFDM Communication System with Limited Feedback, IEEE Veh. Techn. Conf, (VTC-Spring), Yokohama Japan May 2011 Chai, Z.-y., Liu, F., Qi, Y.-t. and Zhu, S.-f. (2012), On the use of immune clonal optimization for joint subcarrier and power allocation in OFDMA with proportional fairness rate. Int. J. Commun. Syst.. doi:10.1002/dac.1395

BibliografÐa [1] ELOT, OTE kai MOTO. Genik kai Eidik Thlepikoinwniak OrologÐa. OTE, Aj na, Ellˆda, 9h èkdosh, AÔgoustoc 1998. [2] J. Proakis, and M. Salehi, Digital Communications 5th Edition. McGraw-Hill Science, 2007. [3] IEEE standard for local and metropolital area networks part 16: Air intergace for fixed and mobile broadband wireless access system amendment 2: Physical and medium access control layers for combined fixed and mobile operation in licensed band and corringendum 1, IEEE Std 802.16e-2005 and IEEE Std 802.16-2004/ Cor 1-2005 (Amendment and Corringendum to IEEE Std 802.16-2004), pp. 1-822, 2006. [4] C. Stevenson, G. Chouinard, Z. Lei, W. Hu, S. Shellhammer, and W. Caldwell IEEE 802.22: The first cognitive radio wireless regional area network standard, IEEE Commun. Mag., vol. 47, no. 1, pp. 130-138, Jan. 2009. [5] D. Tse and P. Viswanath, Fundamentals of Wireless Communication, Cambridge University Press, 2005. [6] H. Liu, and G. Li, OFDM-Based Broadband Wireless Networks-Disign and Optimizaton. NY: Wiley, Nov. 2005. [7] J. G. Andrews, A. Gosh, and R. Muhamed, Fundamentals of WiMAX: Understanding Broadband Wireless Networking, Prentice Hall, 2007. [8] R. Knopp, and P. A. Humblet, Information capacity and power control in single-cell multiuser communications, IEEE Int. Conf. on Commun., pp. 331-335, Seattle, USA June 1995. [9] Evolved universal terrestrial radio access (E-UTRA): physical channels and moduation (release 8), 3 GPP Tech. Rep. 802.16, Oct. 2004. [10] Soft Frequency Reuse Scheme for UTRAN LTE, 3GPP Project Document R1-050 507, May 2005. [Online]. Available:http://www.3gpp.org. [11] OFDMA Downlink Intercell Interference Mitigation, 3GPP Project Document R1-060 291, Feb. 2006. [Online]. Available:http://www.3gpp.org. 34

BibliografÐa 35 [12] I. G. Fraimis, V. D. Papoutsis, and S. A. Kotsopoulos, A Decentralized Subchannel Allocation Scheme with Inter-cell Interference Coordination (ICIC) for Multi-Cell OFDMA Systems, in Proc. IEEE Global Commun. Conf. (Globecom), Miami USA, Dec. 2010. [13] M. Rahman and H. Yanikomeroglu Enhancing Cell-Edge Performance: A Downlink Dynamic Interference Avoidance Scheme with Inter-Cell Coordination, IEEE Trans. Wireless. Commun., vol. 9, no 4, pp. 1414-1425, Apr. 2010. [14] G. Li, and H. Liu, Downlink Resource Allocation for Multi-Cell OFDMA System, IEEE Trans. Wireless. Commun., vol. 5, no 12, pp. 3451-3459, Dec. 2006. [15] S. Sadr, A. Anpalagan and K. Raahemifar, Radio Resource Allocation Algorithms for the Downlink of Multiuser OFDM Communication Systems, IEEE Commun. Surveys & Tutorials, vol. 11, no 3, pp. 92-106, 3rd quart. 2009. [16] J. Jang and K. B. Lee, Transmit power adaptation for multiuser OFDM systems, IEEE J. Sel. Areas Commun.,vol 21,no. 2, pp.171-178, Feb. 2003. [17] G. Li, H. Liu, On the Optimality of the OFDMA Network, IEEE Comm. Lett., vol. 9, pp. 438-440, May 2005. [18] Z. Shen, J. Andrews, B.L Evans, Adaptive Resource Allocation in Multiuser OFDM System with Proportional Rate Constraints, IEEE Tran. Wireless. Commun., vol. 4, no. 6, pp. 2726-2737, Nov. 2005. [19] V. D. Papoutsis, I. G. Fraimis, S. A. Kotsopoulos, Fairness-aware resource allocation for the SISO downlink over frequency-selective channels, in Proc. IEEE Wireless Commun. Netw. Conf. (WCNC), NSW Austalia, Apr. 2010. [20] V. D. Papoutsis, I. G. Fraimis, and S. A. Kotsopoulos, User selection and resource allocation algorithm with fairness in MISO-OFDMA IEEE Commun. Let., vol. 14, no. 5, pp. 411-413 May 2010. [21] V. D. Papoutsis, I. G. Fraimis and S. A. Kotsopoulos, Resource allocation algorithm for MIMO-OFDMA systems with minimum resources guarantee, in Proc. IEEE Intern. Conf. on Electronics, Cicuits and Systems (ICECS), Athens Greece, Dec. 2010. [22] P. W. C. Chan and R. S. Cheng, Capacity Maximization for Zero-Forcing MIMO- OFDMA Downlink Systems with Multiuser Diversity, IEEE Tran. Wireless. Commun., vol. 6, no. 5, pp. 1880-1889, May 2007. [23] A. Alexiou, C. Bouras, V. Kokkinos, and E. Rekkas, An Improved Mechanism for Multiple MBMS Sessions Assignment in B3G Cellular Networks, Wireless Networks, Springer, Verlang, vol. 16, no. 3, pp. 671-686, April 2010.

36 BibliografÐa [24] J. Liu, W. Chen, Z. Cao and K. B. Letaief, Dynamic power and subcarrier allocation for OFDMA-based wireless multicast systems, in Proc. IEEE Intern. Conf. on Commun. (ICC), Beijing China, May 2008. [25] A. O. Richard, A. Dadlani, and K. Kim Multicast Scheduling and Resource Allocation Algorithms for OFDMA-Based Systems: A Survey, IEEE Commun. Surveys and Tutor., no. 99, pp. 1-15, Feb. 2012. [26] I. G. Fraimis, and S. A. Kotsopoulos, A Low-Complexity Resource Allocation Algorithm for MIMO-OFDMA with Spectrum-Guarantee Provisioning, Intern. J. of Digit. Multimed. Broadcast., Hindawi 2012. [27] M. Rahman and H. Yanikomeroglu Enhancing Cell-Edge Performance: A Downlink Dynamic Interference Avoidance Scheme with Inter-Cell Coordination, IEEE Trans. Wireless. Commun., vol. 9, no 4, pp. 1414-1425, Apr. 2010. [28] I. G. Fraimis, and S. A. Kotsopoulos QoS-Based Proportional Fair Allocation Algorithm for OFDMA Wireless Cellular Systems, IEEE Commun. Let., vol. 15, no. 10, pp. 1091-1093, Aug. 2011. [29] E. Yaacoub, and Z. Dawy, A Survey on Uplink Resource Allocation in OFDMA Wireless Networks, IEEE Commun. Surveys & Tutorials, no 99, pp. 1-16, May 2011. [30] I. G. Fraimis, and S. A. Kotsopoulos, A Low-Complexity Resource Allocation Algorithm for OFDMA-based Cellular Networks with QoS Provisioning: A Cross-Layer Design Approach, in Proc. IEEE Wireless Commun. Netw. Conf. (WCNC), Paris, France, Apr. 2012. [31] Z. Hasan, H. Boostanimehr, and V. K. Bhargava, Green Cellular Networks: A Survey, Some Research Issues and Challenges IEEE Commun. Serv. and Tutor., vol. 13, no. 4, pp. 524-540, Nov. 2011. [32] X. Mao, A. Maaref, and K. H. Teo Adpative Soft Frequency Reuse for Inter-cell Interference Coordination in SC-FDMA based 3GPP LTE Uplinks, in Proc., IEEE Global Telecommun. Conf. (Globecom, Dec. 2008. [33] C. Koutsimanis, and G. Fodor, A Dynamic Resource Allocation Scheme for Guaranteed Bit Rate Services in OFDMA Networks, in Proc., IEEE Intern. Conf. on Commun.(ICC), May 2008. [34] I. G. Fraimis, V. D. Papoutsis, and S. A. Kotsopoulos, A distributed radio resource allocation algorithm with interference coordination for multi-cell OFDMA systems, in Proc. IEEE Pers. Indoor and Mob. Radio Commun. Conf. (PIMRC), pp. 1354-1359, Instanbul, Turkey Sept. 2010.

BibliografÐa 37 [35] N. Vlotomas, J. Antoniou, G. Hadjipollas, V. Vassiliou, and A. Pitsillides, Power Control for Efficient Multicasting in IP-based 3G and beyond mobile networks 11th European Wireless, pp. 1-5, Nicosia, Cyprous, April 2005. [36] A. Alexiou, C. Bouras, and V. Kokkinos, Power Saving Techniques in MBMS Multicast Mode, 3rd ACM Intern. Workshop on Wirel. Multim. Network. and Perf. Model.(WMUNPM), pp. 62-69, Chania, Greece, Oct. 2007. [37] C. C. Lee, and R. Steele, Effects of soft and softer handoffs on CDMA system capacity IEEE Trans. on Veh. Techn., vol. 47, no. 3, pp. 830-841, Aug. 1998. [38] Y. Chen, and L. Cuthbert, Optimised Downlink Transmit Power Control during Soft Handover in WCDMA Systems IEEE Wirel. Commun. and Netw. Conf. (WCNC), March 2003. [39] R. Jain, D. M. Chiu and W. Hawe, A quantitave measure of fairness and discriminaton for resource allocation in shared systems, DEC, Research Report TR-301, 1984. [40] A. Andinoyi, M. Rahman, H. Yanikomeroglu, D. Falconer, and Y.-D. Kim, Fairnessaware radio resource management in downlink ofdma cellular relay networks, IEEE Trans. on Wirel. Commun., vol. 9, no. 5, pp. 1628-1639, May 2010. [41] V. Chandrasekhar, J. G Andrews and A. Gatherer, Femtocells networks: A survey, IEEE Commun. Mag., pp. 56-59, Sept. 2008. [42] Y. Zhang, and C. Leung, A Distributed Algorithm for Resource Allocation in OFDM Cognitive Radio Systems, IEEE Trans. on Veh. Technol., vol. 60, no. 2, pp. 546-554, Feb. 2011.

Kefˆlaio 2 Diasfˆlish tou QoS me Egguhmèno EÔroc Z nhc stouc Qr stec se Sust mata Poluekpomp c teqnologðac MIMO-OFDMA 2.1 PerÐlhyh Sto parìn Kefˆlaio exetˆzetai to prìblhma thc katanom c twn diajèsimwn radiopìrwn thc katerqìmenhc zeôxhc asôrmatwn epikoinwniak n sust matwn MIMO pou axiopoioôn thn metˆdosh poluekpomp c kai metadðdoun mèsw epilektik n sth suqnìthta kanali n. H poluekpomp pˆnw apì asôrmata sust mata OFDMA anamènetai na enisqôsei se shmantikì bajmì thn prìsbash se uyhloô rujmoô metˆdoshc efarmogèc se poluˆrijmouc qrhst n, diìti èna asôrmato kanˆli mporeð na diamoirˆstei se pollaploôc qr stec pou aitoôntai to Ðdio perieqìmeno. Epiplèon h qr sh thc teqnologðac MIMO mazð me thn teqnologða prìsbashc OFDMA den prosfèrei mìno diaforismì pollapl n qrhst n sto pedðo thc suqnìthtac allˆ kai sto pedðo tou q rou kai aut h epiprìsjeth idiìthta enisqôei akìma perissìtero thn qwrhtikìthta tou sust matoc. Sunep c h olokl rwsh ìlwn twn proanaferjèntwn teqnologi n kai mejìdwn se èna asôrmato epikoinwniakì sôsthma ja wfel sei shmantikˆ. Epomènwc se autì to Kefˆlaio proteðnetai ènac qamhl c poluplokìthtac algìrijmoc gia epikoinwniakˆ sust mata poluekpomp c pou basðzontai sthn pollapl prìsbash OFDMA kai perilambˆnoun thn teqnologða MIMO. O proteinìmenoc algìrijmoc egguˆtai èna tm ma eôrouc z nhc ston kˆje qr sth kaj c epðshc mei nei thn upologistik poluplokìthta tou probl matoc apì ekjetik se grammik. Axiolìghsh thc proteinìmenhc lôshc epitugqˆnetai mèsw poikðlwn senarðwn prosomoðwshc. Stic prosomoi seic autèc sugkrðnetai h apìdosh tou proteinìmenou algorðjmou se sqèsh me ˆlla sq mata kai teqnikèc thc prìsfathc 38

2.2 Eisagwg 39 diejnoôc bibliografðac pou basðzontai sthn mèjodo prìsbashc OFDMA kai eðnai efarmìsima se epikoinwniakˆ sust mata ìpou tìso o SB ìso kai oi qr stec diajètoun suskeuèc pollapl n kerai n. 2.2 Eisagwg Ta sôgqrona asôrmata sust mata mazð me uphresðec fwn c, anamènetai na parèqoun plhj ra uphresi n me poikðlec apait seic se eôroc z nhc [2]-[6]. Se arketèc uphresðec apaiteðtai ta Ðdia dedomèna na metadðdontai tautìqrona se pollaploôc qr stec. EpikoinwnÐa metaxô enìc pompoô kai poll n dekt n dônatai na epiteuqjeð me dôo trìpouc: eðte a) me metˆdosh shmeðo-proc -shmeðo (unicast periptwsh) b) eðte me metˆdosh shmeðo-proc -pollaplˆ shmeða (poluekpomp ) [2]-[9]. Oi ereunhtikèc ergasðec [2]-[5] meletoôn to fainìmeno thc pollapl c ekpomp c polumesikoô perieqomènou se megˆlo pl joc qrhst n. Pio sugkekrimèna, stic episthmonikèc ergasðec [2], [3], oi suggrafeðc proteðnoun mða ubridik lôsh pou sundiˆzei touc dôo trìpouc metˆdoshc kai prosfèrei thn kalôterh dunat ekmetˆlleush twn diajèsimwn pìrwn, kaj c sthn ergasða [4], h perðptwsh desmeumènou eôrouc z nhc apokleisthkˆ gia uphresðec poluekmpop c (multicast services) diereunˆtai kai sthn ergasða [5], sumperilambˆnetai h perðptwsh sthn opoða tìso o pompìc ìso kai oi dèktec diajètoun pollalèc keraðec. Par' ìla autˆ oi proanaferjèisec melètec anafèrontai se kinhtˆ dðktua pou sthrðzontai se eureðac z nhc diaðreshc k dika pollapl prosbash WCDMA kai ìqi se pollapl prìsbash OFDMA to opoðo eðnai to sq ma diamìrfwshc kai pollapl c prìsbashc pou èqei uiojethjeð gia ta epìmenhc geniˆc asôrmata sust mata [6]-[18]. H teqnologða prìsbashc OFDMA basðzetai sto sq ma orjogwnik c diamìrfwshc suqnìthtac (OFDM) kai ekmetalleôetai to diaforismì pollap n qrhst n twn kanali n pou eðnai epilektikˆ sthn suqnìthta, diìti eðnai polô pijanì ìti en kˆpoioi upoforeðc brðskontai kˆtw apì sunj kec èntonwn dialeðyewn gia merikoôc qr stec, na brðskontai se kalèc sunj kec kanalioô gia kˆpoiouc ˆllouc [10], [13], [15]. Qˆrh loipìn thc exairetik c tou aut c apìdoshc sta epilektikˆ sth suqnìthta kanˆlia, h pollapl prìsbash OFDMA èqei enswmatwjeð se teqnologðec poluekpomp c gia thn apodotik metˆdosh polumesik n ro n se kinhtèc suskeuèc pou qrhsimopoioôn uphresðec thleìrashc [6] kai epðshc apoteleð thn proteinìmenh teqnologða pollapl c prìsbashc gia ta prìtupa thc euruzwnik c asôrmathc prìsbashc BWA. Tèloc, oi suggrafeðc twn ergasi n [12], [13] apodeiknôoun ìti h kalôterh politik gia na apofeuqjeð h endo-kuyelwt parembol eðnai h apokleistik anˆjesh kˆje upoforèa se èna mìno qr sth. Algìrijmoi dunamik c anˆjeshc radiopìrwn èqoun anaptuqjeð prìsfata ste na ekmetalleutoôn kalôtera ton diaforismì pollapl n qrhst n kai na belti soun thn qwrhtikìthta twn asurmˆtwn susthmˆtwn. Eidikìtera sthn episthmonik melèth [14], oi diajèsimoi upoforeðc qwrðzontai se omˆdec kai kˆje qr sthc leitourgeð parˆllhla kai prospajeð na dialèxei thn omˆda upoforèwn me to megalôtero mèso kèrdoc kanalioô, kaj c sthn episthmonik ergasða [15] h enðsqush thc qwrhtikìthtac epidi ketai sunart sei krithrðwn dikaiosônhc

40 Kefˆlaio 2. Diasfˆlish tou QoS me Egguhmèno EÔroc Z nhc stouc Qr stec se Sust mata Poluekpomp c teqnologðac MIMO-OFDMA epiballìmena stouc qr stec. OmoÐwc, sth dhmosðeush [16] oi suggrafeðc parousiˆzoun èna euretikì sq ma ètsi ste oi apait seic twn qrhst n se QoS ikanopoioôntai èqontac ìmwc wc antikeimenikì skopì thn meðwsh thc sunolik c ekpempìmenhc isqôoc. Apì thn ˆllh meriˆ, ìtan pollaploð qr stec apaitoôn to Ðdio polumesikì perieqìmeno ì- pwc sto sq ma 2.1, mporoôme na xeperˆsoume thn politik thc apokleistik c anˆjeshc kˆje upoforèa se èna mìno qr sth kai na epitrapeð o diamoirasmìc enìc upoforèa apì pollaploôc qr stec [7], [9]. Se aut thn perðptwsh, o pompìc egkajistˆ èna kanˆli epikoinwnðac me mia omˆda qrhst n pou aitoôntai to Ðdio perieqìmeno. Autì to eðdoc metˆdoshc onomˆzetai poluekpomp se antðjesh me thn monoekpomp (unicast), ìpou ta dedomèna prèpei na metadðdontai se kˆje èna qr sth xeqwristˆ. Autì eðnai èna spoudaðo pleonèkthma thc metˆdoshc poluekpomp c, to opoðo enisqôei shmantikˆ thn qwrhtikìthta twn asôrmatwn susthmˆtwn. Sq ma 2.1: Omˆdec qrhst n pou apaitoôn to Ðdia dedomèna. Proc aut thn kateôjunsh loipìn, oi suggrafeðc sthn dhmosðeush [7] proteðnoun ènan qamhl c poluplokìthtac algìrijmo gia sust mata OFDMA pou èqei san skopì thn beltðwsh tou rujmoô metˆdoshc tou thlepikoinwniakoô sust matoc. O algìrijmoc anajètei kˆje upoforèa sthn omˆda qrhst n me tic kalôterec sunj kec kanalioô gia autìn ton upoforèa kai ton megalôtero arijmì qrhst n-mèlwn pou aitoôntai to Ðdio perieqìmeno dedomènwn kai sthn episthmonik ergasða [8] proteðnetai ènac euretikìc agìrijmoc anˆjeshc radiopìrwn me skopì th meðwsh thc ekpempìmenhc isqôoc. 'Omwc algìrijmoi autoô tou eðdouc, estiˆzoun se sust mata apl c eisìdou apl c exìdou (SISO) kai den eðnai ˆmesa efarmìsimoi se sust mata MIMO [9], ta opoða anamènetai na diadramatðsoun èna rìlo kleidð stic mellontikèc

2.2 Eisagwg 41 epikoinwnðec BWA [19], [20]. Se peribˆllonta me dialeðyeic, h teqnologða MIMO prosfèrei aôxhsh sthn embèleia tou kanalioô kai thn fasmatik apodotikìthta qwrðc epiplèon fasmatikèc kai energeiakèc apaithseic. Lìgw aut n loip n twn idiot twn, ta sust mata MIMO èqoun sugkentr sei thn prosoq twn ereunht n kai twn kataskeuast n. To genikì diˆgramma enìc tètoiou sust matoc dðnetai sto Sq ma 2.2, ìpou mporoôme na doôme ton diaforismì q rou pou prostðjetai sto sôsthma apì thn parousða pollapl n kerai n. O diaforismìc q rou se sundiasmì me ton diaforismì dialeðyewn thc prìsbashc OFDMA, mporoôn na belti soun shmantikˆ thn olik qwrhtikìthta tou sust matoc. Sq ma 2.2: Genikì diˆgramma enìc thlepikoinwniakoô sust matoc MIMO. H uyhl upologistik poluplokìthta thc bèltisthc katanom c kanali n se èna sôsthma MIMO [19], èqei odhg sei arketoôc ereunhtèc na proteðnoun thn apokleistik anˆjesh kˆje upoforèa se èna mìno qr sth parˆ thn parousða pollapl n kerai n se pompì kai dèkth [20]-[27]. Sthn episthmonik ergasða [18], efarmìsthke h politik aut kai pio sugkekrimèna, qrhsimopoi jhkan upobèltista krit ria katanom c upoforèwn pou protˆjhkan gia pr th fora sthn ergasða [20]. OmoÐwc, oi suggrafeðc sthn dhmosðeush [9], efarmìzoun mða upobèltisth teqnik kai anajètoun kˆje upoforèa sthn omˆda qrhst n poluekpomp c pou prosfèrei to megalôtero kèrdoc sthn qwrhtikìthta tou suat matoc qwrðc na jewroôn

42 Kefˆlaio 2. Diasfˆlish tou QoS me Egguhmèno EÔroc Z nhc stouc Qr stec se Sust mata Poluekpomp c teqnologðac MIMO-OFDMA dikaiosônh sthn katanom fˆsmatoc stouc qr stec. Sto parìn Kefˆlaio loipìn, antimetwpðzetai to prìblhma thc anˆjeshc radiopìrwn se èna asôrmato sôsthma basismèno sthn teqnologða MIMO, ìpou upˆrqoun pollˆplèc omˆdec qrhst n kai kˆje omˆda apaiteð to Ðdio perieqìmeno dedomènwn me eggu seic wc proc thn prosbasimothtˆ touc sto diajèsimo eôroc z nhc. Uiojetìntac aut thn politik, apofeôgoume thn perðptwsh mh exuphrèthseic omˆdac qrhst n lìgw kak n sunjhk n kanalioô. AntÐjeta stic prìsfatec ergasðec [7], [9] pou aforoôn to fainìmeno thc poluekpomp c, QoS eggu - seic den jewroôntai gia touc qr stec kaj c o monadikìc touc stìqoc eðnai h megistopoðhsh tou rujmoô metˆdoshc dedomènwn tou sust matoc. EpÐshc o proteinìmenoc algìrijmoc dðnei kalôterouc rujmoôc dedomènwn sugkrinìmenoc me ˆlla sq mata pou den perilambˆnoun thn poluekpomp stouc mhqanismoôc touc metˆdoshc kai sugkrinìmenoc epðshc me to statikì sq ma thc pollapl c prìsbashc diaðreshc k dika (TDMA). Epiplèon parousiˆzei meiwmènh upologistik poluplokìthta. 2.3 Montèlo tou Sust matoc kai DiatÔpwsh tou Probl matoc To genikì diˆgramma tou upì exètash sust matoc MIMO basismèno sthn prìsbash OFDMA dðnetai sto Sq ma 2.2, ìpou h qwrik poluplexða jewreðtai ìpwc stic ergasðec [9], [18], [20]. JewroÔme wc pompì, èna SB o opoðoc exuphreteð K asôrmatouc qr stec me th bo jeia N upoforèwn. 'Estw ìti N t eðnai o arijmìc twn kerai n ston SB kai N r o arijmìc twn kerai n sthn suskeu tou kˆje qr sth. Tìte, h m tra tou kanalioô tou qr sth k ston upoforèa n eðnai mða N t N r m tra H kn = h kn 11 h kn 12 h kn 1N t h kn 21 h kn 22 h kn. h kn N r1 2N t..... h kn N r2 h kn N rn t (2.1) ìpou, h kn rt eðnai to kèrdoc kanalioô tou apì thn keraða ekpomp c t sthn keraða l yhc r tou qr sth k ston upoforèa n. EpÐshc jewroôme ìti oi idiotimèc thc m trac H kn H T kn eðnai {λ (i) km }M i=1, ìpou M = min(n r, N t ). Opìte, gia sugkekrimèno k kai n, upˆrqei mia omˆda idiokanali n ta opoða orðzontai apì tic parapˆnw idiotimèc sômfwna me thn anˆlush SVD. EpÐshc jewr ntac to N t 1 ekpempìmeno s ma X kn = [x 1 kn, x2 kn,..., xnt kn ] kai to N r 1 lambanìmeno s ma Y kn = [ykn 1, y2 kn,..., ynr kn ], tìte eðnai ( K ) Y kn = H kn X kn p kn + N kn (2.2) k=1 ìpou K X kn p kn, eðnai to sunolikì ekpempìmeno s ma ston upoforèa n, p kn antiproswpeôei k=1 thn isqô ston upoforèa n ìtan anatðjetai ston qr sth k. N kn eðnai to N r 1 diˆnusma jo-

2.3 Montèlo tou Sust matoc kai DiatÔpwsh tou Probl matoc 43 rôbou kai ta stoiqeða tou eðnai anexˆrthta i.i.d. kuklikˆ summetrikˆ gkaousianˆ me mhdenik mèsh tim kai pðnaka diasporˆc N 0. Ta bit twn qrhst n diamorf nontai N sômbola QAM epipèdou M, ta opoða diadoqikˆ sundiˆzontai qrhsimopoi ntac antðstrofo taqô metasqhmatismì Fourier (IFFT) se èna sômbolo OFDMA. Gia èna tetragwnikì QAM, M epipèdou, qrhsimopoi ntac qartogrˆfhsh Gray twn bit, o rujmìc lanjasmènwn bit (BER) mporeð na prosegisteð gia ìqi pèra apì 1 db kai r i kn 4, BERi kn 10 3 wc [28] BER i kn 1 5 exp [ 1.5p kn λ i kn N 0 (2 ri kn 1) r i kn = log 2 ] (2.3) ( 1 + p knλ i ) kn N 0 Γ i, (2.4) kn ìpou Γ i kn =-ln(5 BER i kn )/1.5. Gia eukolða jewroôme BERi kn =BER kai Γi kn =Γ. To megˆlo pleonèkthma tou mhqanismoô metˆdoshc poluekpomp c ègkeitai sto fainìmeno ìti ta dedomèna mporoôn na metadojoôn se pollaploôc dèktec mèsw miac metˆdoshc. Par' ìla autˆ, kˆje qr sthc -mèloc (MU) mðac omˆdac poluekpomp c (MG) èqei diaforetikì lìgo s matoc proc jìrubo (SNR) se èna sugkekrimèno upoforèa apì touc ˆllouc qr stec tou Ðdiou MG. Me ˆlla lìgia, o rujmìc metˆdoshc dedomènwn kˆje MU den eðnai Ðdioc ìtan sto (MG) pou an koun, anatejeð ènac sugkekrimènoc upoforèac. Mia eurèwc apodekt teqnik eðnai na kajorðzetai o ekpempìmenoc rujmìc metˆdoshc dedomènwn mèsw enìc sugkekrimènou upoforèa apì to MU me tic qeirìterec sunj kec kanalioô [7], [9]. Aut h prosèggish bebai nei ìti mða uphresða poluekpomp c mporeð na lhfjeð epituq c se ìlouc touc qr stec enìc MG. Epomènwc, o SB metadðdei dedomèna sto j MG mèsw tou upoforèa n me rujmì metˆdoshc: B r jn = arg min k K j N M i=1 ( log 2 1 + λi kn p ) kn, (2.5) N 0 Γ ìpou, K j dhl nei to sônolo twn qrhst n tou MG j, to B anafèretai sto sunolikì eôroc z nhc tou sust matoc. Epomènwc, o olikìc rujmìc metˆdoshc dedomènwn sto MG j, me th bo jeia thc 2.5, eðnai: me to na dhl nei ton arijmì stoiqeðwn tou sunìlou. Se autì to kefˆlaio jewroôntai oi parakˆtw upojèseic: R jn = K j r jn, (2.6) O SB èqei tèleia gn sh twn plhrofori n thc katˆstashc tou kanalioô (CSI) ìlwn twn qrhst n mèsw afierwmènwn kanali n anatrofodìthshc (feedback blèpe sq ma 2.2). EpÐshc o SB mporeð na gnwrðzei kai na kajorðzei ton mègisto rujmì metˆdoshc dedomènwn enìc qr sth, kaj c epðshc touc upoforeðc mèsw twn opoðwn lambˆnei q ra h metˆdosh.

44 Kefˆlaio 2. Diasfˆlish tou QoS me Egguhmèno EÔroc Z nhc stouc Qr stec se Sust mata Poluekpomp c teqnologðac MIMO-OFDMA Ta ekpempìmena s mata ufðstantai dialeðyeic, oi opoðec metabˆllontai argˆ me to qrìno ste oi suntelestèc tou kanalioô na jewroôntai stajerèc katˆ th diˆrkeia thc anˆjeshc twn radiopìrwn. H sunolik ekpempìmenh isqôc eðnai omoiìmorfa katanemhmenh stouc diajèsimouc upoforeðc kai se kˆje upoforèa h posìthta isqôoe eðnai p kn = p n = P t /N, k = 1,..., K, n = 1,..., N. H enðsqush pou prosdðdei h katanom isqôoc water-filling eðnai oriak se sqèsh me thn omoiìmorfh katanom isqôoc sundiasmènh me prosarmostik kwdikopoðhsh kai diamìrfwsh (ACM), ìpwc apèdeixjhke sthn episthmonik ergasða [12]. JewroÔme thn m tra anˆjeshc upoforèwn Q G N = [x jn ], ìpou x jn = 1 an sto MG j èqei anatejeð o upoforèac n kai x jn = 0 eˆn ìqi. 'Enac upoforèac mporeð na moirˆzetai apì pollapìôc qr stec allˆ mìno eˆn autoð oi qr stec eðnai mèlh tou idðou MG. Kˆje upoforèac mporeð na anatejeð se èna mìno MG. K asôrmatoi qr stec qwrðzontai se G MGs ta opoða lambˆnoun G diaforetikèc uphresðec poluekpomp c. Lambˆnontac epomènwc up' ìyh tic parapˆnw upojèseic, to prìblhma katanom c twn diajèsimwn radiopìrwn me stìqo th megistopoðhsh tou sunolikoô rujmoô metˆdoshc dedomènwn me periorismì sthn sunolik ekpempìmenh isqô kai me tautìqronh exasfˆlish enìc elˆqistou merðsmatoc eôrouc z nhc se kˆje MG, diatup netai wc ex c: upì touc periorismoôc: max x jn,p jn G j=1 n=1 N x jn R jn. (2.7) G x jn = 1, n, (2.8) j=1 x jn {0, 1}, j, n, (2.9) N x jn C j, j, (2.10) n=1 G C j N, C j Z + (2.11) j=1 G j=1 n=1 N x jn p jn P t, (2.12) p jn 0, j, n. (2.13) Sth diatôpwsh tou probl matoc, h duadik metablht x jn dhl nei thn anˆjesh tou upoforèa n sto MG j kai oi periorismoð (2.8) kai (2.9) bebai noun ìti h perðptwsh thc

2.4 Proteinìmenoc Algìrijmoc Katanom c twn Radiopìrwn 45 endo-kuyelwt c parembol c (ICI) apofeôgetai, diìti kˆje upoforèac kataqwreðtai se èna mìno MG. O periorismìc (2.10) egguˆtai èna mèroc apì to diajèsimo eôroc z nhc se kˆje MG. H teqnik thc eggôhshc enìc elˆqistou merðsmatoc eôrouc z nhc se qr stec, èqei epðshc melethjeð sthn ergasða [17] pou aforˆ sust mata me anametadìtec kai sthn melèth [18] pou aforˆ sust mata MIMO me apl metˆdosh mìno. O periorismìc (2.11) shmaðnei ìti to ˆjroisma twn upoforèwn pou mporoôn na egguhjoôn se kˆje MG den mporeð na uperbaðnei ton arijmì twn diajèsimwn upoforèwn tou sust matoc. Tèloc, oi periorismoð (2.12) kai (2.13) dhl noun ton periorismì sthn isqô tou SB, ìpou P t eðnai h sunolik ekpempìmenh isqôc tou SB. EÐnai polô dôskolo na brejeð h bèltisth lôsh tou probl matoc (2.7)-(2.13) mèsa se sôntomo kai kajorismèno qronikì diˆsthma, diìti to prìblhma (2.7)-(2.13) eðnai NP-hard kai parousiˆzei ekjetik upologistik poluplokìthta O(G N ) (enìthta 2.4 ). Perilambˆnei epðshc suneqeðc kai duadikèc metablhtèc kai oi mh grammikoð periorismoð tou auxˆnoun th duskolða eôreshc thc bèltisthc lôshc. Sunep c, katafeôgoume se upobèltistouc euretikoôc algorðjmouc pou eðnai pio tairiastoð gia praktikèc efarmogèc. 2.4 Proteinìmenoc Algìrijmoc Katanom c twn Radiopìrwn Sthn paroôsa enìthta parousiˆzetai kai analôetai o proteinìmenoc qamhl c poluplokìthtac katanom c pìrwn (LCRA) algìrijmoc. o yeudok dikac tou algorðjmou LCRA dðnetai ston pðnaka 2.1 pou akoloujeð: Gia na gðnei pio katanoht h leitourgða tou algorðjmou, o k dikac qwrðzetai se b mata kai autˆ perigrˆfontai ìpwc akoloujeð: EÐsodoi: N = {1, 2,..., N}, G = {1, 2,..., G}, C = {C 1, C 2,..., C G }, R G N = [R jn ] % upologðzetai apì thn (2.6) 'Exodoc: X G N = [x jn ] B ma 1. ArqikopoÐhsh: x jn = 0, gia j = 1,..., G kai n = 1,..., N Wc eðsodoi tou algìrijmou LCRA eðnai ta sônola: twn diajèsimwn upoforèwn N, to sônolo G twn MGs, to sônolo C pou antiproswpeôei thn eggôhsh prìsbashc tou kˆje MG kai h m tra R G N pou èqei wc stoiqeða touc efiktoôc rujmoôc metˆdoshc dedomènwn kˆje MG me kˆje ènan apì touc diajèsimouc upoforeðc. 'Exodoc tou algorðjmou eðnai h m tra katanom c upoforèwn kai sto B ma 1 oi deðktec anˆjeshc upoforèwn x jn jètontai sto mhdèn gia ìla ta MIMO kai ìlouc touc upoforeðc. B ma 2. Kaj c C {}: Brec j G èna ñ N me R jñ R jn j, n

46 Kefˆlaio 2. Diasfˆlish tou QoS me Egguhmèno EÔroc Z nhc stouc Qr stec se Sust mata Poluekpomp c teqnologðac MIMO-OFDMA PÐnakac 2.1: Algìrijmoc Είσοδοι: N = {1, 2,..., N} G = {1, 2,..., G} C = {C 1, C 2,..., C G } έστι ώστε να ικανοποιείται η (2.11) R G N = [R jn ] % υπολογίζεται από την (2.6) Εξοδος: X G N = [x jn ] Βήμα 1. Αρχικοποίηση: x jn = 0, για j = 1,... G και n = 1... N Βήμα 2. Καθώς C {}: Βρες j G και ñ N με R jñ R jn j, n Αν N x jn C j % εξετάζει την (2.10) n=1 C C \ {C j } G G \ { j} Αλλιώς Θέσε x jñ = 1 N N \ {ñ} % ικανοποιεί (2.8) Βήμα 3. Καθώς N {}: Βρες j, n ώστε R j n R jn j, n Θέσε x j n = 1 N N \ {n } % ικανοποιεί (2.8) Υπολόγισε την (2.7). An N x jn C j % exetˆzei thn (2.10) n=1 C C \ {C j } G G \ { j} Alli c Jèse x jñ = 1 N N \ {ñ} % ikanopoieð thn (2.8) Sto deôtero B ma, o SB brðskei to zeôgoc upoforèa n kai omˆdac poluekpomp c j pou prosfèrei perissìtero sthn sunolik qwrhtikìthta. Sthn sunèqeia, o algìrijmoc exetˆzei an to epilegmèno MG dijètei dh to elˆqisto merðdiì tou se eôroc z nhc (sunj kh 2.10). An h sunj kh alhjeôei, o deðkthc tou elˆqistou arijmoô upoforèwn C j tìte to sugkekrimènoc deðkthc bgeðnei apì to sônolo C kai to sugkekrimèno MG exaireðtai apì epìmenec epanal yeic autoô tou b matoc tou algorðjmou. Sthn perðptwsh pou to MG den diajètei ton elˆqisto arijmì kanali n, tìte o upoforèac n kataqwreitai sto MG j kai o sugkekrimènoc upoforèac afaireðtai apì to sônolo twn diajèsimwn upoforèwn N ste na ikanopoihjeð h sunjhkh (2.8). H diadikaða aut epanalambˆnetai mèqri to sônolo C na eðnai kenì alliwc mèqri to kˆje MG na èqei kataqwrhjeð ton egguhmèno arijmì upoforèwn. H diadikasða ja mporoôse na eðqe stamat sei epðshc èan den up rqan ˆlloi diajèsimoi upoforeðc, parˆ to gegonìc ìti kˆpoia

2.5 Anˆlush thc Emplekìmenhc Poluplokìthtac 47 MGs den ja eðqan kataqwrhjeð ton egguhmèno arijmì upoforèwn. H katˆstash aut ìmwc apofeôgetai lìgw thc (2.11). B ma 3. Kaj c N {}: Brec j, n ste R j n R jn j, n Jèse x j n = 1, N N \ {n } % ikanopoieð thn (2.8) Upolìgise thn (2.7). Sto trðto kai teleutaðo B ma, an upˆrqoun upoforeðc oi opoðoi den kataqwr jhkan sto prohgoômeno B ma tìte autoð katanèmontai me to krit rio thc megistopoðhshc tou rujmoô metˆdoshc dedomènwn tou sust matoc. Epomènwc sto B ma autì o algìrijmoc anajètei kˆje upoforèa sto MG pou emfanðzei tic kalôterec sunj kec kanalioô ston sugkekrimèno upoforèa kai metˆ apì upoforèac autìc afaireðtai apì to sônolo N. Autì to B ma enisqôei thn sunolik qwrhtikìthta. 2.5 Anˆlush thc Emplekìmenhc Poluplokìthtac To prìblhma pou perigrˆfetai apì tic exis seic (2.7)-(2.13) eðnai èna prìblhma beltistopoðhshc duadikoô akèraiou programmatismoô me mh grammikoôc periorismoôc. Gia na brejeð h bèltisth lôsh tou probl matoc qreiˆzetai na yˆxoume G N pijanèc anajèseic upoforèwn. 'Ara h exantlhtik anaz thsh parousiˆzei ekjetik poluplìkìthta O(G N ) anaforikˆ me ton arijmì twn upoforèwn. UpenjumÐzetai ìti to G anafèretai ston arijmì twn omˆdwn poluekpmp c tou sust matoc kai to N ston arijmì twn diajèsimwn upoforèwn. Sto B ma 1, o algìrijmoc apaiteð stajerì qrìno gia na sqhmatðsei ta sônola pou perilambˆnontai sthn ulopoðhsh tou algorðjmou kai na upologðsei thn m tra R G N. Sto deôtero B ma, o algìrijmoc brðskei to zeôgoc upoforèa kai omˆdac poluekpomp c pou èqei to megalôtero rujmì metˆdoshc dedomènwn R j,n metaxô G omˆdwn qrhst n poluekpomp c. Sthn perðptwsh pou èna MG èqei lˆbei ton elˆqisto arijmì upoforèwn pou tou antistoiqeð, tìte to MG apokleðetai apì epìmenec epanal yeic tou b matoc autoô. Sthn qeirìterh perðptwsh G sugkrðseic apaitoôntai gia kˆje ènan apì touc diajèsimìuc upoforeðc. Gia N upoforeðc, o algìrijmoc qreiˆzetai G N sugkrðseic. Epomènwc h poluplokìthta tou skèlouc autoô tou algorðjmou ftˆnei na èqei poluplokìthta thc tˆxhc O(G N). Sto B ma 3, o algìrijmoc yˆqnei gia to MG j (bl. PÐnaka 2.1) se sônolo G MG gia touc upìloipouc N G C j upoforeðc. Sto b ma autì o mègistoc arijmìc sugkrðsewn pou j=1 gðnontai eðnai G (N G C j ) kai epomènwc h poluplokìthta pou ftˆnei to b ma autì eðnai O(G (N G C j )). j=1 j=1 O olikìc bajmìc thc uplogistik c poluplokìthtac tou algìrijmou LCRA eðnai O(G N) kai h poluplokìthta thc ergasðac [18] eðnai O(K N) kai pˆnta G K, ìpou upenjumðzetai ìti K eðnai o arijmìc twn qrhst n tou sust matoc. H upologistik poluplokìthta

48 Kefˆlaio 2. Diasfˆlish tou QoS me Egguhmèno EÔroc Z nhc stouc Qr stec se Sust mata Poluekpomp c teqnologðac MIMO-OFDMA tou algorðjmou eðnai thc morf c O(L δ ), me L = G N kai δ = 1 pou eðnai grammik [30], sunep c o proteinìmenoc algìrijmoc LCRA parousiˆzei grammik poluplokìthta. AxÐzei na anaferjeð ìti oi sqediastikèc upojèseic tou algìrijmou, dhlad ìti mìno qr - stec apì to Ðdio MG mporoôn na moirˆzontai ton Ðdio upoforèa kai h metˆdosh MIMO pou uiojet same, mei noun shmantikˆ thn upologistik poluplokìthta tou sust matoc. H e- xantlhtik anaz thsh gia thn bèltisth epilog qr sth gia sust mata MIMO, parousiˆzei poluplokìthta O(K N T /N R N ) [19], upojètontac ìti gia kˆje upoforèa dialègoume èna uposônolo qrhst n kai kˆje eklektìc qr sthc qrhsimopoieð ìlh thn diˆstash apì to diˆsthma tou lambanomènou s matoc. Epomènwc, h eôresh thc bèltisthc lôshc eðnai apagoreutik akìma kai gia sugkrathmènec timèc twn K kai N [19]. Epiplèon, h poluplokìthta tou proteinìmenou algorðjmou eðnai anexˆrthth apì ton arijmì kerai n se pompì kai dèktec kai autì eðnai èna shmantikì pleonèkthma diìti h upologistik poluplokìthta susthmˆtwn MIMO auxˆnei shmantikˆ me thn parousða pollapl n kerai n [19]. O PÐnakac 2.2 pou akoloujeð, sunoyðzei tic poluplokìthtec tou proteinìmenou algìrijmou LCRA kai twn ˆllwn teqnik n. PÐnakac 2.2: Poluplokìthta algorðjmwn Εξαντλητική αναζήτηση LCRA [18] Βέλτιστη ανάθεση [19] Ανάθεση υποφορέων [9] O(G N ) O(G N) O(K N) O(K N T /N R N ) O(G N) 2.6 Montèla Prosomoi sewn kai Parˆmetroi JewroÔme èna sôsthma OFDMA me N = 128 upoforeðc, ìpou o SB exuphreteð G MGs kai kˆje èna apoteleðtei apì Ðdiouc ston arijmì qr stec. Tìso o SB ìso kai oi qr stec eðnai exoplismènoi me suskeuèc pollapl n kerai n kai upojètoume N r = N t = 2 gia tic prosomoi seic mac. To diajèsimo fˆsma eðnai B = 1 MHz kai o prosjetikìc leukìc gkaousianìc jìruboc AWGN eðnai N 0 = 80 dbw/hz. Se ìlec tic prosomoi seic pou parousiˆzontai se autì to Kefˆlaio, jewroôme kanˆli epilektikì sth suqnìthta pou apoteleðtai apì èxi anexˆrthta stoiqeða Rayleigh pollapl c diadrom c (taps) gia kˆje katerqìmenh diˆdosh metaxô kˆje miac apì tic N t keraðec ekpomp c kai tic N r keraðec l yhc gia kˆje qr sth. 'Opwc stic dhmosieôseic [10], [15] kai [31], jewroôme èna ekjetikˆ meioômeno profðl kajustèrhshc isqôoc, ìpou o lìgoc thc enèrgeiac tou l tap proc thn enèrgeia tou pr tou tap na eðnai e 2l. EpÐshc jewroôme mègisth exˆplwsh kajustèrhshc 5 ms kai mègisto fainìmeno doppler 30 Hz. Se ìla ta senˆria prosomoi sewn to kanˆli prosomoi netai 1000 forèc kai 10 qronikˆ deðgmata gia kˆje prosomoðwsh tou kanalioô kai gia kˆje qr sth. Oi kuriìterec parˆmetroi sunoyðzontai ston PÐnaka 2.3. Se ìla ta senˆria prosomoi sewn, h apìdosh tou proteinìmenou algorðjmou LCRA sugkrðnetai gia diˆforec timèc tou C j me thn apìdosh thc mejìdou anˆjeshc upoforèwn sthn dhmosðeush [9] kai thn statik mèjodo anˆjeshc TDMA pou protˆjhke sthn episthmonik ergasða [29], efarmìzontˆc thn se pollaplˆ MGs. SÔmfwna me thn teqnik TDMA, kˆje qr sthc lambˆnei èna dðkaio merðdio apì touc diajèsimouc radiopìrouc anexart twc thn

2.6 Montèla Prosomoi sewn kai Parˆmetroi 49 PÐnakac 2.3: Parˆmetroi arqik n sunjhk n prosomoi sewn Παράμετρος Τιμή Εύρος ζώνης 1 MHz Αριθμός υποφορέων 128 Αριθμός κεραιών εκπομπής 2 Αριθμός κεραιών λήψης 2 Μοντέλο ταχέων διαληψεων Jakes Model Αριθμός στοιχείων πολλαπλής διαδρομής (taps) 6 AWGN φασματική πυκνότητα 80 dbw/hz Αριθμός χρηστών 16 Μέγιστο φαινόμενο doppler 30 Hz katˆstash kanalioô sthn opoða brðsketai. Sto parìn Kefˆlaio, h mèjodoc TDMA efarmìzetai se kˆje MG sômfwna me tic (2.5) kai (2.6). Gia na dieukrinðzetai an o algìrijmoc TDMA efarmìzetai se mèjodo metˆdoshc poluekpomp c (multicast metˆdosh) se mèjodo apl c metˆdoshc unicast metˆdosh), dhl noume wc TDMA-MC, thn multicast TDMA kai wc TDMA-UC thn unicast TDMA. Tìso ston algìrijmo [9], ìso kai sthn statik TDMA, efarmìzetai omoiìmorfh katanom isqôoc. Epiplèon stic prosomoi seic perilambˆnoume dhmofileðc mejìdouc anˆjeshc radiopìrwn, ìpwc h anˆjesh upoforèwn max-snr kai algorðjmouc anˆjeshc monoekpomp c me elˆqistec apait seic twn qrhst n se eôroc z nhc. Wc mèjodo metˆdoshc me elˆqistec apait seic twn qrhst n se eôroc z nhc qrhsimopoioôme ton algìrijmo thc episthmonik c ergasðac mimo, o opoðoc eðnai sqediasmènoc gia sust mata MIMO. AntÐjeta ston algìrijmo max-snr, h dikaiosônh metaxô twn rujm n metˆdoshc dedomènwn twn qrhst n den apoteleð proteraiìthta kai anajètei kˆje upoforèa ston qr sth me to megalôtero SNR. Tèloc, diaforetikèc ekdoqèc tou algìrijmou LCRA jewroôntai sta diˆfora senˆria prosomoi sewn pou akoloujoun sto epìmeno Kefˆlaio. Kˆje ekdoq kajorðzetai apì thn tim tou C j, thn opoða jewroôme Ðdia gia ìla ta MGs se kˆje mða ekdoq tou algorðjmou LCRA. To C j kˆje ekdoq c orðzetai wc C j = N/(m G), ìpou m Z +. Se perðptwsh pou èqoume monoekpomp to m antikajistˆtai apì to w kai h sqèsh metaxô aut n twn dôo metablht n se mða omˆda qrhst n poluekpomp c eðnai w = K j m, j = 1,... G. 'Ara gia metˆdosh me monoekpomp èqoume c k = N/(w G), k = 1,... K, ìpou diapist netai ìti kaj c h parˆmetroc m auxˆnetai, o arijmìc twn egguhmènwn radiopìrwn gia kˆje MG mei netai. AxÐzei na shmeiwjeð ìti kaj c o arijmìc twn MUs se èna MG teðnei sto ˆpeiro, h qwrhtikìthta tou sust matoc gðnetai anexˆrthth apì to mègejoc tou MG ìpwc apodukneðetai [32]. Gia na axiologhjeð h apìdosh tou proteinìmenou algìrijmou, basizìmaste se kˆpoiec metrikèc: 1) thn fasmatik apìdosh ( spectral efficiency) kai 2) ton deðkth dikaiosônhc ( fairness pointer). H fasmatik apìdosh orðzetai apì thn (2.14):

50 Kefˆlaio 2. Diasfˆlish tou QoS me Egguhmèno EÔroc Z nhc stouc Qr stec se Sust mata Poluekpomp c teqnologðac MIMO-OFDMA η = G j=1 n=1 N x jn R jn B. (2.14) O deðkthc dikaiosônhc dðnetai sthn sqèsh (2.15) kai dônatai na pˆrei timèc sto diˆsthma metaxô tou mhdenìc kai thc monˆdac. Eˆn oi pìroi eðnai dðkaia katanemhmènoi se ìla ta MGs, tìte o deðkthc gðnetai Ðsoc me th monˆda [15], [31]. F = ( G G j=1 n=1 ) 2 N R jn ( G N ) 2. (2.15) R jn j=1 Sthn perðptwsh metˆdoshc dedomènwn me thn mèjodo thc apl c metˆdoshc, tìte h sqèsh (2.15) metabˆlletai ìpwc parakˆtw: f = K ( K n=1 k=1 n=1 ) 2 N b kn ( K N ) 2, (2.16) b kn k=1 ìpou, to b kn dhl nei ton rujmì metˆdoshc bit tou qr sth k mèsw tou upoforèwc n. n=1 2.7 Apotelèsmata twn Prosomoi sewn Se aut n thn enìthta parajètoume thn apìdosh tou proteinìmenou algorðjmou LCRA se sôgkrish me diˆfora sq mata multicast kai unicast pou periegrˆfhsan sthn prohgoômenh enìthta mèsa apì diˆfora senˆria prosomoi sewn, ìpwc autˆ dðnontai stic upoenìthtec pou akoloujoôn. 2.7.1 Rujmìc Metˆdoshc Dedomènwn kai DikaiosÔnh gia Diˆforec Timèc tou SNR Sta Sq mata 2.3 kai 2.4 èqoume jèsei to BER= 10 6 kai to SNR metabˆlletai apì 0 e c 40 katˆ 5 kˆje forˆ. O arijmìc twn omˆdwn poluekpomp c sto sôstma eðnai G = 4 me K 1 = K 2 = K 3 = K 4 = 4 MUs h kˆje mða. To Sq ma 2.3 deðqnei thn fasmatik apìdosh tou sust matoc gia diˆforec timèc tou mèsou SNR twn qrhst n, en to Sq ma 2.4 apeikonðzei thn dikaiosônh se sundiasmì me tic diakumˆnseic tou mèsou SNR. Apì to Sq ma 2.3 mporoôme na diapist soume ìti oi algìrijmoi pou enswmat noun sthn ulopoðhs touc metˆdosh multicast katafèrnoun megˆluterec apodìseic apì touc algorðjmouc unicast kai mˆlista ìso h mèsh tim tou SNR megal nei, tìso pio apodotikoð eðnai oi algìrijmoi multicast ènanti twn unicast. Eidikìtera gia ton algìrijmo LCRA blèpoume ìti ìlec oi ekdoqèc tou katafèrnoun kalôterouc rujmoôc metˆdoshc apì ton TDMA-MC pou

2.7 Apotelèsmata twn Prosomoi sewn 51 den qrhsimopoieð wc krit rio gia anˆjesh thn katˆstash kanalioô kˆje MG kai lðgo qamhlìterouc apì ton algorijmì anˆjeshc upoforèwn sthn ergasða [9], o opoðoc den perilambˆnei krit ria periorismoôc gia thn dikaiosônh tou sust matoc. To Sq ma 2.4 epibebai nei ton isqurismì autì kaj c ìlec oi ekdoqèc tou algìrijmou LCRA eðnai pio dðkaiec kai mˆlista anexˆrthta apì tic metabolèc tou SNR. Sq ma 2.3: Fasmatik apìdosh tou sust matoc gia diˆforec timèc tou mèsou SNR. 2.7.2 Rujmìc Metˆdoshc Dedomènwn kai antðstoiqh DikaiosÔnh gia diˆforec timèc BER To parìn senˆrio prosomoi sewn ereunˆ thn fasmatik apìdosh kai thn antðstoiqh dikaiosônh tou proteinìmenou kaj c kai ton proanaferjèntwn algorðjmwn se sunˆrthsh me to BER, to opoðo apoteleð shmantikì deðkth gia to QoS tou sust matoc. Stic prosomoi seic mac, to BER kumaðnetai apì 10 7 e c 10 3 me to SNR na eðnai 20 db. Ta apotelèsmata deðqnoun ìti kaj c h mèsh tim tou BER gðnetai megalôterh to Ðdio sumbaðnei kai me thn tim thc fasmatik c apìdoshc. Par' ìla autˆ, oi algìrijmoi pou aforoôn metˆdosh multicast eðnai pio apodotikoð apì touc autoôc pou aforoôn unicast metˆdosh me thn fasmatik touc apodos na metabˆlletai anˆloga me thn mèsh tim tou BER, kˆti pou de sumbaðnei me to deðkth dikaiosônhc, o opoðoc

52 Kefˆlaio 2. Diasfˆlish tou QoS me Egguhmèno EÔroc Z nhc stouc Qr stec se Sust mata Poluekpomp c teqnologðac MIMO-OFDMA Sq ma 2.4: DikaiosÔnh tou sust matoc gia diˆforec timèc tou mèsou SNR. metabˆlletai elˆqista. 2.7.3 Apìdosh se Epikoinwniakì Peribˆllon me Pollaplˆ MGs Se aut th seirˆ prosomoi sewn, diˆforoi arijmoð MGs jewroôntai kai kumaðnontai apì 2 e c 8, ìpou h mèsh tim tou SNR jewreðtai sta 20 db kai to BER sto 10 6. To Sq ma 2.7 apeikonðzei th fasmatik apìdosh tou sust matoc, diafìrwn algorðjmwn pou perilambˆnoun th metˆdosh multicast sthn ulopoihs touc kai leitourgoôn se peribˆllonta ìpou oi uphresðec multicast alli c ta MGs sto sôsthma eðnai pollaplˆ, en to Sq ma 2.8 apeikonðzei th dikaiosônh tou sust matoc. Apì to Sq ma 2.7, mporoôme na diapist soume thn antistˆjmish pou upˆrqei metaxô tou eôrouc twn radiopìrwn pou eggôatai o algìrijmoc LCRA se kˆje MG kai thc sunolik c fasmatik c apìdoshc. EpÐshc diapist noume ìti kaj c o arijmìc twn omˆdwn poluekpomp c gðnetai megalôteroc, antðstoiqa megal nei kai h tim thc fasmatik c apìdoshc. To fainìmeno autì ofeðletai ston epiplèon diaforismì pou prosjètei h Ôparxh perissotèrwn omˆdwn poluekpomp c sto sôsthma. AntÐjeta ìmwc me thn fasmatik apìdosh, h dikaiosônh mei netai. Se antistoiqða ìmwc me sumperˆsmata thc ergasðac [32], h apìdosh ìlwn twn algorðjmwn ja aggðxei èna ìrio akìma kai an o arijmìc twn MG teðnei sto ˆpeiro.

2.7 Apotelèsmata twn Prosomoi sewn 53 Sq ma 2.5: H fasmatik apìdosh tou sust matoc gia diˆforec timèc tou BER. 2.7.4 Katanom eôrouc z nhc jewroôme dôo diaforetikèc multicast uphresðec pou parèqontai stouc qr stec. Epomènwc, oi qr stec qwrðzontai se dôo MGs, to MG-1 kai to MG-2 me K 1 = K 2 = 8 MUs to kˆje èna. Ta Sq mata 2.9 kai 2.10 apeikonðzoun thn fasmatik apìdosh, kaj c epðshc kai thn dikaiosônh tou sust matoc gia diˆfora megèjh thc mèshc tim c tou SNR, sthn perðptwsh pou den upˆrqei diaforˆ stic ap leiec diˆdoshc metaxô twn dôo omˆdwn qrhst n kai kuriarqoôn oi dialeðyeic tou kanalioô. 'Omoiec grafikèc parastˆseic dðnontai sta Sq mata 2.11, 2.12, ìpou upˆrqei 5 db diaforˆ stic ap leiec diˆdoshc metaxô twn dôo MGs. O rujmìc metˆdoshc (bits/s/hz) kˆje omˆdac poluekpomp c xeqwristˆ parèqetai sta Sq mata 2.13, 2.14. Stic kampôlec apìdoshc tou Sq matoc 2.13 den upˆrqei diaforˆ sthn tim twn apwlei n diˆdoshc metaxô twn dôo MGs kai kajoristikìc parˆgontac stic sunj kec kanalioô tou enìc MG se sqèsh me to ˆllo, eðnai oi gr gorec dialeðyeic. AntÐjeta stic kampôlec tou Sq matoc 2.14, kurðarqoc parˆgontac eðnai oi ap leiec diˆdoshc. EpÐshc o trìpoc me ton opoðo katanèmetai to eôroc z nhc gia tic peript seic pou meletˆme kai gia touc algìrijmouc pou exetˆzoume dðnetai sta Sq mata 2.15 kai 2.16. Se aut thn enìthta jewroôme mða ekdoq tou algorðjmou LCRA me m = 2, to opoðo shmaðnei

54 Kefˆlaio 2. Diasfˆlish tou QoS me Egguhmèno EÔroc Z nhc stouc Qr stec se Sust mata Poluekpomp c teqnologðac MIMO-OFDMA Sq ma 2.6: H dikaiosônh tou sust matoc gia diˆforec timèc tou BER. ìti gia kˆje MG, o algìrijmoc egguˆtai prìsbash se C j = N/(2 2) = 32, upoforeðc, j = 1,..., G. Apì ta Sq mata 2.9, 2.11, diapist noume to arnhtikì antðktupo twn apwlei n diˆdoshc sthn olik fasmatik apìdosh gia ìlouc touc algorðjmouc. Epiplèon, oi apodìseic ìlwn twn sqhmˆtwn eðnai parapl siec sthn perðptwsh ìpou den lambˆnontai up' ìyh oi ap leiec diˆdoshc. Apì thn ˆllh meriˆ, ìtan jewroôntai sto sôsthma oi ap leiec diˆdoshc, to proteinìmeno sq ma apodðdei qamhlìterh olik fasmatik apìdosh apì thn teqnik anˆjeshc upoforèwn sthn ergasða [9] kai megalôterh apì thn teqnik TDMA (bl. Sq ma 2.11). Ta Sq mata 2.10, 2.12 deðqnoun thn meðwsh tou deðkth dikaiosônhc gia ìlec tic teqnikèc kai mia mikr aôxhsh sthn diaforˆ twn deikt n metaxô twn teqnik n. Sthn perðptwsh pou den jewroôntai oi ap leiec diˆdoshc, oi rujmoð metˆdoshc twn MGs faðnetai ìti parousiˆzoun amelhtèec diaforèc, ìpwc epðshc kai to eôroc z nhc to opoðo anatðjetai sthn kˆje omˆda qrhst n. Eidikìtera, h mèsh tim upoforèwn eðnai 64.6 kai 63.4 upoforeðc gia to MG-1 kai MG-2 antðstoiqa sômfwna me to sq ma anˆjeshc upoforèwn thc [9]. O proteinìmenoc algìrijmoc dðnei 64.4 upoforeðc sto MG-1 kai 63.4 upoforeðc sto MG-2 katˆ mèso ìro, en me thn teqnik TDMA upˆrqei apìluth dikaiosônh me 64 upoforeðc gia to kˆje MG.

2.8 Sumperˆsmata 55 Sq ma 2.7: Fasmatik apìdosh sust matoc kai pollaplˆ MGs. Antijètwc, ìtan oi ap leiec diˆdoshc tou s matoc perilambˆnontai stic prosomoi seic, kˆti pou eðnai pio kontˆ sta pragmatikˆ asôrmata sust mata, gðnetai antilhptì ìti h omˆda qrhst n me tic ligìterec ap leiec diˆdoshc, dhlad to MG-2 emfanðzei kalôterh fasmatik apìdosh apì to MG-1 se ìlec tic teqnikèc. To qˆsma apìdoshc metaxô twn dôo, eðnai eurôtero me thn teqnik sthn episthmonik ergasða [9] kai mikrìtero me thn TDMA ap' ìti me thn proteinìmenh teqnik ìpwc faðnetai sto Sq ma 2.14. Epiplèon, to Sq ma 2.16 deðqnei ìti to MG-1 me thn proteinìmenh teqnik èqei megalôtero mèrisma eôrouc z nhc me 37.3 upoforeðc kata mèso ìro, en to sq ma thc [9] tou dðnei 14.3 katˆ mèso ìro. Se aut thn perðptwsh epomènwc o proteinìmenoc algìrijmoc LCRA prosfèrei perissìtera sthn dikaiosônh tou sust matoc. EÐnai epðshc eôkola katanohtì ìti rujmðzontac katˆllhla thn parˆmetro m, mporoôme na dieujetoôme thn dikaiosônh tou sust matoc kaj c epðshc to mèrisma eôrouc z nhc tou kˆje MG. 2.8 Sumperˆsmata Sto Kefˆlaio autì protˆjhke kai analôjhke ènac algìrijmoc anˆjeshc twn radiopìrwn gia thn katerqìmenh zeôxh susthmˆtwn poluekpomp c teqnologðac MIMO pou leitourgoôn

56 Kefˆlaio 2. Diasfˆlish tou QoS me Egguhmèno EÔroc Z nhc stouc Qr stec se Sust mata Poluekpomp c teqnologðac MIMO-OFDMA Sq ma 2.8: DikaiosÔnh tou sust matoc kai pollaplˆ MGs. mèsw epilektik n sth suqnìthta kanali n. H metˆdosh poluekpomp c pou enswmat netai ston algìrijmo auxˆnei shmantikˆ thn qwrhtikìthta tou sust matoc ènanti twn algorðjmwn pou den thn perilambˆnoun, kaj c epðshc kai h Ôparxh pollapl n kerai n se pompì kai dèktec. O proteinìmenoc algìrijmoc apodeðqjhke ìti eðnai arketˆ qr simoc se sust mata poluekpomp c, ìpou pollaplˆ MGs sunupˆrqoun kai antagwnðzontai gia touc diajèsimouc radiopìrouc. O proteinìmenoc algìrijmoc LCRA eðnai ikanìc na parèqei egguhmènh prìsbash stouc diajèsimouc radiopìrouc se kˆje MG me euèlikto trìpo, akìma kai an oi dialeðyeic kai oi ap leiec tou kanalioô tou eðnai polô isqurèc. Parˆllhla, h proteinìmenh lôsh epitugqˆnei qamhl upologistik poluplokìthta, mei nontac thn poluplìthta tou probl matoc apì ekjetik se grammik. Tèloc, h upologistik poluplokìthta gðnetai anexˆrthth apì ton arijmì twn kerai n se SB kai qr stec kai ìpwc analôjhke eðnai sugkrðsimh me ˆlla qamhl c poluplokìthtac sq mata.

2.8 Sumperˆsmata 57 Sq ma 2.9: Sunolik fasmatik apìdosh gia diˆforec timèc tou mèsou SNR ìpou den upˆrqei diaforˆ stic ap leiec diˆdoshc metaxô twn MGs.

58 Kefˆlaio 2. Diasfˆlish tou QoS me Egguhmèno EÔroc Z nhc stouc Qr stec se Sust mata Poluekpomp c teqnologðac MIMO-OFDMA Sq ma 2.10: DikaiosÔnh gia diˆforec timèc tou mèsou SNR ìpou ìpou den upˆrqei diaforˆ stic ap leiec diˆdoshc metaxô twn MGs.

2.8 Sumperˆsmata 59 Sq ma 2.11: Fasmatik apìdosh kai mèsh tim SNR, ìpou upˆrqei 5 db diaforˆ stic ap leiec diˆdoshc metaxô twn dôo MGs.

60 Kefˆlaio 2. Diasfˆlish tou QoS me Egguhmèno EÔroc Z nhc stouc Qr stec se Sust mata Poluekpomp c teqnologðac MIMO-OFDMA Sq ma 2.12: DikaiosÔnh kai mèsh tim SNR, ìpou upˆrqei 5 db diaforˆ stic ap leiec diˆdoshc metaxô twn dôo MGs.

2.8 Sumperˆsmata 61 Sq ma 2.13: Fasmatik apìdosh kˆje MG kai mèsh tim tou SNR qwrðc diaforˆ sthn tim twn apwlei n diˆdoshc metaxô twn MGs.

62 Kefˆlaio 2. Diasfˆlish tou QoS me Egguhmèno EÔroc Z nhc stouc Qr stec se Sust mata Poluekpomp c teqnologðac MIMO-OFDMA Sq ma 2.14: Fasmatik apìdosh kˆje MG kai mèsh tim tou SNR me diaforˆ 5 db sthn tim twn apwlei n diˆdoshc metaxô twn MGs.

2.8 Sumperˆsmata 63 Sq ma 2.15: Katanom eôrouc z nhc qwrðc diaforˆ sthn tim twn apwlei n diˆdoshc metaxô twn MGs.

64 Kefˆlaio 2. Diasfˆlish tou QoS me Egguhmèno EÔroc Z nhc stouc Qr stec se Sust mata Poluekpomp c teqnologðac MIMO-OFDMA Sq ma 2.16: Katanom eôrouc z nhc me diaforˆ 5 db sthn tim twn apwlei n diˆdoshc metaxô twn MGs.

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BibliografÐa 67 [23] A. N. Zaki and A. O. Fapojuwo, a Graph-based Resource Allocation Algorithm for Downlink MIMO-OFDMA Networks, IEEE Global Telecommun. Conf., pp. 1-6, Dec. 2009. [24] M. S. Maw and I. Sasase, Resource Allocation Scheme in MIMO-OFDMA System for User s Different Data Throughput Requirements, IEICE Trans. Commun., vol. E91-B, no. 2, pp. 494-504, Feb. 2008. [25] B. Da and C. C. Ko, Resource Allocation in Downlink MIMO-OFDMA with Proportional Fairness, J. Commun.,Acad. Publ., vol. 4, no. 1, pp. 8-13, Feb. 2009. [26] S. Xiao, X. Xiao, B. Li and Z. Hu, Adaptive Subcarrier Allocation for Multiuser MIMO OFDM Systems in Frequency Selective Fading Channel, in Proc. IEEE Int. Wireless Commun., Networking & Mobile Computing Conf., Wuhan China, Sep. 2005. [27] X. Lu, Z. Li, J. Cai and X. Chen, An Adaptive Resource Allocation Algorithm Based on Spatial Subchannel in Multiuser MIMO/OFDM Systems, in Proc. IEEE Intern. Conf. on Commun. (ICC), Beijing China, May 2008. [28] S. T. Chung, and A. Goldsmith, Degrees of Freedom in Adaptive Modulation: A Unified View, IEEE Trans. Commun., vol. 49, no. 9, pp. 1561-1571, Sept. 2001. [29] H. Rohling, and R. Grunheid, Performance comparison of different multiple access schemes for the downlink of an OFDM communication system, in Proc. IEEE Veh. Techn. Conf. (VTC), vol. 3, pp. 1365-1369, Phoenix USA, May 1997. [30] G. Li, and H. Liu, Downlink Resource Allocation for Multi-Cell OFDMA System, IEEE Tran. Wireless. Commun., vol. 5, no 12, pp. 3451-3459, Dec. 2006. [31] Z. Shen, J. Andrews, B.L Evans, Adaptive Resource Allocation in Multiuser OFDM System with Proportional Rate Constraints, IEEE Tran. Wireless. Commun., vol. 4, no. 6, pp. 2726-2737, Nov. 2005. [32] C. Suh and J. Mo, Resource Allocation for Multicast Services in multicarrier Wireless Communications, IEEE Tran. Wireless. Commun., vol. 7, no. 1, pp. 27-31, Jan. 2008.

Kefˆlaio 3 UlopoÐhsh AlgorÐjmou me Egguhmèno EpÐpedo RujmoÔ Metˆdoshc twn Dedomènwn kai tou BER stouc Qr stec Polukuyelwt n Susthmˆtwn OFDMA 3.1 PerÐlhyh Sto parìn Kefˆlaio meletˆme to prìblhma katanom c twn radiopìrwn se polukuyelwtˆ asôrmata dðktua, basismèna sthn pollapl prìsbash OFDMA, ta opoða parèqoun egguhmmèno epðpedo poiìthtac uphresðwn (QoS) stouc qr stec. Wc parˆmetroi thc lambanìmenhc poiìthtac uphresðac, jewroôme ton rujmì metˆdodhc dedomènwn kai to BER ston kˆje qr - sth kai gia na lôsoume autì to prìblhma proteðnoume èna tropopoihmèno analogikˆ dðkaio algìrijmo qronoprogrammatismoô (PFS). O proteinìmenoc algìrijmoc katanom c twn radiopìrwn apoteleðtai apì dôo fˆseic. Arqikˆ, oi diajèsimoi radiopìroi katanèmontai katˆ tètoio trìpo ste na exasfalisteð èna elˆqisto epðpedo rujmoô metˆdoshc dedomènwn kai sugkekrimèno BER gia ìlouc touc qr stec pou an koun sthn Ðdia klˆsh. Sth sunèqeia, eˆn kai efìson exasfalisteð to apaitoômeno epðpedo QoS tou kˆje qr sth, o algìrijmoc katanèmei touc enapomeðnantec radiopìrouc sômfwna me th mèjodo katanom c tou analogikˆ dðkaiou qronoprogrammatist (PFS). O proteinìmenoc algìrijmoc eðnai katanemhmènoc sto asôrmato dðktuo kai kôria pleonekt matˆ tou eðnai: h qamhl upologistik poluplokìthta kai h ikanìthta tou na diathreð megalôterec analogðec ikanopoihmènwn qrhst n se sqèsh me ˆllec mejìdouc katanom c radiopìrwn pou efarmìzontai se polukuyelikˆ asôrmata dðktua. Mèsw prosomoðwshc, deð- 68

3.2 Eisagwg 69 qnetai ìti h proteinìmenh teqnik upertereð ènanti twn ˆllwn teqnik n. 3.2 Eisagwg Ta mellontikˆ asôrmata kuyelwtˆ sust mata, parˆllhla me thn uiojèthsh thc OFDMA wc teqnologða prìsbashc tou radiofˆsmatoc, anamènetai na parèqoun plhj ra uphresi n me poikðlec apait seic QoS se megˆlouc arijmoôc qrhst n. Epomènwc, h apantaqoô uyhloô rujmoô metˆdoshc dedomènwn kˆluyh kai h paroq egguhmènou epipèdou QoS apoteloôn touc kôriouc stìqouc twn asôrmatwn thlepikoinwniak n parìqwn [1]-[4]. Sumbatikèc teqnikèc katanom c radiopìrwn epanaqrhsimopoðhshc suqnot twn (Reuse-n, n 1) [5] (bl. Parˆrthma Aþ) kai prosfˆtwc proteinìmena statikˆ sq mata kataq rhshc suqnot twn ìpwc h klasmatik epanaqrhsimopoðhsh suqnot twn (FFR) [6]-[9] (bl. Parˆrthma Bþ), den eðnai katˆllhla gia ta epomènhc geneˆc asôrmata dðktua, diìti eðte parèqoun qamhlì rujmì metˆdoshc dedomènwn stic ˆkrec thc kˆje kuyèlhc eðte apaitoôn prìtero sqediasmì kataq rhshc suqnot twn, o opoðoc mei nei thn pl rh axiopoðhsh twn diajèsimwn radiopìrwn [2], [3] kai epiplèon kajistˆ polô dôskolh thn enswmˆtwsh twn epikeðmenwn femtokuttarik n diktôwn [4]. Epomènwc gia na axiopoi soume apodotikìtera to diajèsimo eôroc z nhc kai na parèqoume kalôterh poiìthta uphresi n stouc asôrmatouc qr stec, dunamikoð algìrijmoi kataq rhshc pìrwn èqoun protajeð prìsfata sthn bibliografða, ìpwc stic episthmonikèc ergasðec [1], [2], [3]. Eidikìtera sthn ergasða [1], oi suggrafeðc ulopoioôn èna hmikatenemhmèno algìrijmo katˆllhlo gia polukuyelikˆ dðktua kai megistopoioôn to rujmì metˆdoshc dedomènwn tou sust matoc parablèpontac ìmwc thn apìdosh thc kˆje kuyèlhc sta ˆkra thc. Antijètwc, o katanemhmènoc algìrijmoc kataq rhshc radiopìrwn pou protˆjhke sthn ergasða [2] belti nei thn apìdosh sta ˆkra thc kˆje kuyèlhc qwrðc ìmwc na diereunˆtai h sunolik qwrhtikìthta tou diktôou. OmoÐwc, oi suggrafeðc, sthn ergasða [3], proteðnoun èna kentropoihmèno algìrijmo apofug c parembol n kai epitugqˆnoun enisqumèno rujmì metˆdoshc dedomènwn sta ˆkra thc kuyèlhc me mikr upobˆjmish tou olikoô rujmoô metˆdoshc tou sust matoc kai aôxhsh thc upologistik c poluplokìthtac. EntoÔtoic, kanènac apì touc proanaferjèntec algorðjmouc katanom c pìrwn se polukuyelwtˆ dðktua den egguˆtai sugkekrimèno epðpedo QoS stouc qr stec. Epomènwc sto parìn kefˆlaio, exetˆzoume kai proteðnoume ènan upobèltisto algìrijmo kataq rhshc radiopìrwn pou basðzetai ston qronoprogrammatist PFS kai sqediastik tou proteraiìthta eðnai na diasfalðsei sugkekrimènec stˆjmec QoS stouc qr stec. Oi loipèc upoenìthtec tou parìntoc KefalaÐou organ nontai wc akoloôjwc: To prìtupo tou upo melèth sust matoc kai h diamìrfwsh tou probl matoc ekq rhshc radiopìrwn kai exasfˆlishc sugkekrimènhc stˆjmhc QoS stouc qr stec perigrˆfontai sthn upoenìthta 3.3. H proteinìmenh teqnik ekq rhshc radiopìrwn dðnetai sthn parˆgrafo 3.4, en sthn upoenìthta 3.5 parèqetai h anˆlush thc upologistik c poluplokìthtac thc teqnik c. Oi parˆmetroi kai h mejodologða pou akoloujeðtai stic prosomoi seic tou KefalaÐou dðnontai sthn upoenìthta 3.6, en ta arijmhtikˆ apotelèsmata kai o sqoliasmìc touc, mac ta pa-

70 Kefˆlaio 3. UlopoÐhsh AlgorÐjmou me Egguhmèno EpÐpedo RujmoÔ Metˆdoshc twn Dedomènwn kai tou BER stouc Qr stec Polukuyelwt n Susthmˆtwn OFDMA rèqei h parˆgrafoc 3.7. Tèloc sthn upoenìthta 3.8 katagrˆfontai ta sumperˆsmata tou parìntoc KefalaÐou. 3.3 Montèlo tou Sust matoc kai DiatÔpwsh tou Probl matoc 3.3.1 Perigraf tou sust matoc Sthn paroôsa parˆgrafo parèqoume to prìtupo tou sust matoc kai thn diatôpwsh tou probl matoc, apì thn opoða prokôptei h proteinìmenh teqnik ekq rhshc radiopìrwn. Gia to montèlo tou asôrmatou epikoinwniakoô sust matoc jewroôme tic akìloujec upojèseic: 1. JewroÔme èna polukuyelwtì dðktuo basismèno sthn teqnologða prìsbashc OFDMA, to opoðo apoteleðtai apì L ston arijmì SB. 2. Kˆje SB exuphreteð K l ston arijmì qr stec, ìpou l = 1, 2,... L, mèsw N upoforèwn pou epanaqrhsimopoioôntai se kajènan apì touc SB tou diktôou. 3. To sunolikì eôroc z nhc eðnai B kai ta qronikˆ metaballìmena kanˆlia metaxô tou SB kai twn diafìrwn qrhst n jewroôntai asôrmata kanˆlia epilektikˆ stic suqnìthtec me anexˆrthth diˆleiyh Rayleigh kai mporoôn na jewrhjoôn stajerˆ katˆ thn qronik perðodo anˆjeshc radiopìrwn. 4. H diasumbolik parembol (ISI) afaireðtai pl rwc, lìgw ekmetˆlleushc twn teqnik n OFDM, ìpou to plˆtoc kˆje upoforèa eðnai katˆ poô mikrìteto apì to eôroc z nhc sunoq c tou kanalioô. Katˆ sunèpeia kˆje qr sthc upìkeitai se epðpedh diˆleiyh se kˆje upoforèa [10], [11]. 5. Kˆje SB èqei tèleia gn sh thc katˆstashc kanalioô gia kˆje qr sth pou exuphreteð mèsw CSI pou parèqontai apì touc qr stec. O lìgoc tou s matoc proc parembol sun ton jìrubo (SINR) tou qr sth k ston upoforèa n sumbolðzetai wc γ kn kai dðnetai apì thn exðswsh: γ kn = L K l l=1 m=1 g kn p kn p mn g mn + σ 2, m k, (3.1) ìpou, p mn sumbolðzei thn posìthta isqôoc pou ekqwreðtai ston upoforèa n tou qr sth m kai g mn antiproswpeôei to kèrdoc kanalioô metaxô tou qr sth m kai tou SB pou ton exuphreteð mèsw tou upoforèa n kai perilambˆnei tic ap leiec diadrom c, tic dialeðyeic kai to fainìmeno skðashc. Tèloc, wc σ 2 sumbolðzoume thn isqô tou jorôbou, me σ 2 = N 0 B/N kai N 0 thn fasmatik puknìthta isqôoc tou jorôbou. Katˆ sunèpeia, o epiteôximoc rujmìc metˆdoshc dedomènwn r kn tou qr sth k mèsw tou upoforèa n kai kˆnontac qr sh thn suneq fìrmoula gia thn prosarmostik diamìrfwsh kai kwdikopoðhsh (ACM), dðnetai apì thn exðswsh:

3.3 Montèlo tou Sust matoc kai DiatÔpwsh tou Probl matoc 71 r kn = B N log 2 ( 1 + 1.5γ ) kn, (3.2) ln(5p e ) ìpou, me P e sumbolðzoume ton epidiwkìmeno rujmì metˆdoshc lanjasmènwn bit (BER). E- pðshc orðzoume thn m tra ekq rhshc upoforèwn Y K N = [y kn ], ìpou y kn = 1 eˆn ston k qr sth èqei ekqwrhjeð o upoforèac n kai y kn = 0, an ìqi. Kˆje SB diathreð thn dik tou xeqwrist m tra anˆjeshc upoforèwn. 3.3.2 Majhmatik diatôpwsh tou probl matoc Exetˆzontac tic parapˆnw upojèseic, to prìblhma katanom c radiopìrwn tou sust matoc se kˆje SB diatup netai wc prìblhma duadikoô akèraiou grammikoô programmatismoô (BILP) ìpwc akoloujeð: upì touc periorismoôc: K N max r kn y kn (3.3) k=1 n=1 K y kn = 1, n N (3.4) k=1 y kn {0, 1}, k K, n N (3.5) N y kn r kn Q k, k K. (3.6) n=1 Oi periorismoð (3.4) kai (3.5) exasfalðzoun ìti se kˆje kuyèlh, ènac upoforèac eðnai dunatìn na anatejeð se ènan mìno qr sth, ìpou N kai K eðnai ta sônola twn upoforèwn kai twn qrhst n antðstoiqa se kˆje SB. Me thn sômbash aut loipìn exaleðfoume oloklhrwtikˆ thn endokuttarik parembol (ICI). Epiplèon h sqèsh (3.6), antikatroptðzei tic apait seic tou qr sth k se QoS kai h metablht Q k dhl nei thn elˆqisth apaðthsh QoS tou qr sth k. Tèloc, lambˆnoume up' ìyhn ìti o kˆje SB èqei ìrio sthn olik isqô pou ekpèmpei, thn P t upojètoume. Epomènwc, upˆrqoun dôo akìmh periorismoð sto prìblhma pou aforoôn thn isqô tou SB kai autoð eðnai oi: K k=1 n=1 N p kn P t (3.7) p kn 0, k K, n N (3.8) ìpou h sqèsh (3.7) perigrˆfei ton periorismì sthn olðkh ekpempìmenh isqô kai h sqèsh (3.8) ìti h posìthta isqôoc pou ekqwreðtai se kˆje upoforèc eðnai pˆnta megalôterh kai Ðsh tou mhdenìc.

72 Kefˆlaio 3. UlopoÐhsh AlgorÐjmou me Egguhmèno EpÐpedo RujmoÔ Metˆdoshc twn Dedomènwn kai tou BER stouc Qr stec Polukuyelwt n Susthmˆtwn OFDMA AxÐzei na epishmˆnoume ìti h prospˆjeia eôreshc thc bèltisthc lôshc sto parapˆnw prìblhma, epibarônei shmantikˆ to upologistikì kìstoc. EpÐshc prèpei na analogistoôme ìti h lôsh anˆjeshc radiopìrwn prèpei na lhfjeð mèsa se èna eôlogo qronikì diˆsthma exaitðac gr gorwn metaboll n tou kanalioô. 'Ara, upobèltistoi algìrijmoi epðlushc pou parousiˆzoun qamhl upologistik poluplokìthta protimìntai, idiaðtera se sust mata ìpou o arijmoð qrhst n kai upoforèwn eðnai arketˆ megˆloi. 3.4 Proteinìmenh Teqnik Katanom c twn Radiopìrwn Sthn paroôsa enìthta parousiˆzoume thn proteinìmenh teqnik ekq rhshc radiopìrwn, h opoða eðnai ènac algìrijmoc pou apoteleðtai apì trða b mata ìpwc dðnontai sunoptikˆ parakˆtw: B ma 1: KajorÐzei ta sônola twn diajèsimwn upoforèwn N kai twn qrhst n K kai akìmh to sônolo pou perièqei wc stoiqeða thn èlaqisth apaðthsh QoS twn qrhst n. ArqikopoieÐ thn m tra Y M N jètontac ìla ta stoiqeða thc mhdèn kai katanèmei omoiìmorfa stouc upoforeðc, posìthta isqôoc Ðsh me to mègisto epitreptì ìrio ekpempìmenhc isqôoc tou SB. B ma 2: Anajètei upoforeðc stouc qr stec sômfwna me ton ˆplhsto trìpo anˆjeshc (greedy scheduling) dhlad kˆje upoforèac anatðjetai se qr sth ste o sunolikìc rujmìc metˆdoshc dedomènwn na megistopoieðtai qwrðc na exetˆzontia prohgoômenec anajèseic radiopìrwn. H diadikasða aut tou algorðjmou epanalambˆnetai mèqri na ikanopoihjoôn oi elˆqistec apait seic QoS twn qrhst n. B ma 3: Katanèmei touc enapomeðnantec apì to B ma 2 radiopìrouc, eˆn autoð upˆrqoun sômfwna me ton qronoprogrammatist PFS. O qronoprogrammatist c PFS, jewreðtai eurèwc wc ènac polô elkustikìc sumbibasmìc metaxô mèsou mègistou rujmoô metˆdoshc tou sust matoc kai thc dikaiosônhc twn qrhst n [12], [13]. Prìsfath episthmonik èreuna [14] gia tic teqnikèc anˆjeshc twn radiopìrwn jewreð ton PFS wc isodônamo thc lôshc Nash. SÔmfwna loipìn me ton PFS, se kˆje qronik perðodo apìfashc anˆjeshc t + 1 kai upojètontac ìti o efiktìc rujmìc metˆdoshc dedomènwn tou qr sth k eðnai R k (t + 1), h µ-qronik n periìdwn arijmhtikh mèsh tim mèqri thn qronik perðodo t, eðnai ψ k (t), tìte ja anatejeð upoforèac ston qr sth k, ìpou k = arg max k R k (t+1) ψ k (t). H mèsh arijmhtik tim tou rujmoô metˆdoshc dedomènwn upologðzetai wc: ψ k (t + 1) = (1 1/m) ψ k (t) + I k (t + 1) R k (t + 1)/k, (3.9) ìpou, I k (t) eðnai ènac deðkthc tou qronoprogrammatist pou aforˆ thn qronik perðodo t kai lambˆnei timèc: 1, eˆn ston qr sth k èqei anatejeð upoforèac I k (t) = 0, eˆn ìqi Epomènwc, ìtan anatejeð upoforèac se kˆpoion qr sth, h pijanìthta na tou anatejoôn

3.4 Proteinìmenh Teqnik Katanom c twn Radiopìrwn 73 epiplèon upoforeðc mei netai ˆlloi qr stec ja èqoun megalôterh pijanìthta na touc anatejoôn upoforeðc. ArqikopoÐhsh: Jèse N = {1, 2,..., N}, K = {1, 2,..., K} Q = {Q 1, Q 2,..., Q K } y kn = 0, k K kai n N p kn = P t /N, k K kai n N Sto B ma autì o algìrijmoc sqhmatðzei to sônolo K pou sumbolðzei to sônolo twn qrhst n pou exuphreteð o SB, kaj c epðshc kai to sônolo N twn diajèsimwn upoforèwn. EpÐshc sqhmatðzei to sônolo Q pou perðeqei thn elˆqisth stˆjmh QoS kˆje qr sth se bps. 'Ola ta stoiqeða y kn thc m trac anˆjeshc upoforèwn jètontai sto mhdèn kai epðshc upologðzetai to posì isqôoc pou ekqwreðtai ston kˆje ènan apì touc N upoforeðc. Kaj c K = {}: Brec qr sth k K kai upoforèa n N, ste r kn r mn m K kai n N Eˆn R k < Q k y kn = 1 R k = R k + r kn N \ {n } Upolìgise thn (3.3) Eˆn R k Q k Q \ {Q k } K \ {k} Sto parìn B ma, o algìrijmoc brðskei to zeôgoc qr sth kai upoforèa pou apodðdei to megalôtero rujmì metˆdoshc dedomènwn. Efarmìzetai epomènwc, ˆplhstoc trìpoc anˆjeshc upoforèwn (greedy scheduling). 'Otan kajoristeð autì to zeôgoc upoforèa kai qr sth, tìte exetˆzetai èan o sugkekrimenoc qr sthc k, èqei ikanopoi sei dh thn elˆqisth QoS apiths tou. Eˆn den alhjeôei h upìjesh aut, tìte o sugkekrimènoc upoforèac kataqwreðtai ston qr sth kai to antðstoiqo stoiqeðo sthn m tra anˆjeshc upoforèwn paðrnei thn tim 1. Eˆn ìmwc o rujmìc metˆdoshc dedomènwn ston qr sth upologðzetai Ðsoc h parapˆnw apì thn tim tou stoiqeðou pou tou antistoiqeð sto sônolo Q, tìte apokleðetai to stoiqeðo QoS tou qr sth apì to sônolo Q kai o qr sthc apì to K. Se autì to B ma tou algorijmoô efarmìzoume thn ˆplhsth anˆjesh radiopìrwn me skìpo thn taqôterh sôgklish sto elˆqisto egguhmèno epðpedo QoS twn qrhst n. Kaj c N {}:

74 Kefˆlaio 3. UlopoÐhsh AlgorÐjmou me Egguhmèno EpÐpedo RujmoÔ Metˆdoshc twn Dedomènwn kai tou BER stouc Qr stec Polukuyelwt n Susthmˆtwn OFDMA Brec ton upoforèa n kai ton qr sth m K, ste m = arg max r m n ψ m R m = R m + r m n y m n = 1 N \ {n } Upolìgise thn sqèsh (3.3) Se autì to B ma exetˆzetai kˆje forˆ eˆn to sônolo N eðnai kenì. Eˆn ìqi, tìte shmaðnei ìti èqoume ftˆsei to èlaqisto epðpedo QoS ìlwn twn qrhst n pou exuphreteð o SB kai eqoôn upˆrqoun akìmh upoforeðc pou den èqoun ekqwrhjeð. Tìte o algìrijmoc prospajeð na breð to zeôgoc upoforèa kai qr sth pou megistopoieð ton lìgo tou rujmoô metˆdoshc tou qr sth pan ston upoforèa auton proc thn mesh tim tou rujmoô metˆdoshc tou qr sth. 'Otan apofasisteð autì, tìte ekqwreðtai o upoforèac ston qr sth jètontac to antðstoiqo stoiqeðo thc Y K N Ðso me thn monˆda kai o upoforèac bgaðnei apì to sônolo N. 3.5 Anˆlush thc Upologistik c Poluplokìthtac To prìblhma pou apotup netai stic exis seic (3.3) (3.8) eðnai èna (BILP) prìblhma kai h emplekìmenh upologistik poluplokìthta gia thn exagwg thc bèltisthc lôshc eðnai apagoreutikˆ uyhl. 'Enac SB pou exuphreteð K qr stec mèsw N upoforèwn ofeðlei na exetˆsei K N pijanèc anajèseic upoforèwn. Epomènwc h eujeða epðlush tou probl matoc parousiˆzei ekjetik upologistik poluplokìthta O(K N ). Sthn perðptwsh thc teqnik c mac, to B ma 1 apaiteð stajerì qrìno gia thn arqikopoðhsh twn emplekìmenwn sunìlwn kai thn omoiìmorfh katanom isqôoc stouc upoforeðc. Sto deôtero B ma o algìrijmoc qreiˆzetai na sugkrðnei sthn qeirìterh perðptwsh K qr stec gia na anajèsei ènan sugkekrimèno upoforèa. Gia N diajèsimouc upoforeðc ja qreiasteð na prˆxei N ston arijmì tètoiec sugkrðseic. Epomènwc, autì to B ma tou algorðjmou emfanðzei an tato ìrio poluplokìthtac thc tˆxhc O(K N). Sto B ma 3, upojètontac ìti upˆrqoun N > 0 diajèsimoi upoforeðc pou den èqoun kataqwrhjeð sto prohgoômeno b ma, tìte o algìrijmoc yˆqnei metaxô K qrhst n kai N upofore n na breð to zeôgoc upoforèa-qr sth pou dinei thn mègisth tim ston lìgo rujmoô metˆdoshc dedomènwn ston qr sth mesw tou upoforèa proc to mèso rujmì metˆdoshc tou qr sth. Opìte kai se autì to b ma ja qreiasteð na gðnoun KN sugkrðseic sthn qeirìterh twn peript sewn. Epomènwc, autì to B ma tou algorðjmou èqei upologistik poluplokìthta thc tˆxhc O(K N ). AxÐzei na anaferjeð ìti pˆnta N N. 'Ara h sunolik upologistik poluplìlìthta thc teqnik c eðnai thc tˆxhc O(K N), h opoða eðnai grammik kai apodotik se sôgkrish me thn poluplokìthta O(K N ) thc exantlhtik c anaz thshc [1]. Ston PÐnaka 3.1 sunoyðzontai oi poluplokìthtec ìlwn twn teqnik n pou anafèrjhkan sto parìn kefˆlaio. Shmei netai ìti gia ta sq mata SFR kai PFR kuriarqeð h poluplokìthta thc anˆjeshc pìrwn sthn kentrik perioq thc kuyèlhc me K kai N touc arijmoôc

3.6 Parˆmetroi twn Prosomoi sewn 75 qrhst n kai upoforèwn antðstoiqa, oi opoðoi eðnai sun jwc megalôteroi twn antistoðqwn sthn diaqwristik epifˆneia thc kuyèlhc. An den isqôei h upìjesh aut, tìte h poluplokìthta thc teqnik c eðnai Ðsh me thn poluplokìthta twn qrhst n sta ˆkra thc kuyèlhc. PÐnakac 3.1: Upologistik poluplokìthta teqnik n Τεχνική Υπολογιστική πολυπλοκότητα Reuse-1 O(K N) Reuse-3 O( 1 3 KN) SFR O( K N) PFR O( K N) Προτεινόμενη τεχνική O(K N) Εξαντλητική αναζήτηση O(K N ) 3.6 Parˆmetroi twn Prosomoi sewn JewroÔme asôrmato polukuyelwtì sôsthma pou apoteleðtai apì 19 SB (kuyèlec) me to diajèsimo fˆsma suqnot twn na eðnai 20 MHz kai th suqnìthta tou forèa na eðnai 2 GHz. EpÐshc jewroôme ìti oi diajèsimoi upoforeðc eðnai N = 100. To mègisto e- pitreptì ìrio thc ekpempìmhc isqôoc orðzetai sta P t = 46 dbm kai fasmatik puknìthta jorôbou N 0 = 174dBm/Hz. Oi ap leiec diˆdoshc perigrˆfontai apì thn sqèsh L p (d k ) = 128.1 + 37.6 log(d k ) [db], ìpou d k eðnai h apìstash tou qr sth k apì ton SB se Km. H tupik apìklish gia to fainìmeno thc skðashc eðnai 8 db kai o epidiwkìmenoc rujmìc metˆdoshc lanjasmènwn bit eðnai P e = 10 7. Upojètoume ìti oi qr stec an koun sthn Ðdia klˆsh uphresðac kai topojetoôntai se tuqaðec apostˆseic kai gwnðec apì ton SB pou touc exuphreteð se kˆje kuyèlh. H mikrìterh apìstash apì to SB eðnai ta 35 m kai h megalôterh to 1 Km, pou eðnai h aktðna thc kˆje kuyèlhc sto sôsthmˆ mac. To epilektikì sthn suqnìthta kanˆli apoteleðtai apì èxi anexˆrthta stoiqeða Rayleigh pollap c diadrom c (taps), pou to kˆje èna apì autˆ ta stoiqeða dhmiourgeðtai qrhsimopoi ntac to montèlo tou Jakes [15] me ekjetikˆ meioômeno profðl kajustèrhshc isqôoc ìpwc stic ergasðec [16], [17]. O lìgoc thc isqôoc tou l stoiqeðou proc to arqikì eðnai e 2l. EpÐshc, upojètoume mègisth tim tou fainomènou doppler eðnai 30 Hz. Statistikˆ apìdoshc èqoun exaqjeð apì 300 anexˆrthtec rðyeic qrhst n kai gia 15 qr stec se kˆje kuyèlh. Ta statistikˆ thc kˆje rðyhc sullègontai gia qronikì diˆsthma 100 prosomoi sewn kanalioô. 3.7 Apotelèsmata twn Prosomoi sewn O proteinìmenoc algìrijmoc antiparatðjetai se paradosiakˆ sq mata katˆllhla gia polukuyelikˆ sust mata pou eðte efarmìzoun epijetik politik sthn qr sh tou radiofˆsmatoc, ìpwc to sq ma Reuse-1, eðte aposkopoôn sthn apìdosh uyhlìterwn rujm n metˆdoshc dedomènwn mèsw katakermatismoô tou diajèsimou fˆsmatoc kai apofug thc omokanalik c

76 Kefˆlaio 3. UlopoÐhsh AlgorÐjmou me Egguhmèno EpÐpedo RujmoÔ Metˆdoshc twn Dedomènwn kai tou BER stouc Qr stec Polukuyelwt n Susthmˆtwn OFDMA parembol c (CCI) apì touc geitonikoôc SB san thn teqnik Reuse-3 [5]. EpÐshc, sugkrðnoume thn apìdosh thc proteinìmenhc teqnik c me thn apìdosh prosfˆtwc proteinìmenwn teqnik n ìpwc eðnai h teqnik piac epanaqrhsimopoðhshc suqnot twn (SFR) kai h teqnik merik c epanaqrhsimopoðhshc suqnot twn (PFR), twn opoðwn skopìc eðnai na enisqôsoun to rujmì metˆdoshc dedomènwn stouc qr stec pou brðskontai sta ˆkra thc kuyèlhc [8], [9], ( bl. Parˆrthma Gþ). 'Olec oi teqnikèc anˆjeshc radiopìrwn, twn opoðwn h apìdosh antiparabˆlletai me thn apìdosh thc preteinìmenhc teqnik c ekmetalleôontai ton diaforismì poll n qrhst n diìti kˆnoun qr sh tou qronoprogrammatist PFS. Sq ma 3.1: Ajroistik sunˆrthsh katanom c (cdf) mèsou rujmoô metˆdoshc dedomènwn qr sth. To Sq ma 3.1 apeikonðzei thn ajroistik sunˆrthsh katanom c (ASK) thc mèshc tim c tou rujmoô metˆdoshc dedomènwn twn qrhst n gia thn proteinìmenh teqnik me elˆqisto epðpedo QoS 1 Mbps kai 1.5 Mbps kai twn upoloðpwn teqnik n diaqeðrishc radiopìrwn. H qamhlìterh ourˆ thc ASK megenjônetai sto Sq ma 3.2, ste na mporèsoume na doôme to shmeðo 5% thc ASK, to opoðo sômfwna me th mejodologða axiolìghshc gia to LTE jewreðtai wc o rujmìc metˆdoshc dedomènwn sta ˆkra thc kuyèlhc [18]. Diapist noume ìti me thn proteinìmenh teqnik mporoôme na epitôqoume enisqumènh apìdosh sta ˆkra thc kuyèlhc me thn katˆllhlh rôjmish tou elaqðstou epipèdou QoS. Epomènwc, h proteinìmenh teqnik

3.7 Apotelèsmata twn Prosomoi sewn 77 PÐnakac 3.2: SÔgkrish Teqnik n Τεχνική 5% 95% Χωρητικότητα σε Mbps σε Mbps σε Mbps Reuse-1 0.95 20.15 103.3 Reuse-3 1.16 7.7 50.6 SFR 1.25 17.6 89.1 PFR 1.07 14.5 74.8 Prop.-Q k = 1 Mbps 1.1 16.5 83.8 Prop.-Q k = 1.5 Mbps 1.42 14.25 65.6 Sq ma 3.2: Megèjunsh thc qamhlìterhc ourˆc thc ASK (cdf) tou mèsou rujmoô metˆdoshc dedomènwn qr sth. prosfèrei euelixða sthn prosarmog tou rujmoô metˆdoshc dedomènwn stouc qr stec kˆti pou den mporoôn na epituqoôn oi ˆllec teqnikèc lìgw tou statikoô trìpou leitourgðac touc. EntoÔtoic, pˆnta upˆrqei antistˆjmish metaxô tou rujmoô metˆdoshc dedomènwn thc kuyèlhc sta ˆkra thc kai tou sunolikoô rujmoô metˆdoshc dedomènwn, ìpwc sunoyðzetai ston PÐnaka 3.2. Epiplèon, to Sq ma 3.3 mac parèqei thn pijanìthta parabðashc tou QoS gia ìlec tic emplekìmenec sthn prosomoðwsh teqnikèc. H proteinìmenh teqnik sugkrðnetai me tic pro-

78 Kefˆlaio 3. UlopoÐhsh AlgorÐjmou me Egguhmèno EpÐpedo RujmoÔ Metˆdoshc twn Dedomènwn kai tou BER stouc Qr stec Polukuyelwt n Susthmˆtwn OFDMA Sq ma 3.3: Pijanìthta parabðashc tou egguhmènou epipèdou QoS twn qrhst n. anaferjeðsec teqnikèc gia diˆforec stˆjmec elˆqistou QoS miac uphresðac. Wc pijanìthta parabðashc tou QoS, orðzoume thn pijanìthta na mhn èqoun oi qr stec pou an koun se mia sugkekrimènh klˆsh, to egguhmèno epðpedo QoS thc uphresðac. Apì to Sq ma 3.3, eôkola diapist noume thn anwterìthta thc proteinìmenhc teqnik c, diìti prosfèrei egguhmèno epðpedo QoS kai ˆra enisqumènh poiìthta empeirðac QoE se perissìterouc qr stec se sqèsh me tic ˆllec teqnikèc. 3.8 Sumperˆsmata Sto Kefˆlaio autì ulopoi jhke kai analôjhke ènac algìrijmoc katanom c twn radiopìrwn gia thn beltðwsh tou QoS twn qrhst n. H sqediastik strathgik tou algorðjmou eðnai h diasfˆlish enìc elˆqistou epipèdou rujmoô metˆdoshc dedomènwn stouc qr stec pou lambˆnoun mia sugkekrimènh uphresða. O proteinìmenoc algìrijmoc eðnai katanemhmènoc kai parousiˆzei qamhl upologistik poluplokìthta, pleonekt mata pou ton kajistoôn katall lo gia polukuyelwtˆ sust mata pou exuphretoôn megˆlouc arijmoôc qrhst n. EpÐshc, prìteroc sqediasmìc suqnot twn den apaiteðtai, kˆnontac thn prosj kh anametadot n kai femto-kuyelik n diktôwn pio efikt. Pˆreqei se perissìterouc qr stec èna ikanopoihtikì

3.8 Sumperˆsmata 79 epðpedo QoS, ìpwc epðshc eðnai ikanìc na parèqei uyhlìterouc rujmoôc metˆdoshc sta ˆkra thc kuyèlhc.

BibliografÐa [1] G. Li, and H. Liu, Downlink Resource Allocation for Multi-Cell OFDMA System, IEEE Tran. Wireless. Commun., vol. 5, no 12, pp. 3451-3459, Dec. 2006. [2] I. G. Fraimis, V. D. Papoutsis and S. A. Kotsopoulos, A Decentralized Subchannel Allocation Scheme with Inter-cell Interference Coordination (ICIC) for Multi-Cell OFDMA Systems, in Proc. IEEE Global Com. Conf. (Globecom), Miami USA, Dec. 2010. [3] M. Rahman and H. Yanikomeroglu, Enhancing Cell-Edge Performance: A Downlink Dynamic Interference Avoidance Scheme with Inter-Cell Coordination, IEEE Trans. Wireless Commun., vol. 9, no 4, pp. 1414-1425, Apr. 2010. [4] V. Chandrasekhar, J. G. Andrews and A. Gatherer Femtocell networks: A survey, IEEE Commun. Mag., pp. 59-67, Sept. 2008. [5] V. H. McDonald, The cellular concept, Bell Syst. Technol. J., vol. 58, pp. 15-41, Jan. 1979. [6] S. E. Elayoubi, O. B. Haddada, and B. Fourestie, Performance evaluation of frequency planning schemes in OFDMA-based networks, IEEE Trans. Wireless Commun., vol. 7, no. 5, pp. 1623-1633, May 2008. [7] R. Giuliano, C. Monti, and P. Loreti, WIMAX fractional frequency reuse for rural environments, IEEE Wireless Commun. Mag., vol. 15, no. 3, pp. 60-65, Jun. 2008. [8] Soft Frequency Reuse Scheme for UTRAN LTE, 3GPP Project Document R1-050 507, May 2005. [Online]. Available:http://www.3gpp.org. [9] OFDMA Downlink Intercell Interference Mitigation, 3GPP Project Document R1-060 291, Feb. 2006. [Online]. Available:http://www.3gpp.org. [10] V. D. Papoutsis, I. G. Fraimis and S. A. Kotsopoulos, Fairness-aware resource allocation for the SISO downlink over frequency-selective channels, IEEE Wireless Commun. Network Conf. (WCNC), pp. 1-6, Sydney, NSW, Australia, April 2010. [11] V. D. Papoutsis, I. G. Fraimis and S. A. Kotsopoulos, A Novel Fairness-Aware Resource Allocation Scheme in Multiuser SISO-OFDMA Downlink, Intern, J. 80

BibliografÐa 81 of Veh. Tech., Hindawi Corp., vol. 2010, Article ID 432762, 10 pages, 2010. doi:10.1155/2010/432762. [12] E. Liu and K. Leung, Expected Throughput of the Proportional Fair Scheduling over Rayleigh Fading Cannels, IEEE Commun. Letters, vol. 14, no. 6, pp. 515-517, June 2010. [13] Z. Han, Z. Ji, and K. J. R. Liu Fair Multiuser Channel Allocation for OFDMA Networks Using Nash Bargaining Solutions and Coalitions, IEEE Trans. Commun., vol. 53, no. 8, pp. 1366-1376, Aug. 2005. [14] E. Yaacoub, and Z. Dawy, A Survey on Uplink Resource Allocation in OFDMA Wireless Networks, IEEE Commun. Surveys & Tutorials, no 99, pp. 1-16, May 2011. [15] W. C. Jakes Jr, Microwave Mobile Communications, A Wiley-Interscience Publication, John Wiley & Sons, New York, Chichester, Brisbane, Toronto. [16] Z. Shen, J. G. Andrews, and B. L. Evans, Adaptive Resource Allocation in Multiuser OFDM Systems With Proportional Rate Constraints, IEEE Trans. Wireless Commun., vol. 4, no. 6, Nov. 2005. [17] I. C. Wong, Z. Shen, B. L. Evans, and J. G. Andrews, A low complexity algorithm for proportional resource allocation in OFDMA systems, Proc. IEEE Int. Workshop on Signal Processing Systems, Oct. 13-15, 2004, pp. 1-6. [18] E. Dahlman, H. Ekstrom, A. Furuskar, Y. Jading, J. Karlsson, M. Lundevall and S. Parkvall, The 3G long-term evolution-radio interface concepts and performance evaluation in Proc. IEEE Vehic. Techn. Conf. (VTC), May 2006.

Kefˆlaio 4 BeltÐwsh tou QoS se Sust mata OFDMA: Qr stec me Elˆqistec ApaÐthseic QoS kai Periorismì stic Ourèc Anamon c 4.1 PerÐlhyh Sto parìn Kefˆlaio, proteðnetai kai analôetai ènac qamhl c upologistik c poluplokìthtac algìrijmoc gia thn katerqìmenh zeôxh polukuyelwt n diktôwn, basismènwn sthn teqnik pollapl c prìsbashc OFDMA, me skopì thn paroq orismènou epipèdou QoS stouc qr stec. H proteinìmenh teqnik uiojeteð diastrwmatik sqediastik prosèggish, diìti a- xiopoieð plhroforðec tìso apì to fusikì epðpedo (katˆstash kanalioô twn qrhst n), ìso kai apì to epðpedo zeôxhc dedomènwn (ourèc anamon c qrhst n). H proteinìmenh teqnik eðnai ènac algìrijmoc, katanemhmènoc sto polukuyelwtì dðktuo me kôria peonekt mata: 1) thn qamhl upologistik poluplokìthta kai 2) thn ikanothtˆ tou na diathreð qamhlìtera posostˆ parabðashc tou epipèdou tou QoS stouc qr stec apì ˆllec eurèwc apodektèc gia thn apodos touc teqnikèc sta polukuyelwtˆ asôrmata sust mata. H proteinìmenh teqnik mporeð epðshc na 3) enisqôsei ton rujmì metˆdoshc dedomènwn sta ˆkra thc kuyèlhc (cell-edge data rate) kai 4) na epitugqˆnei kalôterouc deðktec dikaiosônhc se sqèsh me tic ˆllec teqnikèc anaforˆc. Ta arijmhtikˆ apotelèsmata kai h anˆlush thc uplogistik c poluplokìthtac anadeiknôoun thn apodotikìthta tou proteinìmenhc prosanatolismènhc sto QoS prosèggishc. 4.2 Eisagwg H teqnologða pollapl c prìsbashc OFDMA èqei eurèwc anagnwristeð wc h idanik platfìrma prìsbashc tou radiofˆsmatoc gia na uposthriqjoôn uyhl c taqôthtac uphre- 82

4.2 Eisagwg 83 sðec sta asôrmata sust mata epomènhc geniˆc, ìpwc to 3GPP long term evolution (LTE) [1] kai to WiMAX [2]. Oi bèltistec sunj kec enìc diktôou OFDMA apodeðqjhkan stic episthmonikèc ergasðec [4], [5], ìpou sômfwna me ta porðsmata twn ergasi n aut n, h bèltisth politik se èna sôsthma OFDMA enìc SB kai poll n qrhst n, eðnai h anˆjesh kˆje upoforèa se ènan mìno qr sth, exaleðfontac thn endokuyelwt parembol (ICI). Ta mellontikˆ kuyelwtˆ dðktua mazð me thn uiojèthsh thc prìsbashc OFDMA wc teqnologða rˆdio-diepaf c, anamènetai na parèqoun pantaqoô kai uyhloô rujmoô metˆdoshc dedomènwn kˆluyh se megˆlo arijmì qrhst n. Apì thn ˆllh meriˆ, to diajèsimo eôroc z nhc eðnai ènac periorismènoc pìroc kai prèpei na qrhsimopoieðtai me sunetì trìpo. Epomènwc, h anˆgkh eisagwg c ne n apodotik n teqnik n diaqeðrishc pìrwn kajðstatai epitaktik [6] -[12]. PantaqoÔ kˆluyh shmaðnei ìti mia uphresða prèpei na paradðdetai stouc qr stec epituqhmèna kai me uyhl poiìthta, anexˆrthta apì thn topojesða touc kai tic sunj kec kanalioô. Opìte, prèpei na kalôptei kai touc qr stec pou brðskontai sthn pio meionektik jèsh. AutoÐ eðnai oi qr stec pou brðskontai sta ˆkra thc kuyèlhc oi opoðoi ufðstantai uyhlèc ap leiec diˆdoshc kai isqurèc omokanalikèc parembolèc (CCI). Prosfˆtwc proteinìmenec teqnikèc anˆjeshc radiopìrwn pou wc monadikì stìqo jètoun thn megistopoðhsh tou sunolikoô rujmoô metˆdoshc dedomènwn sto sôsthma, ìpwc o algìrijmoc sthn dhmosðeush [6], teðnoun na parablèpoun touc qr stec sta ìria thc kuyèlhc. Gia to lìgo autì, arketèc teqnikèc èqoun protajeð prosfˆtwc me skopì thn antimet pish autoô tou fainomènou kai thn enðsqush tou epipèdou QoS twn qrhst n sta sônora thc kuyèlhc [7] -[12]. H teqnik thc piac epanaqrhsimopoðshc twn suqnot twn (SFR)[7] kai h teqnik thc merik c epanaqrhsimopoðhshc suqnot twn (PFR) [8], oi opoðec èqoun proselkôsei to endiafèron twn ereunht n, aposkopoôn sthn enðsqush tou rujmoô metˆdoshc dedomènwn sta ìria thc kuyèlhc, efarmìzontac politik diaforetikoô bajmoô epanaqrhsimopoðhshc twn suqnot twn kai afièrwshc uyhlìterou epðpedou thc isqôoc stouc qr stec pou brðskontai sta ˆkra thc kuyèlhc (Parˆrthma Bþ). EntoÔtoic, tètoiou eðdouc teqnikèc eðnai statikèc kai qreiˆzontai prìtero sqediasmì suqnot twn pou tic kˆneic akatˆllhlec gia ta mellontikˆ sust mata, ta opoða anamènetai na sumperilˆboun kai femto-kuyelwtˆ dðktua [13]. Epomènwc, dunamikèc teqnikèc diaqeðrishc twn radiopìrwn pou basðzontai sthn pukn epanaqrhsimopoðhsh tou eôrouc z nhc èqoun profˆtwc protajeð. Oi suggrafeðc thc episthmonik c ergasðac [9], efarmìzoun mia teqnik apofug c parembol n, periorðzontac thn metˆdosh mèsw orismènwn upoforèwn se kˆje SB gia na enisqôsoun thn apìdosh sta ìria thc kuyèlhc, kaj c h teqnik thc episthmonik c ergasðac [10] parèqei megalôterh poikilomorfða kanalioô se qr stec sta ìria thc kuyèlhc enisqôontac to rujmì metˆdoshc dedomènwn se autoôc. Sthn episthmonik ergasða [11], epibˆllontai periorismoð elˆqistou rujmoô metˆdoshc dedomènwn stouc qr stec pou brðskontai sta ˆkra thc kuyèlhc, kaj c sthn ereunhtik ergasða [12], proteðnetai h dunamik klasmatik epanaqrhsimopoðhsh twn suqnot twn me skopì th megistopoðhsh tou olikoô rujmoô metˆdoshc dedomènwn en parˆllhla ikanopoioôntai oi elˆqistec apait seic rujmoô metˆdoshc dedomènwn twn qrhst n. An kai teqnikèc ìpwc autèc stic episthmonikèc ergasðec [9], [10], epitugqˆnoun beltiwmènh

84 Kefˆlaio 4. BeltÐwsh tou QoS se Sust mata OFDMA: Qr stec me Elˆqistec ApaÐthseic QoS kai Periorismì stic Ourèc Anamon c apìdosh sta ˆkra thc kuyèlhc, den parèqoun sugkekrimèna epðpeda QoS stouc qr stec kai algìrijmoi san autoôc stic episthmonikèc ergasðec [11], [12] an kai parèqoun QoS eggu seic, parablèpoun tic ourèc anamon c twn qrhst n kai epomènwc apotugqˆnoun na axiopoi soun ton diaforismì kðnhshc (traffic diversity) twn qrhst n. Lambˆnontac up' ìyh ta parapˆnw zht mata, se autì to Kefalaio parousiˆzetai ènac poluepðpedoc algìrijmoc katanom c twn radiopìrwn me stìqo thn pantaqoô uyhloô rujmoô metˆdoshc dedomènwn kˆluyh twn qrhst n. Antikeimenikìc skopìc thc proteinìmenhc teqnik c eðnai h ikanopoðhsh enìc orismènou epipèdou QoS se ìlouc touc qr stec pou an koun sthn Ðdia klˆsh. Ta qarakthristikˆ tou proteinìmenou algorðjmou kai h suneisforˆ tou KefalaÐou sunoyðzontai parakˆtw: ProteÐnetai ènac dunamikìc algìrijmoc katanom c twn radiopìrwn me skopì thn beltðwsh tou sunolikoô rujmoô metˆdoshc twn dedomènwn, en parˆllhla diasfalðzetai se ìlouc touc qr stec èna elˆqisto epðpedo QoS. Parèqetai ènac grammik c polupokot tac epanalhptikìc algìrijmoc, ste na lôsoume to prìblhma. H proteinìmenh teqnik den axiopoieð mìno to diaforismì poll n qrhst n allˆ kai ton diaforismì kðnhshc pou autoð prosfèroun, antðjeta me tic teqnikèc stic episthmonikèc ergasðec [10] -[12] kai sto Kefˆlaio 3. H proteinìmenh teqnik efarmìzei epijetik politik sthn qr sh tou diajèsimou eôrouc z nhc, èqontac wc deðkth epanaqrhsimopoðhshc twn suqnot twn thn monˆda, en parˆllhla den apaiteð ton prìtero sqediasmì suqnot twn ìpwc oi teqnikèc SFR kai PFR. AntÐjeta me proseggðseic ìmoiec twn episthmonik n ergasi n [6], [9], [12], kentrikìc elegkt rac radiodiktôou (RNC) den apaiteðtai. O proteinìmenoc algìrijmoc ekteleðtai se ìlouc touc SB tou diktôou parˆllhla, sumbˆllontac mia epðpedh arqetektonik diktôou. O analogikˆ dðkaioc qronoprogrammatist c (PFS) qrhsimopoieðtai, o opoðoc èqeic eurèwc anagnwristeð wc idanikìc sumbibasmìc metaxô tou mègistou mèsou rujmoô metˆdoshc kai thc dikaiosônhc tou sust matoc [9], [14], [16]. To upoloipì tou KefalaÐou organ netai wc akoloôjwc: To montèlo tou sust matoc pou meletˆme kai h diatôpwsh tou probl matoc perigrˆfontai sthn enìthta 4.3, en o proteinìmenoc algìrijmoc parèqetai sthn enìthta 4.4 kai h upologistik tou poluplokìthta analôetai sthn enìthta 4.5. Oi parˆmetroi pou perilambˆnontai sthn prosomoðwsh dðnontai sthn 4.6 kai ta apotelèsmata sthn enìthta 4.7. Tèloc ta sumperˆsmata tou KefalaÐou anafèrontai sthn enìthta 4.8.

4.3 Montèlo tou Sust matoc kai DiatÔpwsh tou Probl matoc 85 4.3 Montèlo tou Sust matoc kai DiatÔpwsh tou Probl matoc Se aut thn enìthta parèqetai to montèlo tou sust matoc kai h diatôpwsh tou probl matoc apì to opoðo prokôptei o proteinìmenoc algìrijmoc. O proteinìmenoc algìrijmoc sullègei plhroforðec tìso apì to fusikì epipèdo mèsw shmatodosðac thc katˆstashc kanalioô (CSI), ìso kai apì to epðpedo zeôxhc dedomènwn mèsw shmatodosðac thc katˆstashc stic ourèc anamon c (QSI) twn qrhst n. 4.3.1 Montèlo tou Sust matoc Upojètoume èna kuyelwtì, basismèno sthn pollap prìsbash OFDMA dðktuo apoteloômeno apì 19 SB mon c keraðac, ìpou kˆje SB exuphreteð K qr stec exoplismènouc me suskeuèc mon c keraðec (SISO) mèsw N upoforèwn. 'Oloi oi radiopìroi eðnai diajèsimoi se kˆje SB, dhmiourg ntac dðktuo pukn c epanaqrhsimpopoðhshc suqnot twn. Kˆje SB epðshc diathreð K kataqwrhtèc dedomènwn twn qrhst n. JewroÔme akìmh ìti h kðnhsh a- koloujeð to montèlo ˆfixhc Poisson kai o rujmìc ˆfixhc thc kðnhshc sthn antðstoiqh ourˆ anamon c eðnai λ k, k = 1, 2,... K. Kˆje qronik stigm, o SB èqei gn sh thc katˆstashc twn our n anamon c mèsw tou dianôsmatoc q = (q 1, q 2,..., q K ) pou epðshc diathreð. 4.3.2 Montèla kanalioô kai rujmoô metˆdoshc twn dedomènwn To olikì eôroc z nhc tou sust matoc eðnai Ðso me B kai ta qronikˆ metaballìmena kanˆlia metaxô tou SB kai twn diafìrwn qrhst n jewroôntai ìti eðnai asôrmata kanˆlia epilektikˆ sth suqnìthta me anexˆrthth diˆleiyh Rayleigh kai mporoôn na jewrhjoôn stajerˆ katˆ to qronikì diˆsthma katanom c twn radiopìrwn. O lìgoc s matoc proc parembol sun ton jìrubo (SINR) tou qr sth k ston upoforèa n, upodhl netai wc γ kn kai dðnetai apì thn sqèsh: p c g kn γ kn =, m k, (4.1) p c g mn + σ2 j ìpou, p c eðnai h posìthta thc isqôoc pou efarmìzetai ston upoforèa n, n = 1, 2,..., N kai prokôptei apì thn omoiìmorfh katanom thc isquìc stouc upoforeðc tou SB pou eðnai p c = P t /N, ìpou to P t antiproswpeôei th mègisth epitrepìmenh posìthta thc isqôoc sto SB. AxÐzei na anaferjeð pwc ìpwc apodeðqjhke sthn episthmonik ergasða [4], h ekq rhsh thc isqôoc me thn teqnik water-filling epifèrei amelhtèa beltðwsh se sqèsh me thn kataq rhsh stajer c posìthtac thc isqôoc sundiasmènh me thn prosarmostik kwdikopoðhsh kai diamìrfwsh ACM [6]. H parˆmetroc σ 2 eðnai h isqôc tou jorôbou kai h parˆmetroc g kn eðnai h apolab tou kanalioô metaxô tou qr sth k kai tou SB pou ton exuphreteð mèsw tou upoforèa n kai perilambˆnei tic ap leiec diˆdoshc, tic dialeðyeic kai to fainìmeno skðashc. O prokôptwn rujmìc metˆdoshc twn dedomènwn eðnai r kn kai qrhsimpopoi ntac thn exðswsh gia ACM, tìte èqoume:

86 Kefˆlaio 4. BeltÐwsh tou QoS se Sust mata OFDMA: Qr stec me Elˆqistec ApaÐthseic QoS kai Periorismì stic Ourèc Anamon c r kn = B N log 2 ( 1 + 1.5γ ) kn, (4.2) ln(5p e ) ìpou me P e sumbolðzetai o aposkopoômenoc rujmìc metˆdoshc lanjasmènwn bit. EpÐshc orðzoume thn m tra anˆjeshc twn upoforèwn Y K N = [y kn ], ìpou y kn = 1 ìtan o upoforèac n ekqwreðtai ston qr sth k kai y kn = 0 ìtan den sumbaðnei autì. Kˆje SB diathreð thn dik tou m tra anˆjeshc upoforèwn. 4.3.3 Majhmatik diatôpwsh tou probl matoc O skopìc tou proteinìmenou algìrijmou anˆjeshc twn radiopìrwn eðnai arqikˆ h diasfˆlish enìc elˆqistou epipèdou QoS se ìlouc touc qr stec kai deutereuìntwc na belti sei ton sunolikì rujmì metˆdoshc tou sust matoc. Exetˆzontac tic parapˆnw upojèseic, h anˆjesh radiopìrwn se kˆpoio orismèno qronikì diˆsthma qronojurðda, diamorf netai wc èna duadikoô akèraiou grammikoô programmatismoô (BILP) prìblhma, ìpwc parakˆtw: upo touc periorismoôc: K N max r kn y kn (4.3) k=1 n=1 K y kn = 1, n N (4.4) j=1 y kn {0, 1}, k K, n N (4.5) N y kn r kn Q k, k K (4.6) n=1 ìpou K kai N eðnai ta sônola twn qrhst n kai twn upoforèwn se kˆje SB antðstoiqa, oi periorismoð (4.4) kai (4.5) diasfalðzoun ìti kˆje upoforèac ekqwreðtai mìno se èna qr sth se kˆje kuyèlh (apofug ICI). O periorismìc (4.6) anafèretai sto èlaqisto epðpedo QoS tou qr sth k gia mia sugkekrimènh uphresða. Me skopì thn apofug anˆjeshc upoforèa se qr sth pou èqei ken ourˆ anamon c ja prèpei: T N y kn r kn q k, k K, (4.7) n=1 ìpou to T dhl nei to qronikì diˆsthma anˆjeshc radiopìrwn. Na shmei soume ìti gia na brejeð h bèltisth lôsh apaiteðtai h antimet pish apagoreutikˆ terˆstiou upologistikoô fìrtou, ìpou epðshc h lôsh ja prèpei na exasfalisteð se èna eôlogo qronikì diˆsthma. Epomènwc, h taqôthta kai to mikrì upologistikì kìstoc èqoun

4.4 Proteinìmenh Teqnik Katanom c twn Radiopìrwn 87 wc apotèlesma thn diatôpwsh upobèltisthc kai qamhl c poluplokìthtac teqnik c katanom c radiopìrwn, h opoða na eðnai efarmìsimh se sust mata me poluˆrijmouc qr stec kai ekatontˆdec upoforeðc. 4.4 Proteinìmenh Teqnik Katanom c twn Radiopìrwn H paroôsa enìthta parousiˆzei kai analôei thn proteinìmenh teqnik katanom c radiopìrwn, h opoða eðnai ènac epanalhptikìc algìrijmoc pou sunoptikˆ apoteleðtai apì ta parakˆtw b mata: B ma 1: ArqikopoieÐ ta sônola twn diajèsimwn qrhst n (K) kai upoforèwn (N ) se kˆje SB. ArqikopoieÐ to sônolo Q pou perilambˆnei to elˆqisto apaitoômeno epðpedo QoS twn qrhst n gia thn sugkekrimènh uphresða. B ma 2: Anajètei radiopìrouc stouc qr stec sômfwna me ton qronoprogrammatist PFS mèqri thn ikanopoihjeð to elˆqisto epðpedo QoS twn qrhst n. Eˆn bèbaia, den upˆrqoun dedomèna sthn ourˆ anamon c kˆpoiou qr sth, tìte shmaðnei ìti den upˆrqoun epiplèon dedomèna pou na proorðzontai gia autìn kai tìte o sugkekrimènoc qr sthc exaireðtai apì ton algìrijmo. B ma 3: Katanèmei enapomeðnantec upoforeðc sômfwna me ton qronoprogrammatist PFS, eðte mèqri na ekqwrhjoôn ìloi oi upoforeðc, eðte mèqri na mhn upˆrqoun dedomèna stic ourèc anamon c twn qrhst n ston SB. Shmei noume ìti ìpwc anafèrjhke kai sto prohgoômeno Kefˆlaio, o qronoprogrammatist c PFS, jewreðtai ìti se genikèc grammèc katanèmei me dðkaio trìpo touc radiopìrouc enìc sust matoc [14]-[16]. H eôresh thc bèltisthc lôshc gia ton PFS se sust mata pollapl n ferour n èqei exetasteð sthn ergasða [14], allˆ h praktik thc efarmog eðnai arketˆ perðplokh se sust mata me megˆlouc arijmoôc qrhst n kai upoforèwn [14]. Parakˆtw dðnetai o yeudok dikac thc proteinìmenhc poluepðpedhc teqnik c. B ma 1. ArqikopoÐhsh: Jèse K = {1, 2,..., K}, N = {1, 2,..., N}, Q = {Q 1, Q 2,..., Q K } y kn = 0, k K, n N q = (q 1, q 2,..., q K ), k K B ma 2. Kaj c Q {}: Brec k K kai upoforèa n N, me r k = arg max k,n k ψ k, k, n Eˆn N y kn r k,n < Q k n=1 y kn = 1

88 Kefˆlaio 4. BeltÐwsh tou QoS se Sust mata OFDMA: Qr stec me Elˆqistec ApaÐthseic QoS kai Periorismì stic Ourèc Anamon c q k = (q k (r k,n T )) + Eˆn q k = 0 tìte K \ { k} N \ {n } Upolìgise thn sqèsh (4.3) Eˆn N y kn r k,n Q k n=1 Q \ {Q k} B ma 3. Kaj c N {} kai K q k 0: k=1 Brec upoforèa n N kai qr sth k K ìpou k = arg max k y k n = 1 q k = (q k (r k n T ))+ Eˆn q k = 0 tìte K \ {k } N \ {n } Upolìgise thn sqèsh (4.3) Sto B ma 1, o algìrijmoc arqikopoieð ìlec tic emplekìmenec paramètrouc. KajorÐzei ta sônola qrhst n (K), upoforèwn N kai twn elaqðstwn epipèdwn QoS twn qrhst n. Epiplèon sqhmatðzetai to diˆnusma q me stoiqeða thn qwrhtikìthta twn our n anamon c twn qrhst n ston SB. Epishc ìla ta stoiqeða y kn jètontai Ðsa me to mhdèn. Sto B ma 2, o algìrijmoc brðskei ton diajèsimo qr sth kai upoforèa pou megistopoioôn ton lìgo tou rujmoô metˆdoshc dedomènwn ston qr sth mèsw tou sugkekrimènou upoforèa proc ton mèso rujmì metˆdoshc ston qr sth kai ton anajètei ton upoforèa ston qr sth. Metˆ, bgˆzei ton upoforèa apì to sônolo N kai anane nei thn antðstoiqh ourˆ anamon c. Eˆn h eikonik tim thc ourˆc anamon c gðnei Ðsh mikrìterh tou mhdenìc tìte o qr sthc apìballetai apì to sônolo K. Eˆn ikanopoihjeð to elˆqisto epðpedo QoS tou qr sth, tìte apobˆlletai to antðstoiqo stoiqeðo apì to sônolo Q. Sto B ma 3, exetˆzetai eˆn upˆrqoun upoforeðc pou den èqoun ekqwrhjeð sto prohgoômeno b ma kai eˆn upˆrqoun dedomèna stic ourèc anamon c twn qrhst n. Eˆn isqôoun kai oi dôo upojèseic tìte o algìrijmoc anajeteð upoforeðc stouc qr stec sômfwna me ton trìpo anˆjeshc tou qronoprogrammatist PFS. Kˆje forˆ pou anatðjetai ènac upoforèac se ènan qr sth, exetˆzontai oi arqikèc upojèseic tou B matoc kai an den isqôei èstw mða apì tic dôo, termatðzetai h leitourgða tou algorðjmou. r k,n ψ k 4.5 Anˆlush thc Upologistik c Poluplokìthtac To prìblhma pou perigrˆfetai stic exis seic (4.3) (4.6) eðnai èna prìblhma duadikoô akèraiou grammikoô programmatismoô (BILP) kai poluplokìthta eôreshc thc bèltisthc lôshc eðnai apagoreutikˆ uyhl. Se mða kuyèlh me K ston arijmì qr stec kai N ston arijmì

4.6 Parˆmetroi twn Prosomoi sewn 89 upoforeðc. Wc apotèlesma loipìn thc exantlhtik c anaz thshc gia thn eôresh thc bèltisthc lôshc eðnai h ekjetik upologistik poluplokìthta tou probl matoc O(K N ). AntÐjeta, sthn proteinìmenh teqnik, to B ma 1 apaiteð stajerì qrìno gia thn arqikopoðhsh ìlwn twn emplekomènwn paramètrwn. Sto B ma 2, o algìrijmoc qreiˆzetai, to perissìtero na sugkrðnei K qr stec gia kˆje upoforèa kai jewr ntac ìti sto sôsthma diajètoume N upoforeðc, ja qreiastoôn KN epanal yeic, opìte to B ma autì emfanðzei poluplokìthta thc tˆxhc O(K N). Sto trðto B ma kai upojètontac ìti upˆrqoun N > 0 upoforeðc pou den èqoun ekqwrhjeð se qr stec sto prohgoômeno b ma kai upojètontac akìmh ìti upˆrqoun dedomèna stic ourèc anamon c orismènwn K qrhst n, tìte o algìrijmoc exetˆzei anˆmesa se autouc touc qr stec kai gia ìlouc tou enapomeðnantec upoforeðc kai brðskei kˆje forˆ to zeôgoc qr sth kai upoforèa pou megistopoieð ton logì tou rujmoô metˆdoshc ston qr sth mèsw tou upoforèa autoô proc to mèso rujmì metˆdoshc ston sugkekrimèno qr sth. Epomènwc, sthn qeirìterh perðptwsh o algìrijmoc gia K qr stec ja epanalhfjeð se autì to B ma N forèc kai ja èqei poluplokìthta O(K N ). Shmei noume ìti pˆnta K < K kai N < N. Epomènwc, h olik poluplokìthta tou algorðjmou eðnai O(K N ). H poluplokìthta thc proteinìmenhc teqnik c èqei morf ao(c b ) me 0 < a < kai b = 1, h opoða dhl nei ìti o proteinìmenoc algìrijmoc eðnai grammikoô qrìnou algìrijmoc sômfwna me thn ergasða [6] kai apodotikìc sugkrinìmenoc me tic K N epanal yeic pou apaiteð h bèltisth lôsh. 4.6 Parˆmetroi twn Prosomoi sewn 'Ena polukuyelwtì sôsthma apoteloômeno apì 19 kuyèlec (SB) jewreðtai se ìlec tic prosomoi seic, me diajèsimo fˆsma B = 20MHz kai suqnìthta fèrousac 2.0 GHz. O arijmìc twn diajèsimwn upoforèwn eðnai N = 144, kaj c epðshc h mègisth epitrept isqôc metˆdoshc tou SB eðnai P t = 46 dbm me fasmatik puknìthta isqôoc N 0 = 174 dbm/hz. Epiplèon jewroôme P e = 10 7 kai montèlo apwlei n diˆdoshc L p (d k ) = 128.1+37.6 log(d k ) [db], ìpou d k h apìstash tou qr sth k apì ton SB pou ton exuphreteð se Km. EpÐshc, h tupik apìklish tou fainomènou skðashc eðnai 8 db. Upojètoume ìti ìloi oi qr stec an koun sthn Ðdia klˆsh kai katanèmontai me tuqaðo trìpo se diˆforec apìstaseic kai gwnðec apì ton SB, èqontac wc elˆqisth apìstash apì to SB ta 35 m kai mègisth to 1 Km pou eðnai h aktðna thc kuyèlhc. To epilektikì sthn suqnìthta kanˆli apoteleðtai apì èxi anexˆrthta Rayleigh stoiqeða pollapl c diadrom c (taps), ìpou kˆje èna dhmiourgeðtai qrhsimopoi ntac to montèlo tou Jakes. Kˆje stoiqeðo èqei ekjetikˆ meioômeno profðl kajustèrhshc isqôoc me to lìgo tou l stoiqeðou proc to pr to na èqei th morf e 2l. Akìmh h mègisth tim tou fainomènou doppler eðnai 30 Hz. Statistikˆ apotelèsmata èqoun exaqjeð apì thn kentrik kuyèlh kai apì 300 tuqaðec katanomèc qrhst n, ìpou kˆje katanom prosomoi netai gia qronikì diˆsthma 100 prosomoi sewn kanalioô. O rujmìc ˆfixhc dedomènwn stic ourèc anamon c twn qrhst n eðnai λ k = 5 Mbps, k = 1, 2,..., K.

90 Kefˆlaio 4. BeltÐwsh tou QoS se Sust mata OFDMA: Qr stec me Elˆqistec ApaÐthseic QoS kai Periorismì stic Ourèc Anamon c Gia tic teqnikèc SFR kai PFR, jewroôme wc ˆkra kuyèlhc thn perioq pou kalôptei to exwterikì èna trðto thc olik c epifˆneiac thc kuyèlhc. EpÐshc, jewroôme ìti h isqôc gia kˆje upoforèa tou eôrouc z nhc thc diaqwristik c epifˆneiac thc kuyèlhc (cell-edge area) eðnai α p P t /N, en gia touc upìloipouc upoforeðc eðnai (3 α p )P t /2N, ìpou α p eðnai o enisqutikìc parˆgontac kai stic prosomoi seic mac isoôtai me 1.5. Gia thn teqnik PFR, to eôroc z nhc pou eðnai afierwmèno stouc qr stec thc diaqwristik c epifˆneiac, èqei parˆgonta epanaqrhsimopoðhshc 3 kai jewroôme ìti eðnai to misì apì ìlo to diajèsimo fˆsma. To eôroc z nhc pou qrhsimopoieðtai apì qr stec pou brðskontai sthn kentrik perioq thc kuyèlhc èqei parˆgonta epanaqrhsimopoðhshc suqnot twn Ðso me thn monˆda. To profðl isqôoc twn upoforèwn tou PFR eðnai ìmoia me autˆ thc SFR (bl. Parˆrthma Bþ). Sq ma 4.1: Ajroistik sunˆrthsh katanom c (cdf) tou mèsou rujmoô metˆdoshc dedomènwn gia K = 30 qr stec anˆ kuyèlh. 4.7 Apotelèsmata twn Prosomoi sewn O proteinìmenoc algìrijmoc sugkrinetai me klasikèc teqnikèc pou efarmìzontai se polukuyelwtˆ sust mata OFDMA, ta opoða efarmìzoun pukn epanaqrhsimopoðhsh twn diajèsimwn susqnot twn. 'Olec oi teqnikèc anaforˆc, axiopoioôn ton diaforismì poll n qrhst n

4.7 Apotelèsmata twn Prosomoi sewn 91 Sq ma 4.2: Ajroistik sunˆrthsh katanom c (cdf) tou mèsou rujmoô metˆdoshc dedomènwn gia K = 65 qr stec anˆ kuyèlh. diìti efarmìzoun qronoprogrammatismì PFS kai qrhsimpopoioôntai wc prìtupa sugkritik c axiolìghshc. Exetˆzoume dôo diaforetikèc klˆseic tou proteinìmenou algìrðjmou. MÐa me Q k = 750 Kbps kai mða me Q k = 1.25 Mbps, k = 1, 2,..., K kai gia dôo senˆria puknìthtac qrhst n sto dðktuo. 'Ena gia K = 30 qr stec anˆ kuyèlh kai èna deôtero me uperdiplˆsio thlepikoinwniakì fortðo Ðso me K = 65 qr stec anˆ kuyèlh. Ta Sq mata 4.1 kai 4.2, apeikonðzoun thn ASK tou mèsou rujmoô metˆdoshc dedomènwn ston qr sth gia ta montèla uphresðac thc proteinìmenhc teqnik c kaj c kai twn all n sqhmˆtwn anaforˆc. H ASK tou mèsou rujmoô metˆdoshc dedomènwn stouc qr stec tou Sq matoc 4.1 megenjônetai sto Sq ma 4.3 kai tou Sq matoc 4.2 megenjônetai sto Sq ma 4.4 antðstoiqa gia na doôme ton mèso rujmì metˆdoshc dedomènwn sth diaqwristik epifˆneiac thc kuyèlhc pou isoôtai me to 5% thc katanom c sômfwna me th mejodologða axiolìghshc tou LTE [18]. Diapist noume ìti mporeð na epiteuqjeð beltiwmènh epðdosh sthn diaqwristik epifˆneia thc kuyèlhc kajorðzontac katˆllhla to elˆqisto epðpedo QoS me antðktupo ston sunoliko rujmì metˆdoshc dedomènwn twn qrhst n. Sugkekrimèna gia K = 30 qr stec, oi uphresðec me Q k = 750 Kbps kai Q k = 1.25 Mbps elˆqisto epðpedo QoS gia kˆje qr sth, deðqnoun beltðwsh 29% kai 69.7% antðstoiqa, se sugkrish me thn teqnik Reuse-1, ìpou

92 Kefˆlaio 4. BeltÐwsh tou QoS se Sust mata OFDMA: Qr stec me Elˆqistec ApaÐthseic QoS kai Periorismì stic Ourèc Anamon c Sq ma 4.3: Megèjunsh thc Ajroistik c sunˆrthshc katanom c (cdf) tou mèsou rujmoô metˆdoshc dedomènwn gia K = 30 qr stec anˆ kuyèlh. elˆqisto epðpedo QoS den jewreðtai. Epiplèon, oi ekdoqèc tou proteinìmenou algorðjmou uperbaðnoun tic teqnikèc SFR kai PFR twn opoðwn h sqediastik proteraiìthta eðnai h enðsqush tou rujmoô metˆdoshc dedomènwn sthn diaqwristik epifˆneia thc kuyèlhc. H ekdoq Q k = 750 Kbps deðqnei beltðwsh 18% sugkrinìmenh me thn PFR kai 5% sugkrinìmenh me thn SFR. 'OmoÐwc, h ekdoq tou algorðjmou me Q k = 1.25 Mbps apodðdei 55.8% uyhlìtero rujmì metˆdoshc apì thn PFR kai 39.7% apì thn SFR. ParomoÐwc gia K = 65 qr stec, h proteinìmenh teqnik me elˆqisto epðpedo rujmoô metˆdoshc 750Kbps emfanðzei beltðwsh 58.3% ènanti thc teqnik c Reuse-1 kai 16.7% ìtan h elˆqisth apaðthsh eðnai sta 1.25Mbps. Se sqèsh me tic SFR kai PFR to sôsthma emfanðzei enisqumèno rujmì metˆdoshc sta ìria thc kuyèlhc katˆ 18.75% kai 26.67% ìtan h elˆqisth stˆjmh QoS èqei tejeð sta 750Kbps. AntÐjeta se sunj kec uyhloô fortðou kai uyhl c apaðthshc QoS, dhlad sta 1.25 Mbps, o rujmìc metˆdoshc emfanðzei mikr kˆmyh thc tˆxhc tou 12.5% kai 6.67% se sqèsh me tic SFR kai PFR antðstoiqa. H pijanìthta parabðashc tou QoS gia K = 30 qr stec anˆ kelð apeikonðzetai sto Sq ma 4.5 kai gia K = 65 sto Sq ma 4.6, apì ta opoða diapist noume ìti o proteinìmenoc algìrijmoc eðnai ikanìteroc sthn paroq eggu sewn QoS se sqèsh me tic ˆllec teqnikèc,

4.7 Apotelèsmata twn Prosomoi sewn 93 Sq ma 4.4: Megèjunsh thc Ajroistik c sunˆrthshc katanom c (cdf) tou mèsou rujmoô metˆdoshc dedomènwn gia K = 65 qr stec anˆ kuyèlh. mporeð kai kalôptei to apaitoômeno QoS perissìterwn qrhst n kai ˆra apodðdei èna sôsthma me beltiwmèno QoS. Sugkekrimèna, o algìrijmoc me stˆjmh Q k = 750 Kbps emfanðzei 9.23% ligìterh pijanìthta parabðashc se sqèsh me thn teqnik Reuse-1, 5.76% apì thn SFR kai 9.1% apì thn PFR. H ètairh ekdoq tou algorðjmou me Q k = 1.25 Mbps apodðdei 7.91%, 12.82% kai 18.75% ligìterh pijanìthta parabðashc tou QoS kata mèso ìro sugkritikˆ me tic teqnikèc Reuse-1, SFR kai PFR antðstoiqa. Gia megˆlo thlepikoinwniakì fortðo (K = 65 qr stec), h proteinìmenh teqnik pˆli emfanðzei kalôtero QoS katˆ 25.77% kai 40.7% se sqèsh me thn Reuse-1 gia 750 Kbps kai 1.25 Mbps antðstoiqa. Epiplèon gia 750 Kbps kai 1.25 Mbps elˆqistouc rujmoôc metˆdoshc stouc qr stec, h teqnik pou parousiˆzetai sto Kefˆlaio apodðdei meiwmènh pijanìthta parabðashc QoS katˆ 46.14% kai 65.2% antistoðqwc, omoðwc h pijanìthta thc PFR eðnai katˆ 53.71% kai 72.71% qamhlìterh. Tèloc, apì ta Sq mata 4.7 kai 4.8, blèpoume ìti h proteinìmenh teqnik apodðdei megalôtero deðkth dikaiosônhc tou Jain [19], [20] kai ˆra eðnai ikan na katanèmei touc diajèsimouc radiopìrouc me dikaiìtero trìpo apì tic ˆllec teqnikèc pou anafèrontai sthn enìthta.

94 Kefˆlaio 4. BeltÐwsh tou QoS se Sust mata OFDMA: Qr stec me Elˆqistec ApaÐthseic QoS kai Periorismì stic Ourèc Anamon c Sq ma 4.5: Pijanìthta parabðashc tou QoS gia K = 30 qr stec anˆ kuyèlh. 4.8 Sumperˆsmata Sto Kefˆlaio autì protˆjhke kai analôjhke ènac algìrijmoc katanom c twn radiopìrwn, prosanatolismènoc sto QoS tou kˆje qr sth kai o opoðoc eðnai epiplèon ikanìc na enisqôsei ton rujmì metˆdoshc dedomènwn sthn diaqwristik epifˆneia thc kuyèlhc. O algìrijmoc eðnai katanemhmènoc sto dðktuo kai sugkrðnetai me ˆllec dhmofileðc katanemhmènec teqnikèc pou qrhsimopoioôntai sta polukuyelwtˆ sust mata OFDMA. H proseggis tou sto prìblhma katanom c twn pìrwn eðnai poluepðpedh, diìti axiopoieð plhroforðec ìqi mìno apì to fusikì epðpedo allˆ kai apì to epðpedo zeôxhc dedomènwn. Epiplèon, h proteinìmenh lôsh emfanðzei meiwmènh poluplokìthta se sqèsh me thn exantlhtik anaz thsh gia thn eôresh thc bèltisthc lôshc. Ta arijmhtikˆ apotelèsmata deðqnoun h pijanìthta parabðashc tou QoS eðnai arketˆ mikrìterh ìtan to asôrmato sôsthma katanèmei radiopìrouc sômfwna me thn proteinìmenh teqnik. Oi diajèsimoi pìroi katanèmontai me dðkaio trìpo kai tèloc, o proteinìmenoc algìrijmoc apodeðqjhke ìti mporeð na suneisfèrei perissìtero sthn enðsqush tou rujmoô metˆdoshc dedomènwn sth diaqwristik epifˆneia thc kuyèlhc se sqèsh me tic ˆllec teqnikèc pou efarmìzontai se megˆlhc klðmakac polukuyelwtˆ dðktua.

4.8 Sumperˆsmata 95 Sq ma 4.6: Pijanìthta parabðashc tou QoS gia K = 65 qr stec anˆ kuyèlh.

96 Kefˆlaio 4. BeltÐwsh tou QoS se Sust mata OFDMA: Qr stec me Elˆqistec ApaÐthseic QoS kai Periorismì stic Ourèc Anamon c Sq ma 4.7: O deðkthc dikaiosônhc tou sust matoc gia K = 30 qr stec anˆ kuyèlh.

4.8 Sumperˆsmata 97 Sq ma 4.8: O deðkthc dikaiosônhc tou sust matoc gia K = 65 qr stec anˆ kuyèlh.

BibliografÐa [1] E-UTRA and E-UTRAN Overall description; Stage 2 (Release 8), 3GPP Technical Specification TS 36.300 V8.7.0, Dec. 2008.[Online]. Available: http://www.3gpp.org. [2] Mobile WiMAX-part I: A tecnical overview and performance evaluation, Augoust 2006. [3] D. Tse and P. Viswanath, Fundamentals of Wireless Communication, Cambridge University Press. [4] J. Jang and K. B. Lee, Transmit power adaptation for multiuser OFDM systems, IEEE J. Sel. Areas Commun., vol. 21, no. 2, pp. 171-178, Feb. 2003. [5] G. Li and H. Liu, On the Optimality of the OFDMA Network, IEEE Commun. Lett., vol. 9, pp. 438-440, May 2005. [6] G. Li, and H. Liu, Downlink Resource Allocation for Multi-Cell OFDMA System, IEEE Trans. Wireless. Commun., vol. 5, no 12, pp. 3451-3459, Dec. 2006. [7] Soft Frequency Reuse Scheme for UTRAN LTE, 3GPP Project Document R1-050 507, May 2005. [Online]. Available:http://www.3gpp.org. [8] OFDMA Downlink Intercell Interference Mitigation, 3GPP Project Document R1-060 291, Feb. 2006. [Online]. Available:http://www.3gpp.org. [9] M. Rahman and H. Yanikomeroglu Enhancing Cell-Edge Performance: A Downlink Dynamic Interference Avoidance Scheme with Inter-Cell Coordination, IEEE Trans. Wireless. Commun., vol. 9, no 4, pp. 1414-1425, Apr. 2010. [10] I. G. Fraimis, V. D. Papoutsis and S. A. Kotsopoulos A Decentralized Subchannel Allocation Scheme with Inter-Cell Interference Coordination (ICIC) for Multi-Cell OFDMA Systems, in Proc. IEEE Global Commun. Conf. (Globecom), Dec. 2010. [11] T. Q. S Quek, Z. Lei and S. Sun Adaptive Interference Coordination in Multi-cell OFDMA Systems, in Proc., IEEE 20th Intern. Symp. on Pers. Indoor and Mobile Radio Commun. (PIMRC), Sept. 2009. 98

BibliografÐa 99 [12] S. H. Ali and V. C. M. Leung Dynamic frequency allocation in fractional frequency reused OFDMA networks, IEEE Trans. Wireless. Commun., vol. 8, no 8, pp. 4286-4295, Aug. 2009. [13] V. Chandrasekhar, J. G Andrews and A. Gatherer Femtocells networks: A survey IEEE Commun. Mag., pp. 56-59, Sept. 2008. [14] H. Kim and Y. Han A proportional fair scheduling for multicrrier transmission systems, IEEE Commun. Lett., vol. 9, no. 3, pp. 201-212, Mar. 2005. [15] Z. Han, Z. Ji, and K. J. R. Liu Fair Multiuser Channel Allocation for OFDMA Networks Using Nash Bargaining Solutions and Coalitions, IEEE Trans. Commun., vol. 53, no. 8, pp. 1366-1376, Aug. 2005. [16] E. Liu and K. Leung Expected Throughput of the Proportional Fair Scheduling over Rayleigh Fading Cannels, IEEE Commun. Letters, vol. 14, no. 6, pp. 515-517, June 2010. [17] W. C. Jakes Jr, Microwave Mobile Communications, A Wiley-Interscience Publication, John Wiley & Sons, New York, Chichester, Brisbane, Toronto. [18] E. Dahlman, H. Ekstrom, A. Furuskar, Y. Jading, J. Karlsson, M. Lundevall and S. Parkvall, The 3G long-term evolution-radio interface concepts and performance evaluation in Proc. IEEE Vehic. Techn. Conf. (VTC), May 2006. [19] R. Jain, D. M. Chiu and W. Hawe, A quantitave measure of fairness and discriminaton for resource allocation in shared systems, DEC, Research Report TR-301, 1984. [20] K. Ramadas and R. Jain, Mobile WiMAX Part I: A technical overview and performance evaluation, WiMAX Forum, Sept. 2007. http://www.wimaxforum.org/technology/downloads/

Kefˆlaio 5 Teqnik Apofug c twn Omokanalik n Parembol n gia th BeltÐwsh tou QoS sta 'Oria thc Kuyèlhc DiktÔwn OFDMA 5.1 PerÐlhyh To fainìmeno thc omokanalik c parembol c (CCI) eðnai èna basikì prìblhma sta polukuyelwtˆ asôrmata sust mata kaj c mporeð na pl xei se megˆlo bajmì ton rujmì metˆdoshc dedomènwn stouc qr stec kai kat' epèktash thn eklambanìmenh poiìthta uphresðac (QoS) twn qrhst n. Sta polukuyelwtˆ dðktua, h CCI emfanðzetai ìtan to Ðdio eôroc z nhc anatðjetai se diaforetikoôc qr stec se geitonikèc kuyèlec. H CCI pl ttei kurðwc touc qr stec pou brðskontai sta ìria thc kuyèlhc, kaj c h apìstas touc eðnai mikrìterh a- pì touc geitonikoôc SB se sqèsh me touc upìloipouc qr stec kai epomènwc oi parembolèc pou epidèqontai eðnai isqurìterec. Apotelesmatikèc mèjodoi gia thn apofug tou fainomènou apoteloôn oi teqnikèc apofug c twn parembol n kai katanom c radiopìrwn, sômfwna me tic opoðec sugkekrimèna tm mata tou diajèsimou eôrouc z nhc ekqwroôntai se qr stec geitonik n SB. Epomènwc se autì to Kefˆlaio proteðnetai ènac algìrijmoc, katanemhmènoc sto dðktuo skopì thn apofug twn omokanalik n parembol n kai thn enðsqush tou QoS twn qrhst n pou brðskontai sthn diaqwristik epifˆneia thc kuyèlhc (CEUs). Basikˆ qarakthristikˆ thc proteinìmenhc teqnik c eðnai h anˆjesh pìrwn me epilektikìthta stouc qr stec (user selective) kai h apofug sugkroôsewn (collision avoidance) me suqnìthtec pou èqoun anatejeð se qr stec geitonik n SB. O algìrijmoc apaiteð sunergasða metaxô twn geitonik n SB sthn logik ìti h prìjesh anˆjeshc orismènwn radiopìrwn ja prèpei na gðnei gnwst stouc geitonikoôc SB kai autoð na leitourg soun katˆllhla. ApodeiknÔetai ìti h proteinìmenh teqnik epitugqˆnei kalôtera apotelèsmata gia touc qr stec pou brðskontai sta ìria thc 100

5.2 Eisagwg 101 kuyèlhc se sqèsh me tic statikèc teqnikèc pou efarmìzontai sta polukuyelwtˆ sust mata kai epomènwc mporeð na efarmosteð sta sust mata teleutaðac geniˆc. 5.2 Eisagwg 'Opwc anafèrjhke kai se prohgoômena Kefˆlaia, h teqnik pollapll c prìsbashc OFDMA [1] apoteleð thn ekdoq thc yhfiak c diamìrfwshc OFDM gia pollaploôc qr stec [2]. Sthn OFDMA, pollapl prìsbash epitugqˆnetai diair ntac to diajèsimo eôroc z nhc se èna arijmì apì upoforeðc kai ekqwr ntac sônola upoforèwn se xeqwristoôc qr stec. Me thn pollapl prìsbash OFDMA axiopoieðtai o diaforismìc poll n qrhst n diìti eðnai polô pijanì kˆpoioi upoforeðc pou brðskontai upì to kajest c entìnwn dialeðyewn gia kˆpoiouc qr stec, na brðskontai se kal katˆstash kanalioô gia kˆpoiouc ˆllouc qr stec [3]. Ta qarakthristikˆ autˆ, èqoun katast sei thn OFDMA wc thn teqnik diamìrfwshc kai pollapl c prìsbashc gia ta teleutaðac geniˆc asôrmata sust mata ìpwc to IEEE 802.16e kai to LTE-A. EpÐshc, h bèltisth strathgik se sust mata OFDMA eðnai h apokleistik anˆjesh kˆje upoforèa se èna mìno qr sth se kˆje kuyèlh ìpwc èqei apodeiqjeð stic ergasðec [4], [5]. Apì thn ˆllh meriˆ, to eôroc z nhc den eðnai aperiìristo kai o suneq c auxanìmenoc arijmìc twn qrhst n jètei thn anˆgkh gia dhmiourgða nèwn kai apodotikìterwn teqnik n diaqeðrishc kai anˆjeshc twn diajèsimwn radiopìrwn. Arketˆ megˆloc eðnai o arijmìc twn teqnik n pou èqoun protajeð kai upˆrqoun sthn bibliografða gia sust mata pou apoteloôntai apì ènan pompì kai pollaploôc dèktec [6]. Oi perissìterec apì autèc tic teqnikèc estiˆzoun eðte sthn elˆttwsh thc sunolik c ekpempìmenhc isqôoc [7]-[9], eðte sthn aôxhsh thc qwrhtikìthtac tou sust matoc [10]-[13]. Par' ìla autˆ, autoô tou eðdouc oi teqnikèc agnooôn to fainìmeno thc omokanalik c parembol c (CCI) kai epomènwc den mporoôn na efarmostoôn apeujeðac se polukuyelwtˆ sust mata. Sta polukuyelwtˆ asôrmata dðktua, to fainìmeno thc omokanalik c parembol c prokôptei ìtan to Ðdio eôroc z nhc anatðjetai se diaforetikoôc qr stec se geitonikèc kuyèlec. H omokanalik parembol prokaleð shmantik upobˆjmish ston rujmì metˆdoshc twn dedomènwn stouc qr stec kai idiaðtera se autoôc pou brðskontai sta ìria thc kuyèlhc pou ektìc twn isqur n parembol n, upìkeintai kai se megˆlec ap leiec diˆdoshc. Me skopì ton metriasmì tou fainomènou thc omokanalik c parembol c (CCI), èqoun prosfˆtwc protajeð diˆforec teqnikèc kataq rhshc radiopìrwn [14]-[26]. Stic klasikèc teqnikèc apofug c parembol n, diaforetikˆ asôndeta kommˆtia tou diajèsimou eôrouc z nhc katanèmontai se diaforetikèc kuyèlec se diaforetikèc omˆdec qrhst n. Par' ìla autˆ, tètoiou eðdouc teqnikèc eðnai statikèc kai den axiopoioôn pl rwc thn poikilomorfða tou kanalioô. Apì thn ˆllh meriˆ, stic dunamikèc teqnikèc apofug c twn parembol n den apaiteðtai o ek twn protèrwn sqediasmìc katamom c twn suqnot twn kai to fainìmeno twn omokanalik n parembol n metriˆzetai efarmìzontac mhqanismoôc apofug c epanaqrhsimopoðhshc suqnot twn. Sthn episthmonik ergasða [14] parousiˆzetai ènac hmikatanemhmènoc algìrijmoc anˆjeshc twn radiopìrwn pou efarmìzei thn politik apofug c thc CCI allˆ mìno ìtan

Kefˆlaio 5. Teqnik Apofug c twn Omokanalik n Parembol n gia th BeltÐwsh tou QoS 102 sta 'Oria thc Kuyèlhc DiktÔwn OFDMA prìkeitai gia thn beltðwsh thc qwrhtikìthtac tou sust matoc, me apotèlesma na parablèpei touc CEUs. En sthn ergasða [15], oi suggrafeðc exetˆzoun mða dunamik teqnik apofug c twn parembol n me periorismoôc sthn metˆdosh mèsw orismènwn upoforèwn. Sthn episthmonik ergasða [16] proteðnetai ènac prosarmostikìc algìrijmoc, ìpou to prìblhma anˆjeshc radiopìrwn se èna polukuyelwtì dðktuo metatrèpetai se èna katanemhmèno prìblhma beltistopoðhshc exasfalðzontac èna elˆqisto rujmì metˆdoshc dedomènwn stouc qr stec pou brðskontai sthn diaqwristik epifˆneia kˆje kuyèlhc (CEUs). EpÐshc oi suggrafeðc thc ergasðac [17], exetˆzoun thn apìdosh thc teqnik c thc klasmatik c epanaqrhsimopoðhshc suqnot twn (FFR) se megˆlhc klðmakac dðktua me akanìnisto sq ma kuyel n. En stic episthmonikèc ergasðec [18]-[20] to prìblhma katanom c twn radiopìrwn kai apofug c twn parembol n proseggizètai me grˆfouc. Oi episthmonikèc ergasðec [21] kai [22] proteðnoun dunamikèc teqnikèc apofug c twn parembol n gia thn anerqìmenh zeôxh (uplink) twn susthmˆtwn LTE kai basðzontai sthn teqnik SFR. En stic episthmonikèc ergasðec [23], [24] proteðnontai teqnikèc gia apofug twn parembol n sthn katerqìmenh zeôxh se montèla uphresi n ìpou o arijmìc twn upoforèwn pou apaiteð kˆje qr sthc eðnai prokajorismènoc. Sto plaðsio thc anˆlushc tou sugkekrimènou KefalaÐou ereunˆtai to prìblhma katanom c twn radiopìrwn se polukuyelwtˆ asôrmata sust mata OFDMA. Skopìc eðnai h enðsqush tou rujmoô metˆdoshc twn dedomènwn twn CEUs, oi opoðoi upìkeintai sthn pio sfodr morf CCI. Gia na epitôqoume ton stìqo autì proteðnoume ènan algìrijmo apofug c twn CCI, o opoðoc apaiteð thn sunergasða twn geitonik n SB tou diktôou. SunergasÐa metaxô geitonik n SB epitugqˆnetai mèsw thc apofug c anˆjeshc Ðdiwn suqnot twn se qr stec pou exuphretoôn oi geitonikoð SB. Shmei netai ìti o proteinìmenoc algìrijmoc mporeð na efarmosteð tìso gia thn anerqìmenh zeôxh susthmˆtwn OFDMA, ìso kai gia thn katerqìmenh zeôxh susthmˆtwn OFDMA, ìpou ìloi oi radiopìroi den eðnai aparaðthto na qrhsimopoihjoôn, dhlad se sust mata ìpou o arijmìc twn radiopìrwn pou apaiteð kˆje qr sthc eðnai periorismènoc kai pou h apofug twn parembol n eðnai polô qr simh kai praktikˆ efarmìsimh. Epiplèon me ton proteinìmeno algìrijmo den apaiteðtai o sugqronismìc twn qronik n diasthmˆtwn anˆjeshc radiopìrwn ìpwc stouc algorðjmouc sta prohgoômena Kefˆlaia. Oi upìloipec enìthtec tou KefalaÐou organ nontai wc akoloôjwc: To montèlo tou sust matoc pou jewreðtai sto parìn Kefˆlaio, kaj c epðshc kai h diatôpwsh tou probl matoc gia thn beltðwsh tou rujmoô metˆdoshc twn dedomènwn twn CEUs dðnontai sthn enìthta 5.3. Sth sunèqeia sthn enìthta 5.5, perigrˆfontai oi parˆmetroi pou qrhsimopoioôntai stic prosomoi seic kai ta arijmhtikˆ apotelèsmata twn prosomoi sewn parèqontai sthn enìthta 5.6. Tèloc ta sumperˆsmata tou KefalaÐou sunoyðzontai sthn enìthta 5.7. 5.3 Montèlo tou Sust matoc kai DiatÔpwsh tou Probl matoc JewroÔme èna asôrmato thlepikoinwnikì sôsthma apoteloômeno apì L kuyèlec. Sto kèntro kˆje kuyèlhc upˆrqei ènac SB mon c keraðac kai exuphreteð K l qr stec, exoplismènouc epðshc me suskeuèc mon c keraðac (SISO). To diajèsimo eôroc z nhc eðnai B kai wc

5.3 Montèlo tou Sust matoc kai DiatÔpwsh tou Probl matoc 103 basik ontìthta radiopìrwn jewreðtai h upompˆnta (sub-band) (RB), h opoða eðnai èna sônolo geitonik n upoforèwn. H politik thc omadopoðshc twn upoforèwn efarmìzetai kurðwc sta sut mata LTE. H omadopoðhsh twn upoforèwn bohjˆei sthn elˆttwsh tou epðbarou thc shmatodosðac (signalling overhead) tou sust matoc, tìso sthn posìthta plhrofori n anˆdrashc (feedback) gia thn katˆstash kanalioô, ìso kai gia to eôroc plhrofori n pou apaiteðtai gia thn anˆjesh radiopìrwn stouc qr stec [21]-[26]. Epiplèon jewroôme tic akìloujec upojèseic: Ta qronikˆ metaballìmena kanˆlia metaxô qrhst n kai SB eðnai epilektikˆ sth suqnìthta me anexˆrthth diˆleiyh Rayleigh kai mporoôn na jewrhjoôn stajerˆ katˆ to qronikì diˆsthma katanom c twn radiopìrwn. H ISI exaleðfetai entel c lìgw ekmetˆlleushc twn teqnik n diamìrfwshc OFDM, dhlad to plˆtoc kˆje upoforèa eðnai polô mikrìtero apì to plˆtoc sunoq c tou kanalioô kai katˆ sunèpeia kˆje qr sthc upìkeitai se epðpedh diˆleiyh se kˆje upoforèa. O SB èqei pl rh gn sh thc CSI kai kˆje qr sthc anatrofodoteð me akribeðc plhroforðec to SB gia to kanˆli. Kˆje RB mporeð na qrhsimopoihjeð mìno apì ènan kˆje forˆ se kˆje mða kuyèlh. Oi qr stec se kˆje kuyèlh kathgoriopoioôntai se qr stec sto kèntro thc kuyèlhc (CCUs) kai se qr stec sta ˆkra thc kuyèlhc (CEUs). H kathgoriopoðhsh aut kajorðzetai apì èna kat fli apìstashc apì ton SB, to d th, pèra apì to opoðo ènac qr sthc jewreðtai wc CEU ìpwc stic episthmonikèc ergasðec [16], [18] kai [20]. H posìthta thc isqôoc pou kataqwreðtai se kˆje RB enìc CCU eðnai P C = (3 a p )P t /2N, en h isqôc se RB enìc CEU eðnai P E, ìpou P E = a p P t /N me a p na eðnai o parˆgontac enðsqushc thc isqôoc twn CEUs. Me ton arijmì twn diajèsimwn RBs sto sôsthma na eðnai N kai me thn fasmatik puknìthta isqôoc tou jorôbou N 0, h isqôc tou prosjetikoô leukoô gkaousianoô jorôbou (AWGN), dðnetai apì thn sqèsh: σ 2 = N 0 B/N. Epomènwc o lìgoc tou s matoc proc thn parembol kai ton jìrubo, tou qr sth k sto RB n, dðnetai apì thn sqèsh: γ kn = L K l l=1 j=1 g kn p kn g jn p jn + σ 2, j k, (5.1) ìpou to g kn dhl nei thn apolab kanalioô metaxô SB kai qr sth k mèsw tou RB n kai to p kn eðnai h isqôc pou kataqwreðtai sto n RB pou èqei anatejeð ston qr sth k. 'Ara, o rujmìc metˆdoshc tou qr sth k sto RB n eðnai: r kn = B N log 2 ( 1 + 1.5γ ) kn, (5.2) ln(5p e )

Kefˆlaio 5. Teqnik Apofug c twn Omokanalik n Parembol n gia th BeltÐwsh tou QoS 104 sta 'Oria thc Kuyèlhc DiktÔwn OFDMA ìpou P e eðnai o rujmìc metˆdoshc lanjasmènwn bit. Lambˆnontac epomènwc up' ìyh tic parapˆnw upojèseic, to prìblhma anˆjeshc twn radiopìrwn gia thn enðsqush tou rujmoô metˆdoshc twn dedomènwn stouc CEUs diamorf netai wc ex c: upì touc periorismoôc: N max y kn r kn (5.3) n=1 k K E y kn {0, 1}, k K, n N, (5.4) K y kn 1, n N, (5.5) k=1 ìpou, y kn eðnai o deðkthc anˆjeshc radiopìrwn, ste y kn = 1 ìtan to RB n anatðjetai ston qr sth k kai y kn = 0 an ìqi. Oi periorismìc (5.4) exasfalðzei thn swst tim gia ton deðkth anˆjeshc radiopìrwn kai o periorismìc (5.5) diasfalðzei ìti kˆje RB anatðjetai to polô se ènan qr sth se kˆje kuyèlh [21]- [24]. To sônolo K E antiproswpeôei to sônolo twn CEU sthn kuyèlh, me K E K kai èstw K = {1, 2,..., K} to sônolo ìlwn twn qrhst n sthn kuyèlh. EpÐshc K C K kai K = K E + K C, ìpou K C eðnai to sônolo twn CCUS sthn kuyèlh. 5.4 Proteinìmenh Teqnik Apofug c twn Omokanalik n Parembol n Se aut thn enìthta proteðnetai mða teqnik anˆjeshc radiopìrwn gia thn enðsqush twn CEUs se èna polukuyelwtì thlepikoinwniakì sôsthma. Basikì gn risma thc proteinìmenhc teqnik c eðnai h apofug sugkroôsewn (collision avoidance) katˆ thn anˆjesh twn radiopìrwn metaxô geitonik n SB [23], [26]. Gia na epiteuqjeð autì, eisˆgoume to sônolo Ψ (i) = {ψ n (i) } gia kˆje SB i ìpou n {1, 2,..., N}. To stoiqeðo ψ n (i) eðnai èna uposônolo pou perièqei wc stoiqeða touc deðktec twn geitonik n SB pou metadidoôn lambˆnoun dedomèna mèsw tou RB n kai antiproswpeôei kˆje uposônolo tou sunìlou {1, 2,..., L} \ {i}. O SB i mèsw tou Ψ (i) èqei gn sh gia to kˆje RB apì pìsouc ˆllouc geitonikoôc SB qrhsimopoieðtai kai ètsi ja eðnai ikanìc na dialèxei wc upoy fia proc anˆjesh gia touc CEUs ta RBs me tic ìso dunatìn ligìterec parembolèc, dhlad o SB ja prospajeð na efarmìsei politik apofug c twn parembol n kai Ôstera na ekqwr sei radiopìrouc stouc CEUs. Parakˆtw, dðnetai o yeudok dikac thc proteinìmenhc teqnik c: B ma 1. ArqikopoÐhsh: Jèse K E = {1, 2,..., K E }, N = {1, 2,..., N}, N E = {}, N temp = {} y kn = 0, k K, n N

5.4 Proteinìmenh Teqnik Apofug c twn Omokanalik n Parembol n 105 m = 0, Ψ n = {ψ 1, ψ 2,..., ψ N } Eˆn n N (j) E, ìpou j {1, 2,... L} \ {i} Ψ n \ {ψ n } N \ {n } Brec kˆje n N, ste m = ψ n, ψ n Ψ n kai jèse N temp {n } B ma 2. Kaj c K E {}: Kaj c N temp = {} m = m + 1 Brec n N, ste m = ψ n, ψ n Ψ n N temp {n } Brec k K E kai n N temp, ste γ k n γ kn me p k n = P E Jèse y k n = 1 N E {n } N \ {n }, Ψ n \ {ψ n } kai N temp \ {n } K E \ {k } Upolìgise thn (5.3) Sto B ma 1 thc proteinìmenhc teqnik c, ìlec oi metablhtèc arqikopoioôntai. To K E eðnai to sônolo twn CEUs pou brðskontai sthn kuyèlh. To sônolo ìlwn twn diajèsimwn RBc eðnai N, twn RBs pou èqoun anatejeð se CEUs eðnai N E kai N temp eðnai èna bohjhtikì sônolo radiopìrwn pou eðnai qr simo sto B ma 2. AntÐjeta me thn SFR teqnik, sthn proteinìmenh teqnik, to eôroc z nhc twn suqnot - twn pou proorðzetai gia touc CEUs den eðnai prokajorismèno [21], [22], [28], allˆ kajorðzetai dunamikˆ katˆ th diadikasða thc anˆjeshc ìpwc faðnetai sto B ma 2. Me aut thn diadikasða katafèrnoume na prasfèroume megalôtero diaforismì suqnìthtac stouc CEUs kai na belti soume autì to meionèkthma thc SFR. Epiplèon sqhmatðzetai to sônolo Ψ n kai elègqetai poioð apì touc diajèsimouc radiopìrouc qrhsimopoioôntai apì CEUs geitonik n kuyel n kai touc apokleðei apì to sônolo twn diajèsimwn upoforèwn kai to sônolo Ψ n ste na apofôgoume parembolèc metaxô suqnot twn pou qrhsimopoioôntai apì CEUs se geitonikèc kuyèlec kai sta opoða, sômfwna me tic upojèseic thc enìthtac 5.3, kataqwreðtai megalôtero posostì isqôoc se sôgkrish me ta RBs pou èqoun anatejeð se CCUs. EpÐshc, o deðkthc m pou qrhsimopoieðtai gia na dhlwjeð to pl joc twn stoiqeðwn kˆje uposunìlou ψ n tðjetai Ðsoc tou mhdenìc kai katìpin o algìrijmoc yˆqnei na breð tic suqnìthtec pou den qrhsimopoioôntai kajìlou ( ψ n = 0) se geitonikèc kuyèlec gia na sqhmatðsei to sônolo N temp kai na proqwr sei sto B ma 2.

Kefˆlaio 5. Teqnik Apofug c twn Omokanalik n Parembol n gia th BeltÐwsh tou QoS 106 sta 'Oria thc Kuyèlhc DiktÔwn OFDMA Sto B ma 2, o algìrijmoc yˆqnei sto K E kai sto N temp to zeôgoc CEU kai RB me to megalôtero SINR. 'Otan ta breð, anajètei ston qr sth to RB, afaireð ton CEU kai to RB apì ta K E kai N temp antðstoiqa kai antðjetwc sumperilambˆnei to sugkekrimèno RB sto sônolo N E ste aut h plhroforða na qrhsimopoihjeð apì ˆllo geitonikì SB. EpÐshc se perðptwsh pou to sônolo N temp den èqei ˆlla stoiqeða, tìte o deðkthc m auxˆnetai ste to N temp na gemðsei nèa stoiqeða. Dhlad an to arqikì sônolo N temp pou perièqei RBs pou den qrhsimopoioôntai apì geitonikèc kuyèlec adeiˆsei, tìte to m gðnetai 1 kai to N temp gemðzei me touc deðktec twn RBs pou qrhsimopoioôntai se mìno mða geitonik kuyèlh. 5.5 Parˆmetroi twn Prosomoi sewn Se aut thn enìthta parèqoume tic paramètrouc pou tan aparaðthtec gia thn dienèrgeia prosomoi sewn kai axiolìghsh thc proteinìmenhc teqnik c. Se ìla ta senˆria prosomoðwshc to epilektikì sth suqnìthta kanˆli apoteleðtai apì èxi anexˆrthta stoiqeða Rayleigh pollapl c diadrom c (taps). Kˆje stoiqeðo dhmiourgeðtai qrhsimopoi ntac to montèlo tou Jakes [29]. ParomoÐwc me tic ergasðec [30] kai [31], upojètoume ekjetikˆ meioômeno profðl kajusterhshc isqôoc, me to lìgo thc enèrgeiac tou l tap proc aut tou pr tou tap na eðnai e 2l. Gia kˆje prosomoðwsh tou kanalioô qrhsimopoieðtai h proteinìmenh teqnik anˆjeshc radiopìrwn kai upologðzetai o rujmìc metˆdoshc dedomènwn gia kˆje qr sth. To diajèsimo eôroc z nhc eðnai 20 MHz kai h mègisth metatìpish suqnìthtac tou fainomènou doppler eðnai 50 Hz. O arijmìc twn diajèsimwn RBs eðnai N = 100 [27]. H diasporˆ tou prosjetikoô jorôbou eðnai N 0 = 114 dbm/hz kai epðshc jewroôme P e = 10 3. To montèlo apwlei n diˆdoshc pou jewroôme sthn prosomoðwsh eðnai anˆlogo thc apìstashc apì ton SB kai ekfrˆzetai apì thn sqèsh: d β, ìpou d eðnai h apìstash tou qr sth apì ton SB kai β eðnai o ekjèthc apwlei n diˆdoshc kai upojètoume ìti eðnai Ðsoc me 2. JewroÔme sôsthma apoteloômeno apì L = 3 exagwnikèc kuyèlec, ìpou kˆje SB brðsketai sto kèntro thc kˆje kuyèlhc kai eðnai exoplismènoc me mon pankateujuntik keraða ìpwc kai oi qr stec (SISO). Oi qr stec katanèmontai se tuqaðec apostˆseic kai gwnðec apì to SB, ìpou jewroôme elˆqisth apìstash apì to SB ta 35 m kai mègisth ta 750 m pou eðnai h aktðna tou kˆje kelioô kai jewroôme d th = 500m [18], [20]. O arijmìc twn diaforetik n katanom n twn qrhst n eðnai 100 kai o arijmìc prosomoi sewn tou kanalioô eðnai 100 epðshc. Tèloc, jewroôme diplˆsio arijmì CCUs se sqèsh me touc CEUs. 5.6 Apotelèsmata twn Prosomoi sewn Sthn paroôsa enìthta, h proteinìmenh teqnik apofug c twn parembol n sugkrðnetai me upˆrqousec teqnikèc katanom c twn radiopìrwn pou efarmìzontai se polukuyelwtˆ sust - mata. Se autèc tic teqnikèc perilambˆnoume teqnikèc, ìpou suntonismìc parembol n diakuyelwt sunergasða den efarmìzetai kajìlou ìpwc sthn teqnik Reuse-1 (bl.parˆrthma Aþ) efarmìzetai me statikì trìpo ìpwc sta sq mata SFR, PFR (bl. Parˆrthma Bþ) kai Reuse-3. JewroÔme dôo senˆria katanom c twn qrhst n stic kuyèlec. Sto men pr to,

5.7 Sumperˆsmata 107 se ìlec tic kuyèlec èqoume ton Ðdio arijmì qrhst n kai sto deôtero oi geitonikèc kuyèlec èqoun ligìterouc qr stec apì thn kuyèlh thc opoðac sullègoume ta dedomèna thc apìdos c thc. Epiplèon se kˆje senˆrio h analogða CEUs proc CCUs eðnai sto èna trðto. Eidikìtera sta Sq mata 5.1 kai 5.2 apeikonðzetai o rujmìc metˆdoshc twn dedomènwn twn CEUs me thn proteinìmenh teqnik kai tic proanaferjeðsec teqnikèc pou efarmìzontai se polukuyelwtˆ sust mata gia diˆforec timèc tou pl joc twn qrhst n. Kaj c o arijmìc twn CEUs auxˆnei h proteinìmenh teqnik emfˆnizei megalôtero rujmì metˆdoshc twn dedomènwn tìso ìtan to pl joc twn qrhst n stic kuyèlec eðnai Ðdio, ìso kai ìtan oi geitonikèc kuyèlec exuphretoôn ligìterouc apì thn upo melèth kuyèlh. ParathroÔme ìti se sqèsh me tic teqnikèc pou efarmìzoun politik apofug c twn parembol n me statikì trìpo h apìdosh thc proteinìmenhc teqnik c eðnai kalôterh. EpÐshc, h proteinìmenh teqnik petuqaðnei akìma kalôterh apìdosh sto deôtero senˆrio, ìpou to fainìmeno twn CCI den eðnai tìso èntono. EpÐshc sta Sq mata 5.3 kai 5.4 dðnetai o deðkthc dikaiosônhc tou sust matoc [30] stic peript seic pou oi geitonikèc kuyèlec èqoun Ðdio pl joc qrhst n kai ligìtero pl joc qrhst n se sqèsh me thn kuyèlh anaforˆc antðstoiqa. Shmei noume ìti o deðkthc dikaiosônhc tou sust matoc paðrnei timèc metaxô tou mhdenìc kai thc monˆdac. 'Otan upˆrqei apìluth dikaiosônh metaxô twn rujm n metˆdoshc twn qrhst n, tìte o deðkthc dikaiosônhc gðnetai Ðsoc me thn monˆda. Apì to sq mata, diakrðnetai ìti kaj c h mèsh tim tou SNR twn qrhst n auxˆnei, o rujmìc aôxhshc tou deðkth dikaiosônhc eðnai megalôteroc me thn proteinìmenh teqnik. Mˆlista sthn perðptwsh pou stic geitonikèc kuyèlec oi qr stec eðnai ligìteroi kai h anˆjesh suqnot twn stouc qr stec qwrðc parembolèc eðnai pijanìterh, h dikaiosônh tou sust matoc lambˆnei megalôterec timèc. Tèloc sta Sq mata 5.5 kai 5.6 dðnetai h dikaiosônh tou sust matoc stic dôo peript seic pou anafèrjhkan kai prohgoumènwc sthn paroôsa enìthta. ParathreÐtai ìti kaj c auxˆnetai o arijmìc twn CEUs sto sôsthma, h dikaiosônh upobajmðzetai. Bèbaia, sthn perðptwsh pou oi geitonikoð SB exuphretoôn ligìterouc qr stec, h dikaiosônh paramènei se uyhlì epðpedo ìpwc faðnetai apì to Sq ma 5.6. 5.7 Sumperˆsmata Sto Kefˆlaio autì protˆjhke kai analôjhke ènac dunamikìc algìrijmoc apofug c twn parembol n gia polukuyelwtˆ asôrmata sust mata. H apìdosh thc proteinìmenhc teqnik c sugkrðjhke me ˆllec teqnikèc efarmìsimec se polukuyelwtˆ sust mata epðshc pou eðte den efarmìzoun kajìlou politik apofug c twn parembol n, eðte thn efarmìzoun me statikì trìpo. Wc parˆmetroi tou QoS twn qrhst n jewr jhkan o rujmìc metˆdoshc twn dedomènwn kai o deðkthc dikaiosônhc. Apì ta apotelèsmata twn prosomoi sewn diapist jhke ìti h proteinìmenh dunamik teqnik epitugqˆnei kalôtera apotelèsmata gia touc CEUs.

Kefˆlaio 5. Teqnik Apofug c twn Omokanalik n Parembol n gia th BeltÐwsh tou QoS 108 sta 'Oria thc Kuyèlhc DiktÔwn OFDMA Sq ma 5.1: Rujmìc metˆdoshc dedomènwn stouc CEUs me Ðdio arijmì qrhst n stic kuyèlec.

5.7 Sumperˆsmata 109 Sq ma 5.2: Rujmìc metˆdoshc dedomènwn stouc CEUs me ligìterouc qr stec stic geitonikèc kuyèlec.

Kefˆlaio 5. Teqnik Apofug c twn Omokanalik n Parembol n gia th BeltÐwsh tou QoS 110 sta 'Oria thc Kuyèlhc DiktÔwn OFDMA Sq ma 5.3: DikaiosÔnh tou sust matoc stouc CEUs gia diˆforec timèc tou mèsou SNR me K = 60 qr stec se kˆje kuyèlh.

5.7 Sumperˆsmata 111 Sq ma 5.4: DikaiosÔnh tou sust matoc stouc CEUs gia diˆforec timèc tou mèsou SNR me ligìterouc qr stec stic geitonikèc kuyèlec.

Kefˆlaio 5. Teqnik Apofug c twn Omokanalik n Parembol n gia th BeltÐwsh tou QoS 112 sta 'Oria thc Kuyèlhc DiktÔwn OFDMA Sq ma 5.5: DikaiosÔnh tou sust matoc stouc CEUs me Ðdio arijmì qrhst n stic kuyèlec.

5.7 Sumperˆsmata 113 Sq ma 5.6: DikaiosÔnh tou sust matoc stouc CEUs me ligìterouc qr stec stic geitonikèc kuyèlec.

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116 BibliografÐa [24] G. Fodor, C. Koutsimanis, A. Rcz, N. Reider, A. Simonsson, and W. Mller, Intercell interference coordination in ofdma networks and in the 3gpp long term evolution system, Journal of Communications, vol. 4, no. 7, pp. 445-453, Augoust 2009. [25] R. Kwan, C. Leung, and J. Zhang, Proportional fair multiuser scheduling in LTE, IEEE Signal Process. Lett., vol. 16, no. 6, pp. 461-464, June 2009. [26] R. Kwan, and C. Leung, On Collision Probabilities in Frequency-Domain Scheduling for LTE Cellular Networks, IEEE Commun. Lett., vol. 15, no. 9, pp. 965-967, Sept. 2011. [27] M. Rahman, H. Yanikomeroglu, and W. Wong, Interference Avoidance with Dynamic Inter-Cell Coordination for Downlink LTE System, in Proc., IEEE Wireless. Commun. Netw. Conf.(WCNC), Apr 2009. [28] R1-050507, Soft Frequency Reuse Scheme for UTRAN LTE. Huawei, 3GPP TSG RAN WG1 Meeting #41, Athens, Greece, May 2005. [29] W. C. Jakes, Jr., Microwave Mobile Communications. A Wiley-Interscience Publication, John Wiley & Sons, New York, Chichester, Brisbane, Toronto. [30] Z. Shen, J. G. Andrews, and B. L. Evans, Adaptive Resource Allocation in Multiuser OFDM Systems With Proportional Rate Constraints, IEEE Trans. Wireless Commun., vol. 4, no. 6, Nov. 2005. [31] I. C. Wong, Z. Shen, B. L. Evans, and J. G. Andrews, A low complexity algorithm for proportional resource allocation in OFDMA systems, Proc. IEEE Int. Workshop on Signal Processing Systems, Oct. 13-15, 2004, pp. 1-6.

Kefˆlaio 6 Teqnik Elègqou thc IsqÔoc gia thn Diasfˆlish tou QoS se Sust mata Poluekpomp c CDMA 6.1 PerÐlhyh JewroÔme thn metˆdosh dedomènwn uphresi n poluekpomp c (multicasting) apì SB se pollaploôc qr stec eðte me monoekpomp (unicast) eðte me poluekpomp (multicast) se polukuyelwtì dðktuo UMTS. H ekpempìmenh isqôc exartˆtai tìso apì to apaitoômeno epðpedo QoS thc uphresðac, ìso kai apì to pl joc twn qrhst n, thn jèsh touc sthn kuyèlh, kaj c epðshc kai ton trìpo metˆdoshc (unicast multicast). Apì thn ˆllh meriˆ, h isqôc tou SB eðnai periorismènh kai h diasfˆlish tou QoS idiaðtera se omˆdec qrhst n sth diaqwristik epifˆneia thc kuyèlhc kajðstatai exairetikˆ dôskolh. Epomènwc, sto parìn kefˆlaio proteðnetai mða teqnik elègqou kai diaqeðrishc thc isqôoc tou SB me sunergasða geitonik n SB kai diereunìntai oi apait seic se isqô tou SB me thn proteinìmenh teqnik gia thn diasfˆlish tou QoS twn qrhst n kaj c kai me ˆllec strathgikèc diaqeðrishc thc diajèsimhc isqôoc. 6.2 Eisagwg To UMTS apoteleð thn trðth geniˆ (3G) asôrmatwn kuyelwt n diktôwn kai aposkopeð sthn paroq uyhloô rujmoô metˆdoshc twn dedomènwn stouc qr stec parˆllhla me tic uphresðec fwn c kai binteokl sewn. Arqikˆ to UMTS prìsfere uphresðec fwn c kai mhnumˆtwn (SMSs) apokajist ntac èna apokleistikˆ afierwmèno kanˆli (DCH) gia kˆje qr sth. Me thn eisagwg nèwn uphresi n ìpwc to reumatosikì bðnteo (streaming video) kai h thlediˆskeyh pˆnw apì to prwtìkollo IP, dhmiourg jhke h anˆgkh gia epikoinwnða metaxô 117

Kefˆlaio 6. Teqnik Elègqou thc IsqÔoc gia thn Diasfˆlish tou QoS se Sust mata 118 Poluekpomp c CDMA enìc pompoô kai pollapl n dekt n, odhg ntac ta sust mata se shmeðo-proc -pollaplˆ shmeða trìpouc metˆdoshc twn dedomènwn. O apodotikìteroc trìpoc gia thn epðteuxh tètoiou eðdouc epikoinwnðac eðnai mèsw twn teqnologi n euruekpomp c (broadcast) kai poluekpomp c (multicast) [3]-[5]. 'Omwc h isqôc tou SB den eðnai aperiìristh kai ja prèpei na katanèmetai me apodotikì trìpo stouc qr stec ste oi apait seic touc se QoS na ikanopoioôntai [1], [2]. Epiplèon, h apodotik diaqeðrish thc ekpempìmenhc isqôoc apì touc SB exelðssetai se z thma megˆlhc shmasðac, kaj c oi SB kanatal noun arketˆ megˆlo posostì thc sunolik c isqôoc pou qrhsimopoieðtai se èna asôrmato kuyelwtì sôsthma (perðpou 60% ìpwc anafèretai sthn èreuna [6]) kai to auxanìmeno energeiakì kìstoc twn kuyelwt n diktôwn se sundiasmì me to arnhtikì antðktupo sto peribˆllon èqoun odhg sei parìqouc kinht n epikoinwni n kai kanonistikoôc foreðc ìpwc to 3GPP kai h ITU se èreunec gia apodotikìterh qr sh thc diajèsimhc isqôoc [6]-[8]. Se prìsfatec melètec èqoun ereun jei lôseic kai protajeð teqnikèc gia thn apotelesmatik diaqeðrish thc ekpempìmenhc isqôoc tou SB [9]-[17]. Stic ergasðec [9]-[11] diereunìntai teqnikèc gia thn apodotikìterh qr sh thc isqôoc twn SB kai apodeiknôetai ìti h epilog tou katˆllhlou kanalioô gia thn metˆdosh twn dedomènwn sunteleð shmantikˆ sthn aôxhsh thc qwrhtikìthtac thc kuyèlhc. Epiplèon stic ergasðec [12], [13] parousiˆzontai teqnikèc gia thn meðwsh thc isqôoc apì ton SB pou basðzontai sthn epilog tou energeiakˆ apodotikìterou mhqanismì metˆdoshc anˆloga me to pl joc twn qrhst n kai thn apostas touc apì ton SB. En stic ergasðec [14], [15] proteðnontai algìrijmoi elègqou thc ekpempìmenhc isqôoc pou basðzontai sthn sunôparxh kai twn dôo mhqanism n metˆdoshc sthn kuyèlh. O- moðwc stic ergasðec [16], [17] proteðnontai anˆlogec strathgikèc allˆ gia kuyelwtˆ dðktua pou uposthrðzontai apì HAP. OmoÐwc sto parìn Kefˆlaio meletˆtai to prìblhma diaqeðrishc thc ekpempìmenhc isqôc apì ton SB se èna sôsthma UMTS pou metadðdei to Ðdio perieqìmeno se pollaploôc qr stec me egguhmèno epðpedo QoS. ProteÐnetai ènac mhqanismìc, o opoðoc epilègei ton katˆllhlo trìpo metˆdoshc dedomènwn stouc qr stec basizìmenoc sthn energeiak apodotikìthta tou kˆje mhqanismoô anˆloga me ton arijmì twn qrhst n kai thn jèsh touc sthn kuyèlh. H leitourgða tou eðnai parìmoia me thn leitourgða teqnik n pou upˆrqoun sthn bibliografða kai anafèrjhkan sthn prohgoômenh parˆgrafo me thn shmantik diaforˆ ìti eisˆgetai h strathgik thc sunergasðac metaxô geitonik n SB. Diereunˆtai h katanaliskìmenh isqôc gia uphresðec me diaforetikèc apait seic QoS kai pl joc qrhst n, tìso sthn perðptwsh pou èqoume sunergasða geitonik n SB katˆ thn metˆdosh, ìso kai stic peript seic ìpou h metˆdosh pragmatopoieðtai me koinˆ, me apokleistikˆ kai me sundiasmì aut n twn kanali n antðstoiqa. Shmei noume ìti sunergasða metaxô geitonik n SB mporeð na pragmatopoihjeð se qr stec pou exuphretoôntai me afierwmèna kanˆlia kai brðskontai sthn diaqwristik epifˆneia thc kuyèlhc ìpwc sumbaðnei kai sthn perðptwsh thc piac metapomp c (soft handover) pou perigrˆfetai stic ergasðec [18]-[21]. Oi loipèc enìthtec tou KefalaÐou organ nontai wc akoloôjwc:

6.3 Montèlo tou Sust matoc kai DiatÔpwsh tou Probl matoc 119 6.3 Montèlo tou Sust matoc kai DiatÔpwsh tou Probl matoc Meletˆme thn metˆdosh dedomènwn poluekpomp c apì SB pou brðsketai sto kèntro kuyèlhc miac polukuyelwt c dom c ìpwc apeikonðzetai sto Parˆrthma Gþ. Sto kèntro kˆje enìc kuyèlhc upˆrqei ènac SB mon c keraðac kai exuphreteð pollaploôc qr stec me suskeuèc mon c keraðac (SISO sôsthma). JewroÔme thn katerqìmenh zeôxh ìpou metadðdontai polumesikèc uphresðec poluekpomp c (multicast service) stouc asôrmatouc qr stec kai kˆje omˆda qrhst n pou lambˆnei to Ðdio perieqomèno apoteleð mia omˆda poluekpomp c (MG, bl. Kefˆlaio 2). O SB eðnai se jèsh na metad sei thn uphresða eðte mèsw apokleistikˆ afierwmènwn kanali n me ton trìpo metˆdoshc monoekpom c eðte mèsw koinoô kanalioô me ton mhqanismì poluekpomp c. Ston trìpo metˆdoshc dedomènwn me monoekpomp, o SB metadðdei dedomèna stouc qr - stec mèsw apokleistikˆ afierwmènwn kanali n, èna gia kˆje qr sth. H isqôc pou kataqwreðtai se èna afierwmèno kanˆli exartˆtai apì thn apìstash tou qr sth apì ton SB ton rujmì metˆdoshsthc uphresðac kai ton lìgo thc enèrgeiac se kˆje bit proc parembolèc sun to jìrubo (E b /I 0 ) ston qr sth. Se perðpptwsh pou o SB exuphreteð K qr stec mèsw afierwmènwn kanali n tìte h isqôc pou ekpèmpei upologðzetai apì thn exðswsh (6.1) [22]. P CCH + K k=1 P BS = 1 K k=1 (P N +x k ) B (E b /I 0 ) k R k +a L k a B (E b /I 0 ) k R k +a (6.1) ìpou, P CCH eðnai h posìthta isqôoc pou afier netai sta koinˆ kanˆlia elègqou [22] kai P N eðnai h isqôc tou jorôbou. To L k sumbolðzei tic ap leiec diadrom c tou qr sth k, en oi ìroi R k kai E b /I 0 antiproswpeôoun ton rujmì metˆdoshc kai thn poiìthta s matoc tou qr sth k antðstoiqa. To eôroc z nhc sumbolðzetai me B kai o parˆgontac orjogwnikìthtac me a. 'Otan a = 0 èqoume tèleia orjogwnikìthta kai ìtan a = 1 den èqoume kajìlou orjogwnikìthta. Tèloc x k eðnai oi parembolèc apì touc geitonikoôc SB ston qr sth k kai dðnetai apì thn exðswsh (6.2). x k = L l=1 P l BS L kl, (6.2) ìpou L kl eðnai oi ap leiec diˆdoshc apì ton SB l ston qr sth k kai P l BS h ekpempìmenh isqôc tou SB l me l = {1, 2,..., L}. Ston trìpo metˆdoshc me poluekpomp, o SB ekpèmpei dedomèna se pollaploôc qr stec mèsw enìc koinoô kanalioô (FACH). To epðpedo thc ekpempìmenhc isqôoc tou SB eðnai prokajorismèno kai exartˆtai apì ton rujmì metˆdoshc twn dedomènwn kai thn epifˆneia tou kuttˆrou pou kalôptei ìpwc faðnetai ston PÐnaka 6.1 [15], [23]. Epiplèon oi qr stec pou brðskontai sthn diaqwristik epifˆneia èqoun thn dunatìthta na exuphrethjoôn apì ton sundiasmì dôo kai plèon apokleistikˆ afierwmènwn kanali n geitonik n SB. Sthn perðptwsh pou èqoume sunergasða dôo SB gia ton qr sth k èqoume:

Kefˆlaio 6. Teqnik Elègqou thc IsqÔoc gia thn Diasfˆlish tou QoS se Sust mata 120 Poluekpomp c CDMA PÐnakac 6.1: Ekpempìmenh isqôc gia metˆdosh mèsw FACH Ποσοστό κάλυψης της κυψέλης (%) Απαιτούμενη ισχύς (W) Απαιτούμενη ισχύς (W) για υπηρεσία 64 Kbps για υπηρεσία 128 Kbps 10 1.4 2.6 20 1.6 3 30 1.8 3.6 40 2 4.2 50 2.5 5 60 3 6.2 70 3.6 7.8 80 4.8 10 90 6.4 13 95 7.6 15.8 ( Eb N 0 ) k = ( Eb N 0 ) k 1 + ( Eb N 0 ) k l (6.3) ìpou, o lìgoc (E b /N 0 ) k 1 parèqetai apì ton SB 1 kai o lìgoc (E b /N 0 ) k l parèqetai apì ton geitonikì SB l, ìpwc anafèretai kai sthn ergasða [21]. Eˆn o SB thc kuyèlhc pou meletˆme exuphreteð M omˆdec qrhst n poluekpomp c (MGs) kai P m eðnai h isqôc pou apaiteð to MG m tìte ja prèpei: M P m P max (6.4) m=1 ìpou P m eðnai h isqôc pou katanal nei h omˆda qrhst n thc klˆshc m kai P max h mègisth epitrepìmenh ekpomp isqôoc tou SB. 6.4 Proteinìmenh Teqnik DiaqeÐrishc twn Radiopìrwn Sthn paroôsa enìthta parèqetai h proteinìmenh teqnik diaqeðrishc twn radiopìrwn gia thn apodotikìterh diaqeðrish thc ekpempìmenhc isqôoc. Efarmìzetai ston SB kai paðrnoume wc dedomènh thn diakuyelwt sunergasða gia metˆdosh se qr stec sthn diaqwristik epifˆneia thc kuyèlhc, thn opoða apokajistˆ o elegkt rac radiodiktôou (RNC). Parakˆtw akoloujeð o yeudok dikac thc proteinìmenhc teqnik c: 1. ArqikopoÐhsh: Sqhmˆtise to sônolo M = {1, 2,..., M} twn uphresi n sthn kuyèlh Kajìrise R m kai (E b /N 0 ) m 1 gia kˆje m M Upolìgise apostˆseic qrhst n apì SB kai L k, k {1, 2,..., K}

6.5 Parˆmetroi twn Prosomoi sewn 121 Upolìgise thn isqô gia metˆdosh thc uphresðac m me DCHs, P (m) DCH exðswsh (6.1) kai thn isqô me FACH, P (m) F ACH kˆje uphresða 2. Anˆjesh radiopìrwn: Gia kˆje m M apì thn apì PÐnaka 6.1 pou apaiteðtai gia Eˆn P (m) DCH < P (m) F ACH Anˆjese apokleistikˆ afierwmèna kanˆlia stouc qr stec thc uphresðac m Eˆn P (m) DCH P (m) F ACH Anèjese koinì kanˆli stouc qr stec thc uphresðac m Arqikˆ o SB sullègei plhroforðec gia thn jèsh twn qrhst n sthn kuyèlh kai upologðzei tic ap leiec diˆdoshc twn qrhst n. Epiplèon kajorðzetai to epijumhtì epðpedo QoS twn qrhst n bˆsei tou apaitoômenou rujmoô metˆdoshc dedomènwn kai poiìthtac tou s matoc. Sthn sunèqeia, upologðzetai h isqôc pou apaiteðtai gia thn metˆdosh dedomènwn stouc qr stec me apokleistikˆ kanˆlia kai h isqôc pou apaiteðtai gia metˆdosh me to koinì kanˆli. Eˆn h isqôc pou apaiteðtai gia ton trìpo metˆdoshc me monoekpomp eðnai ligìterh se sqèsh me thn isqô pou apaiteðtai gia thn metˆdosh me to koinì kanˆli, tìte o SB metˆdidei me apokleistikˆ kanˆlia stouc qr stec alli c metadðdei me to koinì. 6.5 Parˆmetroi twn Prosomoi sewn H paroôsa enìthta mac parèqei tic paramètrouc kaj c kai tic timèc touc oi opoðec eðnai aparaðthtec gia thn exagwg twn arijmhtik n apotelesmˆtwn pou dðnontai sthn epìmenh enìthta. JewroÔme polukuyelwtì sôsthma ìpwc apeikonðzetai sto Parˆrthma Gþ. Sto kèntro thc kˆje kuyèlhc upˆrqei SB mon c keraðac. Kˆje SB exuphreteð asôrmatouc qr stec me suskeuèc mon c keraðac epðshc (SISO downlink). Upojètoume astikì peribˆllon ìpou oi ap leiec diˆdoshc tou s matoc perigrˆfetai apì to montèlo Okumura-Hata: L k (d k ) = 128.1+37.6 log(d k ) gia kentrik suqnìthta forèa sta 2GHz kai Ôyoc SB ta 15m. H upo melèth kuyèlh eðnai h kuyèlh 1 (bl. Parˆrthma Gþ) kai kajorðzoume to (E b /N 0 ) m 1 tou kˆje CEU ste o SB na afier nei thn mis apì thn sunolik isqô pou apaiteð to DCH tou CEU. Oi upìloipec parˆmetroi sunoyðzontai ston PÐnaka 6.2. 6.6 Apotelèsmata twn Prosomoi sewn Se aut thn enìthta dðnetai h apìdosh thc proteinìmenhc teqnik c kataq rishc twn radiopìrwn bˆsei twn paramètrwn kai twn tim n thc enìthtac 6.5. Parèqontai sq mata pou deðqnoun thn apaitoômenh ekpempìmenh isqô gia diˆforec uphresðec se sqèsh me thn apìstash apì ton SB kai ton arijmì twn qrhst n tou MG.

Kefˆlaio 6. Teqnik Elègqou thc IsqÔoc gia thn Diasfˆlish tou QoS se Sust mata 122 Poluekpomp c CDMA Παράμετρος PÐnakac 6.2: Parˆmetroi prosomoðwshc Τιμή Αριθμός ΣΒ 19 Ακτίνα κυψέλης (d 0 ) 580 m Μέγιστη εκεμπόμενη ισχύς ΣΒ (P max ) 43dBm (20W) Ισχύς στα κοινά κανάλια ελέγχου (P CCH ) 30 dbm (1W) Εκπεμπόμενη ισχύς γειτονικών ΣΒ 37 dbm (5 W) Μοντέλο απωλειών διάδοσης Okumura Hata Παράγοντας ορθογωνικότητας (a) 0.5 (E b /I 0 ) k 5dB Sq ma 6.1: Ekpempìmenh isqôc gia uphresða 64 Kbps kai d/d 0 = 0.9 apìstash qrhst n apì ton SB. Sta Sq mata 6.1-6.4 dðnetai h posìthta thc isqôoc pou ekpèmpei o SB ìtan metadðdei dedomèna me apokleistikˆ afierwmèna kanˆlia stouc qr stec (unicast), me to koinì kanˆli (FACH) kai me apokleistikˆ afierwmèna kanˆlia se sunergasða me geitonikoôc SB. Stic grafikèc parastˆseic thc paroôsac enìthtac mporoôme na diakrðnoume epðshc, to kat fli pèra apì to opoðo eðnai protimìterh h metˆbash apì thn monoekpomp sthn poluekpomp. Eidikìtera sto Sq ma 6.1 jewroôme uphresða me rujmì metˆdoshc 64Kbps kai me touc qr stec pou an koun sthn Ðdia klˆsh uphresðac na brðskontai se apìstash d k /d 0 = 0.9 apì

6.6 Apotelèsmata twn Prosomoi sewn 123 ton SB thc kentrik c kuyèlhc. Sq ma 6.2: Ekpempìmenh isqôc gia uphresða 128 Kbps kai d/d 0 = 0.9 apìstash qrhst n apì ton SB. ParathroÔme ìti sthn perðptwsh pou den upˆrqei sunergasða metaxô geitonik n SB to kat fli gia thn allag apì thn metˆdosh me apokleistikˆ afierwmèna kanˆlia sthn metˆdosh me to koinì kanˆli eðnai oi 12 qr stec, en me thn proteinìmenh teqnik eðnai oi 20 qr stec. OmoÐwc sto Sq ma 6.2 pou o rujmìc metˆdoshc dedomènwn eðnai 128 Kbps, to ìrio eðnai oi 14 qr stec ìtan upˆrqei sunergasða metaxô SB kai oi 10 qr stec ìtan den èqoume sunergasða SB. AntÐstoiqa, sta Sq mata 6.3, 6.4 blèpoume ta ìria ìtan oi qr stec brðskontai se apìstash d/d 0 = 0.95. Ta ìria gia 64Kbps kai 128Kbps eðnai oi 9 qr stec en me thn proteinìmenh teqnik eðnai oi 15 kai 13 qr stec antðstoiqa. Epomènwc, sthn perðptwsh thc proteinìmenhc teqnik c exuphretoôntai perissìteroi qr stec me to apaitoômeno epðpedo QoS prin thn metˆbash sto koinì kanˆli FACH. H suneisforˆ thc proteinìmenhc teqnik c eðnai shmantik se peript seic ìpou h metˆdosh me to koinì kanˆli, se qr stec sta ìria thc kuyèlhc ja prokaloôse eðte upobˆjmish tou QoS, eðte thn upˆrbash tou orðou ekpomp c isqôoc tou SB, ìpwc deðqnetai sta dôo senˆria katanom c qrhst n twn Pinˆkwn 6.3 kai 6.4. Sto Senˆrio A, ìpou jewroôntai dôo MGs pou lambˆnoun dedomèna me 128 Kbps to kajèna, diapist netai ìti h metˆdosh eðte mìno me apokleistikˆ kanˆlia eðte mìno me koinˆ kanˆlia uperbaðnei to ìrio thc mègisthc ekpempìmenhc isqôoc tou SB. To Ðdio isqôei kai gia thn perðptwsh efarmog c tou algorðjmou qwrðc

Kefˆlaio 6. Teqnik Elègqou thc IsqÔoc gia thn Diasfˆlish tou QoS se Sust mata 124 Poluekpomp c CDMA sunergasða SB (Power based) faðnetai ìpou to apaitoômeno epðpedo QoS eðnai adônato na exuphrethjeð. 'Omoia sto Senˆrio 6.4 ìpou upˆrqoun trða MGs me diaforetikèc apait - seic QoS kai jèseic mèsa sthn kuyèlh, faðnetai ìti mìno me thn proteinìmenh strathgik, diasfalðzetai to QoS ìlwn twn qr stwn. Sq ma 6.3: Ekpempìmenh isqôc gia uphresða 64 Kbps kai d/d 0 = 0.97 apìstash qrhst n apì ton SB. PÐnakac 6.3: Senˆrio A Παραμέτροι Υπηρεσία 1 Υπηρεσία 2 Αριθμός χρηστών 8 10 Ρυθμός Μετάδοσης (Kbps) 128 128 Απόσταση χρηστών (d k /d 0 ) 0.9 0.97 Απαιτούμενη ισχύς -DCH (W) 6.6 18.2 Απαιτούμενη ισχύς -FACH (W) 10 15.8 Απαιτούμενη ισχύς -Power based (W) 6.6 15.8 Απαιτούμενη ισχύς -Power based and BS coordination (W) 3.3 9.1

6.7 Sumperˆsmata 125 Sq ma 6.4: Ekpempìmenh isqôc gia uphresða 128 Kbps kai d/d 0 = 0.97 apìstash qrhst n apì ton SB. PÐnakac 6.4: Senˆrio B Παραμέτροι Υπηρεσία 1 Υπηρεσία 2 Υπηρεσία 3 Αριθμός χρηστών 12 10 8 Ρυθμός Μετάδοσης (Kbps) 128 64 64 Απόσταση χρηστών (d k /d 0 ) 0.9 0.9 0.97 Απαιτούμενη ισχύς -DCH (W) 14 4 7.2 Απαιτούμενη ισχύς -FACH (W) 10 4.8 7.6 Απαιτούμενη ισχύς -Power based (W) 10 4 7.2 Απαιτούμενη ισχύς - Power based and BS coordination (W) 7 2 3.6 6.7 Sumperˆsmata Sto parìn Kefˆlaio protˆjhke mia strathgik diaqeðrishc thc diajèsimhc isqôoc gia thn diasfˆlish tou apaitoômenou epipèdou QoS twn qrhst n. EÐnai efarmìsimh se dðktua basismèna sthn pollapl prìsbash CDMA katˆ thn metˆdosh dedomènwn poluekpomp c. MetaxÔ twn dôo diajèsimwn trìpwn metˆdoshc twn dedomènwn, dhlad me monoekpomp mèsw apokleistik n kanali n kai me poluekpomp mèsw koinoô kanalioô, epilègetai o trìpoc metˆdoshc me thn ligìterh apaðthsh se isqô arkeð na diasfalðzetai to apaitoômeno epðpedo

Kefˆlaio 6. Teqnik Elègqou thc IsqÔoc gia thn Diasfˆlish tou QoS se Sust mata 126 Poluekpomp c CDMA QoS qrhst n. Epiplèon eðte lìgw katanom c twn qrhst n sthn kuyèlh eðte lìgw uyhloô apaitoômenou QoS, eðnai pijanìn o SB na adunateð na exuphret sei touc qr stec thc kuyèlhc tou, ìpwc epishmˆnjhke sta Senˆria 6.3 kai 6.4 thc enìthtac 6.6. Gia to lìgo autì, sthn proteinìmenh teqnik eis qjhke h filosofða thc suntonismènhc metˆdoshc stouc qr stec thc diaqwristik c epifˆneiac tou kuyèlhc me th bo jeia geitonik n SB kai ta apotelèsmata èdeixan ìti me thn proteinìmenh teqnik eðnai dunatìn na diasfalisteð to epðpedo QoS twn qrhst n qwrðc upèrbash thc tim c thc mègisthc ekpempìmenhc isqôoc tou SB.

BibliografÐa [1] H. Holma, and A. Toskala, WCDMA for UMTS: HSPA Evolution and LTE, 4th edition, John Wiley & Sons, 2007. [2] E. Dahlamn, B. Gudmundson, M. Nilsson and J. Skold, UMTS/IMT2000 Based on Wideband CDMA IEEE Commun. Magaz. pp. 70-80, Sep. 1998. [3] 3GPP TR 22.146, Multimedia Broadcast/ Multicast Service; Stage 1 (Release 8), 2007, version 8.3.0. [4] C. Christophorou, and A. Pitsillides, An Efficient Handover Algorithm for MBMS Enabled 3G Mobile Cellular Networks IEEE Sympos. on Comp. and Commun. (ISCC), Sardinia, Italy, June 2006. [5] 3GPP TR 23.846, Multimedia Broadcast/ Multicast Service; Architecture and functional description (Release 6). 2003, version 6.1.0. [6] Z. Hasan, H. Boostanimehr, and V. K. Bhargava, Green Cellular Networks: A Survey, Some Research Issues and Challenges IEEE Commun. Serv. and Tutor., vol. 13, no. 4, pp. 524-540, Nov. 2011. [7] 3GPP TR 32.826, Telecommunication management; Study on Energy Saving Management (ESM) Stage 1 (Release 10), Mar. 2010. [8] ITU-T Focus Group on Future Networks (FG FN), FG-FN OD-66, Draft Deliverable on Overview of Energy Saving of Networks, Oct. 2010. [9] A. Alexiou, C. Bouras, and V. Kokkinos, Power Saving Techniques in MBMS Multicast Mode, 3rd ACM Intern. Workshop on Wirel. Multim. Network. and Perf. Model.(WMUNPM), pp. 62-69, Chania, Greece, Oct. 2007. [10] N. Vlotomas, J. Antoniou, G. Hadjipollas, V. Vassiliou, and A. Pitsillides, Power Control for Efficient Multicasting in IP-based 3G and beyond mobile networks 11th European Wireless, pp. 1-5, Nicosia, Cyprous, April 2005. [11] A. Raschella, A. Umbert, G. Araniti, A. Iera, and A. Molinaro SINR-based Transport Channel Selection for MBMS Applications, IEEE Veh. Techn. Conf. (VTC-Spring, pp. 1-5, Barcelona, Spain, April 2009 127

128 BibliografÐa [12] A. Panayides, C. Christophorou, J. Antoniou, A. Pitsillides, and V. Vassiliou, Power Counting for Optimized Capacity in MBMS Enabled UTRAN IEEE Sympos. on Comp. and Commun. (ISCC), pp. 368-373 Marakesh, Morocco, July 2008. [13] A. Alexiou, C. Bouras, and E. Rekkas, A Power Control Scheme for Efficient Radio Bearer Selection in MBMS, IEEE Intern. Sympos. on World of Wirel., Mobile and Multim. Netw. (WOWMOM), pp. 1-8, Espoo, Finland, June 2007. [14] C. Christophorou, and A. Pitsillides, A New Approach for Efficient MBMS Service Provision in UTRAN IEEE Sympos. on Comp. and Commun. (ISCC), pp. 356-361 Marakesh, Morocco, July 2008. [15] A. Alexiou, C. Bouras, and V. Kokkinos, An Efficient Mechanism for Power Control Optimization in MBMS Enabled UTRAN, IEEE Wireless Commun. Network Conf. (WCNC), pp. 1292-1297, Budapest, Hungary, April 2009. [16] G. Araniti, A. Iera, and A. Molinaro, A Power Based Algorithm for Efficient Radio Resource Management Policy in Integrated Terrestial/HAP MBMS Systems, IEEE Global Commun. Conf. (Globecom), pp. 1-5, New Orleans, USA, Nov. 2008 [17] G. Araniti, A. Iera, A. Molinaro, A. Raschella, and A. Umbert On the Optimization of Power Assignment to Support Multicast Applications in HAP-based Systems, IEEE Intern. Conf. on Telecom. (ICT), pp. 219-226, Doha, Qatar, April 2010 [18] C. C. Lee, and R. Steele, Effects of soft and softer handoffs on CDMA system capacity IEEE Trans. on Veh. Techn., vol. 47, no. 3, pp. 830-841, Aug. 1998. [19] W. Choi, and J. Y. Keem, Forward-link capacity of a DS/CDMA system with mixed multirate services IEEE Trans. on Veh. Techn., vol. 50, pp. 737-749, May 2001. [20] Y. Chen, and L. Cuthbert, Optimum size of soft handover zone in power-controlled UMTS downlink systems Electronic Letters, vol. 38, no. 2, pp. 89-90, Jan. 2002. [21] Y. Chen, and L. Cuthbert, Optimised Downlink Transmit Power Control during Soft Handover in WCDMA Systems IEEE Wirel. Commun. and Netw. Conf. (WCNC), March 2003. [22] J. Perez-Romero, O.Sallent, R. Agusti, M. Diaz-Guerra, Radio Resource Management Strategies in UMTS, John Wiley & Sons, 2005. [23] 3GPP TS 25.803. S-CCPCH performance for MBMS (Release 6), 2005, version 6.00.

Kefˆlaio 7 EpÐlogoc 7.1 Sumperˆsmata H paroôsa DD eðqe wc stìqo thn prìtash nèwn teqnik n gia thn beltistopoðhsh tou pareqìmenou QoS stouc qr stec elègqontac krðsimec hlektrikèc kai hlektromagnhtikèc paramètrouc sta sôgqrona asôrmata thlepikoinwniakˆ sust mata. Protˆjhkan teqnikèc pou aforoôsan sust mata MIMO-OFDMA, polukuyelwtˆ sust mata OFDMA kai polukuyelwtˆ sust mata CDMA. Sugkekrimèna ta sumperˆsmata pou prokôptoun eðnai ta ex c: Sto Kefˆlaio 2 ta sumperˆsmata eðnai ìti h proteinìmenh teqnik mporeð na prosfèrei uyhloôc rujmoôc metˆdoshc dedomènwn sto sôsthma lìgw axiopoðhshc thc teqnologðac MIMO kai thc poluekpomp c. ApodeiknÔetai pio dðkaih se sqèsh me ˆllec teqnikèc pou apokleistikìc skopìc touc eðnai h aôxhsh tou sunolikoô rujmoô metˆdoshc dedomènwn kai idiaðtera qr simh ìtan sto sôsthma upˆrqoun pollaplèc omˆdec qrhst n ìpou kˆje omˆda qrhst n apaiteð to Ðdio perieqìmeno. Tèloc, h teqnik eðnai apotelesmatik ìson aforˆ thn poluplokìthta, kaj c parousiˆzei grammik c tˆxhc poluplokìthta. Sto Kefˆlaio 3 o proteinìmenoc epanalhptikìc algìrijmoc mporeð na diaqeiristeð touc diajèsimouc pìrouc ste h pijanìthta parabðashc tou QoS, se sôsthma ìpou qr stec apaitoôn sugkekrimèna elˆqista epðpeda QoS, na eðnai mikroterh se sqèsh me klasikèc teqnikèc katanom c twn radiopìrwn kai prìsfata proteinìmena statikˆ sq mata. E- piplèon prosfèrei megalôterouc rujmoôc metˆdoshc sthn diaqwristik epifˆneia thc kuyèlhc kai h poluplokìthta tou eðnai arketˆ qamhl. Sto Kefˆlaio 4 protˆjhke ìpwc kai sto Kefˆlaio 3 ènac epanalhptikìc algìrijmoc prosanatolismènoc sto QoS twn qrhst n. Parousiˆzei mia prosèggish pio praktik kaj c sunupologðzei tic ourèc anamon c twn qrhst n ston SB. BasÐsthke ston PFS dianèmontac thn isqô omoiìmorfa sto diajèsimo fˆsma kai mporeð na suneisfèrei qamhlìterh pijanìthta parabðashc tou QoS, megalôtero rujmì metˆdoshc sta ìria thc kuyèlhc kai perissìterh dikaiosônh sto sôsthma sugkritikˆ me ˆllec teqnikèc. 129

130 Kefˆlaio 7. EpÐlogoc Sto Kefˆlaio 5 diereun jhke teqnik apofug c twn omokanalikwn parembol n gia thn beltðwsh tou QoS stouc qr stec sth diaqwristik epifˆneia thc kuyèlhc. H posìthta isqôoc pou analogeð se kˆje qr sth eðnai prokajorismènh kai ta sumperˆsmata eðnai pwc h rujmìc metˆdoshc ìpwc kai o deðkthc dikaiosônhc twn qrhst n sta ìria thc kuyèlhc parousiˆzei arket beltðwsh. Sto Kefˆlaio 6 ta apotelèsmata thc teqnik c pou protˆjhke gia sust mata poluekpomp c CDMA èdeixan pwc me ton diamoirasmì thc apaitoômenhc isqôoc twn qrhst n sth diaqwristik epifˆneia tou kelioô se geitonikoôc SB, eðnai dunatìn na diasfalisteð to apaitoômeno QoS qwrðc upèrbash tou orðou ekpomp c isqôoc tou SB. 7.2 Mellontikèc Epektˆseic To antikeðmeno thc anˆptuxhc teqnik n gia th beltistopoðhsh tou QoS kai ton èlegqo twn pìrwn twn asurmˆtwn susthmˆtwn nèac geniˆc apoteleð ènan apì touc pio energoôc tomeðc èreunac ston tomèa twn thlepikoinwni n. Sthn paroôsa DD anaptôqjhkan teqnikèc oi opoðec mporoôn na apotelèsoun thn bˆsh gia mellontik èreuna kai anˆptuxh nèwn kainotìmwn teqnik n. Parakˆtw anafèrontai sunoptikˆ pijanèc epektˆseic kai nèec kateujônseic pˆnw stic teqnikèc pou anaptôqjhkan sthn DD. Epèktash twn teqnik n pou protˆjhkan mporeð na gðnei se sust mata me gnwsiak radiopekoinwnða (Cognitive Radio), ìpou oi epikoinwniakèc domèc pou melet jhkan sthn DD mporoôn na apotelèsoun sôsthmata me gnwsiak radioepikoinwnða jètontac ènan epiplèon periorismì pou aforˆ to epðpedo twn parembol n sto prwteôon sôsthma. Efarmog twn teqnik n se sust mata pou na uposthrðzontai apì anametadìtec (relayaided), ìpou megalôterh ja eðnai h poikilomorfða tou kanalioô ìpwc epðshc kai h poluplokìthta twn pijan n nèwn teqnik n. Epèktash twn proteinìmenwn teqnik n se eterogen dðktua kai dðktua me akanìnistec kuyelwtèc domèc ìpwc ta epðgeia kuyelwtˆ dðktua pou uposthrðzontai apì HAPS (StajmoÔc megˆlou uyomètrou) sust mata femtokuyel n (femtocells). Prosanatolismì twn teqnik n thc DD sthn poiìthta thc empeirðac (QoE) tou qr sth ìpou epiplèon parˆmetroi ja prèpei na sumperilhfjoôn kai oi teqnikèc ja prèpei na axiologhjoôn mèsa apì ˆlla majhmatikˆ montèla kai deðktec.

Parˆrthma Aþ Teqnikèc N-ostoÔ BajmoÔ EpanaqrhsimopoÐhshc twn Suqnot twn Oi teqnikèc pou apoteloôn tic klasikèc teqnikèc epanaqrhsimopoðhshc suqnot twn sta polukuyelwtˆ dðktua eðnai oi Reuse-1 kai Reuse-3. Eˆn to diajèsimo eôroc z nhc epanaqrhsimopoieðtai ìlo se kˆje kuyèlh qwrðc periorismoôc stic suqnìthtec sthn isqô pou kataqwreðtai, tìte briskìmaste sthn teqnik Reuse-1 diakrðnetai sto Sq ma Aþ.1a. H diajèsimh isqôc katanèmetai omoiìmorfa stouc diajèsimouc upoforeðc. Upojètwntac ìti to diajèsimo fˆsma apoteleðtai apì N upoforeðc, tìte h isqôc pou kataqwreðtai se kˆje upoforèa eðnai P bs /N, ìpou P bs eðnai h isqôc tou SB. AntÐjeta, ìpwc faðnetai kai sto Sq ma Aþ.1b, me thn teqnik Reuse-3 to diajèsimo fˆsma qwrðzetai se trða tm mata orjog nia metaxô kai kˆje èna tm ma anatðjetai se kˆje mða kuyèlh miac sustˆdac tri n kuyel n. 'Opwc kai sthn Reuse-1 ètsi kai ed h isqôc tou SB katanèmetai omoiìmorfa stouc upoforeðc, allˆ sthn paroôsa perðptwsh h isqôc kˆje upoforèa eðnai uyhlìterh kai Ðsh me 3P bs /N. Sq ma Aþ.1: Klasikèc teqnikèc epanaqrhsimopoðhshc fˆsmatoc 131

Parˆrthma Bþ Teqnik thc Klasmatik c EpanaqrhsimopoÐhshc twn Suqnot twn (FFR) Oi teqnikèc pou apoteloôn th klasmatik epanaqrhsimopoðhsh suqnot twn eðnai h teqnik thc piac epanaqrhsimopoðhshc suqnot twn kai h teqnik thc merik c epanaqrhsimopoðhshc suqnot twn, oi opoðec parousiˆzontai parakˆtw. Sq ma Bþ.1: Teqnikèc klasmatik c epanaqrhsimopoðhshc fˆsmatoc Bþ.1 'Hpia EpanaqrhsimopoÐhsh Suqnot twn H teqnik thc piac epanaqrhsimopoðhshc suqnot twn (SFR) diaqwrðzei to diajèsimo fˆsma suqnot twn se dôo tm mata, èna gia touc qr stec sthn kentrik perioq thc kuyèlhc (CCUs) kai èna gia touc qr stec sthn diaqwristik epifˆneia thc kuyèlhc (CEUs). 'Opwc faðnetai sto Sq ma Bþ.1a to èna trðto tou eôrouc z nhc proorðzetai gia touc CEUs kai eðnai orjog nio me ta antðstoiqa tm mata fˆsmatoc stouc CEUs stic geitonikèc kuyèlec dhmiourg ntac sustˆdec trðwn kuttˆrwn. To tm ma tou fˆsmatoc pou prokrateðtai gia touc 132

bþ.2 Merik EpanaqrhsimopoÐhsh Suqnot twn 133 CCUs apartðzetai apì tic suqnìthtec pou qrhsimopoioôn oi CEUs stic geitonikèc kuyèlec. Perissìterh eðnai h isqôc pou kataqwreðtai sthn mpˆnta suqnot twn pou proorðzetai gia touc CEUs. Upojètwntac ìti to diajèsimo fˆsma apoteleðtai apì N upoforeðc kai ìti h isqôc se kˆje upoforèa eðnai Ðsh me P bs /N ìtan èqoume epanaqrhsimopoðhsh suqnothtwn Ðsh me èna (Reuse-1), ìpou P bs thn ekpempìmenh isqôc tou SB. Tìte me thn teqnik SFR h isqôc se kˆje upoforèa pou proorðzetai gia touc CEUS eðnai Ðsh me a p P bs /N, ìpou a p eðnai ènac parˆgontac enðsqushc megalôteroc thc monˆdac kai h isqôc stouc upoforeðc pou proorðzontai gia touc CCUS eðnai (3 a p )P bs /2N. H mpˆnta suqnot twn pou proorðzetai gia touc CCUs den mporeð na qrhsimopoihjeð apì touc CEUs, antðjeta an kˆpoioi upoforeðc thc mpˆntac pou proorðzetai gia touc CEUs den èqoun katalhfjeð apì autoôc, tìte mporoôn na anatejoôn se CCU. H kathgoriopoðhsh twn qrhst n gðnetai sun jwc apì thn isqôc tou s matoc pou lambˆnei apì thn apostas apì ton SB. Bþ.2 Merik EpanaqrhsimopoÐhsh Suqnot twn AntÐjeta me thn teqnik thc piac epanaqrhsmopoðhshc suqnot twn, h Ðdea sthn opoða basðzetai h teqnik thc merik c epanaqrhsimopoðhshc suqnot twn (PFR) eðnai h apagìreush qr simopoðhshc kˆpoiwn apì touc sunolikˆ diajèsimouc pìrouc se kˆje kuyèlh ste na exaleðfetai entel c to fainìmeno thc omokanalik c parembol c (CCI) stouc CEUs ìpwc faðnetai sto Sq ma Bþ.1b, ìpou parembolèc sunantˆme mìno metaxô twn CCUs twn geitonik n kuyel n pou o paragontac epanaqrhsimopoðhshc suqnot twn isoôtai me 1. O parˆgontac epanaqrhsimopoðhshc suqnot twn gia to fˆsma pou proorðzetai gia touc CEUs eðnai 3. Gia ta profðl isqôoc twn upoforèwn tou sust matoc isqôei to Ðdio ìpwc sthn SFR (bl. Sq ma Bþ.1).

Parˆrthma Gþ Kuyelwt Dom DiktÔou kai Exis seic gia ton Upologismì twn Apwlei n Diˆdoshc Oi sqèseic pou perigrˆfoun thn apìstash tou qr sth k thc kuyèlhc 1 apì to kèntro thc geitonik c kuyèlhc l eðnai: d 2 k + ( 3d 0 ) 2 2 d k 3d 0 cos[θ k + (l 2)π/3], 2 l 7 d k = d 2 k + (2 3d 0 ) 2 2 d k 2 3d 0 cos[θ k + (l 8)π/6], l = 8, 10,..., 18 d 2 k + (3d 0) 2 2 d k 3d 0 cos[θ k + (l 8)π/6], l = 9, 11,..., 19 ìpou, d 0 eðnai h aktðna thc kˆje kuyèlhc kai d k, θ k eðnai h apìstash tou qr sth k apì to kèntro thc kuyèlhc 1 kai h gwnða tou antðstoiqa. 134

Sq ma Gþ.1: Kuyelwt dom diktôou. 135

Parˆrthma gþ. Kuyelwt Dom DiktÔou kai Exis seic gia ton Upologismì twn Apwlei n 136 Diˆdoshc