Operating Network Load Balancing with the Media Independent Information Service for Vehicular Based Systems

Transcription

1 CHI MA et l: OPERATING NETWORK LOAD BALANCING WITH THE MEDIA INDEPENDENT... Opertng Network Lod Blncng wth the Med Independent Inforton Servce for Vehculr Bsed Systes Ch M, End Fllon, Yunsong Qo, Brn Lee Softwre Reserch Insttute Athlone Insttute of Technology Athlone, Irelnd {c,efllon,ysqo, Astrct A echns s desgned here to relze Network_Lod_Blncng (NLB y drectng hndover sed on Med Independent Hndover for vehculr sed systes. We desgned Predctve_Lnk_Gong_Down event sed on Med Independent Event Servce whch ccurtely esttes the perfornce degrdton to predct vehcle oveents nd Predctve_Hndover_Inforton_Structure (PHIS sed on Med Independent Inforton Servce. Ths ncludes the network geogrphcl nforton, MN s ovng nforton nd network lodng stuton. PHIS s sent to upper lyer olty protocol dynclly s nput for NLB operton, whch utlzes MN drecton fuzzy logc to consder oth the vehcle oveent predcton nd current network lodng stuton nd Optl Cnddte Bse Stton Selecton, whch utlzes the fuzzy MADM lgorth. Results llustrte the proposed pproch reduces ore thn 95% hndover durton n coprson to wthout utlzng ny lnk trggers. Wth the NLB operton, dely s reduced y 1s nd jtter s nerly closed to 0, thus sgnfcntly provng QoS. Keywords- MIH, IEEE 80.1, Hndover, Fuzzy MADM, Network Lod Blncng I. INTRODUCTION For soe te wreless networkng technologes hve een developng rpdly. The ntroducton of cellulr technologes such s Thrd Generton networks (3G together wth ts vrnts HSDPA, HSUPA nd HSPA+ hve enhnced the underlyng cplty of trdtonl telecounctons networks. In the re of wreless networks the ntroducton of 80.11n nd 80.16e hs enhnced the rnge nd flelty of wreless networks. Coupled wth the ncresed cplty n underlyng networks, srt end user devces hve ttrcted sgnfcnt consuer nterest. Mny cellulr devces re now desgned to support W-F, Bluetooth, nd 3G nterfces. Moreover, ny lptops re shpped wth stndrd support for Ethernet, W-F, WMAX, Bluetooth, Wreless Infrred, 3G, etc. Underpnned y techncl dvnces n underlyng networks nd coupled wth ncresed consuer dend for srt devces hve resulted n necessty to support seless hndover n heterogeneous networks. Med Independent Hndover (MIH s drft stndrd under developent y IEEE 80.1 [1] workng group whch proposes to optze hndovers etween heterogeneous IEEE 80 systes nd etween IEEE 80 systes nd cellulr systes. MIH defnes set of tools to echnge nforton, events nd conds to fcltte hndover. In ths pper, we propose odel to prove the hndover perfornce of the estng MIH pleentton. Our pproch ntroduces the followng coponents: predctve hndover trgger event PLGD event n lgorth to select est cnddte BS for hndover sed on fuzzy MADM whch tkes PHIS eleent fro PLGD event s nput n lgorth of relzng NLB usng MIIS for vehculr sed systes. In the proposed schee, new PLGD event whch utlzes the estted te of network flure provded y the thetcl odel s desgned. By ccurtely esttng the te of network flure the PLGD event cn e trggered provdng the Upper Lyer Molty Protocol (ULMP wth suffcent te to ntte the hndover process pror to ctul network flure. We lso defne PHIS n order to councte the requred nforton to ULMP to pleent Optl Cnddte Bse Stton Selecton/Network Lod Blncng (OCBSS/NLB. In the second prt, network selecton lgorth s proposed sed on fuzzy MADA whch tkes the PHIS eleent s nput. PHIS eleent ncludes the MN s current oveent ptterns, dync network perfornce etrcs nd neghorhood nforton. Fnlly new NLB lgorth whch utlzed PLGD event nd PHIS eleent to cheve network resource optzton s proposed. Utlzng the PHIS eleent, the NLB operton s relzed y drectng the hndover sed on the MN s oveent, BS geogrphcl nforton nd current network lod. Fnlly we use hndover to relze NLB. The MNs re llocted y consderng oth the BSs lod stuton s well s the MNs oveent. All of the nforton such s the BSs locton, BSs coverge, BSs lod stuton, MNs 40

2 CHI MA et l: OPERATING NETWORK LOAD BALANCING WITH THE MEDIA INDEPENDENT... ovng nforton nd other requred network nforton re receved fro the MIIS. Severl sulted scenros re undertken whch utlze NS [] together wth the WMAX olty pckge fro NIST [3]. Sulted results presented llustrte the proposed odel proves hndover perfornce nd sgnfcntly proves QoS. In prtculr our results llustrte tht the propose pproch cheves effectve network lod lncng. Ths pper s orgnzed s follows: relted work s descred n Secton II. An MIH ckground s ntroduced n Secton III. Our proposed odel s eplned n Secton IV. In Secton V the eperent envronent s descred together wth detled nlyss of the sulton results. Fnlly conclusons re presented n Secton VI. II. RELATED WORKS A. Hndover Algorth Vrous studes hve nvestgted lgorths to prove hndover perfornce for heterogeneous networks. [11] proposed olty-sed predcton lgorth wth dync LGD trggerng for vertcl hndover y pplyng the Med Independent Inforton Servce (MIIS. The pproch cn dvnce the LGD trgger pont dynclly to predctly prepre for the hndover usng the Possle Movng Are to ndcte net trget cell. [9] proposes novel rchtecture clled Seless Wreless nternet for Fst Trns (SWFT. SWFT reles on fst hndoff echns nd L trggerng usng hndover prolty vlue evluted y hgh speed oveent nd RSS to decde hndoff. Estng hndover echnss re desgned sed on pre-defned threshold (th lgd n order to trgger the LGD event n MIH. Mny of these echnss use RSS s the source perfornce etrc on whch th lgd s ppled s shown n Fgure 1. The LGD event s trggered to ntte the hndover process when the vlue of recorded RSS crosses the vlue of th lgd. (1 s used to clculted th lgd. Such n event trgger echns s perfornce lted s nether the user s dync oveent nforton nor the requred te to prepre for hndover re consdered. A preture or delyed hndover s shown n Fgure nd Fgure 3 wll result n n ncorrect th lgd vlue, resultng n reduced end user perceved QoS nd poor network utlzton. Soe new predctve hndover echnss were proposed n [4] [7] nd [8], whch used the network neghourhood nforton n MIIS to prepre for the pendng hndover efore flure of the underlyng network pth. An enhnced Med Independent Hndover Frework (emihf s desgned n [5] whch etended MIH y llowng for effcent provsonng nd ctvton of QoS resources through trget rdo ccess technology durng the hndover preprton phse. The ove nvestgtons re lted for vehculr sed systes. In the vehculr sed systes, users usully ove t fst speeds n vrous drectons. Wth user oveent chnges, estng lgorths wll result n long hndover durton te nd frequent hndover opertons whch reduce network perfornce, QoS nd resource utlzton. Our proposed odel dffers fro the estng LGD event s t does not utlze pre-defned RSS threshold th lgd In ths work our PLGD event, s proposed n [1], s used trggered y novel thetc odel whch uses the vehcle oveent, the users geogrphcl locton s well s the BSs neghorhood geogrphcl nforton to clculte the hndover ntte te. The tng of such n event s ntended to provde suffcent te for hndover preprton pror to the flure of the current pth. th lgd th lg d lgd Fgure A Preture LGD Trgger Fgure 1 Pre-defned Thresholds LGD Event 41

3 CHI MA et l: OPERATING NETWORK LOAD BALANCING WITH THE MEDIA INDEPENDENT... Fgure 3 A Too Lte LGD Trgger B. Network Lod Blncng Algorth Lod lncng hs een ostly used n coputer systes for lod shrng, however t cn lso een ppled n telecouncton. Lod lncng cn e defned s the process of dvdng nd dstrutng worklod etween ny servers so tht ore worklod cn e served. The of resource llocton sed network lod lncng s to llocte the resources to the ost trffc re; wth lod dstruton the gol s to use hndover to drect the trffc to the resource. Lod lncng cn lso e done n dstruted or centrlzed wy. In generl, lod lncng cn e conducted n sttc or dync nner. Sttc lod lncng s ndependent of the stte of the syste where s n dync lod lncng, decsons re de sed on the current lod stuton nd vllty of resources. The centrlzed pproch reduces sgnlng ut s senstve to node flure. [18] The dstruted pproch reduces sgnlng ut s senstve to node flure. The dstruted pproch on the other hnd s sple nd roust ut requres gret ount of sgnlng nd cnnot optze the syste n the se wy s the centrlzed pproch does. When ppled to WMAX, the ost lkely choce s to use dync lod lncng n dstruted nner. Lod dstruton wth hndovers cn e conducted n nuer of wys. One coonly pproch s clled cell rethng. The lod lncng s done y djustng the trnssson levels of the SBs plot sgnl (shrnkng the cell ccordng to the trffc level, resultng n stuton where MSs t the edge of the cell re forced to conduct rescues hndovers. In [13], new lod lncng slr to cell rethng n cellulr network s proposed y controllng the sze of WLAN cells, for eple, the Access Pont s (AP coverge wth the ethod of chngng the trnssson power of the AP econ essge dynclly. In [14], dstruted lgorth s proposed n whch the APs tune ther cell sze ccordng to ther lod nd neghourhood lod stuton. Cell rethng wll hppen n CDMA systes utotclly s the nuer of MNs ncreses. Ths pproch cn lso e used n the other wreless networks, such s 80.11, nd Mole WMAX, there re soe dsdvntges however [15]. The ggest drwck s tht BS would hve less control on where nd when n MN would conduct the hndover nd hence the posslty to gurntee QoS syste wde would decrese. The worst stuton s tht the MN forced to ntte rescue hndover ght not hve ny other BSs n rnge nd the connecton would e roken. Another pproch s clled trffc lod sed MN ntted hndovers. In ths pproch the lod lncng logc resdes n the MNs, such n pproch y lredy e n use s soe WLAN ternls y choose the lest congested AP sed on esureents de of the cnddte APs. MN ntted lod lncng hndovers cn e esly conducted n Mole WMAX sed on the vlle resource nforton rodcsted n the MOB-NBR ADV essge. A hndover-sed trffc ngeent schee whch cn effectvely del wth hotspot cells n net-generton cellulr networks s proposed n [17]. In the proposed schee, efore hndover eecuton, the trffc lod stutons of the trget cell cn e recognzed n dvnce. The lod dstruton ethod of ost relevnce to ths work s the drected hndover pproch, where the congested SBS forces the MS to hndover to less congested TBS. Ths s good pproch for Mole WMAX s t enles etter control for the BS nd therefore kes t possle to gurntee QoS syste wde. In [16], dync lod lncng schee whch utlzng fed rely sttons plced n cellulr geogrphcl coverge re to prove hndover perfornce n cellulr networks s proposed. III. MEDIA INDEPENDENT HANDOVER BACKGROUND Durng the lst decde, wreless network hve developed rpdly nd ece wdely dopted. Mny devce nufcturers hve ntegrted vrous network nterfces nto ther devces. Mny ole phones support oth W-F, 3G nd luetooth wreless networks. As ths trend n ultnterfce devces contnues, the need to prove the user eperence of ole users y fclttng hndover etween dfferent ed types ncreses. The MIH frework s stndrd eng developed y IEEE 80.1 whch proposes to enle hndover etween IEEE 80 networks nd non IEEE 80 networks. The MIH stndrd provdes lnk-lyer ntellgence nd other relted network nforton to upper lyers to optze hndovers etween heterogeneous networks. Ths ncludes ed types specfed y 3G Prtnershp Project (3GPP, 3G Prtnershp Project (3GPP, nd oth wred nd wreless ed n the IEEE 80 fly of stndrds. 4

4 CHI MA et l: OPERATING NETWORK LOAD BALANCING WITH THE MEDIA INDEPENDENT... Upper Lyers(Lyer 3+ Event Servce Coend Servce Inforton Servce IV. PROPOSED MODEL Upper Lyers (Lyer3+ PH Inforton MIH Functon OCBSSS/NBL LGD PLGD PH Inforton Event Servce Cond Servce Inforton Servce Cond Servce MIH Functon Event PLGD Servce Inforton Servce Lower Lyers (Lyer 1 nd Fgure 4 IEEE 80.1 Med Independent Hndover Functons LGD The portnce of MIH derves fro the fct tht dverse rnge of rodnd wreless ccess technologes re vlle, ncludng GSM, UMTS, CDMA000, WF WMAX, Mole-F nd WPANs [1]. Mult-nodl wreless devces tht ncorporte ore thn one wreless nterfce requre the lty to hndover durng n IP olty sesson. MIH provdes echnss to prepre the trget network efore hndover eecuton occurs therey reducng ltency. MIH defnes the Med Independent Event Servce (MIES for the propgton of events, the Med Independent Cond Servce (MICS whch llows the MIH user to ssue specfc ctons on lower lyers nd the MIIS to provde network detls. The ntercton of these servces s shown n Fgure 4. Fgure 5 IEEE 80.1 Med Independent Hndover Structure Fgure 6 Lower Lyers (Lyer - The Proposed Archtecture In ths secton, our proposed echns s outlned. The PLGD event whch s desgned n [1] s used n our echns. We defne PHIS Inforton structure n order to councte the requred nforton to the upper lyer for the OCBSSS/NLB (Optl Cnddte Bse Stton Selecton/Network Lod Blncng odel. Usng the PHIS the OCBSSS/NLB odel selects the optl cnddte network nd drects the hndover sed on the MN s oveent, BS geogrphcl nforton nd current network lod. The nforton requred to populte the PHIS wll e receved fro the MIIS s shown n Fgure 6. The event nd nforton flow n the proposed odel sed on IEEE MIH s shown n Fgure 18. A. Predctng_Hndover Inforton In our proposed echns, we use or PLGD event to nfor the MN tht hndover wll e needed n certn te sed on the MN s oveent stton, geogrphcl nforton of the BS nd the network lod stuton. The tng of such n event wll provde suffcent te to enle the olty protocol to select the optl cnddte BS nd prepre for hndover. The PLGD event s trggered y the followng two condtons: MN s gong to ove out of the current BS s coverge; The network lod lncng s needed; ths nforton cn drect the MN to prepre hndover. In these two stutons the upper lyer receves the PLGD event nd PHIS whch ndctes when hndover s lkely to occur. We use T PH to represent the estted te t whch hndover wll e requred. When the MN s n oton, the PLGD nd PHIS wll e trggered sed on the MN s nd AP s geogrphcl nforton, the MN s ovng stuton, nd the te needed for the predcted hndover. When pleentng network lod lncng the PHIS wll e sent to the upper lyer sed on the te needed for the predcted hndover. 43

5 CHI MA et l: OPERATING NETWORK LOAD BALANCING WITH THE MEDIA INDEPENDENT... PLGD Mesureent Bsed on Geogrphcl Inforton IEEE 80.1 IS PLGD Confgurton Predctng Lnk Gong Down Fgure 7 Neghour Dscovery PLGD Trgger Predcton Requre HO Te Cnddtes Decson Te Lnk Down Scn Cnddtes Neghour Dscovery Horzontl or Vertcl HO Eecuton Requred Hndover Te Te Requred for Preprng Hndover LD Trgger We use T HO to represent the requred preprng te for the upcong hndover. T HO s needed to dpt the current sesson to the chnged network condtons of the new pth. In ult-odl devce these confgurtons occur on redundnt lternte pth ndependent of the ctve councton on prry pth. Therefore the te requred to prepre for hndover s represented n Fgure 7. The epresson of T HO s presented n (. THO TNeghourDscovery TScnCnddte TLHO TL3HO In (, T NeghourDscovery s the te to ndentfy the cnddte networks, T ScnCnddte s the te requred to proe those networks whle T LHO nd T L3HO re the te requred to pleent L3 nd L hndover. B. ClculteT PH when MN s ovng The MIH stndrd ddresses the support of hndovers for oth ole nd sttonry users. For ole users, hndovers cn occur when wreless lnk condtons chnge due to the users oveent. For the sttonry users, hndovers ecoe nent when the neghorhood chnges, kng one network ore ttrctve thn the others. [1] The MIH stndrd supports coopertve use of nforton vlle t the MN nd wthn the network nfrstructure. The MN node s well-plced to detect vlle networks. The network nfrstructure s well-suted to store overll network nforton, such s neghorhood cell lsts, locton of the MN, nd hgher lyer servce vllty. Both the MN nd the network ke decsons out connectvty. The hndover process cn e ntted y esureent reports nd trggers suppled y the lnk lyers on the MN. In ths pper, we desgn thetc odel to clculte the hndover ntl te sed on the stuton of the users oveent. Wth the MIIS, lot of nforton cn e receved. Wth the nforton s the nput, thetc odel s desgned for the MN to clculte the Avlle Usng Te (AUT of the BSs. The vlue of AUT cn e used to ndcte hndover ntte te, nd lso cn e used to e consdered when select the optl BS. Fgure 4 llustrtes the scenro wth just one MN (P nd one BS (P. Fro Fgure 8, we cn deterne tht the coordnte poston of the BS s P (, y nd the coverge of the se stton s r. The coverge of the BS s therefore gven y (3. ( ( y y r The coordnte poston of the MN s P (, y, the velocty of oveent s v nd the slope s k, s shown n Fgure 4. If we ssue tht the MN oves n strght lne the equton of oveent s gven y (4. y y k ( If the MN keeps ovng wth velocty v, the pont of ntersecton wth the coverge of the BS, D 1 ( d1, y d1 nd D ( d, y d cn e clculted y the followng equtons n (5. ( d ( yd y r ( yd y k( d ( Fro ( n (5, we cn use d s the preters to present y d s n (6. y d k( y d Usng ( n (5 nd (6, qudrtc equton for the d n (7 cn e clculted. (1 k [ y y y y k d D ( d, y d ( ky Fgure 8 k ky ( y P (, y P (, y y ( y k P (, y y Mthetcl Model for PLGD Two solutons n (7 hs re gven y (8. d1 d 4c 4c d r D 1 ( d1, y d1 ] 0 44

6 CHI MA et l: OPERATING NETWORK LOAD BALANCING WITH THE MEDIA INDEPENDENT... The coeffcents for the equton n (7,,, c vlues re then clculted s n (9 c (ky k ky k 1 k (y y k (y y We then clculte d nd y d s n (10 nd (11. r ( d1, d, when( d n( d1, d, when( y d k( y d Suppose the MS s current poston s P (, y, fter t, the MN s poston wll e P (, y, therefore k cn e epressed n (1. k y y The velocty cn e clculted y: P (, y, P (, y nd t n (13. v ( ( y y t We use locton to the ntersecton, the vlue of clculted n (14. d P D 1 to present the dstnce fro the MN s d P D ( ( 1 d y yd d P D 1 cn e We use T AUT to represent the te when the MN oves to the pont of ntersecton. The vlue of T AUT cn e clculted n (15. T AUT d P D 1 v Fnlly, T AUT, the te when the MN oves out of the current BS s coverge cn e clculted n (16, T AUT t ( d ( y yd ( ( y y Usng T AUT (clculted fro the thetc odel, together wth T HO (the te needed to prepre for the hndover n (, we cn clculte T PL. TPL T AUT THO C. Optl Cnddte BS Selecton In ths secton, we ntroduce ethod for selectng the optl cnddte network sed on network lod condtons. Wth ths proposed ethod we cn enhnce the Resource Utlzton nd QoS. The MIIS provdes ddtonl dync perfornce etrcs whch cn e consdered when selectng the optl BSs for hndover. In ths pper, we focus on how to drect hndover sed on the MN s oveent, the neghorhood geogrphcl nforton of cnddte BSs, the network lod of BSs nd vlle ndwdth. In our echns, we use Fuzzy MADM for hndover selecton whch cn prove the network QoS nd stsfy the user. Suppose there re n BSs s the cnddte BSs, when the optl selecton of cnddte BS occurs, there re 4 ttrutes we tke nto consderton; the MN s vlle te of use for BSs (X 1, BSs resource utlzton (X, ndwdth (X 3 nd MN ovng drecton reltve to.bss (X 4. Mtr X n (18 cn e used to represent t. The weghts of ech se stton re W [ w1 w w3 w4 ], the dfferent weghts re ssgned to the preters n order to dff the preters portnce levels. X1 BS1 11 X BS 1 BSn n1 X 1 n X n3 X n4 We use (16 to clculte the MN s vlle use te of ech BSs. The lgorth then drects the hndover to n underutlzed re. The resource utlzton of BS s defned n (19, down U { U, U } We use the one-zero ssocton tr A to descre the stuton of ech MN nd BS. When j =1 ndctes tht MN j s ssocted to BS, nd when j =0 ndctes tht MN j s not ssocted to BS. up The uplnk resource utlzton ( U clculted n (0, up for BS cn e 45

7 CHI MA et l: OPERATING NETWORK LOAD BALANCING WITH THE MEDIA INDEPENDENT... U up j1 ( throughput ubndwdth where s the totl nuer of MNs n the syste, thoughput j s the totl throughput of flows n the downlnk for MN j, ubndwdth s the uplnk ndwdth. Wth the slr nner, the downlnk resource utlzton s gven n (1, U down k j1 ( throughput dbndwdth The MN uses the MIIS to provde the network lod condtons. We use (0 nd (1 to clculte ech BS s resource utlzton percent nd select the optl cnddte BS sed on the MN s velocty nd ovng drecton n the fuzzy rules. Move Fr Awy Sttc 1 μ drecton ( speed j j j j Move Close to reduce the chnce of BS eng selected s the optl cnddte. On the contrry when the vlue of s 1, whch lso ens the MN s ovng close to the BS, t wll gve postve nfluence to selectng BS kng t ore lkely to e the optl cnddte BSs n the cnddte BSs lst. 1(MN s sttc MN ovng close to BS 1(MN s ovng fr wy fro BS All of the vlues of tr X re n dfferent rnges whch re needed to e norlzed. We use tr A to present the norlzed vlues fro tr X. To norlze the ttrutes, frstly we use (4 to clculte the MN s vlle use te of ech BSs nd ndwdth whch re the eneft ttrutes, j j We lso use (5 to norlze the cost type of ttrute of BSs resource utlzton, j j In (4 nd (5, the vlue of nd clculted n (6. cn e Fgure 9 Speed /s Fuzzy Converson Scle for MN s Movng Drecton Reltve to BSs We defne the fuzzy set s follows, {Move Fr Awy, Sttc, Move Close to} to represent to represent the ovng drecton whch s reltve to the BSs. When the MN oves fr wy fro the BSs, the speed s negtve, nd when the MN oves close to the BSs, the speed s postve. The eershp functons of MN ovng drecton reltve to BSs re shown n Fgure 9. Fro Fgure 9, when the MN s ovng velocty reltve to BSs s 0. Ths ndctes tht the MN s sttc reltve to BSs. The vlue of the ovng drecton reltve to BSs s epressed n (. d drecton speed ( ( 1,,..., n n( 1,,..., n The rnge of vlues n X 4, the MN s ovng drecton reltve to BSs, s not needed to norlzed s t s lredy n the rnge [-1,1]. Fro (4 nd (5, we cn get the norlzed tr A s n ( A n1 1 n 13 3 n n4 The gol of the decson logc s to deterne the ost stsfctory cnddte BS ong the set n. We cn use (8 to pleent ths selecton. The fctor s 0-1 fctor whch e clculted n (3. It s used to drect hndover sed on the MN s ovng drecton reltve to the BSs, when s -1, whch lso ens the MN s ovng fr wy to the BS, ths wll 11 1 S AW n1 1 n 13 3 n3 14 w1 s1 4 w s w 3 s3 n4 w4 s4 46

8 CHI MA et l: OPERATING NETWORK LOAD BALANCING WITH THE MEDIA INDEPENDENT... In (8, tr S [ s1 s s3 s4 ] s the score for the ll cnddte BSs, the optl cnddte BS opt cn e got n (9. Sopt ( s1, s,..., sn D. NLB Model In ters of pleentng network lod lncng, the ost portnt consdertons re: Network Lod Metrc Network Lod Mesureent Network Lod Blncng Operton In ths pper we desgn our odel to use drected hndover s the ethod of relzng network lod lncng. In ths secton we ntlly dscussed echnss to esure network lod sttus nd defne lod lncng etrcs. Methods to operte network lncng re then ntroduced. (1 Network Lod Blncng Metrc The lod etrc should descre the lod stuton n reltons to the network resources utlzton. Coonly the nuer of clls nd lockng prolty re used s lod etrcs n trdtonl cellulr networks. In wreless networks such s WLAN, pcket loss, throughput nd dely re used to descre the networks lod sttus. In ths pper, we nly focus on the throughput of the ech BS copred to the BS s ndwdth. Usng the throughput nd ndwdth of the BS we cn get the ech BS s network resource utlzton. ( Network Lod Mesureent To evlute the lncng stuton of the syste, we use the verge lod of the whole syste s n (30, ~ L n U 1 where n s the nuer of the BSs, nd U s the resource utlzton stuton of BS. The fctor l n (31 s then used to descre the lod stte of the whole syste, ( n n U 1 T l,( l [0,1] n n( U 1 the vlue of l [0,1], where 1 ndctes tht the network lod of the whole syste s lnced. The hgher vlue of l shows the ore unlnced of the network lod n the whole syste. (3 Network Lod Blncng Operton In ths secton we ntroduce the ethod of selectng the optl cnddte BSs when the hndover s necessry due to MN olty. Usng ths ethod the nuer of hndovers cn e reduced. However s the nuer of MNs ncreses, the network wll e unlnced durng certn perods. In our odel, lod lncng wll e trggered when the network lod s consdered unlnced s n (31. When the lth vlue of l eceeds the unlnced threshold (, the BS whch s overloded wll need to dstrute soe of the lod to underutlzed neghorhood BSs s shown n Fgure 11 nd Fgure 1. Fro Fgure 11, the syste s unlnced snce BS s sgnfcntly overloded whle BS 0 nd BS re underutlzed. In ths stuton BS 1 dstrutes prts of the lod to BS 0 nd BS s shown n Fgure 1 to relze network lod lncng. The vlue of lth s portnt snce t wll nfluence the te of ntton of network lod lncng. Ipleentng preture lod lncng hndovers y cuse slr png-pong phenoenon s n the rescue hndover decson [18], f reltve hysteress rgn s not used. Conductng ny unnecessry hndovers would e especlly detrentl for rel-te servce flows for whch the hndover process cn e very hevy. 1 Overloded Blnced Fgure 10 The Threshold of Overloded Trgger for Network Lod Blncng Operton Ths png-pong effect s cused y pleentng NLB preturely nd therey ncorrectly esttng resource utlzton. To vod the png-pong phenoenon, lower threshold vlue s used s shown n Fgure 10. lth When the syste s unlnced, the MN wll e requred to pleent hndover sed on the MNs locton, MNs oveent, nd the resource utlzton percent of other BS s. Other portnt fctors whch should e consdered when trggerng lod lncng hndover re the MN velocty nd drecton. In Fgure 11, there re users connectng to BS 0, 7 users connectng to BS 1, nd 3 users connectng to BS. Intlly the MN s connectng to BS 0 nd ovng close to BS 1. Wthout consderton of the MN s ovng velocty nd ovng drecton, the MN y e drected to connect to BS 1 or BS. However, f the drecton of the MN s consdered network lod lncng should drect the MN to connect to BS 1 drectly. Suppose there re users nd n BSs n the syste, the tr of D n s used to descre the dstruton of users n the whole syste s n (3, 47

9 CHI MA et l: OPERATING NETWORK LOAD BALANCING WITH THE MEDIA INDEPENDENT... d D d 11 1 d1n dn BS0 BS BS1 When d j =1 ens the User s connected to BS j, on the contrry, when d j =0 ens the User s dsconnected to BS j. And the tr U n s used to descre the usele BSs for the users n (33, u U u 11 1 u1n un when u j =1 ens the BS j s vlle to User, on the contrry when u j =0 ens the BS j s not vlle to User. Mtr U n nd tr D n s dfferent s the frst tr U n s used to present the connectng stuton where ech user wll only use one BS. Whle n the second tr D n user cn hve ore thn one vlle BS. U0 U1 Fgure 1 Network Lod Blncng Operton The tr P n s used to present the score of ech BS to ech user n (34, p P p 11 1 p p 1n n U WMAX BS (3.0.0 MN Movng Wreless Mole Node1 the vlue of p j s used to present the score of BS j to User, when the MN s ovng, (36 s used to clculte the vlue of p j wth the vlues of the vlle te (t AUT n (16 of BS j for User, the ovng drecton ponts ( d n ( of BS j for User nd the vlues of r j whch s the rte of ndwdth of BS j wth the throughput of User n (35. r j ( ndwdth j throughput j throughput ndwdth throughput j j WMAX BS0 (1.0.0 WMAX BS1 (.0.0 The vlues of t AUT, d nd r j need to e norlzed wth (4 nd (5 to the vlues of t AUT, d nd r j. To consder the sttc MNs, the vlues of t AUT nd d for the vlle BSs re 1. The vlue of p j for ech vlle BSs cn stll e clculte n (36. Fgure 11 Unlnced Network Lod P t j AUT t d j w w r w r The tr P s used for the overloded BS j to select the users whch hve hgher scores n the j lne of P to do the drectng lod to the other underloded BSs lst when dong the network lod lncng. In ths wy, only users who hve ore thn one vlle BS cn e selected to do hndover. The resultng hndover should lso provde users wth etter QoS s result of the score clculted n (36. 48

10 CHI MA et l: OPERATING NETWORK LOAD BALANCING WITH THE MEDIA INDEPENDENT... V. SIMULATION AND EVALUATION In ths secton, we evlute our pproch usng NS [] together wth the WMAX MIH olty pckge fro NIST [3]. In our echns, the network perfornce s proved y two ethods; utlzng PLGD event to estte hndover ntte te nd opertng network lod lncng y drectng hndover fro overloded or underutlzed BSs re. We therefore evlute network perfornce n two spects, hndover perfornce nd the network QoS. Hndover cost cn e used to evlute the hndover perfornce. The hndover ntton nd hndover durton te cn e used to evlute the hndover costs. In ths pper, we copre the hndover costs for three hndover echnss: the PLGD hndover; the LGD hndover wth pre-defned LGD threshold ( 1. 1 ; the LD hndover (hndover wthout ny predctve ethod. To evlute the effect of NLB operton, we cn copre the QoS of the networks (eg., Jtter nd Dely fter the operton of NLB to the stuton of unlnced lod syste. A. Scenro Descrpton Fgure 13 llustrtes the topologcl structure of the sulted networks. Fgure 14 llustrtes the geogrphcl nforton of the networks. 3 BSs re defned, BS0, BS1 nd BS, ther loctons re (1000,1000, (000,1000 nd (1500, users re defned, the MN0, MN1, MN, MN3, MN4, MN5, MN6, MN7, MN8, MN9, MN10, nd wreless node WlNode11, ther loctons re MN0(500, 150, MN1(750,500, MN(1000,50, MN3(1400,100, MN4(1500,550, MN5(1600,1400, MN6(1600,100, MN7(1700,800, MN8(1600,100, MN9(500,500, MN10(500,150, nd WlNode(1600,1400. Whle ll the MNs re dstruted ongst the three BSs, BS1 s confgured to e sgnfcntly ore congested thn BS0 nd BS. snknode0 MN0 MN1 MN WMAX BS0 MN4 UMTS BS MN3 wlnode MN5 MN7 MN6 snknode WMAX BS1 MN8 Fgure 13 Topologc Dgr of the Network MN10 Router1 MN9 snknode1 In the proposed network sulton envronent, MN0 nd MN1 re the recevers whch re connected to the BS0. snknoder0 s the sender nd strts sendng Constnt Bt Rte (CBR vdeo trffc stres wth pcket sze of 4960 ytes t 0.0 second ntervls. MN3, MN5, MN6, MN7, MN8, MN9 nd MN10 re the recevers whch re connected to BS1. snknode1 s nother sender nd strts sendng CBR vdeo trffc stres wth pcket sze of 4960 ytes t 0.0 second ntervls. MN nd MN4 re the recevers whch re connected to BS. snknode s the thrd sender nd strts sendng CBR vdeo trffc stres wth pcket sze of 4960 ytes t 0.0 second ntervls. y MN0 (500,150 MN1 (750,500 MN (1000,50 BS0 (1000,1000 MN4 (1500,550 BS (1500,000 wlnode (1600,1600 MN5 (1600,1400 MN3 MN6 (1400,100(1600,100 MN7 (1700,800 BS1 (000,1000 MN8 (1600,100 MN10 (500,150 MN9 (50,500 Fgure 14 Geogrphcl Mp of the Scenro wlnode s the only ole node n the syste. Intlly wlnode uses BS0. After 10s wlnode oves fro (1600,1600 n esterly drecton to (1600,3000 t dfferent veloctes. wlnode s the recevers whle snknode0 s the sender whch strts sendng CBR vdeo trffc stres wth pcket sze of 4960 ytes t 0.0 second ntervls. Dfferent of speeds, 1/s, /s, 3/s, 5/s, 10/s nd 0/s re used to evlute the nfluence of velocty for the vehculr sed syste when do the sulton eperents. Fgure 14 llustrtes tht wlnode wll requre hndover s t oves out of the coverge of BS0. As the sulton s confgured, network lod lncng wll lso e requred s BS1 s uch congested copred to the neghorng BS0 nd BS. B. Test Results nd Evluton In our odel, the hndover ntton te s dependent on the MN s velocty. The estted te of current pth flure s sent to the upper lyer y the PLGD event to provde the upper lyer olty protocol wth suffcent te to prepre hndover process pror to ctul current pth flure. 49

11 CHI MA et l: OPERATING NETWORK LOAD BALANCING WITH THE MEDIA INDEPENDENT... To nlyze hndover perfornce, the hndover strt te (t strt whch s the te tht the lst pcket s receved fro the prevous network, the hndover end te (t end whch s the te tht the frst pcket s receved fro the lter network s used to evlute hndover durton te (t hndover n (37. t hndover t t strt The hndover strt te n TABLE I descres the te when the hndover s ntted for ech of the pproches; LD event, LGD event ( 1. 1 nd PLGD event. To evlute the nfluence of velocty n the vehculr sed syste, dfferent speed s used s n TABLE I. Fro TABLE I, the results llustrte tht hndover ntte te of the LGD event s erler thn PLGD event when the speed s less thn 5/s. In the stuton where the user s speed s fster however, the LGD event s hndover ntte te s lter thn PLGD event. In ths scenro s result of the hgh velocty of the user s oveent, the LGD event would provde nsuffcent notce to the upper lyer to prepre for hndover pror to underlyng pth flure. end TABLE I HANDOVER START TIME Speed LD LGD PLGD 1/s /s /s /s /s /s /s When utlzng the PLGD event, the hndover durton te s sgnfcntly proved over the LGD event pproch when the user s speeds re fster thn 5/s. Fgure 19 shows the dstruton of the users n the syste fter NLB pleentton when the MN oves n n estwrd drecton. Followng NLB the MN3 nd MN6 receve drected hndover to BS whle MN7 receves drected hndover to BS0. Fgure 0 shows the dstruton of the users n the syste fter NLB pleentton when the MN oves n n northwrd drecton. In such scenro wlnode receves drected hndover to BS, MN3 nd MN7 receve drected hndover to BS0 fro BS1, nd MN5 receves drected hndover to BS fro BS1. Fgure 1 shows the dstruton of the users n the syste fter NLB pleentton when the MN oves n n westwrd drecton. In such scenro MN3 receves drected hndover to BS0 fro BS1, whle MN5 nd MN6 receve drected hndover to BS fro BS1. Fgure shows the dstruton of the users n the syste fter NLB pleentton when the MN oves n n southwrd drecton. In such scenro MN3 receves drected hndover to BS0 fro BS1, whle MN5 nd MN6 receve drected hndover BS fro BS1. The results of dely nd jtter efore nd fter operted network lod lncng re shown n Fgure 3, Fgure 4 nd Fgure 31. Copre Fgure 3 nd Fgure 4, the results shows tht fter the pleentton of NLB jtter s reduced sgnfcntly. Fgure 31 lso llustrtes the dely s reduced fter the pleentton of NLB. Fgure 17 shows the results of coprng the lodng dstruton n the whole syste wth nd wthout pleentng NLB. Fro Fgure 17, we cn see tht the pleentton of NLB hs drected the lod fro the overloded BS1 towrds the underutlzed BS0 nd BS. Fgure 16 ndctes tht verge dely s reduced sgnfcntly wth the pleentton of NLB when the wlnode oves n vrous drectons. Fgure 15 Hndover Durton Te The hndover durton te when usng the LD, LGD nd PLGD events re shown n Fgure 15. The results llustrte tht the LD event s uncceptle s the hndover durton te s over 700s. Ths s ecuse wth the LD events ddn t prepre the hndover efore the current lnk goes down, n ths wy, lot of te s spent on neghor dscovery echns, swtchng of chnnel nd network entry. Fgure 16 Averge Dely Coprson Utlzng NLB nd wthout Utlzng NLB All of the results presented llustrte tht when the proposed odel s utlzed, the te estted for hndover 50

12 CHI MA et l: OPERATING NETWORK LOAD BALANCING WITH THE MEDIA INDEPENDENT... ntton s close to optl s the lgorth for selectng optl cnddte BS tkes the user s olty nto consderton. Also the operton of NLB proves network utlzton nd QoS sgnfcntly. Fgure 17 Network Lodng Dstrutton of the Whole Syste VI. CONCLUSION AND FUTURE WORK In ths pper, novel odel for vehculr sed syste s proposed whch utlzes predctve seless hndover cross heterogeneous wreless network nd relzton of network lod lncng sed on neghorhood geogrphcl nd network lod rel te nforton. In prtculr we use PLGD event whch utlzed the estted te of network lnk down te y thetcl odel sed on the MN s nd BSs geogrphcl nforton nd MN s oveent nforton. Wth the PLGD event, the upper lyer olty protocol cn prepre suffcent te to ntte the hndover efore ctul network pth flure. Secondly, novel PHIS Inforton structure s desgned n MIIS to collect the network lod nforton nd neghorhood geogrphcl nforton. Ths PHIS cn e utlzed when selectng the optl cnddte network durng hndover nd opertng network lod lncng. A Fuzzy MADM lgorth s pleented to select the optl cnddte network sed on the MN s vlle usge te of BS, BSs resource utlzton, ndwdth nd MN ovng drecton reltve to BSs. Furtherore, we desgn nd relzed the ethod of pleentng network lod lncng y drectng hndover fro overloded to underutlzed BS. We present results for vehculr orented sulton n NS whch llustrte tht our odel reduced hndover durton te sgnfcntly when MN s velocty eceeds 5s. The results lso llustrte tht wth the pleentton of network lod lncng n our echns, dely s reduced y 1s nd jtter s nerly closed to 0, llustrtng sgnfcnt proveent n QoS. In the future, the proposed echns could e proved y reserchng on settng the weghtng tr W, when selectng the optl cnddte network nd when the overlod BSs kng the decson of selectng nodes to hndover to the underutlzed networks. And ore cople nd rndo scenros wll e consdered to test the perfornce of the echns n the future reserch. REFERENCES [1] Insttute of Electrcl nd Electroncs Engneers, IEEE Stndrd for Locl nd etropoltn re networks Prt 1: Med Independent Hndover Servces, LAN/MAN Stndrds Cottee of the IEEE Coputer Socety, 1 Jn [] UC Berkeley, LBL, UCS/ISI, Xero Prc (005. NS- Docuentton nd Softwre, Verson.9. [3] NIST. Ntonl Insttute of Stndrds nd Technology. [4] S.J. Yoo, D. Cypher, N. Gole, Predctve Hndover Mechns sed on Requred Te Estton n Heterogeneous Wreless Networks. Mltry Counctons Conference. Sn Dego, CA.pp. 7-7 IEEE Nov. 008 [5] P. Neves, F. Fontes, S. Srgento, M. Melo, nd K. Pentkouss, Enhnced Med Independent Hndover Frework Vehculr Technology Conference, VTC Sprng 009. IEEE 69 th, pp. 1-5, Aprl 009 [6] E. Fllon, Y. Qo, L. Murphy, G. Munten, SOLTA: servce orented lnk trggerng lgorth for MIH pleenttons, Proceedngs of the 6th Interntonl Wreless Counctons nd Mole Coputng Conference, Cen, Frnce, pp , 010 [7] S. Yoo, D. Cypher, nd N. Gole, Predctve Lnk Trgger Mechns for Seless Hndovers n Heterogeneous Wreless Networks, pulshed onlne t www3.nterscence.wley.co, Wreless Counctons nd Mole Coputng. [8] S. Yoo, D. Cypher, N. Gole Tely Effectve Hndover Mechns n Heterogeneous Wreless Networks, Journl, Wreless Personl Counctons, vol. 55, pp , 008 [9] K.R Kur, P. Angolkr, D. Ds, SWFT: A Novel Archtecture for Seless Wreless Internet for Fst Trns, Rlng, R.Vehculr Technology Conference, Snfpore, 008. VTC Sprng 008. IEEE, pp , My 008 [10] S.F. Yng, J.S. Wu, H.H. Hung, A vertcl Med-Independent Hndover decson lgorth cross W-F nd WMAX networks, WOCN 08. 5th IFIP Interntonl Conference on Wreless nd Optcl Counctons Networks, Sury, pp. 1-5, My 008 [11] I. Joe, M.C. Shn, A Molty-Bsed Predcton Algorth wth Dync LGD Trggerng for Vertcl Hndover, Consuer Counctons nd Networkng Conference (CCNC, 010 7th IEEE, pp. 1- [1] C. M, E. Fllon, Y. Qo, B. Lee, Optzng Med Independent Hndover Usng Predectve Geogrphcl Inforton for Vehculr Bsed Systes, UKS 4th Europen Modellng Syposu on Mthetcl Modellng nd Coputer Sulton (EMS 010, Ps, Itly, Noveer 010. [13] Bejerno, Y., Seung-Je Hn, Cell Brethng Technques for Lod Blncng n Wreless LANs, IEEE Trnsctons on Mole Coputng, June 009, vol. 8, pp [14] Grc, E., Vdl, R., Prdells, J., Coopertve lod lncng n IEEE networks wth cell rethng, Coputers nd Counctons, 008. ISCC 008. IEEE Syposu on, Mrrkech, July 008, pp [15] S. H. Lee nd Y. Hn, A Novel Inter-FA Hndover Schee for Lod Blncng n IEEE 80.16e Syste, IEEE 65th Vehculr Technology Conference, 007, pp , Aprl 007. [16] E. Ynz nd O.K. Tonguz, Hndover perfornce of dync lod lncng schees n cellulr networks, 10th IEEE Syposu on Coputers nd Counctons, 005, pp , June 005. [17] D. K, M. Swhney, nd H. Yoon, An effectve trffc ngeent schee usng dptve hndover te n net-generton cellulr networks, Interntonl Journl of Network Mngeent, Volue 17, Issue, pp , Mrch 007. [18] T. Csey, N. Veselnovc, nd R. Jntt, Bse Stton Controlled Lod Blncng wth Hndovers n Mole WMAX, PIMRC

13 CHI MA et l: OPERATING NETWORK LOAD BALANCING WITH THE MEDIA INDEPENDENT... IEEE 19th Interntonl Syposu on Personl, Indoor nd Mole Rdo Counctons, pp.1-5, Deceer 008. User Equpent Network Inforton Servce Provder(NISP User Equpent Proy NISP Network Inforton Servce Provder(NISP MIHF Inforton Servce (Clent MIHF Inforton Servce (Server Inforton Dtse MIHF Inforton Servce (Clent MIHF Inforton Servce (Proy MIHF Inforton Servce (Server Inforton Dtse Interfce etween UE nd Interfce etween Inforton Network Inforton Servce Servce Functon nd Inforton Provder Dtse Interfce etween UE nd Network Inforton Servce Provder Interfce etween two Network Inforton Servce provders Interfce etween Inforton Servce Functon nd Inforton Dtse Other Trggers Other Sources MIHF Event Servce Reote Event Servce MIHF Event Servce Other Trggers Other Sources Lnk Indctons Lnk Indctons Lnk Lyer Lnk Lyer Network Node Network Node Fgure 18 The Event nd Inforton Flow n the Proposed Model sed on IEEE Med Independent Hndover 5

14 CHI MA et l: OPERATING NETWORK LOAD BALANCING WITH THE MEDIA INDEPENDENT... MN( ID17 (5.0.3 MN( ID17 (5.0.3 MN(1 ID16 (5.0. snknode ID4 (.0.0 MN(1 ID16 (5.0. snknode ID4 (.0.0 UMTS BS (5.0.0 ID5 (.0.1 UMTS BS (5.0.0 ID5 (.0.1 snknode0 ID0 (0.0.0 MN0(0 ID9 (3.0.1 MN0(1 ID10 (3.0. ID 1 (0.0.1 WMAX BS0 ID6 (3.0.0 MN(7 ID (4.0.8 MN(7 ID (4.0.8 wlnode0 ID4 (3.0.5 MN(8 ID3 (4.0.9 MN0(3 ID1 (3.0.4 WMAX BS1 ID7 (4.0.0 MN0( ID11 (4.0.3 MN1(0 ID13 (4.0.1 Router1 ID3 (1.0.1 MN1(1 ID14 (4.0. snknode1 ID (1.0.0 snknode0 ID0 (0.0.0 MN0(0 ID9 (3.0.1 MN0(1 ID10 (3.0. ID 1 (0.0.1 WMAX BS0 ID6 (3.0.0 MN(7 ID (4.0.8 MN(7 ID (4.0.8 wlnode0 ID4 (3.0.5 MN(8 ID3 (4.0.9 MN0(3 ID1 (3.0.4 WMAX BS1 ID7 (4.0.0 MN0( ID11 (4.0.3 MN1(0 ID13 (4.0.1 Router1 ID3 (1.0.1 MN1(1 ID14 (4.0. snknode1 ID (1.0.0 Fgure 19 The Dstruton of Users fter Operte NLB (Est Fgure 0 The Dstruton of Users fter Oprete NLB (North MN( ID17 (5.0.3 MN( ID17 (5.0.3 MN(1 ID16 (5.0. snknode ID4 (.0.0 MN(1 ID16 (5.0. snknode ID4 (.0.0 UMTS BS (5.0.0 ID5 (.0.1 UMTS BS (5.0.0 ID5 (.0.1 snknode0 ID0 (0.0.0 MN0(0 ID9 (3.0.1 MN0(1 ID10 (3.0. ID 1 (0.0.1 WMAX BS0 ID6 (3.0.0 MN(7 ID (4.0.8 MN(7 ID (4.0.8 wlnode0 ID4 (3.0.5 MN(8 ID3 (4.0.9 MN0(3 ID1 (3.0.4 WMAX BS1 ID7 (4.0.0 MN0( ID11 (4.0.3 MN1(0 ID13 (4.0.1 Router1 ID3 (1.0.1 MN1(1 ID14 (4.0. snknode1 ID (1.0.0 snknode0 ID0 (0.0.0 MN0(0 ID9 (3.0.1 MN0(1 ID10 (3.0. ID 1 (0.0.1 WMAX BS0 ID6 (3.0.0 MN(7 ID (4.0.8 MN(7 ID (4.0.8 wlnode0 ID4 (3.0.5 MN(8 ID3 (4.0.9 MN0(3 ID1 (3.0.4 WMAX BS1 ID7 (4.0.0 MN0( ID11 (4.0.3 MN1(0 ID13 (4.0.1 Router1 ID3 (1.0.1 MN1(1 ID14 (4.0. snknode1 ID (1.0.0 Fgure 1 The Dstruton of Users fter Oprete NLB (West Fgure The Dstruton of Users fter Oprete NLB (South 53

15 CHI MA et l: OPERATING NETWORK LOAD BALANCING WITH THE MEDIA INDEPENDENT... Fgure 3 WlNode Jtter efore Oprete NLB (Est Fgure 4 WlNode Jtter fter Operte NLB (Est Fgure 5 WlNode Jtter efore Oprete NLB (North Fgure 6 WlNode Jtter fter Operte NLB (North Fgure 7 WlNode Jtter efore Oprete NLB (West Fgure 8 WlNode Jtter fter Operte NLB (West 54

16 CHI MA et l: OPERATING NETWORK LOAD BALANCING WITH THE MEDIA INDEPENDENT... Fgure 9 WlNode Jtter efore Oprete NLB (South Fgure 30 WlNode Jtter fter Operte NLB (South Fgure 31 WlNode Averge Dely Coprson (Est Fgure 3 WlNode Averge Dely Coprson (North Fgure 33 WlNode Averge Dely Coprson (West Fgure 34 WlNode Averge Dely Coprson(South 55