Optimization of Resource Allocation in Wireless Systems Based on Game Theory

Transcription

1 Internatonal Journal of Computer Scences and Engneerng Open Access Research Paper Volume-4, Issue-1 E-ISSN: Optmzaton of Resource Allocaton n Wreless Systems Based on Game Theory Sara Rah 1*, Al El Hore, Jamal El Kaf 3 1*,,3 Department of Mathematcs and Computer Scence, Chouab Doukkal Unversty, Faculty of Scences,PO Box, postcode 4, El Jadda, Morocco Receved: Dec//15 Revsed: Dec/14/15 Accepted: Jan/15/16 Publshed: 3/Jan/16 Abstract: The power allocaton has for long been consdered a major problem for communcaton between many users who share common resources. Wth the emergence of new paradgms such as ad hoc networks, unregulated frequency bands and cogntve rado, the study of power allocaton dstrbuted protocols becomes partcularly relevant. In fact n such networks, termnals can freely choose ther power allocaton strategy wthout followng the rules mposed by a central node. The termnals are consdered to be ndependent actors and t s reasonable to consder that they are ratonal, that s to say, by regulatng ther transmsson power levels, termnals wsh to maxmze ther communcaton qualty. In ths context, t s natural to study the problem of power allocaton of each termnal as part of game theory, consderng the termnal as each players lookng to maxmze ther own utlty functon by controllng ther power emsson. Game theory allows partcularly to study the exstence and multplcty of balancng power allocaton strateges that termnal has no nterest to devate unlaterally.in a multple access channel, the sgnal from a termnal receved by the other termnals as nterference to ther own sgnals. Each termnal of the transmsson qualty depends drectly of the transmsson power level of other termnals. Keywords: Game Theory, Farness Optmzaton, Access Methods, Resource Allocaton, Power. 1-Introducton: The essence of game theory s the study of nteractons between several decson makers whose decsons are nterdependent: what a decson maker or player gets depends not only on what t does but also what the other players are dong. In wreless communcaton, transmtters may be seen as decson-makers who must choose ther settngs. These may typcally nclude the power level of the transmsson sgnal, the portons of the spectrum used, the emsson perods, the type of modulaton used, etc. [1]. When several transmtters use a common part of the spectrum smultaneously and n the same geographcal area, performance related to a communcaton between a transmtter provded wth ts recevers of nterest generally depend on both of the transmtter emttng strategy tself, for example the power level of the transmsson sgnal but also the strateges of other transmtters. So the fact that common resources are shared, ths generates nterference or not, decsons transmtters are naturally nterdependent. It s therefore not surprsng that the game theory plays an ncreasngly mportant part n the area of wreless communcaton. The evoluton of the telecommuncatons world to moble multmeda resultng from technologcal advances have shown that provdng network access s not enough. The need for users movng towards the access to value-added multmeda servces n ther own nomnal envronment regardless of how they access systems. Multmeda servces requre hgh transfer rates and the qualty of servce requrements. They must coexst wth real-tme requrements to servces such as voce servce that does not tolerate varaton n the tme between sendng and recevng packets []. The warranty of these servces by the operator becomes much more dffcult n technologes that take nto account user moblty. The total accessblty on the move to servce more and more consumers and network resources n real-tme and nteractve treatment, requre solutons and technologcal support for managng multple modes of access, transport and controls specfc to each servce or applcaton, such as real-tme servce and relable transport data, vdeo conference or transfer of real-tme vdeo stream, transactonal behavor, payment, etc. New mechansms wll be needed to dfferentate servces and provde the qualty of servce requred. These mechansms nclude admsson control, resource reservaton protocols and packet schedulng polces. The challenge for next generaton networks s to mantan hgh data rates and qualty of servce on the rado lnks (up and down) whch are unrelable for transmssons. CDMA s the most advanced multplexng technque, to be used especally on moble networks of thrd generaton. Whle prevous frequency multplexng technques (FDMA) and tme dvson multplexng (TDMA) manly conssted of dvdng a physcal quantty (a frequency bandwdth or tme elapsng) nto ndvdual slots [3], CDMA does not set advance statc allocaton of these resources and s smlar to the packet data transmsson technology. The communcaton between two mobles s not establshed by a drect electrcal connecton or a wreless 16, IJCSE All Rghts Reserved 1

2 Internatonal Journal of Computer Scences and Engneerng Vol.-4(1), PP (1-13) Jan 16, E-ISSN: system centralzes around a central control unt managng dfferent mobles. The geometrc area to cover s dvded nto cells, each havng a base staton. The communcaton s then provded by the lnks between the base staton and the varous mobles. It s provded by allocatng a channel to each moble [4]. A channel usually employs two transmsson frequences: one s used to communcate nformaton from the base staton to the moble and s called downlnk communcaton; the other s used to communcate nformaton to the moble staton base and s called uplnk. The termnals are assumed able to detect and reuse n an effectve and an opportunstcally way the unused spectrum by other systems. In ths context, the objectve of our work s to understand how termnals nteract when they allocate power among several orthogonal frequency bands on whch you can fnd relay nodes. Ths scenaro s modeled by a set of channels wth a parallel nterference. The natural paradgm, used to explore transmtters, whch s ndependent and selfsh, s the theory of noncooperatve games. Each transmtter s supposed to be a selfsh ratonal decson-maker and t chooses ts strategy, the power allocaton that maxmzes ts own transmsson rate. The power allocaton that maxmzes the termnal rates for the channel wth a selectve frequency nterference. Also the dual problem of power allocaton that mnmzes the power consumpton whch ensures a mnmum rate between dfferent pars of termnals. In ths work, we consder the source-destnaton lnks and relay that s avalable on each band can be used by ssuers. The transmtters decde on ther own poltcal power allocaton between bands and not those of the relay nodes are common. The rest of the paper s organzed as follows: n Part we explan the formalsm of game theory, Part 3 we detal the multple access technques and methods of allowances, Part 4 we explan our theoretcal approach, Part 5 s reserved to smulatons and analyss of results, and conclusons are gven n part 6. -Game theory n wreless systems: To meet growth bandwdth demands of nternet users on moble, dfferent network access technologes knew a begnnng of deployment by operators. A major challenge n a heterogeneous wreless envronment s to allow network selecton mechansms to keep the moble network users always connected anywhere and anytme [1]. For ths, game theory technques were analyzed and adopted to model and understand the compettve and cooperatve scenaros between network operators and users. Ths theory s based on a set of tools to analyze stuatons n whch what s optmal to do to an agent depends on expectatons that t forms on that one or more other agents wll do. The am of game theory s to model these stuatons to determne an optmum strategy for each agent [5], to predct the balance of the game and fnd how to acheve an optmal stuaton. -1 Game theory and network selecton: Game theory s a mathematcal tool used for understandng and modelng the compettve stuatons that nvolve the nteracton of ratonal decson makers wth potentally conflctng nterests. It was adopted n the telecommuncatons envronment, partcularly n wreless networks, cogntve rado networks, and ad-hoc networks for studyng, modelng and analyss of nteractons between ndvduals. When usng game theory n heterogeneous wreless envronment, several challenges and ssues can be dentfed. Indeed, the 4G envronment ams to provde a heterogeneous combnaton network, termnals and servces [6]. In these mult-vendor mult-user envronments, users wth wreless mult-mode moble devces wll have the ablty to connect to one or more access networks dfferng n technology, the range of coverage, avalable bandwdth, the suppler servce, the monetary cost, etc. In ths context, the approach of game theory can model and analyze the cooperatve or the decson makers nteracton between them that we can descrbe as compettve who represent users and network operators. One of the prmary challenges s to dentfy the players and to model the problem wth the cooperatve or noncooperatve approprate game [7]. The players, each user's strategy and objectves must be clearly defned as they represent the man components wth the roles n the game. - Game theory prncple: Ths theory works on the assumpton of ratonalty, whch means t assumes that the players are ratonal ndvduals actng accordng to ther nterest. Whle the man nterest of servce provders s to ncrease revenues by ncreasng the number of ther customers at the same tme, users expect to get the qualty of servce they pay [5]. When consderng the heterogeneous wreless envronment, players are represented by network enttes or user termnals, whch are assumed to be ratonal. Dfferent game templates were consdered under dfferent scenaros [8], most of the solutons presented by the theory of non cooperatve games are used to defne the nteractons between players. The users compete by adoptng dfferent strateges, such as the transmsson rate avalable, the requred bandwdth or submttng offers showng the agreement to pay. The cooperatve approach s modeled as a set of bargan where users are free to negotate to obtan the desred benefts. There s a competton between networks to ncrease ther ndvdual ncome usng dfferent strateges, such as the prces quoted, the avalable bandwdth, and servce 16, IJCSE All Rghts Reserved

3 Internatonal Journal of Computer Scences and Engneerng Vol.-4(1), PP (1-13) Jan 16, E-ISSN: requests. The cooperaton between the networks keep the scenaro n whch a number of dfferent access networks form coaltons to handle servce requests when a sngle access network can not provde t. In ths scenaro, cooperaton s based on the assumpton that wreless networks can cooperate [9], or because the requested servce exceeds network capacty or because they can reduce some of ther costs by cooperaton. By usng game theory we can model realstc scenaros n whch players compete aganst each other and each seeks to maxmze proft. In a cooperatve game, players are supposed to work together to maxmze ther earnngs, but n some cases, they can act selfshly refuse to cooperate and to maxmze ther own beneft or mantan ther own lmted resources. Provocatve mechansms can be adopted n such bearngs, to avert an overall degradaton of QoS. The objectve of usng provocatve schemes s to motvate the players to cooperate n maxmzng overall proft. An mportant aspect that appears as a result of the dynamcs of the wreless envronment, s that some cooperatve players can be seen as selfsh because, wreless nterference may generate some errors, or because of the collsons of packet [1].Ths may end n players cooperaton endng,and as a the consequence,dmnshng the global performance of network. Another mportant aspect s the way the players make ther decsons n a dstrbuted or centralzed. The centralzed approach s rarely used n the resoluton of the problem of multple network access. Ths may be due to the computatonal load ncreases wth ncreasng network sze. Generally game theory s more sutable approaches to dstrbuton wth features auto-confguraton and a lower communcaton overload [6]. The common goal of the approaches of ths theory s to mprove overall system performance (for example, the effcent use of resources, maxmzng throughput, ensurng QoS). -3 Defnton: Game theory s a feld of scence based on a set of analytcal tools for understandng some phenomena observed when several decson centers nteractng, especally when they have conflctng nterests. These tools are effcent for analyzng the stuatons n whch the decson of a player has nfluence on the utlty functon of other players n the game [11]. And t can also be defned as a mathematcal approach, whch conssts of templates and technques to analyze the crtcal behavor of ratonal ndvduals, usually games can be classfed nto two types: compettve and cooperatve game play. -4 the strategc game: The strategc game s the set of rules whch governs player behavor and determnes the gan of the players on the bass of actons accordng to ths termnology; a strategc game requres a clear defnton of the rules of behavor of the players Typologes of the game: Strategc games can be typed accordng to some requrements such as behavor, nformaton of the game and the decson a Cooperatve / compettve games: The games are typed accordng to the behavor of the player relatve to other players, for a player t s ether n cooperaton / competton wth other players. Cooperatve games: A game s cooperatve f the players can pass between themselves agreements whch bnd the bndng manner. We then say that they form a coalton whose members work together. Compettve games: By defnton, n a compettve game we specfy all strategc optons avalable to players, whle the agreements behnd the coaltons n a cooperatve game are not descrbed. Each player ams to get hs property gnorng to the other players b Games decsons wth smultaneous / sequental: The games are typed n order of players' decson, the decsons of the players are taken ether smultaneous or sequental. Games wth smultaneous decsons: In these games, players take ther decsons smultaneously, wthout knowng the decson of other players [8], we can cte some example: Prsoners Dlemma, rock-paper-scssors. Games wth sequental decson: Here the decsons of players are sequentally, e the player decsons are taken wth a tme lag. The decson of the player s nfluated by the decsons already taken by the other players, some examples of games to sequental decson, the more popular t s: the falure Thurs c games n perfect nformaton / Imperfect: In such games are typed accordng to nformaton on the other players, n other sayng s that the player know when he makes hs decson. Perfect nformaton games s a game or actons made earler by nfluental player on the decson of the player wshng to make a decson because the player has nformaton on the actons already carred out by other players and t takes the decsons of players 16, IJCSE All Rghts Reserved 3

4 Internatonal Journal of Computer Scences and Engneerng Vol.-4(1), PP (1-13) Jan 16, E-ISSN: are sequentally [1], excludng than the mperfect nformaton game the player does not have all the nformaton on the other players, or at least two decsons have already been carred out smultaneously, makng the most dffcult decson n the game has perfect nformaton d games n complete / ncomplete nformaton: Ths type s based on the nformaton of the players aganst other players. Complete nformaton games: All game elements are a prevalent expertse among the players, each player knows more precsely the set of behavors possble for all other players and he knows all the payment. games. In all games, the decsons can be represented by a tree, each node s assocated to the player to decde. Each opton s a branch [7]. The gans are related to all endponts, or leaves of the tree. A player, however, does not requre knowng how t reached a node: one account the present state of the game, and the desred postons n the future. When certan movements are allowed only after a gven event, ths event s only one element to materalze n the present state of the game and does not need to be part of hstory [14]. An extensve form game s a decson tree that descrbes the possble actons of the players at each stage of the game, the sequence of rounds of play of the players, and the nformaton avalable to them at every step to make ther decson. Incomplete nformaton games: Ths s a game where each player does not know all the behavor of other players. -4- the performances of the game: A game s defned as the number of players, the set of possble strateges for each player and the specfcaton payments or utltes of players for each combnaton of strateges. Cooperatve games are generally presented n the form of characterstcs whle non-cooperatve game functons are represented n normal form or extensve form, there are dfferent ways to formalze the theory of the game and of the decson and even more so followng the type stuatons n queston [13]. Thus, we dstngush: -4--a Normal form: Whch can sgnfcantly reduce the sze and tme graphcal representaton of a game as a array of gans but are napproprate for repettve games. A game n normal or strategc form game n shape s defned by: All the players, all the possble strateges for each player, the preferences of each player on the set of possble strategc combnatons. All players must be over, All the strateges of each player can be: fnshed, each player decdes to cooperate or not, or nfnte, each player decdes how much good he wants to produce and can choose any value n the set of postve real [6].Preferences may also be represented by a utlty functon or a gan functon [1]. When one s a normal form game, t makes the mplct assumpton that each player chooses hs strategy wthout knowng the choces of other players. -4--b extensve form: Whch are shapes synoptc (tree, branch, leaf) useful to a smple understandng of the possble strateges and the outcome of a game s consdered a sheet n whch we fnd the vector of the respectve gans of the players. Ths knd of representaton becomes complcated when repettve Fgure 1: The extensve form of a strategc stake. Fgure 1 llustrates, well clearly shows the concept of extensve form of strategc game, the player 1 has two choces makng the choce 1 and choce, player also two choces choce1 and choce, player 1 s the who plays frst and player s playng the second, f the player decdes to take one choce as one decson then the reward s x1, and decdes choce then the reward s x, for player f hs choce s choce1 he wll y1 as a reward and f he chose choce reward s y, f the players selected choce1, 1 and players chosen reward 1 choce of both players s x1 y1 respectvely show what s the left leaf of the tree soluton concepts: A soluton concept s a process by whch the balance of a set are dentfed. They are employed as game predctons, suggestng what the result of the game [7], that s to say whch strateges wll or may be used by the players. Domnant strategy equlbrum: A game has domnant strategy equlbrum f for each player, there s a strategy that domnates all other strateges, whatever the strateges of other players. In other words, whatever the strateges of other players, the payment I get playng ths domnant strategy wll be strctly greater than that obtaned by playng another strategy [5]. A domnant strategy wll be played by each player and obvously nobody's nterest to devate from ths balance. The domnant strategy equlbrum s Nash 16, IJCSE All Rghts Reserved 4

5 Internatonal Journal of Computer Scences and Engneerng Vol.-4(1), PP (1-13) Jan 16, E-ISSN: equlbrum. When there, domnant strategy equlbrum s unque. Equlbrum by terated elmnaton of domnated strateges: It s sad that a strategy s domnated for a gven player there s at least another strategy such that, whatever the strateges adopted by the other players, ths alternatve strategy s always at least as good as the frst and strctly better n at least one of the stuatons [11]. If each player s ratonal, assumes that the other players are ratonal and assume that other players assume that t s ratonal, then we can set the game balance as would be acheved by the successve eradcaton of domnated strateges. Nash equlbrum: A player can make several decsons and chose one that wll be the best for hm. The usefulness of a player may depend not only on those decsons but also those of all other players [1]. The concept of soluton of a noncooperatve game s often the Nash equlbrum. The Nash equlbrum s a choce decson of all players as none can beneft by changng hs decson alone. Compettons stuatons can occur at several levels whch requre the adopton of approaches: approach of consderng only one crteron that an agent wants to maxmze and mult-crtera approach of separate requrements and defne notons of balance are senstve to each of them. In the case where each agent has only one evaluaton crtera, the objectve s to determne decsons for each of them, optmal n the sense of the concept of Nash equlbrum. Suppose there are N agents for access to the servce, each lookng to maxmze a sngle utlty functon. U n noted the decson of the agent n, and J n (u,x), ts utlty functon [1]. Ths functon depends on the acton Un of the subscrber n, but also the actons of all the other agents, the varable u= (u1,., un) s N-tuple decsons by N agents. x s a parameter representng the archtecture and poltcs management servce offered. For an archtecture and servce poltcs, x, fxed, N-tuple decsons U*(x)= (u* 1, u* N ) s sad Nash equlbrum f none of N agents can enhance ts utlty functon by modfyng only ts decson. Specfcally, for all n Є {1,,..., N}. We have: J n (u*(x),x) = max J n (u* 1,..,u* n-1,u n,u* n+1,..,u* N,x). (1) But n realty each agent may try to make decsons to maxmze several crtera[13], n ths context, the utlty functon of a J n agent n s a vector, J n = (j n 1,.j n k). Wth the rse of wreless communcaton networks, emerged resource sharng ssues (frequency bands, transmsson power, schedulng, etc.) and confguraton of networks gvng autonomy of decson to the moble termnals of the system. Ths s especally the case for wreless sensor networks, networks n the WBZ frequency bands (WF, Bluetooth, ZgBee), femto-cell networks and ad hoc networks n general. In ths context, therefore game theory s a fully approprate tool to study these networks stable states [14]. Another reason favor of game theory s that n such networks, confgurng communcatons s not statc, t evolves over tme based on parameters such as the number of termnals n the system and the qualty of means of transmttng termnals. Beyond the statc game, game theory offers just repeated game models and stochastc games respectvely consder the strategc mplcatons of the repetton of a game and changes n playng condtons over tme. 3 -multple-access technques: The communcaton channel s bascally a dffuson means. Therefore, a sgnal transmtted by a user may possbly be receved by all the other users located n the area covered by the transmtter [15]. Though ths possblty s very nterestng for certan applcatons, such as broadcastng or televson, t requres strct control of access moble communcatons. The am of moble communcatons s to provde communcaton channels on demand between a moble termnal and a base staton that connects the user wth the fxed network nfrastructure. Of tells the system desgn crtera nclude the capacty, complexty and qualty of servce. All these crtera are nfluenced by the method used to provde multple access. Anyway, the opposte s true [16]: the access methods must be carefully chosen n the lght of the relatve mportance of desgn crtera and characterstcs of the systems. There are several types of mult-user communcaton systems. A frst type s a multple access system wth whch a common channel of communcatons s used by a large number of users [17]. A broadcast network s a second type of moble communcaton n whch multple recevers receves nformaton from a sngle transmtter. Multple access technques, wreless system s based on the solaton of varous sgnals used n varous connectons. The support parallel transmssons n uplnk or downlnk s called multple access. A moble communcates wth a base staton. For ths exchange goes well there must frst be a dalogue between the two allowng one hand synchronzaton messages and also to estmate the channel and establsh the frequency and power of the correspondng emssons that they use when communcatng [15]. The base statons regularly ssue calls to moble wshng to establsh communcaton and contnuously scan a communcaton channel where moble gve ther request. In the case where the base staton has avalable channels, t ndcates to the moble whch frequences wll be used for communcaton. A moble can make contact wth several base statons 16, IJCSE All Rghts Reserved 5

6 Internatonal Journal of Computer Scences and Engneerng Vol.-4(1), PP (1-13) Jan 16, E-ISSN: (Fgure ). They shall exchange the necessary nformaton to decde the staton wth whch the moble wll communcate. Ths wll n prncple the staton that receves the better qualty sgnals. Ths moble staton ndcates at whch frequences wll be used n the followng the notfcaton Moble Locaton Relay staton Base Staton Fgure : Locaton of moble statons, locatons of base statons and relay statons, here there are 4 base statons and relay statons allocaton polces: To admnster dfferent types of communcaton such as voce, packet data, etc wreless communcaton systems are extensvely setted up. These systems can be multpleaccess systems able of supportng communcaton wth multple users sequentally or smultaneously by sharng the avalable system resources [18]. Examples of multple access systems nclude multple-access systems by code dvson (CDMA), the multple access systems by tme dvson (TDMA) and the frequency-dvson multple access systems (FDMA). Tme doman: Sgnals may be transmtted over tme perods that do not overlap. In ths way, sgnals attend the same frequency band; yet, can be effortlessly separated by ther arrval tme.ths method s called TDMA (Tme Dvson Multple Access). Code doman: In the CDMA method (Code Dvson Multple Access), dfferent users emt very low correlaton sgnals there between []. Correlators can therefore be used to extract ndvdual sgnals from a mxture of sgnals transmtted at the same tme and on the same frequency band. In an OFDM transmsson, the nformaton relatng to the transmsson channel such that the SNR sgnal to nose rato allow the transmtter to perform an adaptve allocaton of subcarrers. Ths concept s used n practcal systems, and OFDM s referenced as adaptve modulaton or "BtLoadng". Indeed, n the case of a system wth multple users, you need a very precse technque to be able to allocate to each of them ts valuable resources [1]. Dfferent methods of multple access usng the OFDM transmsson exst: a multple access tme dvson: In an OFDM - TDMA system, each user has a tme nterval durng whch all the subcarrers allocated to t (Fgure 3). It s assumed that the duraton of each tme nterval s equal to the duraton of an OFDM symbol [19]. Modulaton covers all subcarrers accordng to the channel condtons. Ths multple access mode s better than other modes when random allocaton s used, as t benefts from all the gan that has the channel. The advantage of ths type of multple access s the reducton of energy consumpton at the recever whch only works well determned moments. The dsadvantage of ths type of system s the occurrence of problems n the case of remarkable propagaton delay The statc allocaton methods: The areas commonly used to provde the followng access: Spatal Doman: All moble communcaton systems use the fact that the sgnals undergo attenuaton durng ther propagaton. Ths means that the dstant transmtters produce an nterference whch s neglgble compared to the power of the desred sgnal [19]. The technque correspondng to such processng s called SDMA (Space Dvson Multple Access). Frequency doman: Frequency bands occupyng sgnals do not overlap, can be easly separated. Sgnals can be transmtted wthout nterferng wth each other. Ths method s called FDMA (Frequency Dvson Multple Access). Fgure 3: Multple access OFDM-TDMA b multple access frequency dvson: In an OFDM- FDMA system, each user allocates a porton of subcarrers n each OFDM symbol. For each 16, IJCSE All Rghts Reserved 6

7 Internatonal Journal of Computer Scences and Engneerng Vol.-4(1), PP (1-13) Jan 16, E-ISSN: allocated subcarrer applyng an adaptve allocaton method that depends on the SNR. Ths method has advantages and dsadvantages opposte to those of OFDM TDMA method. Dfferent varatons may occur, ncludng: b-1 block FDMA: Each user s allocated a set of adjacent sub-carrers (Fgure 4). The base staton calculates the average gan of adjacent channels for all users and for all blocks. The allocaton of a block to any user s to allocate a sngle block to each user. The frst block wll be allocated to the user who has the best SNR assocated wth that block []. Is contnued by applyng the same procedure wth the blocks and the remanng users, untl all the blocks are allocated. tme dvson duplex systems []. The requested rate may be acheved, n the case of adaptve OFDMA, by several methods adaptve allocaton of subcarrers. These approaches are all based on the fact that the channel gan s not the same for all sub-carrers, or for all users c multple access code dvson: Users are dstngushed from each other by code. The verson of CDMA-OFDM s the most wdely used multcarrer CDMA. In ths type of access, the data sgnal s spread by drect sequence spread spectrum (Fgure 5). The OFDM-CDMA advantage s the soft lmt the ablty of the user, and nstead of OFDM -TDMA and OFDM- FDMA where the error probablty of a bt depends on the channel state to the frequency by whch t s modulated [5], n the case of OFDM CDMA each bt takes advantage of all the channel gan spkes. Fgure 4: Multple Access FDMA block From the above stems the concluson that the best combnaton s that user block whch gves the maxmum amount of frequency average earnngs of all the blocks allocated to the users [3].Ths method has a drawback n the case of presence of a hollow n the frequency response of the transmsson channel, as all adjacent subcarrers wll be affected by ths hollow, and consequently the whole block wll be well receved b- Interleaved FDMA: As a drect result of the dsadvantage that ths multple access mode "Block FDMA," we can see that the coded data transmtted should not be smply assgned to OFDM subcarrers n a sequental order but we must nterlace of frst.so, users allocate subcarrers that are dstrbuted on the frequency axs [4]. The adaptve modulaton s appled on the subcarrers b-3 OFDMA Adaptve: In ths method, a subcarrer s allocated accordng to channel condtons. In a two-way communcaton system, the channel frequency response for each user on each subcarrer can be sent to the transmtter through a feedback or t may be estmated by the transmtter n the Fgure 5: Multple Access OFDM-CDMA Allocaton of subcarrers: Among the N OFDM subcarrers, each user chooses hs randomly n subcarrers. It s possble that two or more users select the same sub-carrers, whch leads to [6] collsons. Consder the two followng cases: A subcarrer may be allocated to a sngle user: Actually, f a subcarrer s chosen by more than one user, t wll be elmnated and t wll bear no nformaton. Ths technque has smplcty n the modulaton and demodulaton [7]. Ths presents a great smplcty from the vewpont sgnalng protocol between the base staton and the termnal. A subcarrer may be allocated to two users: In fact, a subcarrer allocated by both, or by a sngle user, of course, s properly receved. Ths technque s only possble f the two sgnals transmtted on ths subcarrer are orthogonal. Or the two termnal statons have dfferent locatons wth respect to the base staton; ther channel attenuaton factors are then dfferent, whch affects the orthogonalty [8]. Of course, ths technque requres a good sgnal between the base staton and termnals. 16, IJCSE All Rghts Reserved 7

8 Ampltude Internatonal Journal of Computer Scences and Engneerng Vol.-4(1), PP (1-13) Jan 16, E-ISSN: changng a cell, each user can move n the whole system by usng sub-carrers subcarrer number Fgure 6: the ampltude of subcarrers The dynamc allocaton methods: The allocaton of resources s seen at the physcal layer (frequency allocaton and power). Ths part s devoted to's Survey OFDM technques that enable resource allocaton dependng on the qualty of servce requested, ensure optmal system performance, assumng that the nformaton on the correspondng channel to subcarrers are avalable. Therefore, two alternatves are consdered [9]. The frst deals wth the random access pont of vew of the problem, whle the second s adaptve appearance a method of random allocaton: The number of subcarrers n a communcaton system has ncreased and the demand for hgher throughput perssts [3]. In ths secton, we wll descrbe a random OFDM system based on Mult Carrer FDMA, where each user randomly selects subcarrers. In a randomzed OFDMA system, each user randomly allocates a set of n subcarrers, ths set dffers from one user to another. Because of ths random selecton, multple users can choose the same subcarrers [31]. If two or more actve users select the same sub-carrer, then the latter wll collde and can not transmt payload data (n cases where a subcarrer can not be allocated to more than one user). As the number of users vares helpful when the number of subcarrers that are n collson stll vares, whch affects the data transmsson rate [3]. Ths system has advantages and dsadvantages, of these dsadvantages: The problem of the collson of the subcarrers resultng n a loss of capacty [33], non-optmzed use of subcarrers n terms of mnmzng the total power and do not meet the requested QoS: t does not ensure asked throughput. These advantages nclude: The non-necessty of a sgnalng protocol for allouement subcarrers for users because each user knows ts subcarrers and the base staton knows the subcarrers of each user, unqueness sets selected subcarrers allows users to make handover smple [34], because t needs to change the subcarrers when 3-1--b adaptve allocaton method: If the transmtter knows the nformaton about the transmsson channel and by usng an adaptve modulaton, the system performance can be hghly mproved. In partcular, the sub-carrers wth a large channel gan s modulated wth hgh order to transmt more bts / OFDM symbol, whle subcarrers fade deep are modulated wth a low order to transmt or zero bts per OFDM symbol [35]. As for the dfferent subcarrers channel status vares, and as the rate transmtted on the subcarrers vares also, then the power must change wth users and subcarrers [36]. The crtera accordng to whch s the allocaton are: power, the flow rates and the fact that a subcarrer can not be allocated by a sngle user. 4- Theoretcal approach: In ths work, we study power control technques and algorthms dstrbuted allocaton of resources. We frst study the case of dstrbuted power control, or optmzaton focuses on the convergence and stablty of the concurrent use of a resource n the system. Ths type of allowance generally corresponds to a sngle-resource system, such as CDMA. Our algorthm provdes an teratve power control method, whose convergence s guaranteed when certan crtera are respected. The method nvolves makng the followng teratve allocaton: P( k 1) FP( k) u () Wth F defned as: F j g j g f (3) Where P s the vector of the powers allocated to users and u g γ s the target SINR and g j s the channel gan between the j transmtter and recever. Ths apples to a channel sharng between multple transmtters and recevers (channel nterference, such as ad-hoc networks or cellular). F s a matrx representng the qualty of a lnk wth respect to nterference, weghted by the SINR targets, the lowest values are best. The man contrbuton s to show that f the largest absolute egenvalue of ρf F. In addton, t converges to the optmum soluton P* s the power mnmzaton under constrant SINR target. If ths matrx F does not satsfy ths crteron, then the algorthm dverges. In a dstrbuted system, the matrx F s not known by the dfferent actors of the network. A dstrbuted method s to apply the followng power j j 16, IJCSE All Rghts Reserved 8

9 Power Internatonal Journal of Computer Scences and Engneerng Vol.-4(1), PP (1-13) Jan 16, E-ISSN: allocaton: P( k 1) P( k) (4) R( k) Where R ( k) s the SINR acheved at tme k by the recever. The dstrbuted applcaton s nevertheless based on the assumpton that F satsfes the condtons for convergence, or ths matrx s not known by the entre network. Unless a centralzed coordnator wll nform each ssuer, such an algorthm s therefore based on trust no transmtter seeks to have too hgh a SINR, whch would dffer throughout the system. In addton, ths method s applcable on statc channels, but can be generalzed to dynamc channels. In general, the target SINR are predefned and algorthms assume that they allow the convergence of the system. It SINR false check that the targets are compatble wth the state-owned system. If one rather nstead s n a system that wants to defne tself the target SINR values, n order to ensure the convergence thereof, note that the F matrx s set by the values of target γ of each transmsson. To ensure convergence, there must be ρf <1. Mathematcally, we have mn F max F and Gj j j F j j j F j j n other words, the rato between G the target SINR and SIR "uncontrolled power". A smple crteron s to requre transmssons satsfy: G j G j Note that ths constrant has the dsadvantage of not beng flexble: each communcaton s lmted by hs own G ( ) channel gans and assumes the worst G j j case all the neghborng communcatons seekng the largest possble target SINR to ensure, whatever the applcaton SINR neghbors, the convergence of the system. Or f some nearby communcaton lnk to have a lower SINR demand maxmum threshold, then ths lnk G mght choose a hgher target SINR has ts G lmt wthout dvergng the system. j To ensure a mnmum flow to the users, an optmzaton crteron may be to mnmze the number of dssatsfed users. A dssatsfed user s a user who does not reach the r mnmum flow ub,, ths s an outage. Called probablty of falure or outage of the rato between the number of users who do not reach ther mnmum rate and the number of total users. In a communcaton system, the j probablty of poor recepton (outage probablty) s defned as the probablty that the qualty of the lnk between a source and destnaton s less than a certan threshold. S Poutage P( seul) (5) N Or P (x) s the probablty of the event x.we consder a communcaton system n whch the sgnals propagate through several network nodes for gong from a transmtter to a destnaton. Relay playng the part of ntermedate nodes. For the system wth regeneraton, the relays can decode the nformaton and encode agan before the broadcast qualty.the lnk to the system wth regeneraton s then determned by the measurements of each lnk or an outage n any lnk leads to outage of the total system. Ths mples that the outage s the probablty that the mnmum sgnal to nose rato SNR of N hops s below the threshold. th P P [ mn,,..., ] mn out mn 1 N th (6) As aganst the non-regeneratve system, the relay wll not decode the receved sgnal but merely amplfy and transmt.in result; the outage wll occur f the equvalent end to end SNR s below the threshold. P P (7) out eq th Interestngly, for users, to acheve throughput farness.the users can expect smlar rates ndependent of ther condtons. 5. Smulaton and results: Free access to scarce resources nevtably leads to conflcts that penalze neffcent use all partcpants. Indeed, each user tres to maxmze hs personal nterest and tends to approprate resources excessvely to the detrment of others x Number of teratons Fgure 7: Amount allocated power. th Power Allocated Nose Rato 16, IJCSE All Rghts Reserved 9

10 Power Power Power Power Internatonal Journal of Computer Scences and Engneerng Vol.-4(1), PP (1-13) Jan 16, E-ISSN: One soluton to address ths problem s to organze the management of these resources. Ths management must propose regulatory mechansms to ensure a far share to dfferent users. In ths work, we propose a framework for mult-user optmzaton and present an axomatc equty through allocaton problems and schedulng resources x 1 4 Cummulatve Power Power Evoluton occurs when t comes to dstrbutng resources equtably as possble between people. Equty s an mportant assessment factor n all ssues of allocaton, dstrbuton and sharng between users resources; ths ncludes among other dstrbuted systems. The orgnal approach n ths work s to focus on the equtable sharng n the case of schedulng. Most of the tme n producton schedulng, we are nterested to establsh an organzaton that wll help maxmze the gan, mnmze costs and delays, the term farness s characterzed by the followng propertes:.5 User 1 User User 3 User User 5 User Number of Iteratons Fgure 8: nose rato on the channel..5 In fact when desgnng resource sharng systems to users, consderatons of equty are among the major concerns. We therefore analyzed the stuaton where a set of resources are dstrbuted to a set of users havng the same rghts to access and where farness to the users s a desrable goal. Due to resource lmtatons, multple users are potentally n conflct. Thus, equtably dstrbute these resources s a major problem. Ths s partcularly the case of the sharng of computer resources such as storage or computaton tme. We wll apply these concepts to the search for equtable allocaton polces n a resource allocaton problem and a problem of schedulng jobs submtted contnuously modeled by perodc arrvals User 1 User User 3 User 4 User 5 User Number of Iteratons Fgure 1: Power Quantty allocated for each user, farness optmzaton. The frst property requred for equty s mpartalty: ts characterstc s not to favor one over the other. Conversely, farness does not neglect some users to other. It does not put forward a group of people over another and avod all forms of dscrmnaton. Ths therefore results n symmetry or beng unable to make dstnctons between ndvduals accordng to ther dentty. The second property s based on the recognton of ndvdual rghts. But the respect of each ndvdual nvolve to guarantee protecton aganst all forms of domnaton. Ths s an equalty of rghts, not n condtons, but accordng to the needs of ndvduals and n ther treatment, t seeks to lead to a stuaton after whch no wrong remans. 1.8 User 1 User User 3 User 4 User 5 User Number of Iteratons Fgure 9: Evoluton of the power vs. number of teratons, farness optmzaton..4.3 The equtable sharng of resources nvolved when a game s nterrupted s an unsolved problem. Indeed, to legalze gamblng practces t s necessary to gve condtons for these games so t becomes far. Legtmacy s therefore lnked to the noton of farness. Equty s the rule that must dctate the dstrbuton. The same knd of problem Number of Iteratons Fgure 11: Evoluton of the power vs. number of teratons, SINR optmzaton. 16, IJCSE All Rghts Reserved 1

11 Power Internatonal Journal of Computer Scences and Engneerng Vol.-4(1), PP (1-13) Jan 16, E-ISSN: For these propertes, farness respects effcency but at the same tme exceeds t. The effcency and equty are a complementary concepts wthout beng ncompatble. There s no conflct between effcency and equty. The effectveness or performance of a company determnes the standard of lvng whle equty reflects the dstrbuton of the standard of lvng among ndvduals. For example, when each ndvdual seeks to maxmze hs ndvdual performance ndcator, each wll tend to run several transfers n parallel n order to monopolze the bandwdth and ths at the expense of others. At the level of collectve performance measurement ndcators, some tasks wll be rejected n order to mantan an acceptable level of average servce qualty, such as admsson control mechansms n networks Number of Iteratons User 1 User User 3 User 4 User 5 User 6 Fgure 1: Quantty of power allocated to each user by maxmzng the SINR. Thus, a far schedulng to users encourages ther partcpaton, whle an unfar schedulng causes the abandonment of partcpaton. In addton, some methods are able to justfy the choces made and to show that the treatment s far, help resolve conflcts. Each user research methods ndependently to maxmze ts proft. The collectve dmenson s unfortunately sacrfced by these arguments n whch the other s reduced to a role of opponent or a tool to acheve ts ends, n an nterested way. There are ssues of farness when requests exceed avalable resources. In ths case, the mplementaton of a resource allocaton polcy s necessary to separate the users. These polces resource allocaton must obey certan rules; whch allows automatng, assessng and verfyng. The choce of relevant polcy s therefore a company decson, a socal choce. When resources are not suffcent for all users and a conflct occurs, the allocaton polcy s then medate and allocates resources among users. It then seems mportant to desgn arbtraton prncples, whch are based on the noton of farness to the users. It s essental to fnd far trade rules that meet everyone. Productvty and proftablty are not contrary to equty. Productvty s encouragng but should be subject to lmts that promote relatonshps etquette together. It wll seek farness, that cares about effcency, that s not a strct egaltaransm, but equalty n rghts, whch take nto account stuatons. Where the mportance of defnng termnals; not those who refuse the rght of everyone to property, but whch defne the borders and keep the actons of men n good terms, wthout t there s no freedom. In ths part we are nterested n the jont allocaton of resources and power, so every resource, communcatons channel, OFDMA type, may have a power ndependent of other resources. The prolferaton of these degrees of freedom, however, makes t dffcult to acheve global optmzaton centrally. Frst, the problem to solve s often non-convex, and requres knowledge of a large number of varables n the dstrbuted network. The exhaustve search of the optmal soluton s therefore mpractcable. The allocaton of resources and power n wreless networks s a topc that s the subject of research for many years. In the lterature we can fnd several recent syntheses nvolvng dfferent technques. Most of t formalze many types of optmzatons related to the allocaton of resources and power, focused on nterference management. These optmzatons are sorted accordng to the objectves and constrants and exstng algorthms for each problem. The exstng algorthms are based on scenaros where channels are statc. Overall, the power allocaton problem s broken down nto two man categores: Maxmze utlty under maxmum power constrant. Mnmze constraned to the power utlty. Utltes are related to the ablty of users, communcaton channels or target SINR. When the problem nvolves a network wth nterference, such as n a cellular context, the ntegraton of these s essental and complcated algorthms, each allocaton becomng nterdependent. Second, n a realstc system, the envronment changes, for example the effects of fadng and maskng change, user needs may vary, etc. An adaptaton that can follow such a dynamc s therefore hghly desrable. That s why n ths part we wll study the power of resource allocaton systems focused on the followng two aspects: Dstrbuted :a centralzed system to montor the evoluton of the network and solve generalzed optmzaton problems s unrealstc n practce, the exchanges necessary between cells, s the complexty of the overall problem and the speed wth whch the system must answer, 16, IJCSE All Rghts Reserved 11

12 Internatonal Journal of Computer Scences and Engneerng Vol.-4(1), PP (1-13) Jan 16, E-ISSN: Dynamc: the network condtons vary over tme, due to the user moblty, the effects of fadng, as well as by changng the nterference. 6. Concluson: Far approach s on the contrary to generally consdered all gans or losses. It seeks to provde satsfactory solutons for the assembly of equlbrum and arbtraton rules establshed for ths purpose. Farness s "what recognzes everyone's rghts n justce." The man objectve of farness s how to establsh a system of rules to prevent prejudce aganst certan users. Indeed, there are ssues of equty only where there are conflcts. To solve these, a regulatory authorty s generally requred. A medator or manager s then apponted to mantan order and resolve conflcts. It must be far, mpartal and have the desre to do good dstrbuton. Furthermore, equtable dstrbuton s not equal n the strct sense. It's a "far measure", a balance that allows you to make an acceptable form of nequalty, where equalty would not be acceptable. Ths measure should help fnd ways to meet the needs. The objectves of the base staton and termnals are dfferent because we consder that the base staton ams to maxmze the energy effcency of the entre cell, whle the moble termnals only seek to maxmze sgnal to nose rato. So ratonally, moble devces have an nterest n channel gans that support ther ndvdual nterests; even f ths reduces the overall network performance. Ths has encouraged us to study the effects of strategcally channel gans on wreless cell performance. For ths, we studed the ssue of carry-channel gans as a statc game n whch players are moble devces that choose ther deferral to maxmze the power allocated to them by the base staton, the allocated powers beng selected by the base staton to maxmze energy effcency a functon of the cell. By lmtng our analyss to the power allocaton, we can acheve formal results to compare a power allocaton wth real gans channels and a power allocaton wth forward gans channels strategcally. References: [1] Mohanakrshnan M.Azath, Survey on Network and Devce Aware QoS Approach for moble Streamng,Internatonal Journal of Computer Scences and Engneerng,IJCSE,Volume-3,Issue -1,Page No(76-79),14. [] Apoorva Nayak and Rahul Sharma, Performance Evaluaton of mage transmsson over Physcal Layer of IEEE 8.16d wth Antenna Dversty Scheme, Internatonal Journal of Computer Scences and Engneerng, IJCSE, Volume -, Issue-1, Page No (13-136), 14. [3] Jaeok Park and Mhaela van der Schaar, The Theory of Interventon Games for Resource Sharng n Wreless Communcatons, arxv: v [cs.gt], Page No (1-9), 16 Jul 11. [4] Luz A. DaSlva Hanna Bogucka Allen B. MacKenze, GAME THEORY IN WIRELESS NETWORKS, GUEST EDITORIAL, IEEE Communcatons Magazne, Page No (11-111), August 11. [5] Yngda Chen, Interactve Networkng: Explotng Network Codng and Game Theory n multuser wreless communcatons, Lehgh Unversty, ISBN , , ProQuest, Page No (1-68), 8. [6] Dmtrs E. Charlas, Athanasos D. Panagopoulos, A survey on game theory applcatons n wreless networks, do:1.116/j.comnet.1.6., Comput.Netw, Page No (1-1), (1). [7] Ashok M. Kanthe, Power Control through Noncooperatve Game Theory on Wreless Sensor Network, Faculty of Electrcal Engneerng and Computng, Unversty of Zagreb, Croata, Page No (1-5), 1. [8] Wald Saad, Zhu Han, Merouane Debbah, Are Hjørungnes, Tamer Basar, Coaltonal Game Theory for Communcaton Networks: A Tutoral, IEEE Sgnal Processng Magazne, Specal Issue on Game Theory, to appear, Page No(1-8),9. [9] Mark Felegyhaz, Jean-Perre Hubaux, Game Theory n Wreless Networks: A Tutoral, EPFL Techncal report: LCA-REPORT, Page No (1-15), 6. 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[15]Sara Rah, Al El Hore, Jamal El Kaf, analyss and smulaton of ofdm, IJSR, ISSN Onlne: , volume 3, Issue 3, Page No (45-49), March 14.. [16]Sara Rah, Al El Hore, Jamal El Kaf, Study and Analyss of a Nosy Sgnal by Vterb Decodng, IJSR, ISSN Onlne: , Volume 3 Issue 1, Page No (39-398), October 14. [17] Sara Rah, Al El Hore, Jamal El Kaf, Performance study of the OFDM modulaton for the use n Wreless communcaton Systems of the 4G, e-issn: , p-issn: 395-7, Volume: Issue: 6,Page No(119-17),Sep , IJCSE All Rghts Reserved 1