New Distributed QoS Control Scheme for IEEE Wireless Access Networks

Transcription

1 New Dstbuted QoS Contol Scheme fo IEEE Weless Access Netwoks Xaofeng Ba 1, Abdallah Sham 1, Khalm Amjad Meeja 1 and Chad Ass 2 1 The Unvesty of Westen Ontao, Canada, xba6@uwo.ca, asham@eng.uwo.ca, kmeeja2@uwo.ca 2 Concoda Unvesty, Canada, ass@cse.concoda.ca Abstact The IEEE WelessMAN standad povdes a compehensve qualty-of-sevce (QoS) contol stuctue to enable flow solaton and sevce dffeentaton ove the common weless netwok nteface. By specfyng a patcula set of sevce paametes, the meda access contol (MAC) mechansms defned n the standad ae capable of offeng sevce guaantees on the connecton bass. Howeve, the desgn of effcent, flexble and yet bandwdth-savng schedulng algothms fo such QoS povsonng stll emans an open topc. Ths pape poposes a new dstbuted QoS contol scheme that guaantees patcula sevce paamete settngs fo both uplnk and downlnk connectons. Detaled smulaton expements ae pesented to study the pefomance and to valdate the effectveness of the poposed algothm. Index Tems Boadband Weless Access Netwoks, IEEE , Qualty of Sevce, Schedulng. B I. INTRODUCTION oadband weless access (BWA) technology s accepted as a pomsng soluton fo the next geneaton last-mle access systems. Wth less nstallaton peod, lowe mantenance cost and hghe netwok scalablty, ths technology offes moe evenue ponts and bette maket penetaton than ts wed countepat. Suppoted by the obust lnk adaptaton famewok and flexble QoS contol stuctue n the newly developed standad, BWA n patcula povdes a sutable soluton fo delveng boadband Intenet sevces to folage-populated ual aeas, whee wed nfastuctue s economcally nfeasble, as well as to bult-up uban aeas, whee exstng wed access s bottlenecked. The weless metopoltan aea netwok specfcatons, known as WelessMAN, ae defned n IEEE [1]. The standad povdes a set of mechansms to acheve elable and lnk-adaptve hgh ate tansmsson. QoS s suppoted by the standad wth a full set of paametes that pemts sevce dffeentaton up to the connecton level. The mplementaton of such QoS povsonng to mantan the pedefned sevce paametes, howeve, s left fo vendo dsceton. Many eseaches have made tbutay contbutons fom dffeent pespectves. In ths study, we popose a QoS contol scheme that guaantees ndvdual sevce paamete settngs of each uplnk and downlnk connecton. Ths scheme consdes the data contol plane as a collaboatve entty and specfes detaled opeatons pefomed at the base staton and each subscbe staton. The est of ths pape s oganzed as follows: Secton II pesents an ovevew of the physcal (HY) and MAC laye specfcatons n the standad. Secton III and Secton IV ntoduce the motvaton and desgn of the poposed QoS contol scheme. Smulaton esults ae pesented n Secton V and Secton VI concludes ths study. II. OVERVIEW OF THE IEEE WIRELEMAN SYSTEMS The IEEE WelessMAN system contans one cental Base Staton (BS) and one o moe Subscbe Statons (s) n one achtectual cell. The BS s esponsble fo communcatng wth each and egulatng ts behavo. Two opeaton modes ae defned n the standad,.e., pont-to-multpont (M) and mesh modes, along wth dffeent physcal laye specfcatons. In ths secton we befly ovevew the basc concepts defned fo the physcal and MAC laye sevces n the standad. Specfcally, we consde the GHz band sngle cae (SC) system opeatng n M mode. A. HY specfcatons fo WelessMAN-SC systems The physcal laye opeaton s fame based and suppots both Tme Dvson Duplex (TDD) and Fequency Dvson Duplex (FDD) confguatons. Both setup use bust tansmsson fomat whee the bust poflng fo each s adaptve and may change fame-by-fame. In ths secton we focus on the fame stuctue of TDD confguatons. A tansmsson fame s defned as a fxed tme duaton n whch both the downlnk and uplnk tansmsson complete one ound. A fame conssts of two subfames,.e., downlnk and uplnk, desgnated fo BS-to- and -to-bs tansmssons, espectvely. The downlnk subfame begns wth nfomaton fo synchonzaton and a fame contol secton that defnes the tansmsson bust pofle, ncludng modulaton and codng schemes as well as elevant tmng nfomaton, fo each. Followng the fame contol secton s the downlnk data destned to ndvdual s. The downlnk data s gouped nto seveal tansmsson busts usng TDM technque. These tansmsson busts ae dffeentated by the appled Downlnk Inteval Usage Code (DIUC), whch epesents a cetan set of modulaton and codng scheme fo tansmsson. atculaly, the bust mapped nto QSK (Quadatue hase-shft Keyng) constellaton appeas fst, followed by busts mapped nto 16-QAM (Quadatue Ampltude Modulaton) and then 64-QAM (optonal) constellatons. Downlnk subfame s boadcast by the BS to all s. The MAC n each lstens to the downlnk channel and looks fo the MAC heades ndcatng data fo ths. The uplnk Ths full text pape was pee evewed at the decton of IEEE Communcatons Socety subject matte expets fo publcaton n the IEEE GLOBECOM 2006 poceedngs.

2 subfame follows downlnk subfame. Uplnk data tansmsson s oganzed n TDMA fashon whee the uplnk busts ae dffeentated by the sendng s. Each scheduled tansmts nto the uplnk dung ts ganted wndow usng bust pofle assocated wth the Uplnk Inteval Usage Code (UIUC) that was nfomed n the fame contol secton. The bandwdth of a fame s allocated to downlnk subfame wth the ganulaty of one physcal slot (S), and to uplnk subfame wth the ganulaty of one mnslot, whch s 2 m Ss long (m anges fom 0 though 7). The length of one S s defned as the duaton of fou modulated symbols. The symbol ate s a system paamete and s desgned such that thee should be an ntege numbe of Ss wthn one fame duaton. Wth the same HY symbol ate, busts usng dffeent DIUC/UIUC can acheve dffeent bt ate fo the MAC laye data steam. B. MAC sevces and tansmsson schedulng The opeaton of MAC sevces s connecton-oented. A connecton s defned as a undectonal mappng between BS and MAC pees fo the pupose of tanspotng a sevce flow s taffc [1]. A sevce flow s a undectonal flow of MAC sevce data unts wth pedefned QoS paametes. A connecton s dentfed by ts unque Connecton Identfe (CID) and s mapped to a sevce flow. The QoS paametes defned fo the sevce flow s theefoe mplctly povded by the connecton s CID. In ode to accommodate uppe laye applcatons wth dffeent sevce equements, the standad defnes fou types of MAC schedulng sevce. Each connecton s categozed nto one of these fou sevce types, accodng to the popety of applcatons caed by ths connecton. These schedulng sevces and elated QoS paametes ae as follows: (1) Unsolcted Gant Sevce (UGS) the key QoS paametes ae eseved taffc ate, mum latency and toleated jtte. (2) Real-tme ollng Sevce (ts) the key QoS paametes ae mnmum eseved taffc ate, mum sustaned taffc ate and mum latency. The mum latency s only guaanteed fo taffc wthn the mnmum eseved taffc ate. (3) Non-eal-tme ollng Sevce (nts) the key QoS paametes ae mnmum eseved taffc ate and mum sustaned taffc ate. (4) Best Effot (BE) the key QoS paamete s only mum sustaned taffc ate. Each connecton can equest desed bandwdth by sendng a stand-along MAC heade o by nsetng a gant management subheade nto a MAC otocol Data Unt (DU). Though the bandwdth s equested fo a connecton, the gant s howeve ssued to the coespondng. Theefoe, the has the ght to decde the consumpton of a patcula bandwdth allocaton. Snce the bandwdth need fo a UGS connecton s tme-nvaant, the gants fo UGS connectons ae povsoned peodcally by the BS wth fxed value. In ths study we do not consde ths sevce type fo bevty. Excludng UGS connectons, the standad does not specfy detaled schedulng algothm fo othe non-ugs connectons and leaves t fo vendo specfc. III. MOTIVATION OF THE ROOSAL Fom the pevous secton, we can see that the uplnk equest/gant schedulng s cucal fo povdng sevce guaantees to non-ugs connectons. The cost of ths mechansm, howeve, s the exta ovehead equed fo connectons to equest the eal-tme bandwdth needs. Ths cost s a functon of the numbe of connectons concuent n the system and the equest nteval of each connecton. Consde that the 16 bt CID defned n the standad pemts up to 64K connectons unnng smultaneously unde the BS s admnstaton, the bandwdth avalable fo data tansmsson may decease seously n peak hous. Though some delay-toleant connectons can be polled wth a longe nteval, ths pecludes tmely pecepton of the connecton s bandwdth need by the BS. Wth the fxed fame duaton, the BS s delayed pecepton eventually deteoates the nte-connecton statstcal bandwdth multplexng and potentally leads to bandwdth waste. In concluson, the followng pncples should be taken nto consdeaton fo the desgn of an effcent QoS contol scheme: (1) Guaantee sevce paametes fo each connecton; (2) Mnmze the pe-connecton ovehead equed fo bandwdth equest; (3) Optmze the feshness of BS s pecepton on each connecton s bandwdth need. Beang these ponts n mnd, we popose a dstbuted QoS contol scheme that guaantees sevce paametes fo both uplnk and downlnk connectons. We efe to ths scheme as Sng-Cae Schedulng Algothm (SCSA). IV. DISTRIBUTED QOS CONTROL SCHEME FOR IEEE WIRELEMAN-SC SYSTEMS The basc dea of ou SCSA scheme s to move some connecton level functonaltes pefomed by the BS to each theeby lmt the sgnalng ovehead, whle keepng the connecton level QoS povsonng. Specfcally, an Uplnk Request Management Agent (URMA) s nstalled n each and collaboates wth the local schedule of the. Ths URMA patally pocesses each connecton s bandwdth equest at the and geneates up to thee pe- bandwdth equests that wll be sent to the BS. These equests ae labeled wth dffeent poty values and ae sent at the end of the uplnk bust wndow assgned to the n each tansmsson fame. In ths way, the ovehead equed fo bandwdth equest s lmted to be only -elevant and ndependent fom the numbe of connectons unnng n the. Also the BS s fed wth the most ecent nfomaton on the connectons bandwdth need n evey tansmsson fame. Theefoe, we have compled wth the second and thd pncples mentoned above. In the followng dscusson we focus on the fst pncple,.e., povdng connecton level sevce paamete guaantees. A. Uplnk Request Management Agent A URMA conssts of thee modules,.e., sevce Ths full text pape was pee evewed at the decton of IEEE Communcatons Socety subject matte expets fo publcaton n the IEEE GLOBECOM 2006 poceedngs.

3 measuement module, QoS enfocement module and equest geneaton module. The functonaltes pefomed n each module ae descbed as follows: A.1 Sevce measuement module Ths module obtans the nstant bandwdth equest of each connecton accodng to the connecton s queue length and MAC heades equed to tansmt the backlogged taffc. Ths bandwdth equest s uppe-bounded by the connecton s elgble bandwdth equest, whch s computed as: e R = [ t S () t ], 0 (1) 8 e whee s the elgble bandwdth equest of connecton, R s the mum sustaned taffc ate (n bts/second) of ths connecton and t s the system tme. The sevce measuement module mantans a sevce tme fo each non-ugs connecton unnng n the and S () t n (1) s the value of connecton s sevce tme at tme t. The sevce tme apples the concept of Vtual Clock poposed by L. Zhang n [2]. Ths sevce tme s synchonzed wth the system clock when a connecton s establshed and tcks wth the followng value upon the sevce of each DU n the coespondng connecton: B A = 8 (2) ρ whee A s the ncement of connecton s sevce tme, upon the sevce of a DU wth sze of B bytes. ρ s the measuement ate (n bt/second) fo connecton. Fo the sevce tme, ths value should be R. Instead of stampng each aved packet wth ts vtual tme as ntoduced n [2], hee we use a sepaate vaable to ecod a connecton s vtual tme. The eason, as wll be shown late, s that n ou case some packets have to be dopped-font due to volaton of mum latency. The sevce tme thesholds a connecton s sevce ate wthn ts mum sustaned taffc ate. A.2 QoS enfocement module Ths module mantans a QoS tme fo each ts and nts connecton unnng n the. The QoS tme s also ntalzed wth the system clock, howeve tcks wth the value decded by dffeent measuement ate defned n (2). Fo the QoS tme, the value of ρ should be mn R,.e., the mnmum eseved taffc ate (n bts/second) of connecton. The eason fo desgnng two vtual tmes fo a connecton equng mnmum sevce ate s to have the eceved sevce ate guaanteed but not lmted at ts mnmum eseved taffc ate. Ths pont wll be futhe clafed by the dscusson of outbound tansmsson schedulng. The QoS tme enfoces the connecton s sevce ate to meet a guaanteed value. The opeatons pefomed by the QoS enfocement module nclude two steps: (1) Fo each ts o nts connecton, segment ts bandwdth equest nto bandwdth guaanteed () pat and non-bandwdth guaanteed (N) pat,.e., and N, accodng to the coespondng value of QoS tme, denoted as () t,.e.: N Q mn =, 0 R mn 8 [ t Q () t ] Q () t Q () t < t t (3) = (4) The bandwdth equest of a BE connecton s always N, as thee s no sevce guaantee fo ths connecton. (2) Fo each ts connecton, futhe segment ts nto mmnent pat m and non-mmnent pat nm, accodng to the contacted mum latency of ths connecton. The opeaton of ths step s based on the followng facts: f the mum latency deadlne of a DU wll appea n fame n+2, the last oppotunty to schedule tansmsson of ths DU s n fame n+1, n ode to guaantee ts mum latency. Theefoe, the bandwdth needed to tansmt ths DU has to be equested n fame n. The m pat of computed n fame n s thus the bandwdth need fo tansmttng DUs whose mum latency deadlne appeas befoe the end of fame n+2. The nm pat of m s smply. A.3 equest geneaton module Ths module geneates up to thee pe- bandwdth equests, dependng on the sevce type of connectons unnng n the. The pe- bandwdth equests ae potzed, n ode to enable sevce dffeentaton at the BS. These thee bandwdth equests ae defned as: m M nm + j M j N N N + j M j N 0 = (5) 1 = (6) 2 = + (7) k k L whee (=0, 1, 2) denotes the pe- bandwdth equest of poty level, M, N and L ae the sets of ts, nts and BE connectons unnng n the, espectvely. Befoe gong futhe, t s helpful to clafy the backgound bass wheeby these thee potzed equests ae defned: (1) Fom the QoS sense, the pat of a ts o nts connecton s potzed ove ts N pat and the latte s equvalent to the bandwdth equest of a BE connecton; (2) Fom the QoS sense, the m pat of a ts connecton s potzed ove ts nm pat and the latte s equvalent to the pat of a nts connecton. B. Fame geneaton Upon ecevng the potzed bandwdth equests fom s, a new fame s geneated at the BS. Ths eques the nvolvement of thee functonal modules,.e., the Downlnk Request Management (DRM) module, the esouce allocaton module and the fame ceaton module. The opeatons Ths full text pape was pee evewed at the decton of IEEE Communcatons Socety subject matte expets fo publcaton n the IEEE GLOBECOM 2006 poceedngs.

4 pefomed n these modules ae descbed as follows: B.1 Downlnk Request Management module The DRM module functons smlaly to the URMA at a, except that the potzed bandwdth equests fo downlnk ae assocated wth each downlnk bust. Namely, downlnk connectons usng the same DIUC n the next fame ae gouped togethe by a common set of potzed bandwdth equests. Note that uplnk connectons only n the same ae gouped togethe by a common set of potzed bandwdth equests. In the followng dscusson we efe to connectons shang a common set of potzed bandwdth equests as a schedulng goup (SG). B.2 Resouce allocaton module Ths module allocates tansmsson capacty to each SG, accodng to the potzed bandwdth equests. Snce dffeent HY modulaton and codng schemes mply dffeent MAC laye tansmsson capacty, the numbe of symbols equed to tansmt one byte n the MAC DU may vay n evey SG. Theefoe, the potzed bandwdth equests of each SG have to be conveted nto symbol needs and the bandwdth allocaton s fnally accomplshed by symbol assgnment. We do not nclude physcal laye detals due to lmted space. The symbol assgnment follows stct poty ule and s defned as: (1) Symbol need of 0 equests s consdeed fst, then 1 followed by 2 equests, accodng to the numbe of symbols avalable fo data tansmsson n the next fame. Hee the symbol need of (=0, 1, 2) equests ncludes the symbol need of evey SG s equest (both downlnk and uplnk). (2) If at any pont the emanng numbe of symbols cannot accommodate the oveall symbol need of equests, evey SG submttng a equest shaes the avalable symbols n popoton to ts symbol need. (3) If the symbol need of evey SG has been accommodated, the emanng symbols ae assgned to each SG, n popoton to the numbe of connectons ncluded n the SG. (4) The total numbe of symbols assgned to a SG s the sum of symbols eaned by ts 0, 1, 2 equests and any symbols assgned n step 3, f applcable. B.3 Fame ceaton module Ths module convets the above symbol assgnment esult nto tmng nfomaton n tems of S o mnslot, and then a new fame s ceated. C. Outbound tansmsson schedulng Wthn the ganted bust wndow n the uplnk subfame, the schedule at each selects packets fo tansmsson, accodng to each connecton s bandwdth equest and the potzed pe- bandwdth equests stoed n the URMA by the last fame. Specfcally, the 0 equest s honoed fst, then 1 followed by 2 equests, f thee s moe bandwdth avalable. When the schedule has to select the next packet fo tansmsson among multple connectons, some cteon should be defned. Dependng on the type of potzed equest to whch the bandwdth s honoed, thee dffeent ctea ae appled: (1) When multple connectons contend fo bandwdth honoed to the 0 equest, the packet wth the most mmnent mum latency deadlne s selected. Howeve, any packet wth exped mum latency deadlne wll be dopped at the font of the connecton queue. (2) When multple connectons contend fo bandwdth honoed to the 1 equest, the head-of-lne packet of connecton wth the ealest QoS tme s selected. Ths cteon optmzes faness among these contendng connectons. (3) Bandwdth honoed to the 2 equest s equally shaed by each connecton n a ound-obn fashon, despte of the sevce type and equested bandwdth of the connectons. Ths cteon contnues untl the ganted bust wndow expes,.e., even thee may be no equest to be honoed. Howeve, any connecton whose sevce tme exceeds the system clock wll be neglected n the cuent ound. Wth the sevce of each DU n a connecton, the sevce tme tcks accodngly. Howeve, only consumng bandwdth honoed to the 0 and 1 equests ncus the advancement of coespondng QoS tme. Ths enables the eceved sevce ate of a ts o nts connecton to be guaanteed but not lmted at ts mnmum eseved taffc ate. The schedule at the BS pefoms smlaly to the schedule at each, except that the opeaton scope s a downlnk bust wndow. Namely, connectons belongng to the same downlnk SG ae all consdeed when the next packet s selected fo tansmsson. V. SIMULATIVE EXERIMENTS A. Smulaton model We set up a smulaton envonment by ns-2. The netwok conssts of one BS and ten nodes (numbeed fom 1 to 10) locatng 2.5 km away fom the BS. In the downlnk decton thee ae ten ts, ten nts and ten BE connectons ognated fom the BS; whle n the uplnk decton thee ae one ts, one nts and one BE connecton ognated fom each, except 6 and 8. As the supevsed nodes, 6 mantans thee ts and one BE uplnk connectons; whle 8 seves fou nts and one BE uplnk connectons. We assgn the same set of sevce paametes to connectons of the same sevce type,.e., 1M bps fo the mnmum eseved taffc ate of each ts and nts connecton, 1.5 M bps fo the mum sustaned taffc ate of each ts, nts and BE connecton, 3 ms fo the mum latency of each ts connecton. In the smulaton, each connecton unnng n the netwok offes aveagely 1M bps taffc ntensty, except fo connecton 36, whch offes 2M bps taffc ntensty. We focus on the sevce povsonng of thee uplnk connectons: ts connecton 35 unnng n 6, ts connecton 36 unnng n 6 and nts connecton 48 unnng n 8. The fame duaton and system symbol ate n the smulaton ae set to 1 ms and 20M Baud, espectvely. We apply QSK modulaton to the fame contol secton and 16-QAM to each downlnk and uplnk bust used fo data tansmsson. In ode to llustate the effcent nte-connecton statstcal bandwdth multplexng povded by the BS n the poposed SCSA scheme, we also smulate anothe schedulng scheme, Ths full text pape was pee evewed at the decton of IEEE Communcatons Socety subject matte expets fo publcaton n the IEEE GLOBECOM 2006 poceedngs.

5 efeed to as passve (ASV) scheme, whee the bandwdth allocaton s fxed n evey fame and equally shaed by each. B. Smulaton scenaos and esults B.1 Scenao one In the fst scenao we test the effectveness of the poposed SCSA scheme n tems of povdng connecton level sevce guaantees. In the smulaton we have obseved that n ASV, both ts connecton 35 and nts connecton 48 wee staved by about 30% of the mnmum eseved taffc ates. Howeve, n SCSA, the bandwdth povsoned to each of these connectons s well confned wthn the ange between the coespondng R and R mn paametes. Ths s because n ASV the complance of pe-connecton sevce paametes s constaned wthn the local scope of one patcula, though some bandwdth s wasted by othe s. Moeove, the doppng pobabltes due to latency volaton of thee ts connectons n 6 ae 27.04%, 26.61% and 30.4%, espectvely fo connectons 34, 35 and 36 n ASV. Whle ths value s zeo fo connectons 34 and 35, and 25.53% fo connecton 36 n SCSA. We can see snce connecton 36 offes taffc ntensty twce of ts mnmum eseved taffc ate, 25.53% packets ae dopped. Ths value, howeve, s less than the oveloaded poton of ths connecton,.e., 50%. Hence we can conclude that taffc ntensty wthn the mnmum eseved taffc ate of any ts connecton s sevced wthn ts mum latency constant. Aveage bandwdth (bts/second) x 10 6 ts connecton 36 bandwdth ecods n two scenaos offeed ate sevced ate_scenao1 mnmum eseved ate_scenao1 mum sustaned ate_scenao1 sevced ate_scenao2 mnmum eseved ate_scenao2 mum sustaned ate_scenao2 tme (second) Fg. 1 Bandwdth povsoned to connecton 36 n two scenaos B.2 Scenao two In the second scenao, we ncease the mnmum eseved taffc ate paamete of connecton 36,.e., the connecton offeng 2M bps ate, to test the flexblty of the MAC n SCSA. Specfcally, we set the R mn and R paametes of ths connecton to 1.5M bps and 2M bps espectvely, and keep othe settngs the same as n scenao one. Fg. 1 compaes the bandwdth povsonng of connecton 36 by SCSA n two scenaos. The cuves n the fgue pesent the up-to-date aveaged bandwdth povsoned to the connecton. Theefoe, wth the evolvement of tme, each cuve becomes flatte and moe pecsely eveals the oveall offeed/sevced ate of the connecton. We can ecognze that the sevced ates of ths connecton ae constantly guaanteed above ts R paamete and constaned below ts R mn paamete, n both scenaos. The sevce mpovement of connecton 36 n scenao two, howeve, s not wth the cost of degadng the sevce paamete complance of othe connectons. Fg. 2 llustates the bandwdth povsonng of connectons 35 and 48 by SCSA n scenao two. The fgue substantates that thee s no sevce dop fo these two connectons n scenao two. Theefoe, we can conclude that the sevce mpovement of connecton 36 does not affect the contacted sevce povded to ts sblng connectons n the same, e.g., connecton 35, and cousn connectons n dffeent s, e.g., connecton 48. In fact, ths sevce mpovement s contbuted by othe BE connectons unde the flexble esouce manpulaton of the MAC. Aveage bandwdth (bts/second) Aveage bandwdth (bts/second) x 10 5 ts connecton 35 bandwdth ecods n scenao2 offeed ate 5 sevced ate mnmum eseved ate mum sustaned ate x 10 5 nts connecton 48 bandwdth ecods n scenao2 offeed ate 5 sevced ate mnmum eseved ate mum sustaned ate 0 tme (second) Fg. 2 Bandwdth povsoned to connectons 35 and 48 n scenao two VI. CONCLUSION In ths study we poposed a dstbuted QoS contol scheme and examned ts pefomance by smulatons. Ths poposed SCSA scheme guaantees sevce paametes fo each uplnk and downlnk connecton and mnmzes sgnalng ovehead n the data contol plane. Smulaton esults fmly vefed the expected pefomance of the poposed scheme. REFERENCES [1] IEEE Std , IEEE Standad fo Local and Metopoltan Aea Netwoks at 16: A Inteface fo Fxed Boadband Access Systems, Octobe [2] L. Zhang, Vtual Clock: A New Taffc Contol Algothm fo acket-swtched Netwoks, ACM Tansacton on Compute Systems, vol. 9, pp , Ths full text pape was pee evewed at the decton of IEEE Communcatons Socety subject matte expets fo publcaton n the IEEE GLOBECOM 2006 poceedngs.