Upln ll Admsson onrol Technues for Mulmed Pce Trnsmsson n UMTS WDMA Sysem Angel Hernández Soln, Anono Vldovnos Brdjí, Fernndo sdevll Plco 2 Elecroncs Engneerng nd ommuncons Dp. Unversy of Zrgoz. (Spn) nhersol@pos.unzr.es 2 Sgnl Theory nd ommuncons Dp. Polyechnc Unversy of lon (UP); Brcelon (Spn) Absrc- The hrd generon cellulr newor, UMTS, provdes lrge opporunes o offer mulmed pplcons nd servces h mee end o end uly of servce (QoS) reuremens, n more effcen wy, consderng pce d rnsmsson mode. However, hs reures o desgn n effcen flow conrol nd cll dmsson conrol (A). Desgn of A hs specl dffcules gven h cpcy n DMA vres ccordng wh he number of cve users nd he level of nerference. Tng no ccoun he sochsc nure of mulmed rffc nd he chnges n he vlble cpcy n he DMA sysem, n effecve cpcy reues s derved nd used o chrcerze he resources reured by ech moble user n order o mee s respecve QoS reuremens. These reuremens re expressed n erms of re nd dely consrns n ddon o he sgnl o nerference ro. Afer seng n effecve cpcy hreshold for he sysem, lner pproxmon s used o fnd he ol moun of resources reured by ll he moble users lredy dmed n he sysem nd he new connecon reues. Pce rnsmsson s consdered for boh rel me nd non rel me servces whle cenrlzed demnd ssgnmen lgorhm hs been mplemened n order o provde QoS n he pce level. ompuer smulon resuls re gven o demonsre he performnce of he proposed mehod. I. ITRODUTIO The connecon dmsson conrol (A) for moble communcons s one of he mos mporn engneerng ssues n order o gurnee sysem effcency nd uly of servce (QoS) o connecon orened servces. In nerference lmed DMA sysems, good nerference hndlng by rdo resource llocon schemes plys n mporn role o enhnce he performnce nd o ncrese he sysem cpcy. In hs wy, A ndrecly conrols nerference by lmng he number of users n he sysem n order h he negoed sgnl o nerference ro vlues cn be cheved by ech exsng connecon. Wheres, n pce me scle, he medum ccess conrol/flow conrol blnces he sysem nerference nd rrnges rnsmssons on frme o frme bss by schedulng users ccordng wh her QoS reuremens n erms of he mxmum llowed dely, re nd b error re. In ny cse, coordnon beween A nd flow conrol s reured o mee QoS nd conseuenly he resuls obned from pce level hve o be en no ccoun n order o nfer n effcen mehod for A. The flexbly of DMA ccess n ddon o he pce rnsmsson mode mproves sysem effcency bu ncreses he complexy of he A. Gven h n DMA cpcy vres due o chnges n he nerference he desgn of A hs ssoced wo mn desgn problems: ) o se n effecve A hreshold o gurnee he QoS for n negron of vrous servce ypes, nd b) o cheve he mxmum effcency n he sense of resources usge. In fc, A relly operes wo dfferen levels: he frs one chrcerzed by he pce level consrns such s pce loss, dely jer or verge dely nd he second one h llows he sysem cpcy o be shred mong he vrous rffc ypes nd/or o proec he hndoff connecons from he new connecons. Severl reserch sudes hve ddressed hese ssues by mens of sc nd dynmc prorzon nd shrng scheme, ssoced wh sc or dpve reserve of resources. The problem of seng n effecve A hreshold hs been ddressed before n ue lo of wors [4][5][6][]. In generl, wo A syles cn be found n hese references: A h derve n verge cell cpcy bsed on he llowed number of cve connecons nd A bsed on he rnsmed power or he ol nerference level. [4] presens useful expressons for sysem cpcy evluon. However, snce he erlng cpcy s clculed bsed only on blocng re, he communcon uly s no gurneed nd s relon wh erlng cpcy s lef uncler. A dsrbuon funcon of nerference s deermned n order o evlue he blocng probbly. [4] shows h he men nd vrnce of oher-cell nerference cn be pproxmed by he nrcell nerference mulpled by consn coeffcen f. In [5] expressons of he QoS (pce loss) nd GoS (grde of servce) s funcons of rffc nensy nd A hresholds hve been derved lhough only ype of servce s consdered. In [6], n effecve cpcy (re), ng no ccoun he sochsc nure of rffc nd he dely reuremens n mulmed scenro, s used o chrcerze he resources reured by mulmed servces. The proposed mehod, hough useful, hs been shown o be conservve. In [] n nerference-bsed A sregy s proposed. A new user s no dmed by he upln A f he new resulng ol nerference level s hgher hn hreshold vlue. Ths hreshold s he sme s he mxmum upln nose rse nd cn be se by rdo newor plnnng. Alhough hs mehod could gurnee he sgnl o nerference ro for ll dmed connecons, pce level uly consrns n erms of dely reuremens re no ssured. oe h he mos cpcy nlyss concenre smply on rnsmsson chrcerscs nd do no consder he rel me operon of he sysem under sochsclly vryng rffc lod. On he oher hnd, none of he prevous references consder specfc MA proocols n order o provde dfferened QoS n he pce level. We hve nroduced hs specfc fcor. ompuer smulon resuls obned from pce level hve been evlued n order o nfer n effecve cpcy hreshold. In prculr, our sudy hs been ssoced o he Wdebnd ode Dvson Mulple Access (WDMA) upln defned n Unversl Moble Telecommuncon Sysem (UMTS) erresrl rdo ccess (UTRA) nd lmed o he upln. Trnsmssons of rel-me nd non rel-me servces hve been performed n pcezed form over he physcl d chnnel (DPDH) where cenrlzed demnd
ssgnmen proocol hs been mplemened o negre servces wh QoS. oe h hs proposl dffers from pce rnsmsson modes defned for he momen n UTRA (shor nfreuen pce on RAH nd shor number of successve frmes on ommon Pce hnnels (PH) []). However, we hve consdered he menoned lernve n order o rnsm lrge or freuen d pces whou conen for code. In hs cse, ech MS, whch hs pces wng o rnsm, seups dedced code usng n nl Rndom Access reues, wheren he ype nd rffc prmeers re specfed. Then, he newor evlues he reues nd decdes f he necessry resources cn be provded o he MS n order o suppor s QoS. Once he dedced chnnel (code) s ssgned, he MS s no llowed o sr he rnsmsson, needs o w h he bse son (BS) specfes he mes n whch cn rnsm. Boh MS rnsmed powers nd rnsmsson res my be consdered s conrollble resources by he newor. Thus, he schedulng dscplnes BS, n coordnon wh mnmum rnsmed power creron, re responsble for rrngng pce rnsmssons whn her specfed re reuremens nd dely olernces, beng chnnel condons of ndvdul users n mnd. The purpose of he mnmum power conrol creron s o mee he B Error Re (BER) of smulneously rnsmed pces, ssgnng n opmum level o he rnsmed power from ll he MS s n such wy h nerference cused o oher cells s mnmzed nd hus hroughpu s mxmzed. Besdes, he level of nerference BS s lwys mnned under hreshold whle MS oupu powers re consrned. Severl schedulng sreges bsed on sc nd dynmc prores hve been consdered nd proved o perform dfferene QoS. A deled descrpon of he proocol nd he schedulng sreges cn be found n [2]. However, some ssumpons bou power ssgnmen re revewed n secon II n order o suppor he nlyss of he effecve user cpces nd he hreshold sysem cpcy. Once he effecve A hreshold s se, we evlue he performnce of vrble chnnel reservon A polcy bsed on he esmed poson nd movemen of mobles sons (MS s). Ths esmon s performed consderng mesuremens repored by he MS. ompuer smulon resuls demonsre he effcency of he proposed A hreshold n mulmed scenro nd lso he effecve hndoff prory provded by he proposed dsrbued-dpve A polcy. II. ALL ADMISSIO THRESHOLD The se of reuremens ssoced wh MS loced n cell : mxmum dely nd dely jer, mnmum re r, nd mxmum b (BER) or bloc (BLER) error res, cn be mpped no n euvlen (E b /o)., consrn denoed by γ : Eb o wh, W r I, n, P, h, γ + I + η W ex, I ex Pl, ' hl, ' l, o.., P I n,, h, () where E b s he b energy, o he ol nerference densy receved he BS, η o he herml nose specrl densy, I n,. nd I ex, he nrcell nd nercell nerference respecvely, P, he rnsmed power ssoced o he MS loced n cell, h, he ph loss beween MS nd he BS, he number of users n he cell nd W he vlble bndwdh n he cell (chp re). I hs been shown h, consderng h power oupu consrns re ppled o MS, 0 < P, < p,, mx, he power conrol problem n cell s fesble f nd only f [3]: W η( / + j r γ j ( + f ( )) j j η( mx ( I f I (2) ex, ηow, n, ( ) W mn + j p, mxh r γ j We consder mx ( s he mxmum vlble cpcy n he cell, he consumed cpcy by MS nd η( s he reserved cpcy needed o gurny he power consrns o MS s n frme. A mnmum vlue of prmeer η eul o 0. s consdered n order o lm he mxmum ol power receved he BS I ol,. If condon (2) s cheved for se of res nd E b / o vlues, hen he power cn be obned usng (3). ηow wh P res ( + f ) j (3) ˆ W j h, ( + res( r γ, oe h n cern frme, where sch s he number of scheduled users, he relon (4) s ssfed. mx sch res η( 0 + f + f ( ) (4) The ro beween ner nd nrcell nerference f(, nd he chnnel condon should be nown n order o cheve he mnmum rnsmed power creron wh ccurcy. Ro f( s esmed from he ro mesured n he prevous frme. Tng no ccoun condon (2), schedulng he BS rrnges rnsmssons of MS s ccordng o lgorhms reled wh dely nd re reuremens. MS s whch cn no mee Eb/o reuremens re delyed lhough could be n conc wh he bse hrough he Dedced onrol hnnel (DPH) (o perform closed power conrol). Unused resources (power nd nsn of rnsmsson) re ssgned o he res of he users. oe h he wse of cpcy ssoced o DPH mus be dded n (2). In ddon o he schedulng sreges bsed on dely nd re reuremens, we hve consdered chnnel se dependen schedulng lgorhm bsed on he reured vlue of prmeer η [2]. MS s whch reure hgh vlue of η could be delyed n order o provde perms o more users. Once we hve descrbed heorecl expressons for cpcy n he pce level me scle, we wll expln he developmen of he effecve A. In our cse, unle [4][5][6], he scheduler lms he number of MS s rnsmng n frme, hus, pror, every MS hvng perm o rnsm mus rech s Eb/o
consrns (condon (2) s ssfed). So, only mperfecons n he esmon of ro f( could preven, gven h lmos perfec chnnel esmon could be ssumed hns o DPH. Thus, users cn only no ssfy her QoS consrns reled wh dely consrns. Rel me servces drop pces h exceed dely consrns, so specfc drop probbly consrn s mposed s QoS creron. On he oher hnd, smulon resuls show h nl cpcy mx ( mnns he sme sscl dsrbuon, whch hs been shown o correspond o gmm dsrbuon, wh he sme men n vrnce ndependenly of he number of cve users n he sysem, beng only dependen of he propgon prmeers, closed power conrol nccurcy nd he spl dsrbuon of MS s whn he cell. However, n order o perform A, we use n lernve mesure of he cpcy (5), more dependen of curren cve users, whch provde more ccure bound. n sch η f (5) Smulons show h n ( cn be chrcerzed by F-dsrbuon, gven h he produc of f( nd sch cn be modeled s produc of Gmm dsrbuons. Ths dsrbuon s mnned consderng eher one ype of rffc or n negron of rel me nd non rel me servces. However, for he momen, n order o smplfy he nlyss, we wll only consder rel me servces, nd only one ype of rffc. oe h f here re MS s dmed n cell, he probbly of cve users my be expressed s bnoml dsrbuon (6), where ρ s he cvy fcor ssoced o clss MS s. Dsrbuon of cve users s no he sme s dsrbuon of scheduled users. However, whle s below he A hreshold (chrcerzed by he mxmum number of MS llowed, mx, ) hey could be consdered eul, whch smplfes he prmeers of he F-dsrbuon ssoced o n. Pu, ( ) ρ ( ρ ) (6) onsderng he dsrbuon of he vlble cpcy n,, he dely probbly cn be clculed s he frcon of ll cve users h cn no rnsm due o he bsence of vlble cpcy n frme. (7): j Pu, ( ) pn ( m) dm 0 j 0 0 Pdely (7) P ( ) 0 u. (p n s he pdf. of n. ) If we ssume no dely olernce, he mxmum number of llowed users, consderng hreshold o he P dely, represens n dmsson regon bound, gven h n fc, n hs cse, P dely s eul o he droppng probbly. However, hs ssumpon s very conservve gven h we cn ssume some olernce o he dely o lmos ny rel me servce. Insed of, n effecve cpcy,,ef (nroducng he dely nfluence) mus be derved n order o provde more ccure resul. Probbly ε s he probbly h dely ssoced o pces of ny connecon belongng o clss exceed dely reuremens. So, f we re ble o obn he dely dsrbuon of he ndvdul sources, he cpcy of he sysem n erms of number of MS s ( mx ) cn be clculed s (8) nd, n ddon, he effecve cpcy ssoced o MS of clss s (9): mx ef mx( Pr[ dely > Dmx ] ε ) (8) 0: [ mx ] mx, E / (9) where E[ mx ] s he men of he cpcy mx, esmed n perod of me. To obn mx, we need o compue he dely dsrbuon for ndvdul sources consderng her BLER nd servce re reuremens, he vrble wreless cpcy nd he error conrol scheme (selecve repe lgorhm s mplemened). To consder ll hese fcors ogeher n sngle nlycl model seems nccessble, so we hve mde he nlyss n wo seps. The probbly h dely does no exceed dely reuremens s compued s he probbly h cpcy ssgned o he ndvdul connecons, n me nervl eul o dely olernce Dmx couned from he nsn of he pce rrvl o he ueue ( ), s hgher hn he cpcy reured o rnsm ll pces wng n he ueue when pce rrves, ( ) (0). Pr [ dely > Dmx ], Pr( sg, { }, (, + Dmx ) ( )* ) [ (, + Dmx) n * / ( ) n ] sg, { } n (0) Pr Pr( ( ) n ) The probbly () [, + Dmx) n * / ( n ] Pr }( sg, { ) () s clculed usng model h ncludes he selecve repe scheme, he cpcy ssgned o connecon clculed dependng on he dely probbly clculed n (7), P d, nd he error probbly reled o he Eb/o reuremen, P e. lculus of P e ncludes he effecs of he lle devons n he Eb/o due o errors n he esmon of ro f( nd chnnel condons (hey hve been ssclly modeled). Ths model consders h ll pces wng o rnsm mus receve servce whn her specfc dely reuremen. On he oher hnd, he probbly of ueue occupon when pce rrves s clculed from n nlycl model h consders he evoluon n he ueue occupon when he source doesn genere rffc nd when he source s n cve se (remember h rffc s ssumed o be bursy). The nercon beween sources nd he chnges n he ssgned cpcy due o chnges n rffc dsrbuons re ncluded. Dely olernce of users s only represened by he mxmum sze llowed o he ueue nd no ddonl consderons re en no ccoun. A deled descrpon of he nlycl models for ueue nd dely dsrbuon cn be found n [4]. The exenson for n negron of severl rel me users wh dfferen BLER nd re reuremen s mmede consderng he effecve cpcy compued seprely for ech ype of rffc. So, lner
pproxmon cn be used o fnd he ol resources reured by ll he MS s. When n negron of rel me servces wh dfferen dely reuremens s consdered, lner pproxmon hs been shown o be lso vld. However, could be necessry, n some cses, o defne lle reserve of cpcy n order o preven lle devons from he lner pproxmon. oe h he effecve cpcy ssoced o non rel me servces s clculed consderng her men b re n cpcy. In frs nsnce, we cn consder convenonl A h llows new user no he rdo ccess newor f condon (2) s ssfed. [ ], ef + new, ef < E mx (2) cell where new, ef s he effecve cpcy of he new user. III. ALL ADMISSIO OTROL TEHIQUES We hve consdered n dpve A polcy o evlue he performnce of he proposed A hreshold. In order o proec hndoff clls we perform vrble resource reservons for hndoff clls dependng on he MS mobly behvor nd we compre he resuls wh complee shrng pproch. ll dmsson decson s performed n dsrbued mnner ner o h used n [2][3] for fxed cpcy sysems. Ech BS mes n dmsson decson by exchngng se nformon wh he djcen cells perodclly. BS s esme he fuure MS hndoffs usng nformon of power nd uly mesuremens repored by ech MS. We ssume h he power mesuremens wll come from he curren nd djcen cells. The conrol sysem nows whch of he djcen cells re poenl cnddes o hndoff, especlly when chnnel degrdon becomes mporn. A MS plced n degrdon re, defned n he lms of he cell, hs hgh probbly o hndoff whn me nervl. Usng nformon bou he evoluon n he power levels receved by MS n hs regon, could be possble o predc n some cses he drecon of movemen of he MS nd preven n some cses unnecessry resource reservon. Therefore, when MS s predced o hndoff, n ndcon of cpcy reserve eul o,ef s sen o he predced desnon n order o pre-lloce resources for he expeced hndoff. Reserves re nerchnged perodclly beween cells. A reservon my be no longer reured nd cncelled. A hndoff cll, wh effecve cpcy new_hndoff,ef, s cceped f: [ ], ef + new _ hndoff, ef < E mx (3) cell wheres new cll s only dmed f: cell ef + new, ef + pr _ dj _ hndoff j dj _ cells [ ], < E (4) where pr_dj_hndoff s he reserve of cpcy ssoced o he MS s from he djcen cells. oe h hndoff reuess re reed eully ndependenly wheher specfc MS hd mde reservon or no. All he reserved cpcy ny nsn s used n complee shred wy o serve hndoff reuess. Afer successfully hndoff, he reserve of cpcy, f vlble, s decresed n he mx correspondng,ef. IV. SIMULATIO MODEL AD RESULTS We propose cellulr sysem model composed by 9 hexgonl cells (rdus2km). Wrp-round echnue s used o vod border effec. Only nerference from he frs-er of djcen cells s consdered. Mcrocell propgon model proposed n [7] s doped for ph loss. Log-normlly dsrbued shdowng wh sndrd devon of σ 8dB s dded ccordng wh he model proposed n [8]. Addonlly, mul-ph fdng envronmen proposed n [9] s consdered. db nenn gn nd herml nose power of 03dBm re ssumed [7]. MS s hve mxmum oupu power of 27 dbm ccordng wh clss 2 defned n [9], nd move wh speed beween 25 o 50Km/h. Inl loclzon s seleced rndomly (unform dsrbuon). MS cn chnge s drecon of movemen whn n ngle of ±π/6 ech s nd 2π ech 20s. Two nd of rffc sources: Rel Tme Servces (lss I. nd lss I.2 d servces wh dely consrns of 300 ms 50ms respecvely) nd on-rel Tme Servces (lss II - D servces wh non-dely consrns) re consdered. onvoluonl codng re ½ ogeher wh rernsmsson scheme (ARQ) re used o cheve BLER0-2 n boh cses. Rel-me sessons re bsed on Pce lls wh number of pces exponenlly dsrbued wh men 35 pces (lss I.) nd 40 pces (lss I.2), whle servce of 36ps (rnspor bloc of 360bs nd rel rnsmsson re of 20bps) s ssumed. Averge ner-pce rrvl me s 0ms, whle pce cll ner rrvl me s exponenlly dsrbued wh men s. On he oher hnd we ssume h ech user generes sngle connecon/cll nd connecon/clls rrve o he sysem ccordng o Posson process of nensy λ. ll lengh s exponenlly dsrbued wh men 80s nd user leves he sysem s soon s he cll ends. on-rel me rffc sources re bsed on he model presened n [0]. 32Kbps d re servces hve been consdered. We presen some resuls n order o ssess he performnce of he connecon dmsson conrol. Fg compres he droppng probbles compued wh models (7) (Pr_dely_model) nd (0) (Pr_drop_model) nd smulons resuls when only clss I. MS s re consdered. Dely probbly s fr from droppng probbly obned n he smulon. However, he droppng probbly clculed when dely olernce s ncluded n he model s very close o hose obned n he smulon. Smlr resuls re obned for lss I.2. Fg. 2 shows cll dmsson lms when n negron of clss I. nd clss I.2 nd droppng probbly of % s consdered s uly creron (n hs fgure hndoff hs no been consdered n smulons). In Fg. 4,5,6,7 compuer smulons show, for he sme combnon of MS, he effcency of he proposed A mehod boh consderng homogeneous (Fg. 4 nd 6()) nd heerogeneous rffc dsrbuons n cells (Fg 5, 6(b) nd 7) nd mobly beween cells. Droppng probbly s lwys mnned under uly consrns (Fg. 6 nd 6b). On he oher hnd, vrble reservon (Fg. 4 nd 5) provdes good resuls (hndoff re s ner o λ/4.).
Probbly 0.04 Dely Prob. Smulon Resuls. 0.035 Dely Prob. Model Droppng Prob. Smulon Resuls. 0.03 Droppng Prob. Model 0.025 0.02 5 0 60 64 68 72 76 80 84 88 lss I.. umber of users lss I.2. umber of users Pce Droppng Probbly Fg.. Dely nd pce droppng probbly 80 70 60 50 40 30 20 0 Smulon Theorcl 0 0 0 20 30 40 50 60 70 80 lss I.. umber of users Fg. 2. A lms. Inegron clss I. nd I.2. 0.004 0.003 ew cll rrvl re: lss I. 20/80 clls/s. lss I. 20/80 clls/s. S A. Pce droppng. lss I.2 S A. Pce droppng. lss I. 0.002 20 28 36 44 52 60 68 ew ll Offered Trffc (Erl/cell.). lss II Fg. 3. Pce droppng probbly consderng n negron of rel me nd non rel me servces. Probbles 0 0 0 - ew cll rrvl re lss I. 30/80 clls/s. S A. Pb lss I. S A. Ploss lss I. S A. Pb lss I.2 S A. Ploss lss I.2 VR A. Pb lss I. VR A. Ploss lss I. VR A. Pb lss I.2 VR A. Ploss lss I.2 0-2 36/80 44/80 52/80 60/80 68/80 76/80 ew ll Arrvl re (clls/s.). lss I.2 Fg. 4. S vs VR A. ew cll blocng nd hndoff droppng probbly vs. offered rffc. Pce Droppng Probbly Pce Droppng Probbly ew cll rrvl re lss I. 30/80 clls/s. S A. Pce droppng. lss I.2 VR A. Pce Droppng. lss I.2 Fg. 6. S vs VR A. Pce droppng probbly consderng homogeneous () nd heerogeneous (b) rffc dsrbuon n cells. Probbles 0 0 0 - enrl cell. ew cll rrvl re lss I. 30/80 clls/s. lss I.2 46/80 clls/s. 0-2 S A. Pb lss I. S A. Ploss lss I. S A. Pb lss I.2 S A. Ploss lss I.2 VR A. Pb lss I. VR A. Ploss lss I. VR A. Pb lss I.2 VR A. Ploss lss I.2 0-3 0.6 0.7 0.8 0.9..2.3.4 Ro beween dycen nd cenrl cell new cll rrvl re Fg. 5. S vs VR A. ew cll blocng nd hndoff droppng probbly consderng heerogeneous rffc dsrbuon n cells. 36/80 44/80 52/80 60/80 68/80 76/80 0.45 ew ll Arrvl re (clls/s.). lss I.2 ) 0.4 enrl cell. ew cll rrvl re 0.35 mx (men). enrl ell. lss I. 30/80 clls/s. lss I.2 46/80 clls/s. consumed (men). enrl cell. efecve (men). enrl cell. 0.3 mx (men). Adjcen ell. consumed (men). Adjcen cell. S A. Pce droppng. lss I.2. enrl_cell S A. Pce droppng. lss I.2. Adjcen cells efecve (men). Adjcen cell. 0.004 VR A. Pce Droppng. lss I.2. enrl_cell 0.25 0.003 0.6 0.7 0.8 0.9..2.3.4 0.6 0.7 0.8 0.9..2.3.4 Ro beween dycen nd cenrl cell new cll rrvl re Ro beween dycen nd cenrl cell new cll rrvl re b) pcy 0.6 0.55 0.5 enrl cell. ew cll rrvl re lss I. 30/80 clls/s. lss I.2 46/80 clls/s. Fg.7. Dsrbuons of vlble nd consumed cpcy, consderng heerogeneous rffc dsrbuon n cells. Fg. 7 shows he evoluon of he vlble nd consumed cpcy n ddon o he effecve cpcy compued when heerogeneous rffc dsrbuon s consdered. oe h lhough mx cpcy s dfferen n cells, droppng probbly (Fg. 6b) chnges ccordng wh vlues shown n Fg. 7. Smlr resuls re obned when n negron of rel nd no rel me rffc s ssumed (Fg. 3 shows droppng probbly). Alhough resuls re no shown here, he evluon of he nerference levels shows h n nerference-bsed A n he wy of [] resuls n n underesmon of he cpcy. Inerference hreshold mus be se ccordng wh dely reuremens of MS nd dped o e no ccoun he me vrons on rffc sources dsrbuons. V. OLUSIOS In hs pper, we hve evlued he performnce of A mehod for he W-DMA reverse ln, where pce rnsmsson hs been consdered for rel me nd non rel me servces. A cenrlzed demnd ssgnmen proocol hs been mplemened n he pce level n order o provde QoS. Resuls obned from pce level provde useful nformon n order o nduce cpcy bound. Dely consrns ssoced o ndvdul rffc clsses re consdered n order o se n ccure hreshold of A. The resuls show h he proposed A hreshold gurnee sfe dmsson boh consderng unform or non-unform rffc dsrbuons n cells, gven h pce droppng probbly s lwys mnned under he QoS consrns. On he oher hnd, he proposed vrble reservon polcy gurnees QoS nd GoS. VI. AKOWLEDGMETS Ths wor hs been suppored by he grns IYT TI200-248 nd TI200-2222 from he Mnsry of Scence nd Technology of Spnsh Governmen nd FEDER. VII. 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