Efficient Interference Mitigation in mmwave Backhaul Network for High Data Rate 5G Wireless Communications

Transcription

1 I. J. Couicaios Newok ad Syse Scieces hp:// ISSN Olie: ISSN Pi: Efficie Iefeece Miigaio i Wave Backhaul Newok fo High Daa Rae 5G Wieless Couicaios Jia Shi 1 Qiag Ni 1 Claudio Paoloi 1 Facois Mage 1 Lacase Uivesiy Lacase UK Whe-AB S.A. Pais Face How o cie his pape: Shi J. Ni Q. Paoloi C. ad Mage F. (017) Efficie Iefeece Miigaio i Wave Backhaul Newok fo High Daa Rae 5G Wieless Couicaios. I. J. Couicaios Newok ad Syse Scieces hps://doi.og/10.436/ijcs b017 Received: Apil Acceped: May Published: May Aac This pape ivesigaes he pefoace of he W bad illiee wave (Wave) backhaul ewok poposed by ou EU TWEETHER pojec. We focus o he dowlik asissio of he Wave backhaul ewok i which each of he hu seves a cluse of base saios (BSs). I he cosideed backhaul ewok available fequecy esouces ae fis allocaed o he dowlik liks wih he cosideaio of faiess issue. I ode o iigae iefeece i he Wave backhaul ewok each opeaes he poposed algoih aely coopeaio ad powe adapaio (CPA). Ou siulaio esuls show ha he backhaul ewok wih Wave capabiliies ca achieve a sigifica bee houghpu pefoace ha he sub-6 GHz ula high fequecy (UHF) backhaul ewok. Fuheoe ou siulaios also eveal ha he poposed CPA algoih ca efficiely coba iefeece i he backhaul ewok. Keywods Wave Couicaio Backhaulig Iefeece Miigaio 1. Ioducio Tadiioal icowave based cellula ewoks ae facig oe ad oe challeges due o he expoeial gowh of daa affic. Shifig he couicaio specu fo adiioal icowave o illiee wave (Wave) is widely ecogized as oe of he bes aacive soluios o fuue wieless couicaio ewoks deadig high-volue capaciy. Moeove Wave sall cell ewoks have bee hough of as a poisig appoach o boos he coveage ad ae of fuue cellula ewoks [1]. Howeve i is ipoa ad challeg- DOI: /ijcs B017 May 6 017

2 J. Shi e al. ig o desig a backhaul ewok coecig o a explosive gowig ube of sall BSs. Wieless backhaul ewok wih Wave capabiliies ca be a poisig cadidae fo fuue wieless couicaio syses due o is advaages of high capaciy eegy efficie low asissio delay ad low cos ec. Mos of he wok abou Wave couicaio i he lieaue aily focuses o chael odelig [] [3] ad is applicabiliy fo idoo/oudoo evioe ove adiioal cellula ewoks i es of he coveage ad ae pobabiliies [4]. By coas liied sudies such as [5] [6] [7] [8] have ivesigaed Wave backhaul ewoks. The auhos i [5] [6] have sudied he esouce allocaio i heeogeeous backhaul ewok which cosiss of boh wied fibe ad Wave wieless couicaios. I [6] he auhos have ivesigaed he heeogeeous backhaul ewok s pefoace i es of packe delay ad have also show he ew backhaul echologies ove he adiioal wied oly echologies. Recely he auhos i [5] have sudied joi schedulig of adio access ad Wave ad fibe backhaul i hybid heeogeeous ewok wih he capabiliies of device-o-device asissios. By coas he auhos i [7] [8] have ivesigaed Wave oly backhaul ewoks. I [7] hey have oly addessed eegy cosupio issue fo a eewable eegy poweed Wave backhaul ewok ad a Sackelbeg gae based picig schee is poposed o aage he affic laecy ove he backhaul ewok. Massive MIMO aided Wave backhaul ewok has bee addessed i [8] whee he hybid pecedig ad cobiig schee is poposed. Agais his backgoud i his pape we ivesigae he pefoace of he W bad Wave backhaul ewok poposed by ou EU TWEETHER pojec [9] [10]. We focus o he dowlik asissio of he Wave backhaul ewok i which each of he hu seves a cluse of base saios (BSs). I he cosideed backhaul ewok he available fequecy esouces ae allocaed o he dowlik liks based o he geedy algoih wih he cosideaio of faiess issue. I ode o iigae iefeece i he Wave backhaul ewok each opeaes he poposed algoih aely coopeaio ad powe adapaio (CPA). The poposed CPA algoih ca se up coopeaive asissios fo he poo liks; eawhile i also uilizes he saegy of powe adapaio o educe he sog iefeece geeaed by he liks. A age of siulaio esuls icludig he ouage pobabiliy ad su ae ae povided o evaluae he pefoace of he Wave backhaul ewok. Ou siulaio esuls show ha ou backhaul ewok wih Wave capabiliies ca sigificaly oupefo he sub-6 GHz ula high fequecy (UHF) backhaul ewok i es of he ouage pobabiliy pefoace. Fuheoe ou siulaios also eveal ha he poposed CPA algoih ca efficiely coba iefeece i he backhaul ewok. The es of he pape is ogaized as follows. Secio povides he syse odel ad saes he ai assupios. Secio 3 descibes he subbad allocaio ehod. Secio 4 poposes he iefeece iigaio schees. Secio 5 171

3 J. Shi e al. deosaes he pefoace esuls. Fially Secio 6 suaizes he coclusios.. Syse Models Ou pojec aely EU TWEETHER poposes ovel W bad Wave based heeogeeous wieless ewoks wih high daa ae disibuio specu- ad eegy-efficiecy. The cocepual sucue of he poposed ewok is show i Figue 1. The ewok odel poposed by EU TWEETHER cosiss of hee ies which ae ifasucue ie backhaul ie ad access ie. Moe specifically i ifasucue ie we ca se up seveal eabis daa liks via fibe opics fo he couicaios bewee he daa cees ad he poi of peseces (PoP) odes ove hudeds of kiloees. I backhaul ie he W bad Wave backhaul liks ae esablished fo he couicaio bewee he PoP odes ad uliple BSs i access ie. Fially access ie suppos he couicaio fo BSs o use eials whee we apply sub-6ghz UHF couicaio liks. I his pape we will focus o ivesigaig he achievable ae pefoace of he Wave backhaul ie poposed by ou EU TWEETHER pojec. I his pape we coside he dowlik asissio of he Wave backhaul ewok which cosiss of N hu ad N BSs. I ode o capue he ai chaaceisics of he ewok poposed by ou EU TWEETHER pojec we assue ha ay wo hu ae sepaaed by a disace of d0 3 k ad he N BSs ae uifoly disibued i he ewok. Fuheoe we also assue ha he disace of a backhaul lik is i he age of 1k d1 k ad ay wo BSs ae sepaaed by a disace of d 0.6 k. The Wave backhaul asissios i he ewok expeiece boh he pahloss effecs ad he sall-scale fadig. To odel pahloss effecs icludig shadowig fo a Wave lik we eploy he odel of [11] ρ + 10αLlog( d) + χl if LoS LdB ( d) = (1) ρ + 10αN + χn if NLoS whee 4π ρ = 0log( ). () f c A Wave couicaio lik is assued o be o-lie-of-sigh (NLoS) if he lie sege joiig he Wave BS ad he use is blocked by buildigs. Ohewise he lik is hough of as lie-of-sigh (LoS). I () f c is he ca- Figue 1. Cocepual ewok sucue poposed by EU TWEETHER pojec. 17

4 J. Shi e al. ie fequecy a he Wave fequecy bad ad d epeses he disace of a lik. Fuheoe α L ad α N ae he pahloss expoes fo LoS ad NLoS cases especively. χ L ad χ N ae shadowig effecs which ae assued o follow zeo ea log oal disibuio. We defie he LoS pobabiliy of a Wave lik as PL ( d ) which is a deceasig fucio of he legh of he couicaio lik ad hece he NLoS pobabiliy of a Wave lik is PN( d) = 1 PL( d). Whe a lik becoes loge i has a highe pobabiliy of beig a NLoS lik. Noe ha he pobabiliy PL ( d ) ca be chaaceized by blockage odels accodig o vaious couicaio evioes. Fo he sake of heoeical sudy we deploy he secoed aea odel o chaaceize he pacical aay paes. Le us deoe gm ( θ φ ) ad gm ( θ φ ) as he secoed aea paes fo a ad a BS especively. M M ae he ai lobe dieciviy gais ad ae he back lobe dieciviy gais while θ θ ae he beawidhs of he aeas. Le he boe sigh diecios be φ ad φ which ae assued o be 0. Fo sipliciy we assue he aea gai fo a desied sigal lik is G= MM. Howeve each lik ay also have soe iefeece liks ad he aea gai fo a iefeece lik is deoed as G which ca be give by θθ MM wih pobabiliy p= 4π (1 θ) θ M wih pobabiliy p= 4 G π = (3) θ(1 θ) M wih pobabiliy p= 4π (1 θ)(1 θ) wih pobabiliy p=. 4π I (3) we assue he beawidh of a aea such as θ θ ae idepedely ad uifoly disibued i (0 π ]. I ou Wave backhaul ewok each is able o asi ifoaio o is sevig BSs by usig all specu of B Hz available i W bad. Fuheoe we assue a couicaes wih is sevig BSs based o ohogoal fequecy divisio uliplexig (OFDM) eployig M subbads. Hece i he dowlik asissio of he backhaul ewok he achievable ae of a BS seved by is o a subbad ca be wie as ( γ ) R = b log 1 + j. (4) I (4) b is he badwidh of subbad. We defie = {1 N} ( ) icludes he idexes of hu. j coais he idexes of he BSs seved by j hece we have N j =. icludes he idexes of M subbads available i he ewok. I (4) ( j γ ) is he sigal-o-iefeeceplus-oise ae (SINR) of BS seved by j o subbad ad i is defied by γ P G ( L ) h. 1 = I + bσ (5) 173

5 J. Shi e al. I (5) P is he asissio powe of j o subbad ad he asissio powe fo all subchaels ae assued o be he sae. I addiio o he lage-scale fadig effec each couicaio lik also expeieces he sall-scale fadig such as ( j h ) which is he idepede Rayleigh fadig chael bewee j ad BS o subbad. Fuheoe we assue ha all he couicaio liks have he sae oise powe which is deoed by σ i (5). Noe ha I i (5) is he iefeece powe ha suffeed by he asissio fo j o BS. I he cosideed Wave backhaul ewok each fis eeds o assig he available specu esouce o he is sevig BSs i ohe wod each is equied o allocae he M ube of subbads available o is BSs. Howeve he asissios i he ewok will suffe fo he iefeece geeaed by hei co-subbad liks. Theefoe afe subbad allocaio we opeae he poposed iefeece iigaio algoih fo he liks suffeig sog iefeece i ode o ipove he ewok s houghpu pefoace. Le us ow fis discuss he subbad allocaio. 3. Subbad Allocaio As eioed i Secio a is assued o eploy all he available fequecy bads o couicae wih is sevig BSs based o OFDM schee. Theefoe j eeds o allocae M subbads o is ube of BSs aiig o axiize he su ae of he backhaul liks. I ode o achieve he bes ade-off bewee he pefoace ad ipleeaio coplexiy each eploys he geedy algoih fo subbad allocaio. I his pape fo sipliciy ad wihou loss of geealiy he ube of subbads available is lage ha he ube of BSs seved by each i.e. M j. Based o he geedy algoih each allocaes he M subbads i M ieaios i which duig each a ieaio he bes available subbad is assiged. Meawhile o achieve he bes faiess of allocaio ou allocaio oivaes o allocae each BS he sae ube of subbads. I his case he subbad allocaio duig a ieaio ca be descibed as (6) P G h = ax ˆ ( j ) L bσ ( ) whee j icludes he idexes of he subbads assiged o BS seved by ( ) j. ˆ j coais he idexes of he BSs havig he leas ube of subbads assiged. I his way ou subbad allocaio ca esue he bes faiess i es of allocaio. Afe he subbad allocaio he liks usig he sae subbad will cause iefeece o each ohe. Hece he SINR of a couicaio lik such as he SINR i (5) fo BS of j o subbad becoes γ P G ( L ) h P G ( L ) h 1 1 = = ( u) ( u) ( u) 1 ( u) ( u) P G ( L ) h + bσ I + bσ u u j u u j (7) (8) 174

6 J. Shi e al. ( ) whee G u is give i (3). Kow fo (8) he hough-pu pefoace of he ewok ay be sigificaly degaded by a couicaio lik expeiecig sog iefeece. To ipove he ewok s pefoace we eed o opeae iefeece iigaio o eove sog iefeece. 4. Iefeece Miigaio Fo he sake of ipovig houghpu pefoace of ou Wave backhaul ewok i his secio we popose a ovel iefeece iigaio schee aely coopeaio ad powe adapaio (CPA). Afe he subbad allocaio discussed i Secio 3 a desied couicaio lik ay suffe fo sog iefeece iposed by ohe liks usig he sae subbad. Hece he CPA algoih is opeaed fo he poo liks which eihe expeiece sog iefeece fo hei co-subbad liks o geeaig sog iefeece o hei co-subbad liks. Le us deoe he se of he poo backhaul couicaio liks o subbad as Φ give by Φ =Φˆ Φ (9) Φ ˆ = { η < η j } (10) Φ = { Φ } (11) ˆ j whee η is he sigal-o-iefeece (SIR) heshold. I (9)-(11) η is he SIR of he lik ad i ca be wie as η P ( L ) h 1 = ( u) I u u j (1) ( u) whee I is give i (8). The poposed CPA algoih uilizes BS coopeaio o iigae iefeece i he backhaul ewok i which he space ie block codig (STBC) aided coopeaive asissio ca be esablished fo he poo liks. Whe he coopeaio fo he asissio o BS is se up by j ad q he SINR i (8) fo he lik becoes γ P ( L ) h + I 1 ( q) = ( u) I + bσ q u j q. (13) Kow fo (13) he achievable daa ae of BS ca be sigificaly ipoved whe he iefeece I iposed by q is sog. I addiio o ( q) coopeaio ou CPA algoih also eploys he saegy of powe adapaio. I ha case if a lik suffes fo sog iefeece a ay educe he asi powe fo he liks while guaaeeig he iiu sevice qualiy of he lik ove a age of a leas 1 k. By doig his he liks poweed dow will o cause sog iefeece o ohe liks ad hece he su ae of he backhaul ewok will be ipoved. I his pape ou CPA algoih ais o axiize he su ae of he poo liks which ca be expessed as 175

7 J. Shi e al. whee { } s j = ag ax R (14) j Φ = s j coais he iefeece iigaio saegies. Specifically ( ) = eas j asis ifoaio wih he powe P o BS o subbad. By coas ( j ) s = 0 eas ha j asis ifoaio o BS o subbad wih he educed powe β P whee 0 β 1. Noe ha he value of β is elaed o he iiu daa ae equiee ad he iiu asissio age which ca be se up accodig o ewok equiees. Fuheoe i ode o iiize he sigalig bude he hu ae oly equied o exchage biay iefeece ifoaio. Fo ( q) exaple he biay iefeece ifoaio fo I i (13) ca be defied by: ˆ ( q) I 1 = (sog iefeece) if ( q I ) > I ohewise ˆ ( q I ) = 0 (sall iefeece) whee I is he iefeece heshold. Based o he opiizaio poble i (14) he piciples of ou CPA algoih ca be give as follows. 5. Pefoace Resuls I his secio we povide a age of siulaio esuls fo deosaig he achievable pefoace icludig he ouage pobabiliy ad su ae of ou backhaul ewok wih he aid of W bad Wave couicaio. Specifically we also evaluae he pefoace of he poposed CPA algoih i es of iigaig iefeece i he ewok. Fo he sake of heoeical sudy we assue ha hee ae N = 3 hu i he ewok ad fo all siulaios he ube of subbads is M = N /3. Fuheoe we assue ha he oise powe of each lik is assued o be he sae which is σ. The ohe siulaio paaees ae suaized i Table 1. I Figue we ivesigae he ouage pobabiliy pefoace of he Wave backhaul (BH) ewok which is copaed wih he pefoace of he sub-6 GHz UHF oly backhaul ewok. The ouage pobabiliy is defied as he pobabiliy ha he liks i he ewok achieve he daa aes below he iiu ae equiee R τ. Fo he UHF oly backhaul ewok we assue ha he available badwidh is B = 0 MHz ad he caie fequecy is f c =.4 GHz. Wihou loss of geealiy he ohe assupios ae he sae as hose fo he Wave backhaul ewok. Oeved fo Figue he Table 1. Siulaio paaees fo Wave backhaul ewok. Paaee Value Paaee Value B 1 GHz σ 174 db/hz f c 94 GHz P 46 db ( j ) M 10 db M 10 db 10 db 10 db α L.09 α N 3.34 Sd ( χ L ) 5.0 db Sd ( χ N ) 7.6 db 176

8 J. Shi e al. Wave backhaul ewok ca sigificaly oupefo he UHF ewok i all diffee iiu ae equiee sceaios. As show wih he aid of he poposed CPA algoih he Wave backhaul ewok ca achieve a bee ouage pobabiliy pefoace ad a bigge pefoace gap ca be oeved i he age of 0.1GHz R τ 1GHz. Fuheoe whe he SIR heshold η ges highe he CPA algoih ca assis he ewok o achieve a highe pefoace. This is because he CPA algoih opeaes iefeece iigaio fo a lage ube of couicaio liks i he ewok. I Figue 3 we show he ouage pobabiliy of he Wave backhaul ewok wih ad wihou eployig he poposed CPA algoih whe cosideig he diffee BS desiies. Fis of all we ca see ha whe he ube of BSs ges bigge he ouage pobabiliy of he ewok ges highe. This oevaio iplies ha he backhaul couicaio liks have highe pobabiliies of expeiecig sog iefeece as he desiy of BSs seved by he ewok iceases. Secod ou poposed CPA algoih ca sigificaly faciliae he ewok by efficiely iigaig iefeece. The pefoace gai of eployig he CPA says oughly he sae fo all diffee BS desiy sceaios. A las oce agai we oeve ha he ouage pobabiliy becoes salle as he SIR heshold ges bigge i which oe liks ae beefied fo he CPA algoih. Fially Figue 4 shows he effec of he hesholds η ad I o he pefoace of he CPA algoih. I he figue we oce oe shows he sigifica pefoace ipovee of he Wave backhaul ewok by usig he CPA o coba iefeece. As show he su ae of he poo liks iceases as he SIR heshold η o he iefeece heshold I iceases. This is because he CPA opeaes iefeece iigaio fo oe ube of he poo liks as he ube of he poo liks iceases. Howeve i his case i also Figue. Ouage pobabiliy of he backhaul ewoks whe eployig vaious values of R τ 177

9 J. Shi e al. equies highe ipleeaio coplexiy ad cos. Theefoe i is ipoa o choose pope SIR ad ICI hesholds by joily cosideig he syse equiee ipleeaio coplexiy as well as desiable pefoace. Fo Figue 3 ad Figue 4 we ca coclude ha he poposed CPA algoih ca faciliae ou Wave back-haul ewok o achieve a bee pefoace. Figue 3. Ouage pobabiliy of he W bad Wave backhaul ewoks havig diffee desiies of BSs whe assuig 0.3 R τ = Gbps. Figue 4. Su ae of he poo liks i he W bad Wave backhaul ewok eployig he CPA algoih ude he vaious SIR heshold η ad ICI heshold I. 178

10 J. Shi e al. 6. Coclusio I his pape we have ivesigaed he pefoace of he W bad Wave backhaul ewok poposed by ou EU TWEETHER pojec. I ode o ipove he ewok s houghpu pefoace we have poposed he CPA algoih o iigae iefeece i he Wave backhaul ewok. Whe he CPA algoih is eployed he hu ae allowed o se up coopeaive asissios fo he poo liks aleaively he hu ae equied o educe he asissio powe fo soe liks ha geeae sog iefeece o ohe liks. We have povided a age of siulaio esuls icludig he ouage pobabiliy ad su ae of he backhaul ewok. Ou siulaios have show ha ou Wave backhaul ewok ca sigificaly oupefo he UHF backhaul ewok. Fuheoe ou siulaios have also iplied ha he poposed CPA algoih ca efficiely coba iefeece so ha he backhaul ewok achieves a clea bee pefoace. We coclude ha he poposed CPA algoih ca be hough of as a poisig soluio fo iefeece iigaio i ou Wave backhaul ewok. Ackowledgees This wok is suppoed by EU H00 TWEETHER pojec ude ga ageee ube Refeeces [1] Gillo G. Adews J. Buzzi S. Choi W. Haly S. Lozao A. Soog A. ad Zhag J. (014) Wha Will 5G Be? IEEE J. Sel. Aeas Cou hps://doi.og/ /jsac [] Rappapo T. e al. (013) Milliee Wave Mobile Couicaios fo 5G Cellula: I Will Wok! IEEE Access hps://doi.og/ /access [3] Raga S. Rappapo T.S. ad Ekip E. (014) Miliee-Wave Cellula Wieless Newoks: Poeials ad Challeges. Poceedigs of he IEEE hps://doi.og/ /jproc [4] Bai T. ad Heah R. (015) Coveage ad Rae Aalysis fo Milliee-Wave Cellula Newoks. IEEE Tas. Wieless Cou hps://doi.og/ /twc [5] Niu Y. Gao C. Li Y. Su L. Ji D. ad Vasilakos A.V. (015) Exploiig Device-o-Device Couicaios i Joi Schedulig of Access ad Backhaul fo Wave Sall Cells. IEEE J. Sel. Aeas Cou hps://doi.og/ /twc [6] Zhag G. Quek T.Q.S. Kououis M. Huag A. ad Sha H. (016) Fudaeals of Heeogeeous Backhaul Desig Aalysis ad Opiizaio. IEEE Tas. Cou hps://doi.og/ /tcomm [7] Li D. Saad W. ad Hog C.S. (016) Decealized Reewable Eegy Picig ad Allocaio fo Milliee Wave Cellula Backhaul. IEEE J. Sel. Aeas Cou hps://doi.og/ /jsac [8] Gao Z. Dai L. Mi D. Wag Z. Ia M.A. ad Shaki M.Z. (015) MWave Massive-MIMO-Based Wieless Backhaul fo he 5G Ula-Dese Newok. IEEE 179

11 J. Shi e al. Wieless Couicaios hps://doi.og/ /mwc [9] EU TWEETHER Pojec Weie. hps://weehe.eu/ [10] Paoloi C. Leizia R. Napoli F. Ni Q. Reie A. Ziea R. Ade F. Pha K. Koze V. Mage F. Buciu I. Raiez A. Rocchi M. Mailie M. ad Vila R. (015) Hoizo 00 TWEETHER Pojec fo W-Bad High Daa Rae Wieless Couicaios. IEEE 16h Ieaioal Vacuu Elecoics Cofeece (IVEC 015) Apil 015. hps://doi.og/ /ivec [11] Xu X. Saad W. Zhag X. Xu X. ad Zhou S. (015) Joi Deploye of Sall Cells ad Wieless Backhaul Liks i Nex-Geeaio Newoks. IEEE Couicaios Lees hps://doi.og/ /lcomm Subi o ecoed ex auscip o SCIRP ad we will povide bes sevice fo you: Accepig pe-subissio iquiies hough Eail Facebook LikedI Twie ec. A wide selecio of jouals (iclusive of 9 subjecs oe ha 00 jouals) Povidig 4-hou high-qualiy sevice Use-fiedly olie subissio syse Fai ad swif pee-eview syse Efficie ypeseig ad poofeadig pocedue Display of he esul of dowloads ad visis as well as he ube of cied aicles Maxiu disseiaio of you eseach wok Subi you auscip a: hp://papesubissio.scip.og/ O coac ijcs@scip.og 180