On the High Altitude Platform (HAP) W-CDMA System Capacity

Transcription

1 36 B. AHA-AHMED, M. ALVO-AMÓN, L. DE HAO-AE, ON HE HGH ALUDE LAFOM (HA... On the High Altitde latfom (HA W-DMA System aacity Bazil AHA-AHMED, Migel ALVO-AMÓN, Leando de HAO-AE Deatamento Sistemas, Señales y adiocomnicaciones, ES elecomnicación, Univesidad olitécnica de Madid, idad Univesitaia, Madid, 84, Sain bazil@g.ss.m.es Abstact. he efomance of a downlink owe contol model, based on a n-th owe distance law, is evalated fo high altitde latfom station (HAS W-DMA systems. he downlink caacity sing this model is comaed with the link caacity. t is shown that the link caacity is highe than the downlink caacity. Keywods Downlink caacity, link caacity, HAS, owe contol, WDMA. on an n-th exonent of mobile s distance fom the cente of its seving cell was stdied in [] and sed to analyze the fowad link caacity of high altitde latfom W-DMA system in [3] (fo voice sevice only. he dawback of the above mentioned n-th owe of distance owe contol scheme is that it is sitable only fo envionments with low othogonality facto between the ses (φ. that is not the eal case fo the HAs W-DMA system in which φ anges fom.4 to.6 in actice. Fo that eason we oose hee an imoved fom of the above mentioned owe contol scheme. HAS Antenna adiation atten Antenna elative gain [db]. ntodction hee is an insatiable demand fo commnications sevices thoghot the wold, diven lagely by the need fo ntenet access. Wieless offes the only viable ovision means in many scenaios, bt both teestial and satellite systems sffe fom fndamental limitations in cost and caacity. One otential delivey method is fom High Altitde latfoms (HAs, which ae ilotless solaoweed aishis o aicaft oeating at an altitde of to 5 km. A HA may be viewed as eithe a vey tall adio mast o a vey low stationay satellite, and can offe commnications sevices with the best feates of both. Aishi technology is develoing steadily, with commecial alications becoming moe of a eality. Wieless commnication fom HAs offes consideable otential fo new boadband sevices, fo mobile hones and fo niche makets sch as disaste elief o militay whee aid deloyment is a key feate. Wieless commnications sing HAS have been oosed wold wide de to the many advantage of HAS system ove teestial towe-based and satellite systems []. ecently it has been acceted to se HAS as an altenative means to delive the thid geneation M- wieless sevices. Fowad link owe contol is sed in cellla W- DMA systems to edce the intefeence to the othe neighboing cells and incease system caacity. he efomance of a distance based owe contol scheme based Angle of boesight [degees] Fig.. he antenna adiation atten. n this wok, we se the imoved n-th owe of distance owe contol scheme to calclate the HAS downlink caacity of a W-DMA sing the methodology given in [3] and then we comae it with the link caacity.. HAs Downlink owe ontol Model A HAs caying a W-DMA commnication ayload and a mlti-beam hased aay antenna with beam/ gain shaing caability ositioned at altitde (h of km was oosed in [3]. he antenna adiation atten and the geomety of the HAS fowad link intefeence ae deicted in Fig. and Fig., esectively. A se in the HAS sevice aea will exeience intacellla intefeence fom its seving beam ses and inte-

2 ADOENGNEENG, VOL. 3, NO., JUNE 4 37 cellla intefeence fom the adacent beams ses. Let (, q be the coodinates of the mobile with esect to the cente of the cell oected by its seving beam. f, new a + n + b + n + n +. + (6 Fig.. HAS down link intefeence geomety. Using downlink owe contol, the owe tansmitted to a mobile located at distance is given by: f t, ( whee is the efeence owe level assigned to the se located at. he new owe ofile f new ( is given as [4]: f new a + b n n n fo fo >, whee n >, a and b ae the owe contol scheme aametes sch that a + b, and is the distance at which the owe contol scheme changes the law of the owe contol. he ses density ρ, assming a nifom distibtion of N ses in the cell, is ( 3. Downlink aacity Let BS (,, J denote the base station seving the -th cell, as shown in Fig.. Fo a mobile located at (, q in the efeence cell seved by BS, the caie-tointefeence atio (/ is given by G ch t ( G( ψ J ( ψ l ζ ( φ + G( ψ l l ζ ζ β, (7 whee ch is the owe assignment fo the ses channels cca.8, l and l ae the distances fom the mobile to BS and BS esectively, ζ and ζ denote the shadowing coesonding to these two aths, α is the ath loss exonent eqal, G( ψ and G( ψ ae the nomalized antenna gains evalated at the angles nde which the mobile is seen fom the antenna boesights of BS and BS esectively, β is the voice activity facto.5, φ is the othogonality facto. De to the niqe HAS geomety, the tansmit antenna beams of all base stations essentially oiginate fom the same oint [3], so l l and ζ ζ (qasi total coelation. Now the caie to intefeence atio (/ can be given as: whee γ ( / (, t β, (8 γ (, J ( φ G( ψ + G( ψ. (9 Sbstitting fo we get ρ N π. (3 t ( he total owe tansmitted by the base station is whee N π π d θ f d f N π d N π f, (5 π G ( ψ [ N( f ] γ (, / β, ( (4 f / β, ( N f γ, θ ( ( [ ] ( f ( / β [ N( f ] γ (,, ( whee N( is the downlink se caacity ofile.

3 38 B. AHA-AHMED, M. ALVO-AMÓN, L. DE HAO-AE, ON HE HGH ALUDE LAFOM (HA... Now the atio (E b /N is given by E N b G, (3 whee G is the W-DMA ocessing gain. Fom (, G f / β [ N( f ] γ (, inte inte J π G( ψ, G( ψ d dθ α S N, ( π α S N F F. (3 Eb. (4 4.3 Ulink otal ntefeence N he link total intefeence t is given by: Fom this eqation, the downlink caacity ofile N( at the distance is given as: N G f / β. (5 [ E N ] [ f ] γ (, b eq he downlink caacity ( down is given by: down [ N( ] min. (6 A comte ogam has been sed to evalate the otimm vales of a, b, n, n and. 4. HA Ulink aacity t inta ( F inta +. (4 he (/ is given by: [ ] S t. (5 he atio (E b /N is given by: [ E b N ] G [ ]. (6 5. Nmeical eslts n this section we will stdy the link caacity as a fnction of the cell adis. G 5.6, (E b /N eq 7 db, α ntacellla ntefeence Assming that the owe level of the desied signal is S, the intacellla intefeence inta is given by: α ( N S. (7 inta 4. ntecellla ntefeence We will assme that ( i, denotes the i-th mobile at the -th cell and that the beam B is the beam that seves the mobile ( i,. he mobile ( i, is at a distance i, fom the cente of the cell nde stdy. he tansmitted owe of the mobile ( i, is given by: 5 ζ G( ψ S, Sl. (8 he intefeence odced by the mobile ( i, is given by: B 5 ζ, ζ G( ψ, G( ψ l S, (9 l, G( ψ, G( ψ B S. ( We assme a latfom altitde of h.5 km, cells adis of km and a continos owe contol. We fist stdy the case of voice only ses assming that: We begin with the case φ. Fig. 3 shows N( fo the following obtained otimm vales: n.8, /.75, n 6 and a.7. As can be seen the caacity e beam is of 5 ses. N( Θ 3 degee Θ degee / [%] Fig. 3. HAS down link caacity ofile against nomalized distance fom cell cente fo voice ses (φ. Next we stdy the case φ.5, which is the actical case. Fig. 4 shows N( fo the following obtained otimm vales: n 3, /.9, n 6 and a.8. he downlink caacity e beam is now 7 ses. he intecellla intefeence inte de to the J cells nea the cell nde consideation is given by: Using the evios set of aametes n, /, n and a, inte J G( ψ, G( ψ α S N da, ( A we stdy now the case of data only ses assming the following tyical vales: G 6.6,

4 ADOENGNEENG, VOL. 3, NO., JUNE 4 39 (E b /N eq 3 db, α. Fom Fig. 5, we can notice that the downlink caacity is 9 data ses e beam. fo an othogonality facto of.5, wold be of aond 55 voice ses, o 7 data ses, e cell (beam. Fo a HAS system with 9 beams the total actical caacity of the system wold be in the ode of 45 voice ses o 33 data ses. N( 9 Θ 3 degee Θ degee he facto F / [%] Fig. 4. HAS down link caacity ofile against nomalized distance fom cell cente fo voice ses (φ.5. N( 3 Θ 3 degee Θ degee Fig. 6. he facto F as a fnction of. aacity [ses/cell] 9 9 [m] / [%] [m] Fig. 5. HAS down link caacity ofile against nomalized distance fom cell cente fo data ses (φ.5. Fo the link we will assme the same vales sed fo the downlink of G, (E b /N eq and α fo voice and data sevices. Fig. 6 shows the F facto as a fnction of the cell adis. We can notice that the F facto edces with the incement of the cell adis. alclations have been done assming that the nmbe J of cells that odces the intecellla intefeence is 8 ( ties. Fig. 7 shows the link caacity as a fnction of the cell adis fo voice sevice. t can be noticed that the caacity inceases with the cell adis. Fo m (tyical cell adis fo ove-cities HAs systems, the link caacity is 89 voice ses e beam. hs, the caacity fo the link is highe than fo the downlink. Fig. 8 shows the link caacity as a fnction of fo data sevice. t can be noticed that the caacity inceases with the cell adis. Fo m, the link caacity is data ses e beam. Again, the caacity fo the link is highe than fo the downlink. n actical systems the owe contol is imefect. he actical caacity of the HA system consideed hee, Fig. 7. he link caacity as a fnction of (voice ses. aacity [ses/cell] [m] Fig. 8. he link caacity as a fnction of (data ses. 6. onclsions n this wok, the efomance of a modified n-th owe distance based downlink owe contol model is evalated fo high altitde latfom stations (HAS W-DMA systems. he downlink caacity has been comaed with the link caacity. t has been shown that the downlink caacity is lowe than the link caacity. he downlink

5 4 B. AHA-AHMED, M. ALVO-AMÓN, L. DE HAO-AE, ON HE HGH ALUDE LAFOM (HA... system caacity fo an othogonality facto of.5 is in the ode of 7 voice ses e cell o 9 data ses e cell while the link caacity is of 89 voice ses e cell o data ses e cell. efeences [] DJUNN, G. M., FEDENFELDS, J. Establishing wieless commnications sevices via high-altitde aeonatical latfoms: a concet whose time has come? EEE ommnication Magazine. 997, no. 9, [] GEJJ,.. Fowad-link owe contol in DMA cellla systems. EEE ansactions on Vehicla echnology. 99, vol. 4, no., [3] FOO, Y.., LM, W. L., AFAZOLL,., BALAY, L. W. Fowad link owe contol fo high altitde latfom stations W-DMA system. n oceedings of the 54 th Vehicla echnology onfeence Fall., [4] AHA-AHMED, B., ALVO-AMÓN, M., HAO-AE, L. On the downlink caacity of high altitde latfom W-DMA system. n oceedings of S 3. Avieo (otgal 3, Abot Athos... Bazil AHA-AHMED was bon in Mosl, aq, in 96. He eceived the B.Sc. and M.Sc. degees in telecommnication engineeing fom the Univesity of Mosl, in 98 and 985, esectively. He got the h. D degee in telecommnication engineeing fom the olytechnic Univesity of Madid in 3. Fom 985 to 998, he was teaching at the Electical Engineeing Deatment at Mosl Univesity. Bazil has blished moe than 3 scientific onal and confeence aes in the aea of the electomagnetic oagation and DMA systems, aticlaly the DMA caacity. His eseach inteests incldes DMA caacity and E. M. Wave oagation in mico-cellla and macocellla envionments. Migel ALVO-AMON was bon in eyo de Jaca, Hesca, Sain on Jne, 949. He got the ngenieo de elecomnicación degee fom the Escela écnica Seio de ngenieos de elecomnicación of the Univesidad olitécnica de Madid in 974 and the Docto ngenieo de elecomnicación degee fom the same Univesity in 979. He woks as ofesso in the Señales Sistemas y adiocomnicaciones (Signals, Systems and adiocommnications deatment whee he obtained the atedático (Fll ofesso osition in 986. Leando de HAO-AE was bon in Bacelona, Sain, on May 7, 96. He got the ngenieo de elecomnicación degee in 986 and the Docto ngenieo de elecomnicación degee (Ato cm lade in 99 both fom the Escela écnica Seio de ngenieos de elecomnicación of the Univesidad olitécnica de Madid (Det. of Señales, Sistemas y adiocomnicaciones. Since 99 he develos his ofessional caee in the E..S. ngenieos de elecomnicación of the Univesidad olitécnica de Madid (Det. of "Señales, Sistemas y adiocomnicaciones" as Assistant ofesso on the Signal heoy and ommnications aea. ADOENGNEENG EVEWES Jne 4, Volme 3, Nmbe DÝMAL,., Bno Univesity of echnology, Bno FALA,., Bno Univesity of echnology, Bno HAJAH,., Slovak Univ. of echnology, Batislava HALÁMEK, J., zech Academy of Sciences, Bno HANUS, S., Bno Univesity of echnology, Bno HAŤANSKÝ,., Univesity of enčín, enčín KOLOUH, J., Bno Univesity of echnology, Bno KUY, J., Militay Academy, Litovský Mikláš LAE, M., zech echnical Univesity, age MAHO, M., Militay echnical nstitte, Bno NOVÁČEK, Z., Bno Univ. of echnology, Bno EHAČ,., zech echnical Univesity, age OLÍVKA, J., zech echnical Univesity, age UNČOHÁŘ, J., VŠB-echnical Univ., Ostava ADA, Z., Bno Univesity of echnology, Bno SHEJBAL, V., Univesity of adbice, adbice SMÉKAL, Z., Bno Univesity of echnology, Bno SOVKA,., zech echnical Univesity, age ŠEBESA, V., Bno Univesity of echnology, Bno