Average Symbol Error Rate of Maximal Ratio Combining Scheme in the Presence of Multiple Cochannel Interferers

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1 38 ECTI TRASACTIOS O EECTRICA EG. EECTROICS AD COUICATIOS VO. O. AUGUST 3 Avrag Symbol Error Rat of axmal Rato Combnng Schm n th rsnc of ultl Cochannl Intrfrrs Chrasl Chayawan* and Valntn A. Aalo** *Dartmnt of Elctroncs and Tlcommuncaton Engnrng Kng ongut s Unvrsty of Tchnology Thonbur Bango 4 Thaland **Dartmnt of Elctrcal Engnrng Florda Atlantc Unvrsty Boca Raton F 3343 Emal: *chrasl.cha@mutt.ac.th **aalo@fau.du ABSTRACT Th rformanc of dgtal cllular rado systms wth maxmal rato combnng (RC dvrsty s analyd n a flat-fadng channl wth cochannl ntrfrnc and addtv wht Gaussan nos (AWG. It s assumd that th dsrd sgnal may xrnc Rc fadng whl th Raylgh-fadd ntrfrrs may hav smlar or dssmlar avrag man owrs. Closd-form xrssons ar drvd for th avrag rror robablty n th rsnc of multl ndndnt Raylgh-fadd ntrfrrs. Both bnary and -ary lnar modulaton schms ar consdrd. Th analyss s also xtndd to th cas whn th dsrd sgnal has a Rc dstrbuton. Kywords: Cochannl Intrfrnc axmal Rato Combnng Raylgh Fadng Rc Fadng. ITRODUCTIO ultath fadng and cochannl ntrfrnc ar th maor sourcs of rformanc marmnt n wrlss communcaton systms. It s wll nown that antnna dvrsty can sgnfcantly mrov th caacty of many dgtal cllular rado systms by combatng multath fadng and rducng th ffct of cochannl ntrfrnc. In a systm wth otmum dvrsty combnng th sgnals rcvd by svral antnna lmnts can b rorly wghtd and combnd to maxm th outut sgnal-to-ntrfrnc-lus-nos rato (SIR []. Howvr th mlmntaton and rformanc analyss of th otmum combnr (OC rqur channl stmaton for th dsrd sgnal as wll as for all th ntrfrng sgnals whch ar usually qut comlcatd. Whl maxmal rato combnng (RC whch n ractc maxms th outut sgnal-to-nos rato (SR and s subotmal n th rsnc of cochannl ntrfrnc s usually mloyd nstad [] [3]. In many mobl rado systms th assumton of Raylgh fadng channl s usually assumd to modl th channl charactrstcs of both dsrd and ntrfrrng sgnals snc th dstanc btwn mobl and th bas staton s usually random and long nough for th ln of CR3: anuscrt rcvd on Fbruary 3; rvsd on August 3 3. sght (OS comonnt of th dsrd sgnal to b nglctd. Both dsrd and ntrfrng sgnals thrfor xrnc d fadng from mobl unt to th bas staton [] [4] [5]. On th othr hand n mcrocllular mobl rado systms scally n an ndoor nvronmnt th dstanc of dsrd sgnal from th bas staton s usually not far nough to nglct th ln of sght (OS comonnt [7] [8]. In such systms th assumton of Raylgh fadng for both th dsrd and ntrfrng sgnals may not b arorat and th Rc/Raylgh fadng modl may b usd nstad [4] [5]. Th rformanc of RC s consdrably asr to valuat than that of th otmum combnr. Although th otmum combnr outrforms RC th rformanc dffrnc s somtms not substantal n som fadng nvronmnts [] [6]. Th rformanc of an antnna array systm usng RC n a fadng nvronmnt wth cochannl ntrfrnc and an addtv wht Gaussan nos (AWG s usually gvn n trms of outag robablty whch s th robablty that th outut SIR falls blow a rscrbd thrshold valu [] [9]. Avrag rror rat s anothr mortant masur that s commonly usd to charactr th rformanc of many dgtal cllular rado systms. Closd-form rsults for avrag bt rror rat (BER of antnna array systms usng RC n a fadng nvronmnt whn th dsrd sgnal and th ntrfrrs fad ndndntly wth Raylgh statstcs wr gvn for th scal cass of dual-ordr dvrsty wth on domnant cochannl ntrfrr assumng that th dvrsty channls ar corrlatd [3]. Also th avrag BER for -ordr dvrsty wth an arbtrary numbr of dntcal ndndnt ntrfrrs was drvd n [3] and []. In ths ar w drv sm-analytcal xrssons for th avrag symbol rror rat (SER for an -lmnt antnna array systm mloyng RC n th rsnc of ndndnt arbtrary numbr of Raylgh-fadd cochannl ntrfrrs wth thr dntcal or dstnct man owrs for som lnar -ary modulaton schms. Th scal cass of avrag BER of cohrnt and noncohrnt bnary has shft yng s also rovdd. Fnally th xtnson to Rc-fadd dsrd sgnal s also nvstgatd for bnary cas as wll. Th organaton n ths ar s as follow th systm modl of Raylgh fadng channl s rovdd n

2 CHAYAWA AD AAO: AVERAGE SYBO ERROR RATE OF AXIA RATIO COBIIG SCHEE I THE RESECE OF 39 scton II. In scton III th drvaton of sm-analytcal xrssons for th avrag symbol rror rat for an - lmnt antnna array systm mloyng RC n th rsnc of ndndnt arbtrary numbr of Raylghfadd cochannl ntrfrrs wth thr dntcal or dstnct man owrs n som lnar modulaton schms ar drvd. Som scal cass of avrag bt rror rat ar nvstgatd n ths scton as wll. Th xtnson to Rc/ Raylgh fadng modl s studd n scton IV. In addton numrcal consdratons and concluson of ths manuscrt ar fnally gvn n scton V. and VI. rsctvly.. SYSTE ODE In a cllular rado systm wth antnna array rocssng at th bas staton th sgnals rcvd on an -lmnt antnna array oratng n th rsnc of ntrfrrs may b wrttn as rt ( s( ta + n ( s (t (... ar th transmttd sgnals and A (... ar th -dmnsonal drcton-ofarrvals of th dsrd sgnal ( and th ntrfrng sgnals (... W assum that ach comonnt of th vctors A (... follows a comlx Gaussan dstrbuton wth man owr (... Th vctor n s an addtv Gaussan nos vctor wth ro man and covaranc matrx σ I. Whn th sgnal at ach antnna s wghtd by a comlx-valud wght vctor w th outut SIR s gvn by [] H x A A s a Gamma dstrbutd random σ varabl wth df gvn by [] [9] x x x Γ( ( x x x and th random varabl has th xonntal dstrbuton gvn by (5 x (6 σ ( s th sgnal-to-nos owr rato of th dsrd sgnal ( and -th ntrfrng sgnal. W assum throughout that th ntrfrng owrs ar mutually ndndnt. Whn th ntrfrrs hav dntcal owr (.. for... th df of random varabl can b shown to b gvn by ( x. Γ (7 Whn th ntrfrrs hav dssmlar man owrs th df of s gvn by H H w A A w H ( w Rw ( x (8 th random covaranc matrx R s gvn by H R A A + σ I. (3. Th surscrt H dnots th Hrmtan transos of th comlx matrx. Whn th rcvr mloys RC th wght vctor on ach antnna s roortonal to th dsrd sgnal vctor (.. w A and th corrsondng outut SIR can b shown to b gvn by [3] x (4 + x Th df of th outut SIR s thn gvn by + ( ( ω + [( ω + ] ( ω dω x w may substtut (5 for x ( x and (7 or (8 for ( ω and valuat th rsultng ntgral. Whn th ntrfrrs hav qual man owr th rsult s gvn by (9

3 4 ECTI TRASACTIOS O EECTRICA EG. EECTROICS AD COUICATIOS VO. O. AUGUST 3 ( x ( Γ ( + C Γ Γ + C n ( ( + ( n! s th bnomal coffcnt! n! whch agrs wth m m n [ q. (]. In th s I rsnc of ntrfrrs wth nondntcal man owrs w hav ( / Γ + C + ( ( Γ +. ( 3. AVERAGE SYBO ERROR RATE In ths scton w drv th avrag symbol rror rat (SER whch s gvn by ( ( d ( ( dnots th condtonal SER for th dsrd -ary sgnalng schms n an AWG channl dndng on th ty of dtcton schm mloyd at th rcvr. In artcular w consdr cohrnt and dffrntally cohrnt -ary SK (SK and DSK -ary quadratur amltud modulaton (QA and noncohrnt -ary frquncy shft yng (FSK. For a gvn SIR lt ( dnot th condtonal symbol rror rat (SER n an AWG channl for th dsrd - ary sgnalng schm. Thn th avrag SER (avragng ovr th df of th SIR gvn n (9 may b wrttn as ( y + ( y + x Γ( y dyd (3. Intrchangng th ordr of th ntgratons (3 may b r-wrttn as ( y+ ( y x Γ ( y + ( d dy. (4 W not that th nnr ntgral n (4 s th avrag SER th avragng s don ovr th df of th dsrd sgnal SR (.. no ntrfrrs. Thus for a gvn -ary sgnalng schm wth -ordr RC dvrsty oratng n a Raylgh fadng channl wth no ntrfrrs ( and avrag dsrd sgnal SR ϑ w dfn th ntgral ϑ ( ϑ ( d. (5 Γ( any rsarchrs hav studd th ntgral n (5 for svral lnar modulaton schms []-[5]. For dntcal man-owr Raylgh-fadd ntrfrrs w substtut (7 n (4 and usng (5 w hav + y Γ ( y ( ( y+ Γ y dy + y C y ( ( y+ dy. (6 Smlarly whn th ntrfrrs hav dffrnt man owrs w hav + ( dy. y C y y (7 It s worth notng that for th scal cass of noncohrnt bnary has shft yng th avrag bt rror rat ( (6 wth and can b drvd by substtutng (5 n ( ( x α (8 for bnary SK α for bnary FSK. Thn th rsult bcoms

4 CHAYAWA AD AAO: AVERAGE SYBO ERROR RATE OF AXIA RATIO COBIIG SCHEE I THE RESECE OF 4 C Γ + Γ ψ + + α (9 whch agrs wth [] as a scal cas of aagam fadng channl wth m m ψ α β ( α s I α β α xt x t ( + t dt α. Γ > ( s th conflunt hyrgomtrc functon of th scond nd [7]. In th rsnc of ndndnt Raylghfadd ntrfrrs wth dssmlar man owr w hav + α ( C Γ + ψ. ( lnar modulatons for whch th ntgral n (5 has bn valuatd n th ltratur. 3. DSK For DSK w hav [] [3] DSK DSK sn ( ϑ d θ. ( cos cosθ [ y+ + ϑ( cos cosθ ] sn C Γ ( + Γ (5 In th rsnc of qual man-owr ntrfrrs w substtut (5 n (6 and ntrchang th ordr of ntgraton. Uon smlfyng th rsult w hav Ρ ( ν. (6 DSK In addton for th cas of cohrnt bnary has shft yng modulaton schm wth dntcal man-owr ntrfrrs wth a substtuton of rf c( α ( n (6 and som mathmatcal manulaton th avrag bt rror rat ( C s thn gvn by C Γ ( + ( 4 Γ( κ C C ψ (3 whch also agrs wth [ q.(4] and w hav C C ( + 4 C Γ + ψ (4 + + } Ρ DSK ( ν / ( θ + cos cos ψ ν ( cos cosθ dθ (7 and ν +. ot that th fnal rsult n (7 s obtand by a sml chang of varabl xθ /. Smlarly n th rsnc of nondntcal man-owr ntrfrrs th rsult bcoms DSK sn C Γ + Ρ (. (8 DSK Th xrssons n (6 and (8 can b asly valuatd numrcally wth any dsrd dgr of accuracy. For th cas of bnary DSK ( (6 and (8 rduc to (9 and ( wth α. 3. SK For SK w hav [3] [5] n th cas of Raylgh-fadd ntrfrrs wth dssmlar man owrs []. xt w consdr a numbr of -ary

5 4 ECTI TRASACTIOS O EECTRICA EG. EECTROICS AD COUICATIOS VO. O. AUGUST 3 ( ϑ + + ϑ( θ sn sc dθ. y SK (9 Consquntly whn qual man-owr ntrfrrs rsnt at th rcvr w substtut (9 n (6 and ntrchang th ordr of ntgraton to obtan q + sn ( µ θ ν QA ψ ν dθ q 4 + sn µ θ ψ ν dθ 4 (35 SK C Γ ( + Γ for th cas of dntcal man-owr ntrfrrs. Also whn th ntrfrrs hav dstnct man owrs th rsult bcoms Ρ SK Ρ ( (3 ν SK ( ν ( + sn sc θ ψ ν d θ. (3 Whn th ntrfrrs hav dstnct man owrs th rsult bcoms SK C Γ ( QA QA Ρ (. (3 SK For QA w hav [4] [5] q ( y µϑ ϑ + + d sn θ θ q 4 µϑ y sn dθ (33 θ QA C ( Γ + (. (36 QA 3.4 oncohrnt FSK FSK For noncohrnt -ary FSK w hav [3] [6] ( ϑ ( C y + + ϑ. (37 Whn th man owrs of ntrfrrs ar qual w substtut (37 n (6 to obtan FSK C Γ + Γ C ( ψ +. ν (38 Smlarly whn th ntrfrrs hav dssmlar man owrs th rsult bcoms q 4( and µ 3log (. Thn substtutng (33 n (6 and ntrchangng th ordr of ntgraton w hav QA C Γ ( + ( ν QA Γ( (34 FSK C Γ + ( + ( C ψ. (39 For th scal cas of noncohrnt bnary FSK ( (38 and (39 rduc to (9 and ( rsctvly wth α /.

6 CHAYAWA AD AAO: AVERAGE SYBO ERROR RATE OF AXIA RATIO COBIIG SCHEE I THE RESECE OF EXTETIO TO RICE/RAYEIGH FADIG In mcrocllular mobl rado systms th assumton of Raylgh fadng for both th dsrd and ntrfrng sgnals may not also b arorat snc th dstanc btwn th bas staton and mobl s usually not far nough to nglct th ln of sght (OS comonnts. roagaton masurmnts n urban mcrocllular nvronmnts as wll as ndoor rado channls hav shown that th rcvd sgnal nvlo has a Rc dstrbuton ndcatng th rsnc of th OS or scular comonnts [7] [8]. Thrfor t s rasonabl to assum that th ntrfrng sgnals xrnc dr fadng than th dsrd sgnal snc th ntrfrrs ar usually furthr away from th bas staton than th dsrd sgnal. In ths scton w assum that th dsrd sgnal has a Rc dstrbuton whl th ntrfrrs ar Raylgh dstrbutd. W assum furthr that th Rc factors of th dsrd sgnal on th antnnas ar dntcal and dfnd as κ m m s th man valu of ach comonnt n A. Th avrag SR of th dsrd sgnal x s now a noncntral Ch-squar dstrbutd random varabl wth df gvn by ( x+ κ x κ x κ ( + x I x. (4 Substtutng (7 and (4 n (9 th df of outut SIR whn th ntrfrrs hav qual man owr s gvn by ( Γ ( κ + + κ ( Γ + [( + ] +! Γ ( + C +. (4 Whn th ntrfrrs hav nondntcal man owrs by substtutng (8 and (4 n (9 th rsult bcoms ( ( κ ( κ ( + + ( + ot that whn κ + +! + [( +! ]. (4 (4 and (4 rduc to th df for th Raylgh fadng cass gvn n ( and ( rsctvly. xt w drv th avrag BER for th cas of Rc-fadd dsrd sgnal. Th rsults may b asly xtndd to th cas of -ary sgnalng. 4. oncohrnt Dtcton In th rsnc of a Rc-fadd dsrd sgnal and qual man-owr Raylgh-fadd ntrfrrs w may substtut (8 and (4 n ( to obtan th avrag BER for th noncohrnt dmodulaton cas as ( κ κ + + C Γ + Γ! ψ n x x x rf c ax dx + α / n Γ( n a C n a + 4 a + (43 Whn th ntrfrrs hav nondntcal man owrs th BER s obtand by substtutng (8 and (4 n ( to gv κ + κ Γ ( + + (!! + α ψ. (44 + W obsrv that (9 and ( ar th scal cass of (43 and (44 corrsondngly whn κ. 4. Cohrnt Dtcton Whn th rcvr mloys cohrnt dmodulaton and th ntrfrrs hav qual man owr w may substtut ( and (4 n ( and us th rlaton of [8] > n >. (45 Aftr som manulaton th avrag BER s gvn by C κ κ + α C ( 4! + Γ ( + α + C ( + α Γ ( +

7 44 ECTI TRASACTIOS O EECTRICA EG. EECTROICS AD COUICATIOS VO. O. AUGUST 3 + α ψ (46 In th rsnc of dstnct man-owr Raylgh-fadd ntrfrrs th avrag BER s C n κ + κ α C! 4 n + α C Γ ( n+ ψ + n+. n (47 5. UERICA COSIDERATIOS In ths scton w rsnt som numrcal rsults for th avrag symbol rror rat (SER n som slctd cass. In ach cas w lot th SER vrsus th avrag outut SIR dfnd as th rato of avrag owr of th dsrd sgnal to th avrag owr of ntrfrrs lus nos owr. In Fg. th SER for 4 and 6-DSK s lottd aganst avrag SIR n th rsnc of ( 3 qual man-owr ntrfrrs for an RC systm wth four dvrsty branchs ( 4. W obsrv that as th numbr of ntrfrrs n th systm ncrass th systm rformanc dtrorats. In Fg. th SER of noncohrnt 4-FSK s lottd aganst th numbr of qual-owr ntrfrrs n th systm wth th SR fxd at db and th ntrfrnc-to-nos rato (IR fxd at db. W obsrv from th fgur that whn th systm s ntrfrnc-lmtd ( >> th systm rformanc stll mrovs substantally although th RC systm gnors th rsnc of th ntrfrrs and maxms th outut SR. Also whn thr ar no ntrfrrs ( n th systm th rformanc rachs th bst snc RC s th otmum combnng schm n a nos-only systm. Fnally for th Rc/Raylgh fadng modl w rsnt th systm rformanc for bnary modulaton schms. In Fg. 3 th BER for DSK and cohrnt BSK ar lottd aganst SIR for a systm wth sx ( 6 qual man-owr ntrfrrs and a Rc-fadd dsrd sgnal ( κ and wth dffrnt valus of th dvrsty ordr. From th fgur w obsrv that th BER dcrass as th Rc factor ncrass du to th rsnc of strongr OS comonnts btwn th mobl unt and th bas staton. For xaml for a DSK systm at a BER of -4 th systm wth a Rc factor of κ has dvrsty gan of.7 db n usng 3 ovr and has dvrsty gan of 6.9 db n usng 3 ovr wth a Rc factor of. Thus th us of dvrsty rcton n th rsnc of Raylgh-fadd cochannl ntrfrnc mrovs systm rformanc mor sgnfcantly n a Raylgh fadng channl than n a Rc fadng channl. κ 6. COCUSIO In ths ar w hav studd th ffct of cochannl ntrfrnc on th rformanc of dgtal cllular mobl rado systms. Th ntrfrrs wr assumd to b subct to ndndnt Raylgh fadng whl th dsrd sgnal was subct to thr Raylgh or Rc fadng. Th avrag SER of maxmal rato combnr whch maxms th outut SR n th rsnc of cochannl ntrfrnc and nos s analyd. Sm-analytcal xrssons that rovd a convnnt tool for th systm rformanc analyss ar drvd for both th df of th outut SIR and th avrag SER. Som closd-form xrssons of th scal cass of BER ar also studd as wll. Th analyss assumd an arbtrary numbr of cochannl ntrfrrs wth dntcal or wth dffrnt avrag owrs. REFERECE []. H. Wntrs "Otmum combnng n dgtal mobl rado wth co-channl ntrfrnc" IEEE. Slct. Aras Commun. vol. Sac uly 984. []. Cu and A. Shh Outag robablty of cllular rado systms usng maxmal rato combnng n th rsnc of multl ntrfrrs IEEE Trans. Commun. vol. 47 no August 999. [3]. Cu D. Falconr and A. Shh rformanc valuaton of otmum combnng and maxmal rato combnng n th rsnc of co-channl ntrfrnc and channl corrlaton for wrlss communcaton systms obl twors and Alcatons vol [4] A. Shah and A.. Hamovch rformanc analyss of maxmal rato combnng and comarson wth otmum combnng for mobl rado communcatons wth cochannl ntrfrnc IEEE Trans. on Vh. Tchn. vol uly. [5] Y. Yao and A. U. H. Shh Invstgaton nto cochannl ntrfrnc n mcrocllular mobl rado systms IEEE Trans. on Vh. Tchn. vol ay 99. [6]. D. Anna and A. H. Aghvam "rformanc of otmum and subotmum combnng at th antnna array of a W-CDA systm" IEEE. Slct. Aras Commun. vol. 7 no Dcmbr 999. [7] R.. Bulttud and G. K. Bdal "roagaton charactrstcs n mcrocllular urban mobl rado channls at 9 H" IEEE. Slct. Aras Commun. Vol anuary 989. [8] T. S. Raaort "Charactraton of UHF multath rado channls n factory buldngs" IEEE Trans. Antnnas roagat. Vol August 989. [9] V. Aalo and C. Chayawan Outag robablty of cllular rado systms usng maxmal rato combnng n Raylgh fadng channl wth multl

CHAYAWA AD AAO: AVERAGE SYBO ERROR RATE OF AXIA RATIO COBIIG SCHEE I THE RESECE OF 45 ntrfrrs Elctroncs ttrs vol. 36 no.5. 34-35 uly. [] V. A. Aalo and.

8 CHAYAWA AD AAO: AVERAGE SYBO ERROR RATE OF AXIA RATIO COBIIG SCHEE I THE RESECE OF 45 ntrfrrs Elctroncs ttrs vol. 36 no uly. [] V. A. Aalo and. Zhang "rformanc analyss of maxmal rato combnng n th rsnc of multl qual-owr cochannl ntrfrrs n a aagam fadng channl IEEE Trans. Vh. Tchnol. vol. 5 no. arch. [] C. Chayawan and V. A. Aalo Avrag rror robablty of dgtal cllular rado systms usng RC dvrsty n th rsnc of multl ntrfrrs to aar n IEEE Trans. Wrlss Commun. [] G. Fdl "Error robablty for dtcton of - DSK sgnals n slow nonslctv aagam fadng" Elctroncs lttrs vol. 3 no Arl 994. [3]. Sun and I. S. Rd "rformanc of DSK SK and noncohrnt FSK n wrlss Rcan fadng channls" IEEE Trans. Commun. vol. 47 no. 6 un 999. [4]. u T. T. Thung and C. C Cha "Error robablty rformanc of -branch dvrsty rcton of QA n Raylgh fadng" IEEE Trans. Commun. vol. 46 no. Fbruary 998. [5]. S. Aloun and A.. Goldsmth "A unfd aroach for calculatng rror rats of lnarly modulatd sgnals ovr gnrald fadng channls" IEEE Trans. Commun. vol. 47 no. 9 Stmbr 999. [6] B. Slar Dgtal Communcatons: Fundamntals and Alcatons rntc-hall Englwood Clffs [7].. Slatr Conflunt Hyrgomtrc Functon. Cambrdg Unvrsty rss 96. [8] I. S. Gradshtyn and I.. Ryh Tabls of Intgrals Srs and roducts Acadmc rss.y. 98. Chrasl Chayawan was born n Thaland on ovmbr 969. H rcvd th B.E. dgr n lctroncs ngnrng from Kng ongut s Insttut of Tchnology adrabang n 99 and.s. and h.d. dgrs from Unvrsty of assachustts at Amhrst and Florda Atlantc Unvrsty n 997 and rsctvly. Bfor h has ontd th Dartmnt of Elctroncs and Tlcommuncaton Engnrng n th Kng ongut s Unvrsty of Tchnology Thonbur (KUTT h word wth Control Data Thaland and IB Thaland as a customr ngnr. In 995 h got a scholarsh from th Royal Tha mbassy to study S. and h.d. n USA. Currntly h has bn on th Faculty of KUTT Bango Thaland n th Dartmnt of Elctroncs and Tlcommuncaton Engnrng. Valntn A. Aalo was born n gra on arch H rcvd th B.S..S. and h.d. dgrs n lctrcal ngnrng from Southrn Illnos Unvrsty at Carbondal n and 99 rsctvly. Snc 99 h has bn on th Faculty of Florda Atlantc Unvrsty Boca Raton h s now an Assocat rofssor n th Dartmnt of Elctrcal Engnrng. H snt th summrs of 994 and 995 wth th Satllt Communcatons and tworng Grou at Rom aboratory Grffss Ar Forc Bas Rom Y as a Faculty Rsarch Assocat. Hs rsarch ntrsts ar n th aras of wrlss communcatons adatv array rocssng satllt communcatons and radar sgnal rocssng. Dr. Aalo s a mmbr of Tau Bta and svral IEEE socts. H srvs as an Edtor for Dvrsty and Fadng Channl Thory for th IEEE TRASACTIOS O COUICATIOS. Symbol Error Rat SIR(dB Fg. : Avrag Symbol Error Rat vrsus SIR of 4 and 6-DSK wth a four-lmnt RC antnna array n th rsnc of ( 3 dntcal man-owr Raylgh-fadd ntrfrrs. Dr. Chrasl Chayawan s a mmbr of Tau Bta.

9 46 ECTI TRASACTIOS O EECTRICA EG. EECTROICS AD COUICATIOS VO. O. AUGUST 3 Symbol Error Rat o. of Intrfrrs Fg. : Avrag Symbol Error Rat vrsus numbr of ntrfrrs for oncohrnt 4-FSK wth th dvrsty or ordr as a aramtr n th rsnc of dntcal man-owr Raylgh-fadd ntrfrrs. - - κ DSK BSK Symbol Error Rat -3-4 κ SIR(dB Fg. 3: Avrag BER vrsus SIR of DSK and cohrnt BSK wth th dvrsty ordr as a aramtr n a Rc/Raylgh fadng channl wth sx dntcal manowr ntrfrrs.

Level crossing rate of relay system over LOS multipath fading channel with one and two clusters in the presence of co-channel interference

Level crossing rate of relay system over LOS multipath fading channel with one and two clusters in the presence of co-channel interference INFOTEHJAHORINA Vol 5, March 6 Lvl crossng rat of rla sstm ovr LOS multath fadng channl th on and to clustrs n th rsnc of cochannl ntrfrnc Goran Ptovć, Zorca Nolć Facult of Elctronc Engnrng Unvrst of Nš