Analysis of a Power Line Communication System Over a Non-white Additive Gaussian Noise Channel and Performance Improvement Using Diversity Reception.

Transcription

1 Anayss of a ower ne Communcaton ystem Over a on-whte Addtve Gaussan ose Channe and erformance Improvement Usng Dversty Recepton. Munsh Mahuur Rahman Majumder Dept of EECE, MI, Dhaa, Bangadesh Dept of EEE, BUE, Dhaa-, Bangadesh e-ma: mmr.eece@mst.edu.d e-ma: spmajumder@eee.uet..d Astrt - erformance mprovement of a power ne communcaton system s presented here consderng the nose as a cycostatonary non-whte Gaussan random process. erformance of a power ne communcaton system s severey deterorated y fadng and mutpath effect. he mpusve nose s consdered tme varant, has short duraton, random occurrence wth a hgh power spectra densty (D. It causes t error n the sgna. Usng orthogona frequency dvson mutpexng (OFDM technque, the effect of mpusve nose and fadng can e mproved greaty. An anaytc approh s presented to evauate the performance of a power ne communcaton n n the presence of the aove mtatons. he smuaton resuts show that there s deteroraton n system BER due to tme and frequency dependence of nose and the degradaton s found to e sgnfcant at hgher t rates and andwdth. he system suffers penaty n recever senstvty due to non-whte nature of the nose process. In ths paper, an anaytca approh usng dversty recepton s carred out to examne the performance mprovement of a power ne channe n fadng and mpusve nose. he system t error rate (BER s compared numercay for oth nary phase shft eyng (BK and OFDM system. he BER resuts show that there s sgnfcant mprovement n OFDM. Aso the performance s remaray upgraded usng dversty recepton. Key Words Cycostatonary nose; attenuaton; DF(proaty densty functon; Whte nose; Interference; Varance; etc. I. IRODUCIO he man source of ower-ne nose s caused y Eectrc appances connected to the ne [-3]. Essentay, the power-nes or assocated hardware mpropery generate unwanted rado sgnas that overrde or compete wth desred rado sgnas. ower-ne nose can mpt rado and teevson recepton - ncudng cae V head-end pc-up and Internet servce. Dsrupton of rado communcatons, such as amateur rado, can aso occur [4]. oss of crtca communcatons, such as poce, fre, mtary and other smar users of the rado spectrum can resut n even more serous consequences. Vrtuay a power-ne nose, orgnatng from utty company equpment, s caused y a spar or arcng ross some power-ne reated hardware [, 5]. Durng the ast two decades severa research wors has een reported on the modeng and charterzaton of power ne nose [6]. ose n a power ne resuts due to the effect of corona, mpuse votages, eectrc arc etween the nes, and affect the communcaton n severey [8-9]. he nature of power ne nose s found to e a non-whte cycostatonary process[]. he modeng and smuaton of C system usng severa types of nose are aso reported [-4]. In a ower-ne, the t error rate (BER performance of a communcaton n mpared y power ne noses. hese noses consst of statonary ground nose and tme varant mpusve nose. Impusve nose appears as osson dstruton. he mutpath deay spread s a tme dsperson charterstcs of the channe. he sgna s made up of the sum of many sgnas, eh traveng over a separate path. nce these path engths are not the same, the nformaton carred on a C channe experences a spread n deay as t traves etween the transmttng staton and the recevng staton. Furthermore, the same mutpath envronment causes severe oca varatons n sgna as these mutpath sgnas are added constructvey and destructvey at the recevng antenna. he mpusve nose and mut-path effects are the man ftors consdered for degradng the power ne communcaton (C performance. OFDM separate overa transmtted data n many parae ndependent su-streams. he ong symo duraton tme maes OFDM perform etter than snge carrer scheme for mut-path channe. OFDM may perform etter than snge carrer when the channe s nterfered y mpusve nose, snce t can spread the mpusve nose over mutpe symos due to nverse fast Fourer transform (IFF. gna degradaton n a power ne communcaton due to mutpath fadng, tme dsperson etc. can e overcome y dversty technque [5]. he asc concept of dversty s that eh of the transmtted sgnas s receved through a numer of separate channes. When severa numer of ndvdua channe carryng the same nformaton are receved over mutpe channes that exht ndependent fadng wth comparae strengths. he chances that a the ndependenty faded sgna components experence the same fadng smutaneousy are greaty reduced [6]. In ths paper, we provde an

2 anaytca approh to fnd the t error rate (BER performance of a ower ne Communcaton n the presence of mpusve nose and fadng wth dversty n recepton usng mutpe recevng antennas. We have presented an anaytca approh to fnd the t error rate (BER performance of a communcaton n mpared y power ne nose whch s consdered as non-whte addtve Gaussan cycostatonary process [7]. In ths paper, we have nvestgated the BER performance n a power ne communcaton consderng the C nose to e a non-whte addtve Gaussan cycostatonary process. We propose that n a C envronment, frsty the BER performance can e mproved y usng OFDM and secondy, the performance s remaray upgraded usng dversty recepton. II. AAYI OF O-WHIE ADDIIVE GAUIA OIE A. YEM MODE he oc dagram of the power ne communcaton system for dversty recepton used for ths anayss s shown n fg.. he dgta data from the ntegent eectroncs devce (IED are mutpexed and transmtted from the sustaton to a centra contro staton through a wreess n. he sgna transmtted s companed wth nose from the power ne and s receved y the recever aong wth channe nose. We consder BK moduaton and coherent demoduaton at the recever. uttng t we can wrte, n ( ( n ( exp ( ( In ths equaton ( t E [ ( t ] s the nstantaneous nose varance. nce the varance ( t s a perodc functon of the frequency, the DF s aso a perodc functon. uch that; for any nteger j. n n j hs s an mportant reaton ecause the tme dependent or non statonary features of nose are represent mathematcay n the cosed form of DF. et the receved sgna s gven y, r(t = s(t + n(t s(t = sgna component n(t = nose component et us assume that the power of sgna s constant for a short duraton t t t, o the reference sgna for ths tme duraton can e expressed as: ( t cos( f C t (3 he power can e cuated as, t t ( t dt (4 Fg : ower ne Communcaton networ B. HEOREICA AAYI ose n a power ne has a perodc feature wth frequency ; where s the perod of AC mans. Hence the amptude dstruton can e assumed as Gaussan. herefore, power ne nose s assumed to e cycostatonary addtve Gaussan nose whose mean s zero and the varance s synchronous to the AC votage of mans. Wth ths assumpton, the proaty densty functon (DF of cycostatonary addtve Gaussan nose s gven y, n ( t ( n( t exp ( t t he sgna s processed n a narrow and wth and-pass and and-rejecton fters of centre frequency f. C. CYCOAIOARY OIE A cycostatonary addtve Gaussan nose whose mean s zero and varance s synchronous to the AC votage of the mans the DF of such nose at the nstance t = s can e expressed as, n ( n exp (5 ( ( Here, ( t E[ ( t] (6 = Instantaneous varance of the nose. and E(. = Enseme average. Based on the assumpton that ( t s a perodc functon the enseme average s reped y the average nstantaneous power of the normazed waveform taen at every. hen for, we have nstantaneous power (varance of (t as; m m ( j (7 m j C

3 m j m j In a cycostatonary nose charterstcs t m ( ( m ow, ths functon can e approxmated a sampe functon wth a sma numer of parameters. For ths purpose the mode empoys the foowng perodc functon to approxmate ( t, as such n (8 (9 t ( A sn t ( Here, =,,... (- A, and n denotes the charterstcs of the nose. By Fourer seres expanson we get, t ( A cos t B sn t ( where, ( t dt ; for n A ( t cos tdt ; n...( B ow n ( t ( t sn tdt ; (3 ACos tdt t Bn tdt...(4 n ( t A n t (5 4 B Cos t (6 4 t A B n ( Cos (7 n = Mean of the varance wthn a t perod. = σ D. BER CACUAIO We now BER =. 5 erfc E (8 E R E s s s B s (9 o, R BER.5erfc n s ( A B n ( Cos s A B n ( Cos...( BER (.5erfc [R(] ( III. EFFEC OF O-WHIE GAIA OIE In precedng sectons, a smpe method of representng the performance of a power ne communcaton n n the presence of the nose n roadand and narrow and communcaton channe has een demonstrated. he man purpose of ths demonstraton s to fnd out the BER n the presence of non-whte addtve Gaussan nose. In ths wor, we have proposed a mode for BER for oth frequency dependent and frequency ndependent cases, whch cannot e represented y conventona modes. It can e a usefu too for the performance evauaton of ower ne Communcaton (C. It can e used as a too for the desgn and evauaton of power ne communcaton system, and aso as a powerfu mean for the studes n nterference and fadng envronment of the nose n power nes. VI. DIVERIY RECEIO o far, we have anayzed the BER performance of a power ne system n the presence of non-whte addtve Gaussan noses. o, the channe s transmtted sgna avaae, and eh verson of sujected to ths mpusve nose, fadng, tme dsperson, and other degradatons. o overcome a those mparments and mprove sgna quaty, we propose dversty recepton technque. In dversty technque the recever has more than one verson of the transmtted sgna s receved through a 3

4 dstnct channe. When severa verson of the sgna, carryng the same nformaton are receved over mutpe channes that exht ndependent fadng wth comparae strengths, the chances that a the ndependenty faded sgna components experence the same fadng smutaneousy can e greaty reduced. VII. IGA COMBIIG FOR DIVERIY RECEIO Dversty technques can ncrease the system capty and mprove communcaton reaty[7]. By transmttng and recevng mutpe copes of data, a MIMO system can effectvey comat the effects of fadng. Due to the hgh hardware cost of a MIMO system, antenna dversty technques have een apped n MIMO system desgn to reduce the system compexty and cost. he ft that the transmtted sgna must traverse a potentay dffcut envronment wth scatterng, refecton, refrton and so on and may then e further corrupted y therma nose n the recever means that some of the receved copes of the data w e etter than others. hs redundancy resuts n a hgher chance of eng ae to use one or more of the receved copes to correcty decode the receved sgna. In ft, spe tme codng comnes a the copes of the receved sgna n an optma way to extrt as much nformaton from eh of them as posse. Most wor on wreess communcatons had focused on havng an antenna array at ony one end of the wreess n - usuay at the recever. Usng mutpe antennas mproves performance of the recever remaray. hs process of recevng dverse copes of the data s nown as dversty recepton and s what was argey studed [8]. Antenna arrays can provde dversty paths to comat mutpath fadng of the desred sgna and are ae of reducng the power of nterferng sgnas at the recever. he Comnng methods consdered n ths paper are maxma rato comnng (MRC Maxma rato comnng represents a theoretcay optma comner over fadng channes as a dversty type n recever dversty n a communcaton system. heoretcay, mutpe copes of the same nformaton sgna are comned so as to maxmze the nstantaneous R at the output [9]. However system desgns often assume that the fadng s ndependent ross mutpe dversty channes. Maxmum Rato Comnng comnes the nformaton from a receved ranches for a mutpe antenna system n order to ncrease the R. We empoy dfferent gans to eh antenna to get etter the sgna to nose rato for the jont sgnas. We use the dfferent proportona constant ftors and gan s approxmatey equa to the route mean square of the sgna eve. Maxmum Rato Comnng can provde the dversty gan and array gan ut t does not assstance n spata mutpexng scenaro. A smpe dagram of Branch Antenna Dversty s shown n Fgure. Maxmum Rato Comnng generay wors y 4 weghtng eh ranch wth a compex ftor of W and then addng up the r ranches. he receved sgna can e wrtten as x(th. he overa sgna can e wrtten as, ( j ( r y t x ( t w h exp{ ( }.(3 If we aow the phase for ranches, then R of y(t can e wrtng as MRC x ( r r w w h...(4 x s the transmtted energy sgna. ovng the aove expresson y tang the dervaton wth respect to w provdes maxmum comnng vaues. In other words, eh ranch s mutped wth ts sgna-to-nose rato. he resutng R can e wrtten as x ( r MRC... (5 When addng up the ranches of R, the tota R w e compshed. Fg : VIII. h r gna Comnng (Maxmum Rato Comnng AAYI OF IMUIVE OIE As mentoned earer, C nose can e termed as ground nose and mpusve nose. he ground nose s assumed to e addtve whte Gaussan nose (AWG wth zero mean and varance w. he arrva of mpusve nose foows a osson process [4] wth a rate of λ unts per second, so that the event of arrvas n t seconds has the proaty dstruton [5], e t ( t /!,,... (6 he duraton tme of the mpusve nose nose and tme perod s. s defned as the tota average occurrence of the mpusve nose duraton n tme and s the average duraton wthout mpusve nose n tme, n whch duraton ony AWG s present [8]. From (,

5 e (! nose e nose ( e nose ( (! (! / ( At hgher vaue of, e (7 nose A. BER OF IGE CARRIER BK UDER IMUIVE OIE.! Q.5 erfc E nose E nose (35 IX. ERFORMACE IMROVREME HROUGH DIVEIY RECEIO For OFDM, we assume that n case of dversty recepton s equa to the numer of recever, then s gven y[-] [.5 ( ] [.5 ( ]...(36 assumng.5(+µ and.5(- µ /4Γ c If the BER under mpusve nose s and BER under AWG s w, then the BER of a snge carrer BK s gven y [9], furthermore (8 w nose ( nose w (9 ow, E Q (3 E and w Q (3 Where E s the sgna energy per t, and are the power spectra densty of the mpusve nose and AWG respectvey. We get BER n BK under mpusve nose as ( nose nose E E nose.5 erfc ( nose. 5 erfc w...(3 B. BER OF IGE CARRIER OFDM UDER IMUIVE OIE. For OFDM, et the D of overa nose (ncudes mpusve nose and AWG e m where m s gven y [8-9] m (33 If AWG nose power s and mpusve nose power s, then µ s defned as (34 and BER of OFDM system under AWG and mpusve nose s Q E m so, the BER n dversty recepton s gven y, Where 4 c Γ c = R n OFDM E m E nose (37 (38 and the rato of Impusve nose power ( to AWG nose power ( µ s gven y, c (39 c s cuated tang =.,.5 and. and =, 4, 6 and 8 X. IMUAIO REU In order to nvestgate the BER performance n a power ne communcaton system n the presence of non-whte addtve Gaussan nose ased on the formuas derved n the prevous sectons, we used computer smuaton wth MAAB. he expresson of the sgna to nose rato s deveoped consderng the frequency and tme dependence of the cycostatonary nose. he system t error rate (BER s then evauated numercay for severa system parameters e system t rate, Fourer coeffcents of the non-whte Gaussan nose process etc. he smuaton resut s shown eow: 5

6 Fg.3 : ot of BER vs. consderng BER s ndependent of frequency, pot s shown for R = Mps. Fg.4 : ot of BER vs. consderng BER s ndependent of frequency, pot s shown for R = ps. Fg.6 : ot of BER vs. consderng BER s dependent of frequency, pot s shown for R = e5 XI. DICUIO O REU Foowng the theoretca approh presented n secton II, we evauate the t error rate (BER performance of a power ne communcaton system wth whte and nonwhte power spectra densty of nose. he resuts are presented n fg.3 through fg.6 for varous system parameters. Fg.3 shows the pot of BER versus for dfferent vaues of Fourer coeffcents of the nose varance. It s notced that there s sgnfcant mprovement n BER performance dependng on the vaues of Fourer coeffcents A and B. Optmum performance corresponds to a set of vaues of A and B. mar resuts are depcted n fg.4 for data rate ps. Comparson of fg.3 and fg.4 shows that there s deteroraton n system BER due to hgher data rate. Resuts for frequency dependent nose D are depcted n fg.5 and fg.6 consderng the Fourer coeffcents as aove. It s notced that system performance s mproved n the case of frequency dependent nose whch s consdered as a narrowand nose. A. OFDM system wth dversty recepton. he BER performance s anayzed and compared for oth BK and OFDM channe n snge carrer recever. he resuts show that the performance s sgnfcanty mproved n OFDM. Resuts for dversty recepton system are dscussed n the foowng sectons. Fg.5 : ot of BER vs. consderng BER s dependent of frequency, pot s shown for R = e6. 6 B. BER performance n Impusve nose hree nose scenaros s consdered, namey Heavy dstured, Moderatey dstured and ghty dstured [,]. For pottng equaton (36, the parameters are taen from [] where IA s the nter arrva tme of the mpusve nose, whch s the recproca of the arrva rate λ. he parameters as sted eow:

7 ABE I ARAMEER OF HE IMUIVE OIE CEARIO amda=/.96 Impusve nose scenaro IA (/ λ nose - I Heavy dstured.96s.64ms II. Moderatey dstured.96s.67ms III. ghty dstured 8.967s.7ms mu=., amda=/.96-4 Fg: 8: ot of BER vs. R n dfferent vaues of µ, tang λ=/.96 mu= mu=. mu= E/o For BK E/o Fg.7(a: ot of BER vs. R n OFDM system for µ=. and λ=/ mu=.5, amda=/ E/o Fg. 7(: ot of BER vs. R n OFDM system for µ=.5 and λ=/ OFDM scenaro I OFDM scenaro II OFDM scenaro III BK scenaro I BK scenaro II BK scenaro III For OFDM 5 5 E/o Fg.9: BER n BK and OFDM under mpusve nose n dfferent scenaro gven n tae I. C. erformance mprovement n dversty recepton From the aove anaytca resuts t s cear that the BER performance of power ne communcaton can e mproved usng OFDM. Moreover t can e further mproved sgnfcanty usng dversty recepton. Usng equaton (36, the resuts show that the performance s mproved to a sgnfcant eve. Agan the mprovement n ncreasng numer of recever s shown n fgs., and. - mu=., amda=/ = E/o Fg. 7(c: ot of BER vs. R n OFDM system for µ=. and λ=/ sgma =.5 nose=.67 amda=/.96 =4 = E/o Fg.: BER performance n dversty recepton (=, 4, 6.

8 For cheme I : gma^=., nose=.64, amda= /.96 cheme II : gma^=.5, nose=.67, amda= /.96 cheme III: gma^=., nose=.7, amda= /8.967 Fg. : (Dversty recepton for =,,4,6 and 8 BER performance n dversty recepton Improvement (db Fg.: ot of performance Improvement (db n dversty recepton vs numer of antenna. XII. o of Antennas COCUIO In ths paper, frsty we evauate the t error rate (BER performance of a power ne communcaton system wth whte and non-whte power spectra densty of nose. econdy, a smpe method of mprovng the performance of a power ne communcaton n n the presence of the mpusve nose, fadng and mutpath effect n roadand and narrow and communcaton channe has een demonstrated. he man purpose of ths demonstraton s to fnd out the BER n the presence of aove mentoned mparments. In ths wor, we have proposed a mode to mtgate the osses for mpusve nose, fadng and mutpath effect y OFDM technque and recepton dversty. It can e a usefu too for the performance upgradng of ower ne Communcaton (C[6]. However, the mportance of ths proposed mode s not ony the ntroducton of a too for the desgn and evauaton of power ne communcaton system, however, n dversty recepton, the optmzaton of the antennas has not een studed, remans for future wors. REFERECE sgma =. sgma =.5 sgma =. [] JAE VA REBURG; D. Ing (Eectrca and Eectroncs, "Effectve coupng for power ne communcatons" A. Unversty of Johannesurg, Jan 8. 8 [] Y.H. Ma,..o, enor Memer, IEEE, and E. Gunawan, Memer, IEEE. erformance Anayss of OFDM ystems for Broadand ower ne Communcatons Under Impusve ose and Mutpath Effects. IEEE ranston on ower Devery, Vo-, no-, Apr 5. [3] Ezo Bger, tefeno Ga, Yong-Hwan ee, H. Vncent oor, A. J. Han Vnc and W. H. ranter, ower ne Communcaton guest edtora, IEEE jounna on sected areas n Communcatons, Vo.4, no.7, Juy 6. [4] Massa KAAYAMA, Introducton to Roust, Reae and Hgh-peed ower-ne Communcaton ystems IEICE trans. Fundamentas, VO E84-A, no-, Dec. [5]. hawa, H. Hoar and G. Maruayash, ower ne data transmsson, IEICE echnca report, A89-7, March 989. [6] Artce from john nosott.doc, "ower-ne Communcatons (C or Broadand-over-ower- ne (B" crc powerne proposa, ov 4. [7] Anndya Majumder and James Coffery. Jr, "ower ne communcaton an overvew", IEEE Xpore, Oct/ ov 4. [8] Massa KAAYAMA, Introducton to Roust, Reae and Hgh-peed ower-ne Communcaton ystems IEICE trans. Fundamentas, VO E84-A, no-, Dec. [9] A. Voggsang,. angguth, G. Koerner, H. tecener, and R. Krnorr, Measurement, charterzaton and smuaton of nose on powerne channes, n roc. 4th Int. ymp. ower ne Commun. App., Apr., pp [] Masaa Katayama, enor Memer, IEEE, aaya Yamazato, Memer, IEEE, and Hrau Oada, Memer, IEEE: A Mathematca Mode of ose n arrowand ower ne Communcaton ystems: IEEE JOURA O EECED AREA I COMMUICAIO, VO. 4, O. 7, JUY 6. [] M. Zmmermann and K. Dostert, Anayss and modeng of mpusve nose n road-and powerne communcatons, IEEE rans. Eectromagn.Compat., vo. EMC-44, no., pp , Fe.. [] H. Meng, Y.. Guan, and. Chen, Modeng and anayss of nose effects on roadand power ne communcatons, IEEE rans.owerde., vo., no., pp , Apr. 5. [3] M. Katayama,. Itou,. Yamazato, and A. Ogawa, Modeng of cycostatonary and frequency dependent powerne channes for communcatons, n roc. 4th Int. ymp. ower ne Commun. App., Apr. 5, pp [4] O.C Hoojen, A channe mode for the ow-votage power ne channe: measurement and smuaton resuts roc. 997 Internatona ymposum on ower ne Communcatons and ts Appcatons, pp.5-56,997. [5] M. anaa and R. omeya, he nose charterstcs and transmsson charterstcs on data transmsson usng power ne, IEICE trans., VO J69-B, no-, pp.47-49, Oct [6] Dasue Umehara, Hdeyu shyor, and Yoshteru Morhro: erformance Evauaton of CMFB ransmutpexer for Broadand ower ne Communcatons under arrowand Interference ower ne Communcatons and Its Appcatons, 6 IEEE Internatona ymposum on 6, pp [7] hn ch hawa, and auma Maeda: "erformances of FH/MFK ump ehood Rato Decson Methods and ther Appcatons for ower ne Communcatons", Journa of eecommuncatons, Voume 3, Issue, June [8] Khafa. A-Mawa and Zahr M. Hussan: erformance of Bt- Intereaved Coded OFDM n ower ne Communcatons wth Impusve ose he 9 Internatona Conference on Advanced echnooges for Communcatons, pp [9] Mohammed Aoud Kadhm and Dr Wdad Isma "erformance ransmt and Receve Dversty echnques for Dfferent Moduaton gna", Journa of eecommuncatons, Voume 4, IUE, EEMBER..