A Fquncy Hpping 16-DAPSK Rdi Invstigtin Dvid Wdg Mil Cmmunictins Dptmnt Hwltt-Pckd Ltis, Bistl Nvm 29th, 1995 Astct: A di systm suppting n nd t nd thughput f 2.5Mps is ppsd in this pt. Th intndd pplictin f th di is in hm ntwking pducts. A fquncy hpping di pting in th 2400MHz ISM nd is dscid. Th mdultin fmt usd is 16-DAPSK. This cks ff t DQPSK in chnnls with sv tim dispsin. Th dt tffic cid y th di is fist ssssd. This is ncssy t stlish wht cntl mchnisms my implmntd in th systm. Th sidntil, ind di ppgtin nvinmnt is thn cnsidd. This nls th dminnt mchnisms in th civ t pdictd. Th nlysis psntd cncluds tht 16-DAPSK mdm with tw nch divsity cptin is cpl f pviding stisfcty qulity f svic in th intndd pting nvinmnt. Intnl F HP Accssin Intnl Us Dt Only Only Cpyight Hwltt-Pckd Cmpny 1995
F HP Intnl Us Only Cntnts 1. Intductin 3 2. Functinl Spcifictin 3 3. PHY Ly Issus - 16-DAPSK nd th Ind Chnnl 4 3.1 Chctistics f th Rsidntil Ind Chnnl 4 3.2 Ovviw f Rdiwv Ppgtin E Mchnisms 5 3.3 Pfmnc Anlysis f 16-DAPSK 5 3.3.1 Thml Nis 5 3.3.2 Fst Fding 7 3.3.3 Rndm FM 8 3.3.4 Divsity Rcptin in Ryligh Fding 8 3.3.5 Tim Dispsin 10 3.3.6 Dminnt E Mchnisms in th Ind Chnnl 11 3.3.7 Ovll Pfmnc Cuvs f 16-DAPSK 11 4. MAC Ly Issus - E Cntl f Asynchnus nd Multimdi Svics 14 5. Cnclusins 15 6. Rfncs 15 Rvisin Histy 28/11/95 Dft 29/11/95 Rls 1.0 2
F HP Intnl Us Only 1. Intductin This dcumnt is intndd t pdict th pfmnc f nwnd fquncy hpping mdm ppsd f stg tw Pncm hm ntwking pducts. In s wh th is cuntly insufficint vidnc t pdict th pfmnc f such systm, th futu wk ncssy t futh d-isk th ppsl is dscid. 2. Functinl Spcifictin Th di systm is intndd s stg tw in fmily f hm ntwking pducts. This wuld ff thughput impvmnt v th stg n pduct. Th fist stg di is likly t n ISM nd fquncy hpping di mplying 2 lvl FSK. It is highly dsil f stg tw pducts t l t cmmunict with th instlld s f stg n dvics. Stg tw dis must dsignd with gd t th fllwing quimnts: 2.5Mit/s thughput vill t th us. Intpility with lw t stg n dvics. Th tgtd pting nvinmnt is sidntil in-uilding. Sm lvl f svic must vill in th ppgtin nvinmnts, such s in ffic spc. Th dis must 'inxpnsiv'. In dditin t ths, num f pfmnc quimnts lting t th ntu f th tffic still undfind. It is uncl if th link will hv t cy l tim dt f multimdi pplictins. This is imptnt s it dfins th guntd ndwidth nd ltncy quimnts f th link. Tl 2.1 shws num f ptntil uss f hm ntwk, nd th typ f svic it quis: Applictin Cnnctin Fm T Cmmunictin svic Snd fil t pint PC Pint synchnus Rmt hd disk ccss mt PC PC synchnus CD-ROM vid plyck CD-ROM n mt PC PC dnd ischnus CD-ROM udi plyck CD-ROM n mt PC PC dnd ischnus CD-ROM fil ccs CD-ROM n mt PC PC synchnus CD udi plyck CD CD-ROM Wilss spks dnd ischnus Tlphny Phn hndst Phn ssttin Nwnd ischnus Tl 2.1 Cmmunictin svics quid y nd pplictins Clly thn, mny f th ptntil svics qui nly n synchnus, thnt lik cnnctin. Hwv, stg n pducts cpl f suppting ll th synchnus svics, lit t lw t. A vlu pint clly distinguishing stg tw pducts fm xisting stg n dvics is ndd. Th cncpt f 'multimdi cpl' ng f dis suppting vid nd CD qulity udi wuld pvid this. Th implictins f this l-tim quimnt n cntl in th MAC will cnsidd lt. 3
F HP Intnl Us Only 3. PHY Ly Issus - 16-DAPSK nd th Ind Chnnl Th di systm ing ppsd is n unqulisd 16-DAPSK civ, with tw nch switchd divsity cptin. Th wk psntd h invstigts if such systm cn pt succssfully in mst ind, sidntil typ di chnnls. Th undlying pmis is tht within th sidntil ind chnnl, th dly spd is sufficintly lw tht n qulis is unncssy nd pssily vn dtimntl. This sctin is intndd t invstigt th vlidity f this sstin. If th systm w ptd in high dly spd nvinmnt thn it wuld ck ff t QPSK in d t pvid svic t hlf th dt t. In d t invstigt th pfmnc f 16-DAPSK di in th ind sidntil nvinmnt, th fllwing issus discussd: Dsciptin f ind sidntil di chnnl chctistics. Assssmnt f th imptnc f th vius mchnisms in th Ind Chnnl. Quntittiv nlysis f 16-DAPSK nd QPSK pfmnc givn ths mchnisms. 3.1 Chctistics f th Rsidntil Ind Chnnl A cnsidl munt f wk hs n pulishd dsciing th simultd pfmnc f 16-DAPSK und vius pting cnditins. In d t nlys this wk it is fist ncssy t undstnd th pmts f th ppsd Pncm Stg 2 civ nd it's pting nvinmnt. Ths cn summisd s fllws:- Fquncy hpping tnsmissin in th 2400MHz ISM nd. 3 Mps n i dt t. 100mW (20dBm) mximum tnsmit pw. 20 db mdultd ndwidth is 1MHz. Th fllwing sttmnts dsci th typicl intndd pting nvinmnt f th di: Dly Spd A typicl ms dly spd will 20ns giving nmlisd dly spd f 0.06 f 3Mps systm. Dly spds f 100ns will nly ncuntd in ffic spc, which is nt th tgt pting nvinmnt, s hlf spd svic is ccptl und ths cnditins, giving nmlisd dly spd f 0.15 nd 1.5Mps dt t. Pth Lss In 'typicl' ick uilt hus, th pth lss is such tht ng f gt thn 10 mts cnnt guntd, givn tnsmittd pw f 20dBm nd civ snsitivity f -85dBm. In 'typicl' tim cnstuctd hus, th pth lss is gnlly lw nd s ng is incsd. Expimntl vidnc suggsts ths ssumptins vlid, lthugh pth lss pdictins ntiusly inxct scinc. Th dly spds lw in sidntil nvinmnt s th pth lss is quit high v ltivly sht distnc. This is in cntst t n ffic nvinmnt which hs gt distncs f pn spc, s th civ is sujctd t ys with gt pw nd lng dlys. Simultin nd xpimntl wk futh invstigting th pfmnc f th ind chnnl will dscid in lt pt. 4
F HP Intnl Us Only 3.2 Ovviw f Rdiwv Ppgtin E Mchnisms Th di ppgtin nvinmnt limits th pfmnc f di systms. Signls iv t th civ vi sctting mchnism. Th xistnc f multipl ppgtin pths with diffnt tim dlys, ttnutins nd phss givs is t highly cmplx, tim vying tnsmissin chnnl. It is ncssy t chctis th ntu f th chnnl in d t dtmin hw mdultin schm will pfm. Th num f mchnisms which xist in th di ppgtin chnnl which cn cus s in multilvl dmdult. Ths listd lw:- Thml nis Fst fding Rndm FM Tim dispsin It is imptnt t xcis cutin whn ttiuting s t ch f ths mchnisms s thy nt ntily indpndnt pcsss. All f ths ffcts sult f th sctting mchnism f th di ppgtin chnnl. Hwv, cnsidl insight int th pfmnc f th systm cn gind y stting with chnnl which cntins n mchnisms, nd thn dding ch in tun t stlish it's ltiv imptnc. Th pfmnc f th 16-DAPSK civ will nlysd in this wy in th fllwing sctin. 3.3 Pfmnc Anlysis f 16-DAPSK Nw cnsid th mchnisms which limit th pfmnc f 16-DAPSK di. Ech f th mchnisms listd v will ddd in tun t th nlysis. 3.3.1 Thml Nis This psnts th s cusd y th ductin in signl stngth du puly t pth lss. Th mchnism h is th intductin f dditiv whit Gussin nis. Th E pfmnc cuv f 16-DAPSK in thml nis 1 is shwn in figu 3.3-1. Fm this cuv, it is pssil t dfin th snsitivity f th civ. If n vg it pility f 10-3 is dfind s th wst t ccptl, thn th cuv shws tht n E f 15dB is quid t th civ. Nw dtmin th civd signl pw tht cspnds t n E f 15dB. It is knwn tht: S N = E N. R B (3.3-1) E N db = SdBW 10. lg(ktb) 10. lg(nf)+10. lg(b) 10. lg(r) (3.3-1) E N db = SdBm+99 db NF = 10dB (3.3-1) R = 3Mps 5
t y i il p i t g v A F HP Intnl Us Only 1 0.1 0.01 0.001 1 10 4 1 10 5 0 10 20 30 40 50 Pfmnc in thml nis E (db) Figu 3.3-1 Pfmnc f 16-DAPSK in AWGN S, civd signl pw f -85dBm sults in n vg it t f 10-3 nd is thf th snsitivity limit f th civ. Figu 3.3-2 shws th mpping twn E nd civd signl stngth. An upp limit cn plcd n th civd signl stngth. Th tnsmittd pw is 20dBm nd th cupling cfficint f tw istpic dits is 38dB. S, th civd pw will nv gt thn -20 dbm. This dfins th quid dynmic ng f th civ t 65dB. Rciv snsitivity Dynmic ng f th civ 0 10 20 30 40 50 60 70 80 E (db) -100-90 -80-70 -60-50 -40-30 -20 Rcivd Pw (dbm) Figu 3.1-2 E t civd pw mpping A chnnl cntining nly AWGN is th idl pting nvinmnt f di civ. Oth chnnl ffcts will nw cnsidd. Th jctiv is t dtmin hw much ths ddd ffcts wsn th pfmnc f th civ ynd th -85dBm thticl nis pfmnc limit. 6
p g v A F HP Intnl Us Only 3.3.2 Fst Fding Ryligh fding is n intfnc mchnism which sults fm th cnstuctiv nd dstuctiv suppsitin f di wvs. Ryligh fding ffcts th mgnitud nd phs f civd signl. Th civd signl pw vitin hs th sttistics f Ryligh ndm vil. Th phs ngl vitin is unifmly distiutd. In chnnl cntining nly thml nis, givn signl stngth pducs n E which hs cspnding vg BER. In chnnl which fds with Ryligh sttistics, th instntnus signl stngth my vy y up t 40dB. Duing fds, th t incss dmticlly cus f th wsnd E, in dp fds th signl stngth my dp lw th civ snsitivity limit. Cnsquntly, fding chnnl with th sm vg civd pw s n AWGN chnnl will suff m s. Altntivly, th vg signl stngth ndd t chiv givn BER in fding is gt thn th signl stngth ndd t chiv tht BER in nis ln. As E dput is th mchnism, incsing th tnsmittd pw cn duc th t 2 cusd y this mchnism. Th t f chng f nvlp nd phs fluctutin is functin f th nmlisd Dppl shift. Th Dppl shift is givn y qutin (3.1-2):- f d = f c. v d c = 300 Mm/s Spd f light (3.3-2) f d = 16Hz f c c v d = 2 m/s Mx spd f mvmnt = 2400 MHz ci fquncy (3.3-2) As th syml t is 750 kud, th nmlisd dppl, f d.t s is 2.4.10-5. This is ngligily smll nd s qusi-sttiny Ryligh fding ccus. Th pfmnc f qusi-sttiny Ryligh is dscid y Ryligh fding cuv, with nmlisd Dppl f z 3. Figu 3.3-3 clly shws tht th vg signl stngth ndd t chiv pticul BER in fding chnnl is gt thn tht in chnnl cntining nly AWGN. 1 0.1 ytili ti 0.01 0.001 1 10 4 1 10 5 0 10 20 30 40 50 E (db) Pfmnc in qusi-sttiny fding Pfmnc in thml nis Figu 3.3-3 Pfmnc f 16-DAPSK in Qusi-sttiny Ryligh Fding 7
p g v A F HP Intnl Us Only 3.3.3 Rndm FM Ryligh fding ls intducs phs fluctutins, ndm FM. Th gtst t f phs chng ccus t th ttm f fds. Hwv, unlik th pvius mchnism, it isn't pssil t incs th tnsmit pw t duc th fd dpth nd thf impv th t. Incsing th tnsmittd pw will incs th civd pw t th ttm f fd, ut th munt f phs chng t th ttm f th fd will unffctd. Cnsquntly, ndm FM sults in n iducil t, which is unchngd with incsing signl stngth. Th iducil t wsns with incsing nmlisd Dppl. This is cus th fquncy f fding is dtmind y th Dppl t. S, th high th Dppl, th m ftn fds nd thf pid phs chngs ccu. Figu 3.3-4 shws th pfmnc f 16-DAPSK with incsing lvls f nmlisd Dppl 1. 1 0.1 y tili ti 0.01 0.001 1 10 4 1 10 5 0 20 40 60 80 100 E (db) FdT = 0.03 (Nmlisd Dppl) FdT = 0.01 FdT = 0.003 FdT = 0.001 Figu 3.3-4 Pfmnc f 16-DAPSK in Ryligh Fding Th iducil ntu f s cusd y ndm FM is clly shwn in Figu 3.3-4. As th nmlisd Dppl in th ind chnnl is significntly lw th vlus plttd n this gph, th iducil du t ndm FM will nv chd. S, th cuv du t Ryligh fding in th ind chnnl hs n ndm FM inducd iducil. Cnsquntly, n incs in signl stngth lwys yilds n impvmnt in t. 3.3.4 Divsity Rcptin in Ryligh Fding Divsity cptin is pwful mns f mitigting th ffcts f Ryligh fding. Th pvius tw sctins cnclud tht signl stngth fluctutin is th dminting mchnism s fding in th ind chnnl is qusi-sttiny. Using tw nch divsity will sult in n svd signl stngth nvlp which hs fw dp fds. S, f th sm vg E with 2 nch divsity th fw usts du t dp fding. 8
n t p g v A F HP Intnl Us Only Figu 3.3-5 shws tht slcting th tt f tw Ryligh fding nvlps sults in n svd signl stngth which hs fw dp fds. This cts t duc th s cusd y dp fding. Figu 3.3-6 clly shws tht dding tw nch divsity in chnnl with qusi-sttiny Ryligh fding tks th pfmnc cuv cls t tht f civ pting in chnnl cntining nly AWGN. 10 0 ht g s l n gi S 10 20 30 40 0 100 200 300 400 500 Osvd signl stngth Fist Ryligh nvlp Scnd Ryligh nvlp tim Figu 3.3-5 Rductin f dp fding thugh divsity cptin 1 0.1 ytili ti 0.01 0.001 1 10 4 1 10 5 0 10 20 30 40 50 E (db) N divsity Tw nch divsity Thml nis Figu 3.3-6 Pfmnc f 16-DAPSK with divsity in qusi-sttiny fding 9
p c u d I F HP Intnl Us Only 3.3.5 Tim Dispsin Tim dispsin in th di chnnl cts t spd th civd ngy in tim. This givs is t int-syml intfnc. Figu 3.3-7 dmnstts th ffct f dly spd n 16-DAPSK systms, withut divsity, nd with tw nch divsity. Th systm simultin includs isd csin chnnl filting with n lph f 0.5, this is tight thn th lph f 0.6 which will implmntd in th l systm. 0.1 ytili ti l 0.01 0.001 1 10 4 1 10 5 0.001 0.01 0.1 1 Nmlisd ms dly spd, d N divsity Tw nch divsity Figu 3.3-7 Iducil ts f 16-DAPSK in dispsiv chnnl Tl 3.3-1 shws hw systm with tw nch divsity wuld pfm. Dt Rt RMS Dly spd Mdultin fmt Nmlisd dly spd Bit pility E t ccptl? 3 Mps 20 ns 16-DAPSK 0.06 2-5 Ys 3 Mps 40 ns 16-DAPSK 0.12 5-4 Ys 3 Mps 100 ns 16-DAPSK 0.3 3-2 N - ckff 1.5 Mps 100 ns DQPSK 0.15 5-4 Ys Tl 3.3-1 A 16-DAPSK mdm with QPSK ckff in dispsiv chnnl Ths iducil ts du t dly spd in th chnnl ssum tht th civ is wking n th iducil fl. This is tu whn th is high signl stngth t th civ. Hwv, t th limit f th civ ng th will lwys gin wh s ing cusd y nis ltd mchnisms s wll s y th dly spd pfmnc f th civ. Pfmnc in this gin will cnsidd nxt. 10
F HP Intnl Us Only 3.3.6 Dminnt mchnisms in th Ind Chnnl Th nlysis in th pvius sctins hs shwn tht tw mchnisms dmint in th ind chnnl. Ths : Fst Fding Tim dispsin Fst fding cuss civd signl stngth fluctutins, this in tun cuss s du t p civd signl stngth. Th cuvs in figu 3.3-6 dsci th t du t this mchnism. As th s ltd t signl stngth, this mchnism ds nt sult in n iducil t. Tim dispsin in th chnnl cuss int-syml intfnc. Incsing th signl stngth cnnt duc th lvl f ISI, s this mchnism sults in n iducil t. Th cuvs in figu 3.3-7 shw th iducil ts du t this mchnism. E mchnisms which nt lvnt in th ind chnnl : Thml nis Dppl inducd ndm FM Th nis pfmnc cuv ln f 16-DAPSK ds nt giv ny insight int th pfmnc f 16-DAPSK in chnnl with qusi-sttiny Ryligh fding. Hwv, signl stngth dput is th mchnism in fst fding nd th nis pfmnc cuv cn usd t dtmin th instntnus BER in qusi-sttiny fding. Rndm FM is sult f Dppl nd sults in n iducil t. Hwv, nmlisd Dppl is insignificnt in th ind chnnl. 3.3.7 Ovll pfmnc cuvs f 16-DAPSK Givn ny pticul vg civd E, it cn gntd y n f tw mchnisms: Fst fding Tim dispsin S, th pility f n du t ith mchnism is givn y th inmil thm nd is illusttd in figu 3.3-8. A it my cctly civd if n is cusd y th fst fding nd tim dispsin. This is n unlikly vnt (P i.p f ) nd it's inclusin cts t duc th implid pility f it. In d t dtmin n upp und n th cmind pility f it, this ffct will ignd. S, th cmind pility f it du t ith mchnism is givn y:- P = P i.p f + P i.(1 P f )+(1 P i ).P f P i = Dispsin pility (3.3-3) P = P i + P f P i.p f P f = Fst fding pility (3.3-3) S, this xpssin cn usd t gnt fmily f vll pfmnc cuvs f 16-DAPSK in incsing lvls f dly spd. 11
p g v A F HP Intnl Us Only Fst fding Pf RX Bit z Suspct Dispsin z TX it z Pi 1 - Pf z E Pf z E 1 - Pi z 1 - Pf z OK Figu 3.3-8 Cmind pility f it givn tw mchnisms Figu 3.3-9 shws tht in th tgt pting nmlisd dly spd f 0.06, th civ wks dwn t n vg civd pw f -82dBm. This is within 3dB f th thticl nis limitd snsitivity. Th civ is wking n th iducil fl dwn t civd pw f -70dBm. F civd pws lw thn this, fst fding ls intducs s. 1 0.1 ytili ti 0.01 0.001 1 10 4 1 10 5 0 10 20 30 40 50 E (db) d = 0.06 (Nmlisd ms dly spd) d = 0.13 d = 0.3 Thml nis Figu 3.3-9 Tw nch divsity 16-DAPSK in dispsiv, qusi-sttiny chnnl It is nw pssil t dsci th pdictd pfmnc f th systm givn num f chnnl cnditins. Cnsid ch cnditin in tun: Gd civd signl stngth (>-70dBm) nd nml ms dly spd (<20ns) 12
F HP Intnl Us Only This chnnl is likly t fund in sidntil uilding, up t 10 mts fm th tnsmitt. It is xpctd tht this wuld th mst cmmn pting cnditin f th civ. Th civ is wking n th iducil fl, with n t f 2.10-5, this t is quit stisfcty. P civd signl stngth (<-70dBm), nml ms dly spd (20ns). As th distnc fm th tnsmitt incss t 20 mts, th civd signl stngth my stt t dp lw -70dBm. Hwv, th ms dly spd is unlikly t is v 20ns. Th civ is n lng wking n th iducil fl. Fst fding nw cntiuts t th vll t. Th t iss t 10-3 whn th vg civd pw is -82 dbm. S, f this munt f dly spd, th civ wks dwn t within 3dB f th thticl snsitivity limit in nis. Th incsd t wuld sult in thughput hit. It is xpctd tht th s wuld usty, cusing pckts t lst. Th implictins f this n th cding will cnsidd in lt sctin. Any signl stngth, incsd ms dly spd (40ns). It is pssil, ut unlikly tht s f dly spd f this mgnitud will xist in th ind sidntil nvinmnt. It is mst likly t sn whn th civ is wll sptd fm th tnsmitt, nd is likly t ccmpnid y p civd signl stngth. Th civ wks n th iducil fl dwn t civd pw f -75dBm, with n iducil t f 5.10-4. F civd pw lw -75dBm, fst fding cntiuts t th t. Th t chs 10-3 t civd pw f -78dBm. S, th link will pvid stisfcty pfmnc. Any signl stngth, high ms dly spd (100ns). This cnditin is unlikly t fund in sidntil chnnl. It my fund if th systm w ptd in n ffic nvinmnt, with lg pn pln spcs f m thn 50 mts in lngth. Und ths cnditins th 16-DAPSK 3Mps systm pducs n iducil f 6.10-3, which is unccptl. Th systm wuld thn ck ff t DQPSK mdultin with 1.5Mps dt t, hlving th nmlisd dly spd. This sults in n iducil t f 5.10-4. This t cms ws thn 10-3 whn th vg civd pw is -78 dbm. S, svic is mintind t hlf th dt t. This is cnsidd ccptl s th civ is nt lly intndd f this pting nvinmnt. 13
F HP Intnl Us Only 4. MAC Ly Issus - E Cntl f Asynchnus nd Multimdi Svics Stg tw pducts ff th synchnus nd l tim dt svics. Ths vius typs f svic qui num f diffnt ptctin mthds. Th ind di chnnl sults in usty s. This mns tht gnlly, pckt is civd ntily withut, th nti pckt is highly in. This mns FEC cding within n pckt hs littl vlu. On tnsmit pckt will hv lngth f ppximtly 1ms. This undstnding f th di chnnl is imptnt s it llws th mst pppit cntl schm t chsn f ch f th tnsmittd dt typs. Nw cnsid th quimnts f ch f th svic typs:- Asynchnus (Fil tnsf) Fm tnsmit ARQ is suitl f synchnus dt s th n l tim cnstints n th ivl tim f th dt. Nwnd Ischnus (Rl tim vic / tlphny) F vic tlphny, th is tight tim cnstint, n nd t nd dly f lss thn 10ms is quid. Givn th 1ms pckt lngth, n ARQ ptcl culd ptntilly ptd h. If svl tnsmits unsuccssful, th pckt is thn dppd s th dt hs n vlu nc nth smpl fm th vic cd hs ivd. Th nd t nd dt t is vy lw, 32kps.. Bdnd Ischnus (Vid / CD qulity udi) CD-ROM plys cpl f stming dt ut t th fllwing ts: Singl Spd Dul Spd Qud Spd 1.2 Mps 2.4 Mps 4.8 Mps Tl 2.2 CD-ROM utput dt t Th singl spd CD-ROM stndd ws dsignd t nsu it culd stm ut MPEG, which pducs 1.2Mps cntinuus t dt. It will num f ys f th MPEG2 stndd, quiing 4.8Mps will cm vill. MPEG ncdd dt cn d ut f ply t ith vil fixd t. Dcding MPEG ntully sults in vil t dt stm. This is cus diffnt scn imgs nd ts f chng f img sult in diffnt lvls f cmpssin. Hwv, mst ntwks cnnt hndl vil t dt, s MPEG plys gnlly pt in thi cntinuus t md. In this md, n utput uff is usd, vil t dt fills this uff whilst it is d ut t th ntwk t th 1.2Mps cntinuus t. This intducs tim dly. S pviding th ltncy intducd y th di link is ngligil in cmpisn t this dly, nd t nd pfmnc will unffctd. Clly thn, th thughput css th di link must t lst 1.2Mps. Givn th ppsd n i t is 3Mps, it shuld pssil t suppt this with s. Evn pckt tnsmit ARQ schm wuld intduc lss thn 10ms dly, which is tivil cmpd t th dly intducd y th utput uff in th MPEG dcd itslf. 14
F HP Intnl Us Only 5. Cnclusins This pt hs dscid th cmmunictin mds quid f stg tw Pncm systm. An nlysis f 16-DAPSK pfmnc hs dmnsttd tht this mdultin fmtin my pvid stisfcty pfmnc in n ind sidntil chnnl whn cmind with tw nch divsity cptin. Th simultin wk psntd ssums pst dtct cmintin divsity. In pcticl systm switchd divsity wuld usd s it quis nly n civ chin. It is ncssy t stlish if th pfmnc f switchd divsity is cmpl with pst dtct cmintin divsity. As th chnnl is qusi-sttiny, it is pssil tht th pfmnc dgdtin will miniml. Th chctistics f th sidntil ind chnnl hv n cnsidd. It hs n suggstd tht th chnnl xhiits qusi-sttiny Ryligh fding, with mdst lvls f ms dly spd. Th mchnisms in th chnnl thf :- Fst fding Tim dispsin Anlysis hs dmnsttd tht 3Mps 16-DAPSK mdm cmind with tw nch divsity culd ptntilly yild stisfcty pfmnc in chnnl such s this. In s f gd signl stngth, th t f th civ is dtmind y th iducil gntd y dispsin in th chnnl. In s f p civd signl stngth, th t hs cntiutin fm fst fding s wll s tim dispsin. Th cding implictins f diffnt cmmunictin svics w thn cnsidd. Th quid cmmunictin svics cn ctgisd s fllws:- Asynchnus (Fil tnsf) Nwnd ischnus (Rl tim vic / Tlphny) Bdnd ischnus (Vid / CD qulity udi) It ws cnsidd fsil t suppt ll ths typs f tffic with th ppsd di systm. Rl tim svics such s tlphny hv lw thughput quimnt. Nn-ltim svics such s vid hv much gt thughput quimnt, ut lss stingnt dlivy tim nds. This is cus uffing cn usd t vcm jitt intducd y th cctin mchnism in th ntwk. 6. Rfncs 1. R.J. Cstl, "A Rpid Rspns Multilvl Diffntil Mdm f Nwnd Mil Fding Chnnls", PhD thsis, Univsity f Bistl, Oct 1993, pp. 70-73. 2. K. Fh, "Wilss Digitl Cmmunictins", Pntic-Hll, pp.78-79. 3. Y.C. Chw, A.R. Nix & J.P. McGhn, "Thticl nd Simultd Evlutin f 16-DAPSK in Mil Fding Chnnls", 43th IEEE Vhicul Tchnlgy Cnfnc, pp. 120-124, July 1993. 4. Y.C. Chw, A.R. Nix & J.P. McGhn, "E Pfmnc f cicul 16-DAPSK in Fquncy-Slctiv Ryligh Fding Chnnls with Divsity Rcptin.", 45th IEEE Vhicul Tchnlgy Cnfnc, pp. 419-423, July 1995. 15
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