Multipath Interference Characterization in Wireless Communication Systems

Transcription

1 Muliph Inrfrnc Chrcrizion in Wirl Communicion Sym Michl ic BYU Wirl Communicion Lb 9/9/ BYU Wirl Communicion 66

2 Muliph Propgion Mulipl ph bwn rnmir nd rcivr Conruciv/druciv inrfrnc Drmic chng in rcivd ignl mpliud nd ph rul of mll chng λ/ in h pil prion bwn rcivr nd rnmir. For Mobil rdio cllulr, PCS, c h chnnl i im-vrin bcu moion bwn h rnmir nd rcivr rul in propgion ph chng. Trm: yligh Fding, ic Fding, Fl Fding, Frquncy Slciv Fding, Slow Fding, F Fding. Wh do ll h mn? 9/9/ BYU Wirl Communicion 67

3 LTI Sym Modl h r h δ δ δ lin-of-igh propgion muliph propgion r lin-of-igh componn muliph componn 9/9/ BYU Wirl Communicion 3 68

4 9/9/ BYU Wirl Communicion 4 Som Imporn Spcil C All h dly r o mll nd w pproim for ll r um of compl rndom numbr rndom mpliud nd ph if i lrg nough, hi um i wll pproimd by compl Guin pdf, ~, ~ I I m m { } { } { } [ ] π π, ~ whn U E E E E m 69

5 9/9/ BYU Wirl Communicion 5 Som Imporn Spcil C All h dly r o mll nd w pproim for ll [ ] [ ] r I I φ X X r I φ φ, ~ X, ~ X 7

6 9/9/ BYU Wirl Communicion 6 Imporn PDF, ~, ~ u U w W u I u u p X X U w I w p X X W X X on-cnrl Chi-qur pdf ic pdf, ~, ~ u U w W u u p X X U w p X X W X X Chi-qur pdf yligh pdf 7

7 9/9/ BYU Wirl Communicion 7 Bc o Som Imporn Spcil C All h dly r o mll nd w pproim for ll r I φ ic pdf icn fding > r I φ yligh pdf yligh fding 7

8 9/9/ BYU Wirl Communicion 8 Som Imporn Spcil C All h dly r mll nd w pproim for ll φ r I yligh pdf Lin-of-igh wih yligh Fding > φ r I yligh pdf yligh fding 73

9 Mulipliciv Fding In h p wo mpl, h rcivd ignl w of h form φ r F Th fding h form of rndom nuion: h rnmid ignl i muliplid by rndom vlu who nvlop i dcribd by h ic or yligh pdf. Thi i omim clld mulipliciv fding for h obviou ron. I i lo clld fl fding inc ll pcrl componn in r nud by h m vlu. 9/9/ BYU Wirl Communicion 9 74

10 An Empl H h δ δ πf f f co πf H H f h r S f f H f db f S f W W f f???? W??? W? f log log f 9/9/ BYU Wirl Communicion 75

11 Empl coninud i vry mll S f h r S f f H f nuion i vn cro h ignl bnd i.. chnnl rnfr funcion i fl in h ignl bnd f W W f f W W f i vry lrg S f H f nuion i unvn cro h ignl bnd -- hi cu frquncy lciv fding f W W f f W W f 9/9/ BYU Wirl Communicion 76

12 Anohr imporn pcil c Th dly r ll diffrn: < < < r inrymbol inrfrnc if h dly r long nough, h muliph rflcion r rolvbl. 9/9/ BYU Wirl Communicion 77

13 Two common modl for non-mulipliciv fding Tpd dly-lin wih rndom wigh 3 r Addiiv compl Guin rndom proc r ξ cnrl limi horm: pproimly Guin P 9/9/ BYU Wirl Communicion 3 78

14 Muliph Inniy Profil Th chrcrizion of muliph fding ihr fl mulipliciv or frquncy lciv non-mulipliciv i govrnd by h dly: mll dly fl fding mulipliciv fding lrg dly frquncy lciv fding non-mulipliciv fding Th vlu of h dly r qunifid by h muliph inniy profil S uncorrld cring US umpion hh powr S *, E h h S δ S { } E h { }. mimum c dly or muliph prd T m. vrg dly 3. dly prd or or 9/9/ BYU Wirl Communicion 4 79

15 Chrcrizion uing h muliph inniy profil S. mimum c dly or muliph prd T m powr Compr Compr muliph muliph prd prd T T m wih m wih ymbol ymbol im im T T : : T T m < m < T T fl fl fding fding frquncy frquncy nonlciv nonlciv fding fding T T m > m > T T frquncy frquncy lciv lciv fding fding. vrg dly 3. dly prd or or 9/9/ BYU Wirl Communicion 5 8

16 Spcd Frquncy Corrlion Funcion S f powr Fourir Xform f f Compr Compr cohrnc cohrnc bndwidh bndwidh f f wih wih rnmid rnmid ignl ignl bndwidh bndwidh W: W: f f > > W fl fl fding fding frquncy frquncy nonlciv nonlciv fding fding f f < < W frquncy frquncy lciv lciv fding fding f i h corrlion bwn h chnnl rpon o wo ignl funcion of h frquncy diffrnc bwn h wo ignl. Wh i h corrlion bwn rcivd ignl h r pcd in frquncy f f -f? Cohrnc bndwidh f iicl mur of h rng of frqunci ovr which h chnnl p ll pcrl componn wih pproimly qul gin nd linr ph. quion 8-3 r commonly ud rlionhip bwn dly prd nd cohrnc bndwidh 9/9/ BYU Wirl Communicion 6 8

17 Tim Vriion Imporn Imporn Aumpion Aumpion Muliph Muliph inrfrnc inrfrnc i i pil pil phnomnon. phnomnon. Spil Spil gomry gomry i i umd umd fid. fid. All All crr crr ming ming up up h h chnnl chnnl r r ionry ionry whnvr whnvr moion moion c, c, h h mpliud mpliud nd nd ph ph of of h h rciv rciv ignl ignl rmin rmin conn conn h h chnnl chnnl ppr ppr o o b b im-invrin. im-invrin. Chng Chng in in muliph muliph propgion propgion occur occur du du o o chng chng in in h h pil pil locion locion of of h h rnmir rnmir nd/or nd/or rcivr. rcivr. Th Th fr fr h h rnmir rnmir nd/or nd/or rcivr rcivr chng chng pil pil locion, locion, h h fr fr h h im im vriion vriion in in h h muliph muliph propgion propgion propri. propri. compl gin nd ph hif r funcion of pil locion. h ; δ lin-of-igh propgion δ δ muliph propgion 9/9/ BYU Wirl Communicion 7 8

18 Spilly Vrying Chnnl Impul pon chnnl impul rpon chng wih pil locion gnrliz impul rpon o includ pil informion h ; h h ; Trnmir/rcivr moion cu chng in pil locion Th lrgr, h fr h r of chng in h chnnl. Auming conn vlociy v, h poiion i could b chngd o im i uing /v. 9/9/ BYU Wirl Communicion 8 83

19 9/9/ BYU Wirl Communicion 9 Gnrliz h Muliph Inniy Profil { } { } *, δ h E S S h h E hh { } { } { } { } h h E S h h E S h h E S S h h E hh ; ; ; ; ;, ; ; ;, ;, ; ; ;, ;, * * * * δ From bfor Th gnrlizion US umpion US umpion v / WSS umpion hi funcion i h y o h WSSUS chnnl 84

20 A loo S; S ; S ; S S S ; S 9/9/ BYU Wirl Communicion 85

21 Tim Vriion of h Chnnl: Th Spcd-Tim Corrlion Funcion S ; S ; d ingr long dly i 9/9/ BYU Wirl Communicion 86

22 Tim Vriion of h Chnnl: Th Spcd-Tim Corrlion Funcion T pcifi h n o which hr i corrlion bwn h chnnl rpon o inuoid n im nd h rpon o imilr inuoid im. Cohrnc Tim T i mur of h pcd im durion ovr which h chnnl rpon i nilly invrin. Slowly vrying chnnl hv lrg T nd rpidly vrying chnnl hv mll T. 9/9/ BYU Wirl Communicion 87

23 9/9/ BYU Wirl Communicion 3 -minion of pcil c [ ] r [ ] [ ] r compl Guin V v / compl Guin ndom Proc wih uocorrlion { } E * From bfor Th gnrlizion 88

24 Commonly Ud Spcd-Tim Corrlion Funcion Tim Invrin Lnd Mobil J < < J π v λ Eponnil v π λ Guin cngulr v π λ v in π λ v π λ 9/9/ BYU Wirl Communicion 4 89

25 Chrcrizion of im vriion uing h pcd-im corrlion funcion T F Fding T < T corrld chnnl bhvior l l hn ymbol fding chrcriic chng mulipl im during ymbol pul hp diorion Slow Fding T > T corrld chnnl bhvior l mor hn ymbol fding chrcriic conn during ymbol no pul hp diorion rror bur 9/9/ BYU Wirl Communicion 5 9

26 Dopplr Powr Spcrum Frquncy Domin Viw of Tim-Vriion S ν Fourir Xform T f d ν Tim vriion on h chnnl r vidncd Dopplr brodning nd prhp, in ddiion Dopplr hif of pcrl lin. Dopplr powr pcrum Sν yild nowldg bou h pcrl prding of inuoid impul in frquncy in h Dopplr hif domin. I lo llow u o gln how much pcrl brodning i impod on h rnmid ignl funcion of h r of chng in h chnnl. Dopplr Sprd of h chnnl f d i h rng of vlu of ν ovr which h Dopplr powr pcrum i nilly non zro. 9/9/ BYU Wirl Communicion 6 9

27 Dopplr Powr Spcrum nd Dopplr Sprd S ν Compr Compr Dopplr Dopplr Sprd Sprd f d f wih d wih rnmid rnmid ignl ignl bndwidh bndwidh W: W: f d ν f d f > d > W f f fding fding f d f < d < W low low fding fding quion 8 - r commonly ud rlionhip bwn Dopplr prd nd cohrnc im 9/9/ BYU Wirl Communicion 7 9

28 Tim Invrin Lnd Mobil J Eponnil ordr Burworh Common Dopplr Powr Spcr S ν δ ν S ν ν ν S v π v / λ / λ ν v / λ S ν S ν S ν S ν ν ν ν Guin cngulr S S ν ν π v / λ ν λ v / λ v / v / λ < ν < v / λ ohrwi S ν ν ν 9/9/ BYU Wirl Communicion 8 93

29 Puing i ll oghr S ; Fourir rnform f S f ; pcd-frquncy, pcd-im corrlion funcion f f pcd-frquncy corrlion funcion f T pcd-im corrlion funcion f S Fourir rnform Fourir rnform S ν muliph inniy profil powr Dopplr powr pcrum ν S ; ν dν S ; ν d f d S ; ν cring funcion 9/9/ BYU Wirl Communicion 9 94

30 Scring Funcion S ; ν dly frquncy ν 9/9/ BYU Wirl Communicion 3 95

31 frnc John Proi, Digil Communicion, Third Ediion. McGrw-Hill. Chpr. Willim J, Edior, Microwv Mobil Communicion. John Wily & Son. Chpr. Willim Y. C. L, Mobil Cllulr Communicion, McGrw-Hill. Pron, J. D., Th Mobil dio Propgion Chnnl, John Wily & Son. Brnrd Slr, yligh Fding Chnnl in Digil Communicion ym Pr I: Chrcrizion, IEEE Communicion Mgzin, July 997, pp Pr Bllo, Chrcrizion of ndomly Tim Vrin Linr Chnnl, IEEE Trncion on Communicion Sym, vol., no. 4, Dcmbr 963, pp H. Clr, A Siicl Thory of Mobil dio cpion, Bll Sym Tchnicl Journl, vol. 47, no. 6, July-Augu 968, pp M. J. Gn, A Powr-Spcrl Thory of Propgio9in in h Mobil dio Environmn, IEEE Trncion on Vhiculr Tchnology, vol. VT, Fbrury 97, pp , 9/9/ BYU Wirl Communicion 3 96