Spread Spectrum System

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태윤 궉
5 years ago
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1 Wieless Couniaion Channel

2 Conens 전파환경 : 요소 Fee spae popagaion Shadowing Rayleigh/Riean fading Delay spead & Coheen Bandwidh Dopple shif & Coheen ie Reipoiy Popagaion pediion odel Pefoane in fading hannel K.B.Lee 확산대역시스템및코드분할다중접속

3 전파환경 : 요소 Pah Loss (Fee spae popagaion, ) Shadowing Rayleigh/Riean Fading Delay Spead & Coheen Fequeny Dopple Shif & Coheen Tie K.B.Lee 확산대역시스템및코드분할다중접속 3

4 Fee Spae Popagaion A d Reeived Powe: P PG 4 n : R x anenna effiieny n R x anenna gain: G A 4 n p P 4d d Reeived Powe: P PG G 4d P p d A e P P, as fo a fixed G does no hange wih fo a fixed A K.B.Lee 확산대역시스템및코드분할다중접속 4

5 P d P d P d Powe aio(db) 0 log 0 log P d Ex) d d Powe aio 6dB 6dB o d 0d Powe aio 0dB 0dB de 실질적환경: 4 d K.B.Lee 확산대역시스템및코드분할다중접속 5

6 K.B.Lee 확산대역시스템및코드분할다중접속 6

7 Shadowing K.B.Lee 확산대역시스템및코드분할다중접속 7

8 Rayleigh / Riean Fading Rayleigh Fading 의발생 K.B.Lee 확산대역시스템및코드분할다중접속 8

9 K.B.Lee 확산대역시스템및코드분할다중접속 9 Rayleigh Fading - Mulipah fading Sho-e fading Fas fading - Reeived signal i() & q() ae Gaussian.v. ( Cenal lii heoe) db db db o ( ) ( ) ( ) q i A A A A e e A w A e jw j )sin ( )os ( )sin ( sin )os ( os )sin ( sin )os ( os } Re{ )) ( os( ) ( ) (

10 Rayleigh Disibuion e( ) i( )os w q( ) sinw ( )os( w ( )) Coplex nube epesenaion ( ) ~( e ) i( ) jq ( ) ( ) e j ( ) i ( ) q ( ) Envelope of e( ) ( ) an q( ) i( ) Le i i, q i( ), q( ) epesen, q : Gaussian.v. wih P( ) exp( ) : Unifo disibuion : Rayleigh disibuion [0, ) K.B.Lee 확산대역시스템및코드분할다중접속 0

11 E E i q E P( ) 0 P( ) d exp Sho e Rx signal powe of Mean Rx signal powe : E e ( ) : () K.B.Lee 확산대역시스템및코드분할다중접속

12 Riean Fading - Line of sigh, o Doinan signal oponen exiss. e( ) ( )os( ( )) ( )os( ( )) n( ) - Envelope PDF: P ( ) - Riean paaee K los los whee I ( ) is he odified Bessel funion. 0 exp los 0log E los K.B.Lee 확산대역시스템및코드분할다중접속 o los / LOS 0log / Diffuse

13 Delay Spead & Coheene Bandwidh Delay spead (powe delay pofile) Coheen Bandwidh(B) : 상관계수가 0.5 이하가되기위하여필요한 주파수간격 Coelaion a f and f R f S f S f, f f f K.B.Lee 확산대역시스템및코드분할다중접속 3

14 Coelaion oeffiien b g f Cov b g b g S f S f h, Sb fg Sb fg Co b g b g S f S f h b g b g, E S f E S f e j Sb fg b g b g b g b g 0 R f S f E S f E S f R f S f R b g b g b g b g S f K.B.Lee 확산대역시스템및코드분할다중접속 4

15 Coheen bandwidh fo apliude B ; fo AM Open Aea : 0.s B 800KHz Sububan : 0.5s B 300KHz : s delay spead Coheen bandwidh fo phase B ; 4 fo FM/PM Wideband vs. aowband CDMA vs. TDMA K.B.Lee 확산대역시스템및코드분할다중접속 5

16 Dopple Spead & Coheen Tie Desibe he ie vaying naue of he hannel (Vehile oveen...) Dopple Spead (f d ) : A easue of speal boadening - When he Tx signal feq = f, he Rx signal feq = (f - f d ) ~ (f + f d ) - f d : funion of f, q, veloiy, ( V ). K.B.Lee 확산대역시스템및코드분할다중접속 6

17 Coheene ie(t) : ie duaion ove whih wo x signal have a song apliude oelaion f is he axiu fd T f, 9 6f, f Ineleaving K.B.Lee 확산대역시스템및코드분할다중접속 7

18 Channel Model 0 Channel Ipulse Funion 0 Channel Repesenaion 0 0 ( ) K.B.Lee 확산대역시스템및코드분할다중접속 8

19 ITU-R Channel ITU-R Vehiula Channel Speifiaion Tap Channel A Channel B Dopple Relaive Avg. Powe (db) Relaive Avg. Powe (db) Speu Delay(nse) Delay(nse) (48.5%) (3.3%) CLASSIC (38.5%) (57.4%) CLASSIC (6%) (3%) CLASSIC (4.9%) (6%) CLASSIC (.5%) (0.%) CLASSIC (0.5%) (.4%) CLASSIC K.B.Lee 확산대역시스템및코드분할다중접속 9

20 Popagaion pediion odel Okuua 모델 Haa 모델 Lee 모델 Longley - Rie 모델 Cos - 3 Haa 모델 Ray - Taing 모델 K.B.Lee 확산대역시스템및코드분할다중접속 0

21 Okuua 모델 - 실측값을바탕으로전파감쇠중앙값예측곡선도시 다양한전파환경과지형의보정인자 기지국, 이동국유효안테나높이에따른보정인자 - 경로거리 - Caie fequeny VHF ( 00 MHz ) UHF (453, 9, 30, 430, 90 MHz) K.B.Lee 확산대역시스템및코드분할다중접속

22 - 주위환경 : Uban, Sububan, Open aea(ual aea) - 지형 Quasi sooh eain Iegula eain ( Rolling-hill eain, Geneal sloped eain, Mixed land-sea,...) - Anenna heigh gain fao K.B.Lee 확산대역시스템및코드분할다중접속

23 - 모델파라메타 주파수 50MHz ~,000MHz 경로거리 k ~ 00k 기지국유효안테나높이 30 ~ 000 (00) 이동국안테나높이 ~ 0 (3) 경로내지형종류 이동국주위환경 준완만지형, 불규칙한지형 도심지, 준시가지, 개방지 K.B.Lee 확산대역시스템및코드분할다중접속 3

24 - 기준전파감쇠중앙값예측 L dbl A f, d H h, d H h f 50 F u u e u e, L 50 L F 손실의 edian value fee spae 손실 A u (f,d) 기준손실중앙값 (w... L F ) H u ( h e, d ) H u ( h e, f ) f d h e, h e 기지국유효안테나높이이득인자이동국유효안테나높이이득인자주파수경로거리유효안테나높이 K.B.Lee 확산대역시스템및코드분할다중접속 4

25 - 예측절차 해당주파수와경로거리, 유효안테나높이를참조하여기준전파감쇠중앙값예측 준완만지형상의도심지에서전파감쇠중앙값을기준값으로설정 (quasi-sooh, uban) 준완만지형상의도심지이외의지역에대한예측은해당보정인자적용 - 한계 : 수식화되지않은예측 K.B.Lee 확산대역시스템및코드분할다중접속 5

26 K.B.Lee 확산대역시스템및코드분할다중접속 6

27 K.B.Lee 확산대역시스템및코드분할다중접속 7

28 Haa 의공식 - Okuua가도출해낸여러예측 Cuve를수식의형태로간소화 - 수식화된예측 Okuua uve 기준전파감쇠중앙값예측곡선주변환경에대한보정인자예측곡선 유효안테나높이이득인자예측곡선 - 수식화되지않은예측 Okuua uve 전파경로대한보정인자 K.B.Lee 확산대역시스템및코드분할다중접속 8

29 - 시가지 L 50 db log a h log h log R 0 f 3.8log 0 b 0 0 h b * 이동국유효안테나높이이득인자 중소도시대도시 a a h.log f 0.7 h.56log f h 8.9 log0.54h.0db, f 00MHz 3. log.75h 4.97dB, f 400MHz 0 - 준시가지 L dbl 시가지 log f 개방지 L dbl 시가지.78log f 8.33log f K.B.Lee 확산대역시스템및코드분할다중접속 9

30 K.B.Lee 확산대역시스템및코드분할다중접속 30 Pefoane in Rayleigh Fading Tx : Rx : ) ( os ) ( ) ( )sin ( )os ( Re )) ( os( os ) ( ) ( q i q i e e A A j j s os ) (

31 Mulipliaive hannel bb g s bb g b g b g e j s e b b g b g b g jbg b K.B.Lee 확산대역시스템및코드분할다중접속 3

32 K.B.Lee 확산대역시스템및코드분할다중접속 3 Sai BPSK : Pob. of eo P Q E e b F H G I K J 0 Fading d dx e P P d Eo P f Eo T Q Eo P T T P E T x b exp = P

33 Le y P b Eo T, hen y PT, d P g = z z 0 y PT O 0 x y y e dxdy O Pdy y sin, x os P b Eo g = z z O an PT 0 0 z z an 0 0 sin e dd PT e d sind F F G H G H F G H 4 b E b O g O PT os an I K ; BPSK O O PT F H G II J K J K J O E b I K J K.B.Lee 확산대역시스템및코드분할다중접속 33

34 FSK ( Coheen deeion ) b g P Eo b g Eb O DPSK ( Diffeenial deoding ) b g P Eo b g Eb O K.B.Lee 확산대역시스템및코드분할다중접속 34

35 K.B.Lee 확산대역시스템및코드분할다중접속 35

36 BER of BPSK (linea) E b BER : Pe Q 0 K.B.Lee 확산대역시스템및코드분할다중접속 36

37 K.B.Lee 확산대역시스템및코드분할다중접속 37 Pdf of SR / /, f e SR g f d f d f g d f f d d d d dg d d f e e e E SR f

38 Jensen s Inequaliy - If f is a onvex fn. & is a.v. hen x E{ f ( x)} f ( E{ x}) f (x) onvex - If is a onave fn. & is a.v. hen f x x E{ f ( x)} f ( E{ x}) f (x) onave x

39 Jensen s Inequaliy f(x). E{ f ( x)} f ( E{ x}). = p f ( x ) p f ( x ) = f ( p x p x ) RV : X ( 예) x x x x x pob x x pob x x x ( ) ( ) = ( ) f x f x f E{ f ( x)} f ( E{ x}) x = ( x x ) /

11 주차 M 진디지털변조 (1) 통과대역신호의표현 (2) Quadrature Phase Shift Keying (QPSK) (3) Minimum Shift Keying (MSK) (4) M-ary Amplitude Shift Keying (M-ASK) (5) M-ar

11 주차 M 진디지털변조 (1) 통과대역신호의표현 (2) Quadraure Phase Shif Keying (QPSK) (3) Minimum Shif Keying (MSK) (4) M-ary Ampliude Shif Keying (M-ASK) (5) M-ary Frequeny Shif Keying (M-FSK) (6) M-ary Phase Shif Keying