하나의그룹 FH/FDMA 시스템에서 겹쳐지는슬롯수에따른성능분석 구정우 jwku@eve.yonsei.ac.kr 2000. 4. 27 Coding & Information Theory Lab. Department of Electrical and Computer Engineering, Yonsei Univ.
차례 (Contents) 1. 도입 (Introduction) 2. 순방향링크 FH/FDMA System 의송신기 3. 문제제기 4. 모의실험 / 결과분석 5. 결론 Coding and Information Theory Lab. -2-
도입 (Introduction) FH/CDMA 시스템이란? 다중사용자를각각다른주파수도약패턴을 사용해서구분 freq user1 : user2 : user3 : time FH/FDMA 시스템이란? 다중사용자를주파수분할방식으로구분하고 그룹으로묶어서그룹별로도약 freq user1 : user2 : user3 : time Coding and Information Theory Lab. -3-
순방향링크 FH/FDMA system 의송신기 binary data 2-FSK u(t) Mapper (# of users=k) u 1 (t) u 2 (t)... u K (t) j 2 f e 1 e j 2 f e 2 j 2 f t v 1 (t) v 2 (t) K t t... v K (t) s ( t 1 ) 1 s2 ( t 2 )... sk ( t K ) s (t) selector code 1 code 1... code p k 중계기 (transponder) code generator 통신위성체내중계기 (transponder) 의출력단에해당 K 명의사용자신호를동일한도약패턴을사용해서그룹으로전송 Coding and Information Theory Lab. -4-
문제제기 (FDMA Group Hopping) 주파수도약슬롯들의직교를보장했을때수신기의검출개념도 f 7 user1 : f 6 user2 : f 5 hopping pattern f 4 user1 : 1 2 4 3 6 7 5 1 2 4 3 6 7 5 user2 : 2 4 3 6 7 5 1 2 4 3 6 7 5 1 f 3 transmitted data bit f 2 user1 : 0 1 0 1 0 1 0 1 1 1 0 0 1 0 user2 : 0 1 1 0 0 1 0 0 1 1 1 0 1 1 f 1 f 0 0 7T 14T Coding and Information Theory Lab. -5-
문제제기 (FDMA Group Hopping) 주파수도약슬롯들이비직교일경우수신기의검출개념도 user1 : user2 : f 7 f 6 hopping pattern user1 : 1 2 4 3 6 7 5 1 2 4 3 6 7 5 user2 : 2 4 3 6 7 5 1 2 4 3 6 7 5 1 f 5 f 4 f 3 f 2 transmitted data bit user1 : 0 1 0 1 0 1 0 1 1 1 0 0 1 0 f 1 f 0 user2 : 0 1 1 0 0 1 0 0 1 1 1 0 1 1 0 7T 14T => prob(error when a hit occurs) = 1/2 => prob(error when a hit occurs) = 0 Coding and Information Theory Lab. -6-
)( ) (# o ( 사용자 문제제기 (FDMA Group Hopping) 앞의두그림에대한비교 / 분석 구분 직교성보장 직교성무시 user2 에의한 hit 발생안함 발생 사용자수 # of slots 문제제기 한정된주파수도약대역폭 : 주파수도약심볼간의직교성불가능 주파수도약슬롯간의겹침현상 : 동기를잃은사용자에의한 hit 발생 실험을통해성능저하를최소로하는최적의 q값을제안하고자함 Coding and Information Theory Lab. -7-
hopp 9.6 24 total tone 96 9.6 12 48 k 70 9.6 7 smo 24 kh # hoppi of 13 30 or 개 모의실험 / 결과분석 모의실험에적용된파라미터 / 도약패턴 / 실험방법 시스템의주파수도약대역폭에따른직교주파수도약슬롯수 (q ortho ) 구분 2-FSK 4-FSK data rate 주파수도약패턴 (Lempel-Greenberger 방법이용 ) 차수 n = 9 이고, 원시다항식 h(x) = x 9 + x 4 + 1 도약시퀀스특성 : q=2 k (k=3, 4,, 9), L=511, H max (F)=2 9-k, N=2 k Coding and Information Theory Lab. -8-
주도대 29 (M( 30 40 개 70729 1) 120 162 181 개 ) ( 130 # 19 1 29 30 80 23 주도대 (M( 70758 개 ) 240 323 362 개 ) 38 ( 130 39 3 모의실험 / 결과분석 2-FSK 에서주파수도약대역폭과주파수도약패턴심볼의크기에따른겹쳐지는슬롯수 # of overlaping slots, 4-FSK 에서주파수도약대역폭과주파수도약패턴심볼의크기에따른겹쳐지는슬롯수 KM ( q q 1 1) Ref. 겹쳐지는슬롯수 : N KM ortho, ( N 0 인정수) slot slot Coding and Information Theory Lab. -9-
2-FSK 일때성능분석 w ss = 70 MHz 동기를잃은사용자수와겹쳐지는슬롯수에따른결과 Performance Comparison According to # of Asynchronous Users and Overlapping Slots in FH/FDMA (Eb/No=11dB, W ss =70 MHz, L=1, 2-FSK) 198 개 (Q=512) 196 개 (Q=256) 191 개 (Q=128) 181 개 (Q=64) 162 개 (Q=32) 120 개 (Q=16) 29 개 (Q=8) 1.00E-04 0 10 20 30 40 50 60 70 80 # of Asynchronous Users (K') Coding and Information Theory Lab. -10-
K = 32 일때주파수도약심볼크기에따른결과 Performance Comparison According to Symbol Size (Eb/No=11dB, W ss =70 MHz, L=1, 2-FSK, K'=32) 8(29) 16( 120) 32( 162) 64( 181) 128(191) 256(196) 512(198) Symbol Size (q) Coding and Information Theory Lab. -11-
K = 64 일때주파수도약심볼크기에따른결과 Performance Comparison According to Symbol Size (Eb/No=11dB, W ss =70 MHz, L=1, 2-FSK, K'=64) 8(29) 16( 120) 32( 162) 64( 181) 128(191) 256(196) 512(198) Symbol Size (q) Coding and Information Theory Lab. -12-
2-FSK 일때성능분석 w ss = 70 MHz 동기를잃은사용자수와겹쳐지는슬롯수에따른결과 Performance Comparison According to # of Asynchronous Users and Overlapping Slots in FH/FDMA (Eb/No=11dB, W ss =70 MHz, L=1, 2-FSK) 198 개 (Q=512) 196 개 (Q=256) 191 개 (Q=128) 181 개 (Q=64) 162 개 (Q=32) 120 개 (Q=16) 29 개 (Q=8) ( N slot mod 2) ( N slot mod 2) 1 0 1.00E-04 0 10 20 30 40 50 60 70 80 # of Asynchronous Users (K') Coding and Information Theory Lab. -13-
K = 32 일때주파수도약심볼크기에따른결과 Performance Comparison According to Symbol Size (Eb/No=11dB, W ss =70 MHz, L=1, 2-FSK, K'=32) ( N slot mod 2) 1 ( N slot mod 2) 0 8(29) 16( 120) 32( 162) 64( 181) 128(191) 256(196) 512(198) Symbol Size (q) Coding and Information Theory Lab. -14-
K = 64 일때주파수도약심볼크기에따른결과 Performance Comparison According to Symbol Size (Eb/No=11dB, W ss =70 MHz, L=1, 2-FSK, K'=64) ( N slot mod 2) 1 ( N slot mod 2) 0 8(29) 16( 120) 32( 162) 64( 181) 128(191) 256(196) 512(198) Symbol Size (q) Coding and Information Theory Lab. -15-
결과분석 (1) 왜 ( N mod 2) 0 인경우가 ( N mod 2) 1인경우보다성능이우수한가? slot slot 1197 1169 1190 1161 slot number ( Ns) 542 514 371 343 N q3 540 511 370 341 N q2 주파수도약슬롯수 q=8, 사용자수 K=100, user1 이위치한주파수도약슬롯 = q 2 N q2 N q2 200 172 200 171 N q1 N q1 1 29 30 # of overlapping slots ( Nslot ) Coding and Information Theory Lab. -16-
N slot = 29 user1 의슬롯위치 : N s =172(0) or 173(1) user1 을 hit 할가능성이있는사용자의슬롯위치 : user86 (N s =171 or 172) : user87 (N s =173 or 174) p h (K =1) = 2/99 Prob(Async. users exist in q i-1 and user1 exists in q i ) N slot = 30 (( mod 2) 1) N slot (( mod 2) N slot 0) user1 의슬롯 : N s =171(0) or 172(1) user1을 hit할가능성이있는사용자의슬롯 : user86 (N s =171 or 172) p h (K =1) = 1/99 Prob(Async. users exist in q i-1 and user1 exists in q i ) Note : N slot = 30 일때성능우수 Coding and Information Theory Lab. -17-
(2) 왜 N mod 2) 의값이동일할때성능이비슷한가? ( slot q의증가 : # of overlapping slots, N slot 이증가하므로성능저하를가져옴 q의증가 : 주파수도약패턴의 processing gain을증가시키므로성능향상을가져옴 Coding and Information Theory Lab. -18-
w ss = 130 MHz Performance Comparison According to # of Asynchronous Users and Overlapping Slots in FH/FDMA (Eb/No=11dB, W ss =130MHz, L=1, 2-FSK) 196 개 (Q=512) 191 개 (Q=256) 182 개 (Q=128) 162 개 (Q=64) 123 개 (Q=32) 40 개 (Q=16) ( N slot mod 2) 1 ( N slot mod 2) 0 1.00E-04 0 10 20 30 40 50 60 70 80 # of Asynchronous Users (K') Coding and Information Theory Lab. -19-
w ss = 295 MHz Performance Comparison According to # of Asynchronous Users and Overlapping Slots in FH/FDMA (Eb/No=11dB, W ss =295MHz, L=1, 2-FSK) 189개 (Q=512) 178개 (Q=256) 155개 (Q=128) 108개 (Q=64) ( mod 2) 1 N slot ( N slot mod 2) 0 1.00E-04 0 10 20 30 40 50 60 70 80 # of Asynchronous Users (K') Coding and Information Theory Lab. -20-
w ss = 500 MHz Performance Comparison According to # of Asynchronous Users and Overlapping Slots in FH/FDMA (Eb/No=11dB, W ss =500MHz, L=1, 2-FSK) 181 개 (Q=512) 160 개 (Q=256) 120 개 (Q=128) 39 개 (Q=64) ( N slot mod 2) 1 ( N slot mod 2) 0 1.00E-04 0 10 20 30 40 50 60 70 80 # of Asynchronous Users (K') Coding and Information Theory Lab. -21-
4-FSK 일때성능분석 w ss = 70 MHz 동기를잃은사용자수와겹쳐지는슬롯수에따른결과 Performance Comparison According to # of Asynchronous Users and Overlapping Slots in FH/FDMA (Eb/No=8dB, W ss =70 MHz, L=1, 4-FSK) 396개 (Q=512) 391개 (Q=256) 382개 (Q=128) 362개 (Q=64) 323개 (Q=32) 240개 (Q=16) 58개 (Q=8) ( N slot mod 4) ( N slot mod 4) 2,3 0 0 10 20 30 40 50 60 70 80 # of Asynchronous Users (K') Coding and Information Theory Lab. -22-
K = 32 일때주파수도약심볼크기에따른결과 Performance Comparison According to Symbol Size (Eb/No=8dB, W ss =70 MHz, L=1, 4-FSK, K'=32) ( N slot mod 4) 2,3 ( N slot mod 4) 0 8(58) 16( 240) 32( 323) 64( 362) 128(382) 256(391) 512(396) Symbol Size (q) Coding and Information Theory Lab. -23-
K = 64 일때주파수도약심볼크기에따른결과 Performance Comparison According to Symbol Size (Eb/No=8dB, W ss =70 MHz, L=1, 4-FSK, K'=64) ( N slot mod 4) 2,3 ( N slot mod 4) 0 8(58) 16( 240) 32( 323) 64( 362) 128(382) 256(391) 512(396) Symbol Size (q) Coding and Information Theory Lab. -24-
결과분석 (1) 2-FSK와마찬가지로 ( mod4) 0 인경우가 ( N mod4) 2, 3 N slot slot 보다 성능우수 Coding and Information Theory Lab. -25-
w ss = 130 MHz Performance Comparison According to # of Asynchronous Users and Overlapping Slots in FH/FDMA (Eb/No=8dB, W ss =130MHz, L=1, 4-FSK) 391 개 (Q=512) 382 개 (Q=256) 363 개 (Q=128) 324 개 (Q=64) 246 개 (Q=32) 80 개 (Q=16) ( N slot mod 4) 2,3 ( N slot mod 4) 0 0 10 20 30 40 50 60 70 80 # of Asynchronous Users (K') Coding and Information Theory Lab. -26-
w ss = 295 MHz Performance Comparison According to # of Asynchronous Users and Overlapping Slots in FH/FDMA (Eb/No=8dB, W ss =295MHz, L=1, 4-FSK) 378개 (Q=512) 355개 (Q=256) 309개 (Q=128) 216개 (Q=64) 26개 (Q=32) ( mod 4) 1,2, 3 N slot ( N slot mod 4) 0 0 10 20 30 40 50 60 70 80 # of Asynchronous Users (K') Coding and Information Theory Lab. -27-
w ss = 500 MHz Performance Comparison According to # of Asynchronous Users and Overlapping Slots in FH/FDMA (Eb/No=8dB, W ss =500MHz, L=1, 4-FSK) 361 개 (Q=512) 320 개 (Q=256) 240 개 (Q=128) 77 개 (Q=64) ( N slot mod 4) 1 ( N slot mod 4) 0 0 10 20 30 40 50 60 70 80 # of Asynchronous Users (K') Coding and Information Theory Lab. -28-
결론 / 추후연구방향 2-FSK 시스템 ( N mod 2) slot 0 인경우에성능우수 K = 32와 64일때 ( N mod 2) 0인경우가 noncoherent 변조방식을 slot 사용했을때의비슷한 범위를고려한다면, ( N mod 2) 1 대략 1dB 의이득이있음 slot 보다 4-FSK 시스템 ( N mod4) slot 0 ( N mod 4) 0 slot 인경우에성능이가장우수 인경우가다른경우에비해대략 1dB 의이득이있음 Note : M-ary FSK 변조방식을택하는 FH/FDMA 시스템에서는 ( mod M ) 0 만족하는주파수도약슬롯수 q 를선택해야함 N slot 을 위결과에대한정확한성능분석은계속진행되어야함 Coding and Information Theory Lab. -29-