EMLAB Modeling of Digital Communication Systems using Simulink Chap.13 Simulink Examples 13.3 Spread Spectrum 13.4 Antenna Nulling

EMLAB 1 간섭이 없는 AWGN 환경에서 spread spectrum 을 이용한 BPSK 13.3 Spread Spectrum Spread Spectrum Simulink Model without In-Band Interference BPSK signal; sampling time: 1s Spread spectrum; sampling time: 0.1s

EMLAB Spread Spectrum Simulink Model without In-Band Interference (cont’d) Received signal – BPSK Demodulated signal Transmitted signal Transmitted signal – BPSK Modulated signal Transmitted signal – BPSK Spread Spectrum signal AWGN 에서 BPSK 의 이론적 에러율을 계산해보면 (E b /N 0 =3dB 일 때 ) 에러 개수를 100 개로 제한하고, E b /N 0 =3dB 일 때 시뮬레이션 한 결과는 → 차이가 거의 없음 → spreading 이 BER 특성에 미 치는 영향이 없음.

EMLAB 3 대역 내 간섭이 있는 경우 Spread Spectrum Simulink Model with In-Band Interference 1kHz, 1V p_p, 30V p_p 비교 Spread spectrum; sampling time: 0.01s, 0.001s 비교

EMLAB 4 Spectrum Analyzer 결과 Spread Spectrum Simulink Model with In-Band Interference (cont’d) Spread Spectrum BPSK 잡음 진폭 : 1V p_p

EMLAB Spread Spectrum Simulink Model with In-Band Interference (cont’d) Transmitted Signal: 100 chips/bit Despread Signal: 100 chips/bit 잡음 진폭 : 1V p_p

EMLAB Spread Spectrum Simulink Model with In-Band Interference (cont’d) Transmitted Signal: 1000 chips/bit Despread Signal: 1000 chips/bit

EMLAB Spread Spectrum Simulink Model with In-Band Interference (cont’d) Transmitted Signal: 1000 chips/bit Despread Signal: 1000 chips/bit BPSK Spread Spectrum signal Spread Spectrum signalTransmitted Signal – Before BPSK Modulated Received Signal – BPSK Despread

EMLAB Spread Spectrum Simulink Model with In-Band Interference (cont’d) 잡음 진폭 : 60V p_p Transmitted Signal: 100 chips/bit Received Signal: 100 chips/bit

EMLAB 9 RLS 필터를 사용하여 간섭을 상쇄시킴 Spread Spectrum Simulink Model with In-Band Interference and Excision filter length=32, forgetting factor=1, initial input variance=0.1

EMLAB 10 잡음 진폭 : 60V p_p, RLS filter 적용 Spread Spectrum Simulink Model with In-Band Interference and Excision (cont’d) Received Signal: 100 chips/bit RLS 에러 진폭

EMLAB Antenna Nulling

EMLAB Antenna Nulling (cont’d)

EMLAB 13 앞의 관계식을 이용하면 13.4 Antenna Nulling (cont’d)

EMLAB 13.4 Antenna Nulling (cont’d) 14 S/I = 0dB 일 때 송신 신호 잡음 신호 잡음 신호 위상차 복조

EMLAB 15 가중치 계산 부 13.4 Antenna Nulling (cont’d)

EMLAB 16 S/I = 0dB, 10dB 일 때 – 모두 에러가 없음을 확인 Antenna Nulling (cont’d)