详解MATLAB Simulink通信系统建模与仿真 随书源码-第4章信道.rar

clear all nSamp = 8; %矩阵脉冲的取样点数 numSymb = 1000000; %每种snr下传输的符号数 ts = 1/(numSymb*nSamp); t = (0:numSymb*nSamp-1)*ts; M=4; %QPSK的符号类型数 SNR=-3:3; grayencod = [0 1 3 2] %Gray编码格式 for ii=1:length(SNR) msg = randsrc(1,numSymb,[0:3]); msg_gr = grayencod(msg+1); msg_tx = pskmod(msg_gr,M); msg_tx = rectpulse(msg_tx, nSamp); h = reyleigh(10,t); msg_tx1=h.*msg_tx; msg_rx = awgn(msg_tx,SNR(ii)); msg_rx1 = awgn(msg_tx1,SNR(ii)); msg_rx_down = intdump(msg_rx,nSamp); msg_rx_down1 = intdump(msg_rx1,nSamp); msg_gr_demod=pskdemod(msg_rx_down,M); msg_gr_demod1=pskdemod(msg_rx_down1,M); [dumay graydecod] = sort(grayencod);graydecod = graydecod - 1; msg_demod = graydecod(msg_gr_demod+1); msg_demod1 = graydecod(msg_gr_demod1+1); [errorBit BER(ii)] = biterr(msg, msg_demod,log2(M)); [errorBit1 BER1(ii)] = biterr(msg, msg_demod1,log2(M)); [errorSym SER(ii)] = symerr(msg, msg_demod); [errorSym1 SER1(ii)] = symerr(msg, msg_demod1); end semilogy(SNR,BER,"-ro", SNR,SER,"-r*",SNR,BER1,"-r.", SNR,SER1,"-r+") legend("AWGN信道BER","AWGN信道SER","Rayleigh衰落+AWGN信道BER","Rayleigh衰落+AWGN信道SER") title("QPSK在AWGN信道和Rayleigh衰落信道下的性能") xlabel("信噪比（dB）") ylabel("误符号率和误码率")