MQAM误码率与误符号率的实带通和复基带matlab仿真

close all,clear,clc; %实带通仿真 for en = -50:1:20 Eb_N0 = en; %信噪比，以dB表示 %Eb_N0 = 15; %信噪比，以dB表示 p = 0.5; %信号中取0的概率 M = 256; %M进制QAM num = 200; %产生num*log2(M)个信号,必须为2的倍数 data_in = rand(1,num*log2(M)); %伪随机数法产生2进制信号 data_in = double(data_in>p); %串并转换 data_Iin = zeros(1,num); %用于记录I路成型脉冲的幅度 data_Qin = zeros(1,num); %用于记录Q路成型脉冲的幅度 data_I = zeros(1/2*log2(M),num); %用于记录I路发出的信息 data_Q = zeros(1/2*log2(M),num); %用于记录Q路发出的信息 for n = 1:log2(M):length(data_in)-log2(M)+1 data_I(:,(n-1)/log2(M)+1) = data_in(n:n+1/2*log2(M)-1)'; count = d2gray(data_in(n:n+1/2*log2(M)-1)); data_Iin(1,(n-1)/log2(M)+1) = -(sqrt(M)-1)/2+count; data_Q(:,(n-1)/log2(M)+1) = data_in(n+1/2*log2(M):n+log2(M)-1)'; count = d2gray(data_in(n+1/2*log2(M):n+log2(M)-1)); data_Qin(1,(n-1)/log2(M)+1) = -(sqrt(M)-1)/2+count; end %发射端成型 shape = rcosfir(0.5,20,20,1,'sqrt'); %根升余弦滤波器 data_IIin = zeros(1,20*length(data_Iin)); for n = 1:length(data_Iin) data_IIin(1,(n-1)*20+1) = data_Iin(1,n); end data_QQin = zeros(1,20*length(data_Qin)); for n = 1:length(data_Qin) data_QQin(1,(n-1)*20+1) = data_Qin(1,n); end data_Iin_shape = conv(data_IIin,shape); %I路成型 data_Qin_shape = conv(data_QQin,shape); %Q路成型 %发射端调制 t = 0:1:length(data_Iin_shape)-1; CI = cos(t*pi/2); CQ = sin(t*pi/2); transmit = CI.*data_Iin_shape - CQ.*data_Qin_shape; %figure %subplot(2,1,1); %plot(transmit((length(shape)+1)/2:(length(shape)+1)/2+99)); %显示的时候去掉延时 %title('transmit wave','fontsize',20); %加入AWGN Es = (M-1)/12*sum(shape.^2); %计算码元平均能量 Eb = Es/(log2(M)); %计算比特平均能量 Eb_N0 = 10^(Eb_N0/10); N0 = Eb/Eb_N0; noise = normrnd(0,sqrt(N0/2),1,length(transmit)); %生成正态分布的噪声 transmit = transmit + noise; %加噪声 %subplot(2,1,2); %plot(transmit((length(shape)+1)/2:(length(shape)+1)/2+99)); %显示的时候去掉延时 %title('transmit wave(with noise)','fontsize',20); %接收端解调与匹配 receiveIRF = transmit.*CI; %I路解调 receive_Ifilter = 2*conv(shape,receiveIRF); %I路匹配 receive_Ifilter = receive_Ifilter((length(shape))/1:(length(shape))/1+length(data_IIin)-1); %去掉延时 %{ figure subplot(2,1,1); plot(receiveIRF((length(shape)+1)/2:(length(shape)+1)/2+99)); title('接收端I路射频波形','fontsize',20); subplot(2,1,2); plot(receive_Ifilter(1:100)); title('接收端I路匹配波形','fontsize',20); %} receiveQRF = -transmit.*CQ; %Q路解调 receive_Qfilter = 2*conv(shape,receiveQRF); %Q路匹配 receive_Qfilter = receive_Qfilter((length(shape))/1:(length(shape))/1+length(data_QQin)-1); %去掉延时 %{ figure subplot(2,1,1); plot(receiveQRF((length(shape)+1)/2:(length(shape)+1)/2+99)); title('接收端Q路射频波形','fontsize',20); subplot(2,1,2); plot(receive_Qfilter(1:100)); title('接收端Q路匹配波形','fontsize',20); %} %匹配信号判决 receiveI = zeros(1,length(data_Iin)); for n = 1:length(receiveI) %取出最佳采样点的信号 receiveI(1,n) = receive_Ifilter(1,(n-1)*20+1); end receiveII = zeros(1/2*log2(M),length(data_Iin)); for n = 1:length(receiveI) count = 0; %计算最佳采样点的格雷码次序 temp = sqrt(M); if receiveI(n)>=sqrt(M)/2-1 count = temp; else temp = temp - 1; for m = sqrt(M)/2-1:-1:-(sqrt(M)/2-2) if receiveI(n)<m && receiveI(n)>=m-1 count = temp; break; end temp = temp - 1; end end if count == 0 count = 1; end count = count - 1; receiveII(:,n) = d2b(count,receiveII(:,n)); %把最佳采样点的电平值转换为二进制信号 end receiveQ = zeros(1,length(data_Qin)); for n = 1:length(receiveQ) %取出最佳采样点的信号 receiveQ(1,n) = receive_Qfilter(1,(n-1)*20+1); end receiveQQ = zeros(1/2*log2(M),length(data_Qin)); for n = 1:length(receiveQ) count = 0; %计算最佳采样点的格雷码次序 temp = sqrt(M); if receiveQ(n)>=sqrt(M)/2-1 count = temp; else temp = temp - 1; for m = sqrt(M)/2-1:-1:-(sqrt(M)/2-2) if receiveQ(n)<m && receiveQ(n)>=m-1 count = temp; break; end temp = temp - 1; end end if count == 0 count = 1; end count = count - 1; receiveQQ(:,n) = d2b(count,receiveQQ(:,n)); %把最佳采样点的电平值转换为二进制信号 end %串并转换 receive = zeros(1,length(data_in)); for n = 1:log2(M):length(data_in)-log2(M)+1 receive(n:n+1/2*log2(M)-1) = receiveII(:,(n-1)/log2(M)+1)'; receive(n+1/2*log2(M):n+log2(M)-1) = receiveQQ(:,(n-1)/log2(M)+1)'; end %data_in(1:10) %receive(1:10) %绘制眼图 %eye_picture(data_Iin_shape(41:length(data_Iin_shape)),20); %title('发射端','fontsize',20); %eye_picture(receive_Ifilter(41:length(receive_Ifilter)),20); %title('接收端','fontsize',20); %计算误符号率和误比特率 % BERI = data_I~=receiveII; BERQ = data_Q~=receiveQQ; ber = (sum(sum(BERI))+sum(sum(BERQ)))/length(data_in);%计算误比特率 if M > 4 SER = sum(BERI) + sum(BERQ); else SER = BERI + BERQ; end SER = SER > 0; ser = sum(SER)/length(SER);%计算误符号率 plot(en,ser,'b.'); hold on; plot(en,ber,'r.'); hold on; end %理论计算误符号率和误比特率 en_theory_db = -50:1:20; en_theory = 10.^(en_theory_db/10); PsI = zeros(1,length(en_theory)); for n = 1:length(en_theory) PsI(n) = 2*(sqrt(M)-1)/sqrt(M)/2*erfc(sqrt(3*log2(M)/(M-1)/2*en_theory(n))); end Ps = 2*PsI-PsI.^2; %计算误符号率 hold on; plot(en_theory_db,Ps,'b','LineWidth',2); Pb = zeros(1,length(en_theory)); %计算误比特率 for n = 1:length(en_theory) Pb(n) = 1/log2(sqrt(M))*PsI(n); end hold on; plot(en_theory_db,Pb,'r','LineWidth',2); legend('PS','PB'); %}