speed_bpsk.m

关于通信基本原理的仿真

%%%%% 基于BPSK扩频仿真实例 %%%%%%%%%%%%
clc;
clear all;
EbN0dB=1:2:9;%设定信噪比
errLimit=50;%比特错误门限
N=100;
SP=4; %扩频因子
speed=rand(1,SP)>0.5;
speed=1-2*speed;
speed=sqrt(1/SP)*speed;    %产生扩频码以及归一化处理
for ii=1:length(EbN0dB)
errCount=0;
totalN=0;
sigma2(ii)=1/(2*(10^(EbN0dB(ii)/10)));
while errCount<errLimit
    source=rand(1,N)>0.5;
    trans=1-2*source;
    for k=1:length(source)
        trans2((k-1)*SP+1:k*SP)=trans(k)*speed;
    end
    receiver=trans2+sqrt(sigma2(ii))*randn(1,N*SP);
    for kk=1:length(source)
        demodata(kk)=sum(receiver((kk-1)*SP+1:kk*SP).*speed);
    end
    data=demodata<0;
    temp=sum(abs(source-data));
    errCount=errCount+temp;
    totalN=totalN+N;
end
ber(ii)=errCount/totalN;
end
ber;
semilogy(EbN0dB,ber,'-o');