chilg_test.m

对Vblast—oFdm系统地仿真

clear all;
close all;

min_snr=0;
max_snr=40;
step_snr=2;

frame_num=500;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

L=3;
var0=(1-exp(-1))/(1-exp(-L));
ll=0:L-1;
pdp=var0.*exp(-ll);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
snr=min_snr:step_snr:max_snr;
bits_total=64*frame_num;
randn('state',0);
table=[-1 1]; %调制用
err=zeros(1,length(snr));
for snrIndex=1:length(snr);
    last=[0;0];
    for ii=1:frame_num
        data=randn(1,64)>0;
        x=table(data+1); % 星座点映射
        hint1=sqrt(pdp(1))*1/sqrt(2)*(randn(1,1)+i*randn(1,1));
        hint2=sqrt(pdp(2))*1/sqrt(2)*(randn(1,1)+i*randn(1,1));
        hint3=sqrt(pdp(3))*1/sqrt(2)*(randn(1,1)+i*randn(1,1));
        ll=eye(80);
        % 产生三径Rayleigh信道
        channel1=hint1*ll;
        channel2=hint2*ll;
        channel3=hint3*ll;
        hint=[hint1 hint2 hint3];
        H_f=fft(hint,64);
        m=(ifft(x)).';
        
        cp_m=[m(end-16+1:end); m];
        %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
        % 一个ofdm符号抽样的平均功率
        n=mean(abs(cp_m).^2);
        %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
        % 平均功率归一化
        cp_m=cp_m/sqrt(n);
        sigma=1/10.^(snr(snrIndex)/10);
        % 通过信道
        cp_mmm=[last; cp_m];
        yy=channel1*cp_mmm(end-79:end)+channel2*cp_mmm(end-80:end-1)+channel3*cp_mmm(end-81:end-2)+sqrt(sigma)*1/sqrt(2)*(randn(1,80)+i*randn(1,80)).';
        last=cp_mmm(end-1:end);
        % 恢复信号功率
        yy=yy*sqrt(n);
        
        % 去除cp
        yy=yy(17:end).';

        tt=fft(yy);
        % 频域均衡
        tt=tt./H_f;
        bits=real(tt)>0;
        err(snrIndex)=err(snrIndex)+sum(data~=bits);
    end
end
aveBer=err/bits_total;
figure(1);
semilogy(snr,aveBer);
axis([min_snr max_snr 10.^-5 1]);
grid on;