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    文件类型: .m
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    发布日期: 2021-05-12
  • 语言: Matlab
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资源简介

此内容是 利用MIMO_OFDM进行的基础信道估计算法

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代码片段和文件信息

%------------------------------------------
% EE359 final project Fall 2002
% Channel estimation for a MIMO-OFDM system
% By Shahriyar Matloub               
%------------------------------------------

clear all;
%close all;
i=sqrt(-1);
Rayleigh=1;
AWGN=0;                             % for AWGN channel 
MMSE=0;                             % estimation technique
Nsc=64;                             % Number of subcarriers
Ng=16;                              % Cyclic prefix length
SNR_dB=[0 5 10 15 20 25 30 35 40];  % Signal to noise ratio
Mt=2;                               % Number of Tx antennas
Mr=2;                               % Number of Rx antennas
pilots=[1:Nsc/Ng:Nsc];              % pilot subcarriers 
DS=5;                              % Delay spread of channel
iteration_max=200;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Channel impulse response %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%

if (Rayleigh)
    N=50;
    fm=100;
    B=20e3;
    fd=(rand(1N)-0.5)*2*fm;
    theta=randn(1N)*2*pi;
    c=randn(1N);
    c=c/sum(c.^2);
    t=0:fm/B:10000*fm/B;
    Tc=zeros(size(t));
    
    Ts=zeros(size(t));
    for k=1:N
       Tc=c(k)*cos(2*pi*fd(k)*t+theta(k))+Tc;
       Ts=c(k)*sin(2*pi*fd(k)*t+theta(k))+Ts;
    end
    r=ones(Mt*Mr1)*(Tc.^2+Ts.^2).^0.5;
    index=floor(rand(Mt*MrDS)*5000+1);
end

MEE1=zeros(1length(SNR_dB));
MEE2=zeros(1length(SNR_dB));

for snrl=1:length(SNR_dB)
    snrl
    estimation_error1=zeros(Mt*MrNsc);
    estimation_error2=zeros(Mt*MrNsc);
    R1=besselj(02*pi*fm*(Nsc+Ng)/B);
    sigma2=10^(-SNR_dB(snrl)/10);
    aa=(1-R1^2)/(1-R1^2+sigma2);
    bb=sigma2*R1/(1-R1^2+sigma2);

    for iteration=1:iteration_max
        %iteration    
        if AWGN==1
            h=ones(Mt*Mr1);
        else
            phi=rand*2*pi;
            h=r(index+iteration)*exp(j*phi);
            %h=rand(Mt*MrDS);
            h=h.*(ones(Mt*Mr1)*(exp(-0.5).^[1:DS]));
            h=h./(sqrt(sum(abs(h).^22))*ones(1DS));
        end



        CL=size(h2);                                               % channel length
        data_time=zeros(MtNsc+Ng);
        data_qam=zeros(MtNsc);
        data_out=zeros(MrNsc);
        output=zeros(MrNsc);

        for tx=1:Mt
            data_b=0*round(rand(4Nsc));                                  % data
            data_qam(tx:)=j*(2*(mod(data_b(1:)+data_b(2:)2)+2*data_b(1:))-3)+...
            2*(mod(data_b(3:)+data_b(4:)2)+2*data_b(3:))-3;
            for loop=1:Mt 
                data_qam(txpilots+loop-1)=(1+j)*(loop==tx);              % pilots
            end
            data_time_temp=ifft(data_qam(tx:));
            data_time(tx:)=[data_time_temp(end-Ng+1:end) data_time_temp];
        end
    
        for rx=1:Mr
            for tx=1:Mt
                output_temp=conv(data_time(tx:)h((rx-1)*Mt+tx:));
                output(rx:)=output_temp(Ng+1:Ng+Nsc)+output(rx:);
            end
            np=(sum(abs(output(rx:)).^2)/length(output(rx:)))*sigma2;
            noise=(randn(size(

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