singlecarrierfdequalization.m

单载波频域均衡算法完整Matlab仿真程序

echo off;
clear all;
close all;
clc;
%单载波频域均衡处理
fprintf( 'Single Carrier Frequency Domain Equalization Simulation\n\n\n') ;
tic  %启动时钟
%------------------------------------------------------------------- %
%                   Parameters  Declaration                          %
%------------------------------------------------------------------- %
%Initialize the parameters初始化参数
%FrameNum = input('number of frames transmitted is(default=5000) =');
FrameNum=5000;%发送的数据帧数
if isempty(FrameNum)
    FrameNum = 5;
end
%FrameSize = input('size of each frame is(default=256) =');
FrameSize=256; %每帧数据的大小
if isempty(FrameSize)
    FrameSize = 256;
end
%Chan =input('channel IR is(default=[0.227 0.46 0.688 0.46 0.227]) =');
Chan=[0.227 0.46 0.688 0.46 0.227];%通道脉冲响应
if isempty(Chan)
    Chan = [0.227 0.46 0.688 0.46 0.227];
end
CPLen = FrameSize/8;%循环前缀大小CPLen=256/8=

% ------------------------------------------------------------------- %
%             Generate Transmit Signal  & BPSK Modulation             %
% ------------------------------------------------------------------- %
% generate the random binary stream for transmitting
% 产生随机的二进制流对于发射
BitsTranstmp = randint(1,FrameNum*FrameSize);
% BitsTranstmp(1:10)为0,1的数据流
% modulate,generate the BPSK symbols
Table        = [-1 1];
% After the step upon,Table = [-1.0000-0.0000i 1.000]
BitsTrans    = Table(BitsTranstmp+1);%产生发送的二进制数据流

% 增加循环前缀
% ------------------------------------------------------------------- %
%                               Add CP                                %
% ------------------------------------------------------------------- %
% the function RESHAPE is to rearrange the BitsTrans to add cp for
% convenience,reshape 重新安排BitsTrans用于增加cp
AddCPtmp   = reshape(BitsTrans,FrameSize,FrameNum);%原始数据部分
AddCP      = zeros(FrameSize+CPLen,FrameNum);      %最终增加CP的数据
AddPrefix  = FrameSize-CPLen+1:FrameSize;          %存放CP的位置

% the matrix below is as the same function of add cp to each frame one
% by one,增加每帧
AddCP      = [AddCPtmp(AddPrefix,:);AddCPtmp];     %将原始数据的部分数据作为CP

% ------------------------------------------------------------------- %
%                         Go Through The Channel                      %
% ------------------------------------------------------------------- %
RecChantmp = filter(Chan,1,AddCP);                     %经过通道滤波处理

%----------------------------------------------------------------------
%  function explain :y = filter(b,a,x)
%  y = filter(b,a,X) filters the data in vector X with the filter desc-
%  ribed by numerator coefficient vector b and denominator coefficient
%  vector a,if x is a matrix,filter operates on the columns of X,so we
%  could use filter here.
%----------------------------------------------------------------------
BerSnrTable = zeros(10,7);
for snr = 0:9
    BerSnrTable(snr+1,1) = snr*5;
    
    % convert Eb/N0 from unit db to normal numbers
    BerSnrTable(snr+1,2) = 10^(BerSnrTable(snr+1,1)/10);
    
    % standard deviation of AWGN noise,噪声的标准偏差
    BerSnrTable(snr+1,3) = 1/sqrt(2*BerSnrTable(snr+1,2));
    
    % add noise,增加噪声
    RecChan = awgn(RecChantmp,snr*5,'measured');
    
    % ------------------------------------------------------------------- %
    %                            Remove The CP                            %
    % ------------------------------------------------------------------- %
    RemovCP = zeros(FrameSize,FrameNum);
    % the rows of (CPLen+1:FrameSize+CPLen)of matrix RecChan is the
    % numbers which we wanted
    RemovCP = RecChan(CPLen+1:FrameSize+CPLen,:);
    
    % ------------------------------------------------------------------- %
    %                   Frequency Domain Equalization                     %
    % ------------------------------------------------------------------- %
    % reshaping the matrix RemovCP for frequency domain equalization
    BitsFilt = reshape(RemovCP,1,FrameSize*FrameNum);
    TimeBitsRec = zeros(1,FrameSize*FrameNum);
    
    % fft of channel coeffients通道系数fft
    FreqChan = fft(Chan,FrameSize);
    for i = 1:FrameNum
        FreRectmp = zeros(1,FrameSize);
        for j = 1:FrameSize
            FreRectmp(j) = BitsFilt(j+(i-1)*FrameSize);
        end

        % fft of received frames,接收帧
        FreqRec = zeros(1,FrameSize);
        FreqRec = fft(FreRectmp);
        
        % equaliztion coefficients,均衡系数
        EqCoe = zeros(1,FrameSize);
        EqCoe = conj(FreqChan)./(BerSnrTable(snr+1,3)^2+abs(FreqChan).^2);
        
        % equaliztion,均衡
        EqualFram = zeros(1,FrameSize);
        EqualFram = FreqRec.*EqCoe;
        
        % received bits of time domain,using ifft时域接收位,使用ifft
        TimeFram = ifft(EqualFram);
        
        %gained the received bits after equalization获取均衡后的接收位
        for j1 = 1:FrameSize
            TimeBitsRec(j1+((i-1)*FrameSize)) = TimeFram(j1);
        end
    end
    
    % 执行判决处理
    % ------------------------------------------------------------------- %
    %              Make Decision (Including Demodulate BPSK)              %
    % ------------------------------------------------------------------- %
    BitsRec = zeros(1,FrameSize*FrameNum);
    for m = 1:FrameSize*FrameNum
        Real =real(TimeBitsRec(m));
        if Real>0
            BitsRec(1,m)=1;
        else
            BitsRec(1,m)=0;
        end
    end
    
    % ------------------------------------------------------------------- %
    %                Compute Bits&Frame Error Number&Rate                 %
    % ------------------------------------------------------------------- %
    % compute the frame error rate and number
    RecFrame = reshape(BitsRec,FrameSize,FrameNum);
    GenFrame = reshape(BitsTranstmp,FrameSize,FrameNum);
    FrameErrNum = 0;
    for n = 1:FrameNum
        if GenFrame(:,n) == RecFrame(:,n)
            FrameErrNum = FrameErrNum;
        else
            FrameErrNum = FrameErrNum+1;
        end
    end
    BerSnrTable(snr+1,6) = FrameErrNum;
    BerSnrTable(snr+1,7) = FrameErrNum/FrameNum;
    
    % comput the bits error rate and number
    [ErrNum,Ber] = symerr(BitsTranstmp,BitsRec)

    BerSnrTable(snr+1,4) = ErrNum ;
    BerSnrTable(snr+1,5) = Ber ;
    % end of (for snr = 0:9)
end

figure(1);
plot(BerSnrTable(:,1),BerSnrTable(:,4),'o-');grid on;
title({'Simulation of Single Carrier with Frequency Domain Equalization';'Modulation Method:BPSK';'Channel Coefficients [0.227 0.46 0.688 0.46 0.227]';'';'bit error number of SC-FDE simulation'})
xlabel('SNR(db)');ylabel('BIT ERR NUMBER')

figure(2)
plot(BerSnrTable(:,1),BerSnrTable(:,5),'o-');grid on;
title({'Simulation of Single Carrier with Frequency Domain Equalization';'Modulation Method:BPSK';'Channel Coefficients [0.227 0.46 0.688 0.46 0.227]';'';'bit error rate of SC-FDE simulation'})
xlabel('SNR(db)');ylabel('BIT ERR RATE')

time_of_sim = toc
echo on;