ofdm.m

基于第三代通讯wimax核心编码ofdm编码的matlab性能仿真

clear all;
para=128;                                              % Number of parallel channel to transmit (points)
fftlen=128;                                            % FFT长度
noc=128;                                               % 载波数
nd=100;                                                % Number of information OFDM symbol for one loop
ml=2;                                                  % Modulation level : QPSK
sr=250000;                                             % Symbol rate
br=sr.*ml;                                             % Bit rate per carrier
gilen=32;                                              % Length of guard interval (points)
ebn0=2:0.5:10;                                         % Eb/N0

for iiii=1:length(ebn0);
    nloop=100;                                         % 仿真循环次数
    noe = 0;                                           % 差错数初值
    nod = 0;                                           % 传输数据初值
    eop=0;                                             % 差错信息包数初值
    nop=0;                                             % 传输信息包数初值

    for iii=1:nloop       
        %seldata=rand(1,para*ml*nd)>0.5;                % 产生信源
        seldata=randint(1,para*ml*nd);
        %Serial to parallel conversion
        paradata=reshape(seldata,para,ml*nd);          

        % QPSK modulation
        [ich,qch]=qpskmod(paradata,para,nd,ml);
        kmod=1/sqrt(2);                                  %归一化                             
        ich1=ich.*kmod;
        qch1=qch.*kmod;

        %IFFT 
        x=ich1+qch1.*i;
        y=ifft(x);
        ich2=real(y);
        qch2=imag(y);

        %Gurad interval insertion 
        [ich3,qch3]= giins(ich2,qch2,fftlen,gilen,nd);   %parallel to Serial conversion
        fftlen2=fftlen+gilen;

        %Attenuation Calculation 
        spow=sum(ich3.^2+qch3.^2)/nd./para;            
        attn(iiii)=0.5*spow*sr/br*10.^(-ebn0(iiii)/10);
        attn(iiii)=sqrt(attn(iiii));

        %Receiver
        %AWGN addition
        ich4=ich3+attn(iiii)*randn(1,length(ich3));
        qch4=qch3+attn(iiii)*randn(1,length(qch3));

        % [ich4,qch4]=comb(ich3,qch3,attn(iiii));

        %Guard interval removal
        [ich5,qch5]= girem(ich4,qch4,fftlen2,gilen,nd); %Serial to parallel conversion

        %FFT
        rx=ich5+qch5.*i;
        ry=fft(rx);
        ich6=real(ry);
        qch6=imag(ry);

        % demoduration 
        ich7=ich6./kmod;
        qch7=qch6./kmod;
        [demodata]=qpskdemod(ich7,qch7,para,nd,ml);

        %Parallel to serial conversion
        demodata1=reshape(demodata,1,para*nd*ml);

        % Bit Error Rate (BER) 
        % instantaneous number of error and data
        noe2=sum(abs(demodata1-seldata));               
        nod2=length(seldata);                           

        % cumulative the number of error and data in noe and nod
        noe=noe+noe2;
        nod=nod+nod2;

        % calculating PER
        if noe2~=0
            eop=eop+1;
        else
            eop=eop;
        end
        eop;
        nop=nop+1;
  end

    % 输出结果
    per(iiii)=eop/nop;
    ber(iiii)=noe/nod;
    fprintf('%f\t%e\t%e\t%d\t\n',ebn0(iiii),ber(iiii),per(iiii),nloop);
end
semilogy(ebn0,ber,'*-');
grid on
xlabel('ebn0');ylabel('Probability of Bit Error');
legend('OFDM');