www.gusucode.com > MC-CDMA系统的仿真matlab源码程序 > mc-cdma/rayleigh(移动信道)/user4LSLMMSEML.m

    % 清除内存，计时开始 6径Rayleigh信道,导频数不能取太小，取20效果较好
clear 
tic;
%设置参数
totalwords=18000;
numusers=4;
wordsize=2;
linktype=0;   %下行链路
ifftsize=256;
procgain=16;  %扩频码的长度
guardtime=40;
guardtype=2;
frameguard=ifftsize+guardtime;  % Guard Time between successive frames (one symbol period)
% 产生要发送的双极性二进制随机数
seed=1234;
rand('seed',seed);	                    	% Set to new seed
seqnumlist = randperm(procgain);
Datatx = zeros(numusers,totalwords);
basesignal0=zeros(1,totalwords*procgain);
for k = 1:numusers,
	Datatx(k,:)=floor(rand(1,totalwords)*2^wordsize);%产生2^wordsize进制发送数据
    %进行映射
     mapping=get80216map(2^wordsize);
     B=Datatx(k,:);
     for i=1:length(B),
     Datatx1(i)=mapping(1+B(i));
     end;
    seqnum=seqnumlist(k);%取得用户k的扩频码
%扩频
    basesignal_0=tranCDMA(Datatx1,procgain,seqnum,linktype);
    basesignal0=basesignal0+basesignal_0; %各个用户的扩频信号进行合并
 end
%ofdm调制
NumCarr =180;	    %数据载波数
%=============
% 每载波要传输多少数据
%=============
Numsymb = ceil(length(basesignal0)/NumCarr);
%如果传输的数据不是数据载波的整数倍，则在后面补零
if length(basesignal0)/NumCarr ~= Numsymb,
	DataPad = zeros(1,Numsymb*NumCarr);
	DataPad(1:length(basesignal0)) = basesignal0;
	basesignal0 = DataPad;
end
clear DataPad;
%PilotIndex=[45 69 93 117 141 165 189 213];     % pilot interval=24
%生成数据和导频图案
Pilot_number=20;
Pattern=ones(ifftsize,Numsymb);  % the position of data is set as 1.
Pattern(129,:)=0;                 % DC=0
Pattern([1:28,230:256],:)=0;      % guard band=0
Pattern([34:10:224],:)=4;       % the position of pilot is set as 4.
PilotIndex=find(Pattern==4);   % the pattern of pilot
DataIndex=find(Pattern==1);   %the pattern of data
%生成导频数据
pilotini=randsrc(length(PilotIndex),1,[1 -1;0.5 0.5])*sqrt(2);
%生成数据矩阵
Data=zeros(size(Pattern));
Data(PilotIndex)=pilotini;
Data(DataIndex)=basesignal0;
%==================================
%Find the time waveform using IFFT
%==================================
BaseSignal = ifft(Data);       %ifft是对列进行ifft变换。
%将后guardtime拷贝，作为循环前缀，即：L＝guardtime，N＝EndSignal。
BaseSignal=[BaseSignal((end-guardtime+1):end,:); BaseSignal];
%BaseSignal = reshape(BaseSignal,1,size(BaseSignal,1)*size(BaseSignal,2))   %先取第一列，再取第二列，……
%===============
% CHANNEL MODEL
%===============
fc=3.5e9;  
V=75;         %V km/h
fdmax=V*fc/3e8/3.6   %fmax=V*fc/C
% channel have delay
fade=Rayleigh(fdmax);
% fade=Rayleigh_CH2(fdmax);
path1=ones(frameguard,1)*fade(1,[1+5000:Numsymb+5000]).*BaseSignal;
path2=ones(frameguard,1)*fade(2,[1+5000:Numsymb+5000]).*BaseSignal;
path3=ones(frameguard,1)*fade(3,[1+5000:Numsymb+5000]).*BaseSignal;
path4=ones(frameguard,1)*fade(4,[1+5000:Numsymb+5000]).*BaseSignal;
path5=ones(frameguard,1)*fade(5,[1+5000:Numsymb+5000]).*BaseSignal;
path6=ones(frameguard,1)*fade(6,[1+5000:Numsymb+5000]).*BaseSignal;

path01=reshape(path1,1,size(path1,1)*size(path1,2));
path02=reshape(path2,1,size(path2,1)*size(path2,2));
path03=reshape(path3,1,size(path3,1)*size(path3,2));
path04=reshape(path4,1,size(path4,1)*size(path4,2));
path05=reshape(path5,1,size(path5,1)*size(path5,2));
path06=reshape(path6,1,size(path6,1)*size(path6,2));

%the delay is [0 0.31 0.71 1.09 1.73 2.51] us
path11=[path01 zeros(1,10)];    % the largest delay is 10 sample                                                                                                                          
path12=[zeros(1,1) path02 zeros(1,9)];
path13=[zeros(1,3) path03 zeros(1,7) ];
path14=[zeros(1,4) path04 zeros(1,6)];
path15=[zeros(1,7) path05 zeros(1,3)];
path16=[zeros(1,10) path06];
RxSignal0=path11+path12+path13+path14+path15+path16;
RxSignal0=RxSignal0(1:length(path01));

H_real=zeros(ifftsize,Numsymb);      % the real channel impulse response
for k=1:ifftsize
    H_real(k,:)=H_real(k,:)+fade(1,[1+5000:Numsymb+5000])*exp(-j*2*pi*(k-1)*0/ifftsize)+fade(2,[1+5000:Numsymb+5000])*exp(-j*2*pi*(k-1)*1/ifftsize)+...
                            fade(3,[1+5000:Numsymb+5000])*exp(-j*2*pi*(k-1)*3/ifftsize)+fade(4,[1+5000:Numsymb+5000])*exp(-j*2*pi*(k-1)*4/ifftsize)+...
                            fade(5,[1+5000:Numsymb+5000])*exp(-j*2*pi*(k-1)*7/ifftsize)+fade(6,[1+5000:Numsymb+5000])*exp(-j*2*pi*(k-1)*10/ifftsize);
end;
H_real= H_real([29:229],:);
ber1=[];
ber2=[];
ber3=[];
berreal=[];
mse1=[];
mse2=[];
mse3=[];
%LMMSE 参数设置
switch wordsize
    case 2
        beita=1;         % beita=E{|Ck|^2}*E{1/|Ck}^2}=constant
    case 4
        beita=17/9;      % beita=17/9 for 16-QAM , and beita=1 for QPSK
    case 6
        beita=2.6854;    % beita=2.6854 for 64-QAM
    otherwise
        error('error mapping type!')
end
             
L=10;
ratio=L/NumCarr;
for ri=1:256    %相关函数
    for ci=1:256
        if ri==ci
            Rhh(ri,ci)=1;
        else
            Rhh(ri,ci)=(1-exp(-j*2*pi*ratio*(ri-ci)))/(j*2*pi*ratio*(ri-ci));  % attention !!!
        end
    end
end

for SNR=0:5:30
RxSignal=awgn(RxSignal0,10^(SNR/10),'measured',1234,'linear');
%==================
% RECEIVER SECTION
%==================
% remove cyclic prefix
symbwaves=reshape(RxSignal,frameguard,Numsymb);
symbwaves = symbwaves(guardtime+1:frameguard,:); % Strip off the guard interval
%fft变换
Yf=fft(symbwaves);
 %=======================================Estimation===============================================
%提取导频数据
	Rec_Pilot=Yf(PilotIndex);
%估计导频处的信道频域响应
	H_Pilot=Rec_Pilot./pilotini;
    H_Pilot=reshape(H_Pilot,Pilot_number,Numsymb);
    X=6:10:196;
    XI=1:201;
    H1 = INTERP1(X,H_Pilot,XI,'linear','extrap');
    H10=abs(H1);
 % LMMSE estimation
C=beita/10^(SNR/10);     % constant coefficient 
M=[29:229];
N=[34:10:224];
Rpp=Rhh(N,N);
Rhp=Rhh(M,N);
Wt=Rhp*inv(Rpp+C*eye(length(N)));            % weight matrix of LMMSE estimation
H2=Wt*H_Pilot;
H20=abs(H2);
%ML
 F=dftmtx(ifftsize);
 L=11;
 Fh=F([34:10:224],[1:L]);
 Fu=F([29:229],[1:L]);
 H3=Fu*inv(Fh'*Fh)*Fh'*H_Pilot;
 H30=abs(H3);
  %计算MSE
 mse1=[mse1,mse(abs(H_real-H1))]
 mse2=[mse2,mse(abs(H_real-H2))]
 mse3=[mse3,mse(abs(H_real-H3))]
 Rx=Yf;
 Rx1=Yf;
 Rx2=Yf;
 Rxreal=Yf;
 Rx([29:229],:)=Rx([29:229],:)./H1.*H10;
 Rx1([29:229],:)=Rx1([29:229],:)./H2.*H20; 
 Rx2([29:229],:)=Rx2([29:229],:)./H3.*H30;%最大合并比，×第i个子载波处的随机幅度
 Rxreal([29:229],:)=Rxreal([29:229],:)./H_real.*abs(H_real);
  % extract data
  DemSig=Rx(DataIndex);
  DemSig1=Rx1(DataIndex);
  DemSig2=Rx2(DataIndex);
  DemSigreal=Rxreal(DataIndex);
  DemSignal=reshape(DemSig,1,size(DemSig,1)*size(DemSig,2));   %LS估计值
  DemSignal1=reshape(DemSig1,1,size(DemSig1,1)*size(DemSig1,2));  %MMSE估计值
  DemSignal2=reshape(DemSig2,1,size(DemSig2,1)*size(DemSig2,2)); %ML
  DemSignalreal=reshape(DemSigreal,1,size(DemSigreal,1)*size(DemSigreal,2));%理想估计值
%解扩
subsignal=[];
subsignal1=[];
subsignal2=[];
subsignalreal=[];
for k=1:numusers
    seqnum = seqnumlist(k);
[data0,subsignal0]=recCDMA(DemSignal,procgain,seqnum,linktype);
subsignal=[subsignal;subsignal0];
[data1,subsignal10]=recCDMA(DemSignal1,procgain,seqnum,linktype);
subsignal1=[subsignal1;subsignal10];
[data2,subsignal20]=recCDMA(DemSignal2,procgain,seqnum,linktype);
subsignal2=[subsignal2;subsignal20];
[datareal0,subsignalreal0]=recCDMA(DemSignalreal,procgain,seqnum,linktype);
subsignalreal=[subsignalreal;subsignalreal0];
end
%去掉映射
Datarx=invmapping(subsignal,mapping,wordsize);%LS估计值
Datarx1=invmapping(subsignal1,mapping,wordsize); %MMSE估计值
Datarx2=invmapping(subsignal2,mapping,wordsize);%ML
Datarxreal=invmapping(subsignalreal,mapping,wordsize);
%计算误码率
ber10=err(Datatx,Datarx,totalwords,numusers);
ber20=err(Datatx,Datarx1,totalwords,numusers);
ber30=err(Datatx,Datarx2,totalwords,numusers);
berreal0=err(Datatx,Datarxreal,totalwords,numusers)
ber1=[ber1,ber10]       %LS估计值
ber2=[ber2,ber20]       %MMSE估计值
ber3=[ber3,ber30]       %ML估计值
berreal=[berreal,berreal0]
end

figure
subplot(1,2,1)
k=0:5:30
semilogy(k,ber1,'-ms')
grid on
hold on
semilogy(k,ber2,'-r*')
semilogy(k,ber3,'-go')
semilogy(k,berreal,'-.b')
axis([0 30 10^(-4) 1])
xlabel('SNR/dB'),ylabel('BER')
legend('\fontsize{8}LS','\fontsize{8}LMMSE','\fontsize{8}ML','\fontsize{8}理想')
set (gcf,'color',[1 1 1])
subplot(1,2,2)
k=0:5:30
semilogy(k,mse1,'-ms')
grid on
hold on
semilogy(k,mse2,'-r*')
semilogy(k,mse3,'-go')
axis([0 30 10^(-4) 1])
xlabel('SNR/dB'),ylabel('MSE')
legend('\fontsize{8}LS','\fontsize{8}LMMSE','\fontsize{8}ML')

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