www.gusucode.com > MC-CDMA系统的仿真matlab源码程序 > mc-cdma/rayleigh(移动信道)/LS4usertwoD.m
% 清除内存，计时开始 4用户瑞利信道256点
clear
tic;
%设置参数
totalwords=18000;
numusers=4;
wordsize=2;
linktype=0; %下行链路
NumCarr=256;
procgain=16; %扩频码的长度
guardtime=40;
guardtype=2;
frameguard=NumCarr+guardtime; % Guard Time between successive frames (one symbol period)
fc=3.5e9;
V=75; %V km/h
fdmax=V*fc/3e8/3.6 %fmax=V*fc/C
% 产生要发送的随机数
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
%=============
% 每载波要传输多少数据
%=============
Numsymb = ceil(length(basesignal0)/180);
%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)/180 ~= Numsymb,
DataPad = zeros(1,Numsymb*NumCarr);
DataPad(1:length(basesignal0)) = basesignal0;
basesignal0 = DataPad;
end
clear DataPad;
%=================
% pilot settings
%=================
fnum=40;%频域导频数
tnum=800;%时域导频数
%生成数据和导频图案
Pattern=ones(NumCarr,Numsymb); % the position of data is set as 1.
Pattern(129,:)=0; % DC=0
Pattern([1:28,230:256],:)=0; % guard band=0
Pattern([31:5:226],[1:2:Numsymb])=4; % the position of pilot is set as 4.%Nt=2,Nf=5
Pattern_Pilot=find(Pattern==4); % the pattern of pilot
Data_Pattern=find(Pattern==1); %the pattern of data
Data=zeros(size(Pattern));
Data(Data_Pattern)=basesignal0; %插入用户数据
%生成导频数据
Pilot_Data=randsrc(length(Pattern_Pilot),1,[1 -1;0.5 0.5])*sqrt(2);
Data(Pattern_Pilot)=Pilot_Data;
%==================================
%Find the time waveform using IFFT
%==================================
BaseSignal = ifft(Data); %ifft是对列进行ifft变换。
%=================================
%Add a Guard Period
%=================================
BaseSignal=[BaseSignal((end-guardtime+1):end,:); BaseSignal];
%BaseSignal = reshape(BaseSignal0,1,size(BaseSignal0,1)*size(BaseSignal0,2)); %先取第一列，再取第二列，……
%===============
% CHANNEL MODEL， channel have delay
%===============
fade=Rayleigh(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 抽样频率为4MHz,[0 1.24 2.84 4.36 6.92 10]samples
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(NumCarr,Numsymb); % the real channel impulse response
for k=1:NumCarr
H_real(k,:)=H_real(k,:)+fade(1,[1+5000:Numsymb+5000])*exp(-j*2*pi*(k-1)*0/NumCarr)+fade(2,[1+5000:Numsymb+5000])*exp(-j*2*pi*(k-1)*1/NumCarr)+...
fade(3,[1+5000:Numsymb+5000])*exp(-j*2*pi*(k-1)*3/NumCarr)+fade(4,[1+5000:Numsymb+5000])*exp(-j*2*pi*(k-1)*4/NumCarr)+...
fade(5,[1+5000:Numsymb+5000])*exp(-j*2*pi*(k-1)*7/NumCarr)+fade(6,[1+5000:Numsymb+5000])*exp(-j*2*pi*(k-1)*10/NumCarr);
end
H_real= H_real([29:229],:);
ber1=[];
ber2=[];
ber3=[];
berreal=[];
mse1=[];
mse2=[];
mse3=[];
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(Pattern_Pilot);
%估计导频处的信道频域响应
H_Pilot=Rec_Pilot./Pilot_Data;
H_Pilot=reshape(H_Pilot,fnum,tnum);
for m=1:size(H_Pilot,1);
H_tdir(m,:)=interp1([1:2:Numsymb],H_Pilot(m,:),[1:Numsymb],'linear','extrap'); % linear interpolation in time domain
end
for k=1:Numsymb
H1(:,k)=interp1([3:5:198]',H_tdir(:,k),[1:201]','linear','extrap'); % linear interpolation in frequency domain
end
F=dftmtx(NumCarr);%ML estimation in frequency domain
L=11;
Fh=F([31:5:226],[1:L]);
Fu=F([29:229],[1:L]);
H2=Fu*inv(Fh'*Fh)*Fh'*H_tdir;
%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
%LMMSE
C=beita/10^(SNR/10); % constant coefficient
M=[29:229];
N=[31:5:226];
Rpp=Rhh(N,N);
Rhp=Rhh(M,N);
Wt=Rhp*inv(Rpp+C*eye(length(N))); % weight matrix of LMMSE estimation
H3=Wt*H_tdir;
mse1=[mse1,mse(abs(H_real-H1))]
mse2=[mse2,mse(abs(H_real-H2))]
mse3=[mse3,mse(abs(H_real-H3))]
Rx1=Yf;
Rx2=Yf;
Rx3=Yf;
Rxreal=Yf;
Rx1([29:229],:)=Rx1([29:229],:)./H1.*abs(H1);
Rx2([29:229],:)=Rx2([29:229],:)./H2.*abs(H2);
Rx3([29:229],:)=Rx3([29:229],:)./H3.*abs(H3);
Rxreal([29:229],:)=Rxreal([29:229],:)./H_real.*abs(H_real);
DemSig1=Rx1(Data_Pattern);
DemSig2=Rx2(Data_Pattern);
DemSig3=Rx3(Data_Pattern);
DemSigreal=Rxreal(Data_Pattern);
DemSignal1=reshape(DemSig1,1,size(DemSig1,1)*size(DemSig1,2)); %LS+LS
DemSignal2=reshape(DemSig2,1,size(DemSig2,1)*size(DemSig2,2)); %LS+ML
DemSignal3=reshape(DemSig3,1,size(DemSig3,1)*size(DemSig3,2)); %/LS+LMMSE估计值
DemSignalreal=reshape(DemSigreal,1,size(DemSigreal,1)*size(DemSigreal,2));%理想估计值
%解扩
subsignal1=[];
subsignal2=[];
subsignal3=[];
subsignalreal=[];
for k=1:numusers
seqnum = seqnumlist(k);
[data10,subsignal10]=recCDMA(DemSignal1,procgain,seqnum,linktype);
subsignal1=[subsignal1;subsignal10];
[data20,subsignal20]=recCDMA(DemSignal2,procgain,seqnum,linktype);
subsignal2=[subsignal2;subsignal20];
[data30,subsignal30]=recCDMA(DemSignal3,procgain,seqnum,linktype);
subsignal3=[subsignal3;subsignal30];
[datareal0,subsignalreal0]=recCDMA(DemSignalreal,procgain,seqnum,linktype);
subsignalreal=[subsignalreal;subsignalreal0];
end
%去掉映射
Datarx1=invmapping(subsignal1,mapping,wordsize);
Datarx2=invmapping(subsignal2,mapping,wordsize);
Datarx3=invmapping(subsignal3,mapping,wordsize);
Datarxreal=invmapping(subsignalreal,mapping,wordsize);
%计算误码率
ber10=err(Datatx,Datarx1,totalwords,numusers);
ber20=err(Datatx,Datarx2,totalwords,numusers);
ber30=err(Datatx,Datarx3,totalwords,numusers);
berreal0=err(Datatx,Datarxreal,totalwords,numusers)
ber1=[ber1,ber10]
ber2=[ber2,ber20]
ber3=[ber3,ber30]
berreal=[berreal,berreal0]
end;
MSE_LS=mse1;
MSE_ML=mse2;
MSE_LMMSE=mse3;
figure
subplot(1,2,1)
k=0:5:30
semilogy(k,ber1,'-ms')
hold on
semilogy(k,ber3,'-go')
semilogy(k,ber2,'-r*')
semilogy(k,berreal,'-.b')
grid on
axis([0 30 10^(-4) 1])
xlabel('SNR/dB'),ylabel('BER')
legend('\fontsize{7}LS+LS','\fontsize{7}LS+LMMSE','\fontsize{7}LS+ML','\fontsize{7}理想')
set (gcf,'color',[1 1 1])
set(gca,'xtick',[0:5:30])
subplot(1,2,2)
k=0:5:30
semilogy(k,MSE_LS,'-ms')
hold on
semilogy(k,MSE_ML,'-r*')
semilogy(k,MSE_LMMSE,'-go')
grid on
axis([0 30 10^(-4) 1])
xlabel('SNR/dB'),ylabel('MSE')
legend('\fontsize{7}LS+LS','\fontsize{7}LS+ML','\fontsize{7}LS+LMMSE')
set (gcf,'color',[1 1 1])
set(gca,'xtick',[0:5:30])
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