www.gusucode.com > MC-CDMA系统的仿真matlab源码程序 > mc-cdma/sui3/1users/pilotLS_Lmmse_Ml2.m
% 清除内存，计时开始 SUI3 信道
clear
tic;
%设置参数
totalwords=1920*5;
numusers=1;
wordsize=2;
linktype=0; %下行链路
seqnum=3; %1～64之间取值
ifftsize=256;
procgain=4; %扩频码的长度
windowtype=0;
guardtime=32;
guardtype=2;
delay=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
rand('seed',1234);
datatx = floor(rand(1,totalwords)*2);
datatx = datatx-1;
index = find(datatx>=0);
datatx(index) = datatx(index)+1;
%扩频
basesignal=tranCDMA(datatx,procgain,seqnum,linktype);
index = find(basesignal<0);
basesignal(index) = basesignal(index)+1; %符号转换，将双极性信号变为单极性信号
%将二进制转换为2×wordsize进制，以备映射
B=bin2high(basesignal,wordsize);
%ofdm调制
NumCarr =192; %取得载波数
%=============
% 每载波要传输多少数据
%=============
numsymb = ceil(length(B)/NumCarr);
%如果传输的数据不是载波的整数倍，则在后面补零
if length(B)/NumCarr ~= numsymb,
DataPad = zeros(1,numsymb*NumCarr);
DataPad(1:length(B)) = B;
B = DataPad;
end
clear DataPad;
% Mapping to the signal constellation follow
mapping=get80216map(2^wordsize);
for i=1:length(B),
ModSignal(i)=mapping(1+B(i));
end;
Xf=reshape(ModSignal,NumCarr,numsymb);
%PilotIndex=[45 69 93 117 141 165 189 213]; % pilot interval=24
PilotIndex=[45:24:213];
DCIndex=129;
Wk=[1 0 1 0 0 0 1 1]'; % DownLink pilotini
pilotini=1-2*Wk; % BPSK modulation for pilot
DataIndex=[29:229]; % the other carriers except guard carriers
Xf=[zeros(28,numsymb);Xf(1:16,:);zeros(1,numsymb);Xf(17:39,:);zeros(1,numsymb);Xf(40:62,:);zeros(1,numsymb);...
Xf(63:85,:);zeros(1,numsymb);Xf(86:96,:);zeros(1,numsymb);Xf(97:107,:);zeros(1,numsymb);Xf(108:130,:);zeros(1,numsymb);...
Xf(131:153,:);zeros(1,numsymb);Xf(154:176,:);zeros(1,numsymb);Xf(177:192,:);zeros(27,numsymb)];
Xf(PilotIndex,:)=pilotini(:,ones(1,numsymb)); % pilot insertion
Cpp=diag(Xf(PilotIndex)); % diagonal matrix composed of pilot
%==================================
%Find the time waveform using IFFT
%==================================
BaseSignal = ifft(Xf); %ifft是对列进行ifft变换。
%=================================
%Add a Guard Period
%=================================
BaseSignal0=[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
%===============
% generate channel parameter which is unknown to receiver
P = [0 -5 -10]; %db
P = 10.^(P/10); % calculate linear power
K=[1 0 0];
s2=P./(K+1);
m2=P.*(K./(K+1));
fade1=sqrt(s2)*sqrt(1/2)*(1+j);
fade2=m2;
fade=fade1+fade2;
path1=BaseSignal*fade(1);
path2=BaseSignal*fade(2);
path3=BaseSignal*fade(3);
path11=[path1 zeros(1,delay*2)];
path12=[zeros(1,delay) path2 zeros(1,delay)];
path13=[zeros(1,delay*2) path3];
RxSignal0=path11+path12+path13;
RxSignal0=RxSignal0(1:length(path1));
H_real=fft([fade(1) zeros(1,delay-1) fade(2) zeros(1,delay-1) fade(3)].',256);
H_real= H_real([29:229]);
H_real1=repmat(H_real,[1 numsymb]);
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
Ip=eye(8); % generate an identity matrix
L=delay*2;
ratio=L/ifftsize;
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=0:2:20
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);
Hp=inv(Cpp)*Yf(PilotIndex,:); % find the channel response at the pilot frequency
%LMMSE
C=beita/10^(SNR/10); % constant coefficient
Rpp=Rhh(PilotIndex,PilotIndex);
Rhp=Rhh(DataIndex,PilotIndex);
Wt=Rhp*inv(Rpp+C*Ip); % weight matrix of LMMSE estimation
%ML
Nc=256;
n=(0:Nc-1)';
k=0:Nc-1;
F=1/sqrt(Nc)*exp(-j*2*pi*n*k/Nc); % generate an Nc by Nc unitary FFT matrix, satisfy:F'=inv(F)
% Fuh=F(DataIndex,1:3);
Nh=5;
Fhh=F(DataIndex,1:Nh);
Fuh=F(PilotIndex,1:Nh);
DemSig1=[];
DemSig2=[];
DemSig3=[];
DemSigreal=[];
for k=1:numsymb
H_ls(:,k)=interp1(PilotIndex',Hp(:,k),[DataIndex]','linear','extrap'); % 'linear' outperforms 'cubic'
H_lmmse(:,k)=Wt*Hp(:,k); % LMMSE estimation
H_ml(:,k)=Fhh*pinv(Fuh)*Hp(:,k);
DemSig1(:,k)=Yf(DataIndex,k)./H_ls(:,k);
DemSig2(:,k)=Yf(DataIndex,k)./H_lmmse(:,k);
DemSig3(:,k)=Yf(DataIndex,k)./H_ml(:,k);
DemSigreal(:,k)=Yf(DataIndex,k)./H_real1(:,k);
end
esterr1=H_ls-H_real1; % LS estimation error
esterr2=H_lmmse-H_real1; % LMMSE estimation error
esterr3=H_ml-H_real1; % ML estimation error
mse1=[mse1,mse(abs(esterr1))] % Mean Square Error of LS estimation
mse2=[mse2,mse(abs(esterr2))] % Mean Square Error of LMMSE estimation
mse3=[mse3,mse(abs(esterr3))] % Mean Square Error of LMMSE estimation
DemSig1([PilotIndex,DCIndex]-28,:)=[];
DemSig2([PilotIndex,DCIndex]-28,:)=[];
DemSig3([PilotIndex,DCIndex]-28,:)=[];
DemSigreal([PilotIndex,DCIndex]-28,:)=[];
DemSignal1=reshape(DemSig1,1,size(DemSig1,1)*size(DemSig1,2)); % complex signal to be de demapped
DemSignal2=reshape(DemSig2,1,size(DemSig2,1)*size(DemSig2,2));
DemSignal3=reshape(DemSig3,1,size(DemSig3,1)*size(DemSig3,2));
DemSignalreal=reshape(DemSigreal,1,size(DemSigreal,1)*size(DemSigreal,2));
%去掉映射
Datarx1=invmapping(DemSignal1,mapping,NumCarr,numsymb,wordsize);
Datarx2=invmapping(DemSignal2,mapping,NumCarr,numsymb,wordsize);
Datarx3=invmapping(DemSignal3,mapping,NumCarr,numsymb,wordsize);
Datarxreal=invmapping(DemSignalreal,mapping,NumCarr,numsymb,wordsize);
%将2^wordsize进制转换为二进制，
Datarx10=high2bin(Datarx1);
Datarx20=high2bin(Datarx2);
Datarx30=high2bin(Datarx3);
Datarxreal0=high2bin(Datarxreal);
%解扩
[datarx1, subsignal1] = recCDMA(Datarx10,procgain,seqnum,linktype);
[datarx2, subsignal2] = recCDMA(Datarx20,procgain,seqnum,linktype);
[datarx3, subsignal3] = recCDMA(Datarx30,procgain,seqnum,linktype);
[datarxreal, subsignalreal] = recCDMA(Datarxreal0,procgain,seqnum,linktype);
%计算误码率
ber10=err(datatx,datarx1,totalwords);
ber20=err(datatx,datarx2,totalwords);
ber30=err(datatx,datarx3,totalwords);
berreal0=err(datatx,datarxreal,totalwords);
ber1=[ber1,ber10]
ber2=[ber2,ber20]
ber3=[ber3,ber30]
berreal=[berreal,berreal0]
end
figure
subplot(2,2,1)
k=0:2:20
semilogy(k,ber1,'-r*')
hold on
semilogy(k,ber2,'-ro')
semilogy(k,ber3,'-rs')
semilogy(k,berreal,'-.b')
grid on
axis([0 20 10^(-4) 0.5])
xlabel('SNR/dB'),ylabel('BER')
legend('LS','LMMSE','ML','理想')
set (gcf,'color',[1 1 1])
set(gca,'xtick',[0:2:20])
hold off
subplot(2,2,2)
k=0:2:20
semilogy(k,mse1,'-r*')
hold on
semilogy(k,mse2,'-ro')
semilogy(k,mse3,'-rs')
grid on
axis([0 20 10^(-4) 1])
xlabel('SNR/dB'),ylabel('MSE')
legend('LS','LMMSE','ML')
set (gcf,'color',[1 1 1])
set(gca,'xtick',[0:2:20])
hold off
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