www.gusucode.com > MC-CDMA系统的仿真matlab源码程序 > mc-cdma/sui3/1users/preambleLS4user.m
% 清除内存，计时开始 SUI3 信道，先扩频后映射
clear
tic;
%设置参数
totalwords=1920;
numusers=4;
wordsize=2;%QPSK 映射
linktype=0; %下行链路
%seqnum=3; %1～8之间取值
NumCarr=256;
procgain=16; %扩频码的长度
guardtime=16; %保护带为最大时延（此处为delay*2）的4倍时误码性能最好
guardtype=2;
delay=2;
frameguard=NumCarr+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);%随机产生procgain个1到procgain中的值，即1-16
Datatx = zeros(numusers,totalwords);
basesignal0=zeros(1,totalwords*procgain);
for k = 1:numusers,
Datatx(k,:) = genrand(1,1,totalwords,'+-');%随机产生1行totalwords列双极性二进制数
seqnum = seqnumlist(k);%产生的Walsh码是16×16的矩阵，每行都是一个扩频序列，不同用户可以选其中的不同行作为扩频码（最大用户数为16)
%扩频
basesignal_0=tranCDMA(Datatx(k,:),procgain,seqnum,linktype);
basesignal0=basesignal0+basesignal_0;
end
basesignal=basesignal0+numusers;
%将十进制转换为2^wordsize进制，以备映射
B=dec2QOH(basesignal,numusers,wordsize);
%ofdm调制
%=============
% 每载波要传输多少数据
%=============
Numsymb = ceil(length(B)/192);%取整近似
%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(B)/192 ~= 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;
%生成数据和导频图案
Pattern=ones(NumCarr,Numsymb+2); % the position of data is set as 1.
Pattern(129,:)=0; % DC=0
Pattern([1:28,230:256],:)=0; % guard band=0
Pattern([45:24:213],:)=4;% the position of pilot is set as 4.
Pattern(:,[1,2])=0;
Data_Pattern=find(Pattern==1); %the pattern of data除了导频和保护带和直流的数据部分
%生成数据矩阵
w=round(rand(1,Numsymb)); % generate Wk，0和1
Data=zeros(size(Pattern));
for n=3:Numsymb
Data([45,93,189,213],n)=1-2*w(n); % [-84,-36,60,84]=1-2W,1和-1
Data([69,117,141,165],n)=2*w(n)-1; % [-60,-12,12,36]=1-2W'，1和-1
end
Data(Data_Pattern)=ModSignal; %插入用户数据
clear ModSignal;
% 插入帧头
Data([29:229],1)=2*[1+j,0,0,0,1+j,0,0,0,1+j,0,0,0,1-j,0,0,0,-1+j,0,0,0,1+j,0,0,0,1+j,0,0,0,1+j,0,0,0,1-j,0,0,0,-1+j,0,0,0,1+j,0,0,0,1+j,0,0,0,1+j,0,0,0,1-j,0,0,0,-1+j,0,0,0,1-j,0,0,0,1-j,0,0,0,1-j,0,0,0,-1-j,0,0,0,1+j,...
0,0,0,-1+j,0,0,0,-1+j,0,0,0,-1+j,0,0,0,1+j,0,0,0,-1-j,0,0,0,0,0,0,0,-1-j,0,0,0,1-j,0,0,0,1+j,0,0,0,-1-j,0,0,0,-1+j,0,0,0,1-j,0,0,0,1+j,0,0,0,-1+j,0,0,0,1-j,0,0,0,-1-j,0,0,0,1+j,0,0,0,-1+j,0,0,0,-1-j,0,0,0,1+j,0,0,0,1-j,0,0,0,-1-j,0,0,0,1-j,0,0,0,1+j,0,0,0,-1-j,0,0,0,-1+j,0,0,0,-1+j,0,0,0,-1-j,0,0,0,1-j,0,0,0,-1+j,0,0,0,1+j]';
Data([29:229],2)=2*[1,0,-1,0,-1,0,-1,0,1,0,1,0,1,0,1,0,-1,0,1,0,-1,0,-1,0,-1,0,1,0,-1,0,1,0,1,0,1,0,1,0,-1,0,1,0,1,0,1,0,-1,0,1,0,-1,0,1,0,1,0,-1,0,-1,0,1,0,-1,0,1,0,-1,0,1,0,1,0,-1,0,1,0,1,0,-1,0,-1,0,-1,0,1,0,-1,0,-1,0,-1,0,-1,0,-1,0,1,0,1,0,0,0,1,0,-1,0,-1,0,1,0,-1,0,1,0,1,0,1,0,1,0,-1,0,1,0,1,0,1,0,1,0,-1,0,1,0,-1,0,-1,0,-1,0,-1,0,1,0,1,0,-1,0,1,0,-1,0,-1,0,-1,0,-1,0,-1,0,-1,0,-1,0,-1,0,1,0,1,0,1,0,-1,0,-1,0,-1,0,1,0,1,0,-1,0,-1,0,-1,0,1,0,-1,0,-1,0,1,0,-1,0,-1,0,-1]';
%==================================
%Find the time waveform using IFFT
%==================================
BaseSignal = ifft(Data); %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，……%并串变换
%===============
% CHANNEL MODEL， channel have delay
%===============
% generate channel parameter which is unknown to receiver
% 抽样频率f＝4MHz，周期0.25us,信道延迟Delay=[0 0.4 0.9]us，故延迟的抽样为
% 0.4/0.25=1.6,0.9/0.25=3.6，即2和4。
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);%时域
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);%频域实际信道响应
H_real= H_real([29:229]);
H_real1=repmat(H_real,[1 Numsymb+2]);%reshape
ber1=[];
ber2=[];
ber3=[];
berreal=[];
mse1=[];
mse2=[];
mse3=[];
for SNR=0:2:16
RxSignal=awgn(RxSignal0,10^(SNR/10),'measured',1234,'linear');
%==================
% RECEIVER SECTION
%==================
% remove cyclic prefix
symbwaves=reshape(RxSignal,frameguard,Numsymb+2);
symbwaves = symbwaves(guardtime+1:frameguard,:); % Strip off the guard interval
%fft变换
Yf=fft(symbwaves);
%=======================================Estimation===============================================
%估计导频处的信道频域响应
H_Pilot1=Yf([29:4:125,133:4:229],1)./Data([29:4:125,133:4:229],1);
H_Pilot2=Yf([29:2:127,131:2:229],2)./Data([29:2:127,131:2:229],2);
x1=[1:4:97,105:4:201].';
y1=[1:201]';
H01=INTERP1(x1,H_Pilot1,y1,'linear'); % 帧头1估计值内插
x2=[1:2:99,103:2:201].';
H02=INTERP1(x2,H_Pilot2,y1,'linear'); % 帧头2估计值内插
% 两个帧头的平均
H03=(H01+H02)/2;
H1=repmat(H01,[1 Numsymb+2]);
H2=repmat(H02,[1 Numsymb+2]);
H3=repmat(H03,[1 Numsymb+2]);
mse1=[mse1,mse(abs(H_real-H01))]
mse2=[mse2,mse(abs(H_real-H02))]
mse3=[mse3,mse(abs(H_real-H03))]
Rx1=Yf;
Rx2=Yf;
Rx3=Yf;
Rxreal=Yf;
Rx1([29:229],:)=Rx1([29:229],:)./H1;
Rx2([29:229],:)=Rx2([29:229],:)./H2;
Rx3([29:229],:)=Rx3([29:229],:)./H3;
Rxreal([29:229],:)=Rxreal([29:229],:)./H_real1;
DemSig1=Rx1(Data_Pattern);%取数据部分
DemSig2=Rx2(Data_Pattern);
DemSig3=Rx3(Data_Pattern);
DemSigreal=Rxreal(Data_Pattern);
DemSignal1=reshape(DemSig1,1,size(DemSig1,1)*size(DemSig1,2)); % complex signal to be de demapped%并变串
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,wordsize);
Datarx2=invmapping(DemSignal2,mapping,wordsize);
Datarx3=invmapping(DemSignal3,mapping,wordsize);
Datarxreal=invmapping(DemSignalreal,mapping,wordsize);
%将2^wordsize进制转换为二进制，
Datarx10=QOH2dec(Datarx1,numusers,wordsize);
Datarx20=QOH2dec(Datarx2,numusers,wordsize);
Datarx30=QOH2dec(Datarx3,numusers,wordsize);
Datarxreal0=QOH2dec(Datarxreal,numusers,wordsize);
%解扩
datarx1=[];
datarx2=[];
datarx3=[];
datarxreal=[];
for k=1:numusers
seqnum = seqnumlist(k);
[datarx10, subsignal1]=recCDMA(Datarx10,procgain,seqnum,linktype);
datarx1=[datarx1;datarx10];
[datarx20, subsignal2]=recCDMA(Datarx20,procgain,seqnum,linktype);
datarx2=[datarx2;datarx20];
[datarx30, subsignal3]=recCDMA(Datarx30,procgain,seqnum,linktype);
datarx3=[datarx3;datarx30];
[datarxreal0, subsignalreal]=recCDMA(Datarxreal0,procgain,seqnum,linktype);
datarxreal=[datarxreal;datarxreal0];
end
%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;
figure
subplot(2,2,1)
k=0:2:16
semilogy(k,ber1,'-rh')
hold on
semilogy(k,ber2,'-ro')
semilogy(k,ber3,'-rx')
semilogy(k,berreal,'-.b')
grid on
axis([0 16 10^(-4) 1])
xlabel('SNR/dB'),ylabel('BER')
legend('帧头1','帧头2','平均','理想')
set (gcf,'color',[1 1 1])
set(gca,'xtick',[0:2:16])
subplot(2,2,2)
k=0:2:16
semilogy(k,mse1,'-rh')
hold on
semilogy(k,mse2,'-ro')
semilogy(k,mse3,'-rx')
grid on
axis([0 16 10^(-4) 1])
xlabel('SNR/dB'),ylabel('MSE')
legend('帧头1','帧头2','平均')
set (gcf,'color',[1 1 1])
set(gca,'xtick',[0:2:16])
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