ofdm信道估计和均衡源码程序 - matlab通信信号

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标题：ofdm信道估计和均衡源码程序
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所属分类: 通信信号资源类型：文件大小: 15.65 KB 上传时间: 2016-01-24 21:56:30 下载次数: 42 资源积分：1分提供者: matlab源码 ofdm信道估计和均衡源码程序

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ofdm信道估计和均衡源码程序，程序员在编程的过程中可以参考学习使用，希望对IT程序员有用，此源码程序简单易懂、方便阅读，有很好的学习价值！

部分代码如下：

%author：liuqingwei May 12th 2006 9:40 PM.

%OFDM Channel Estimation Based on Comb Pilot

%IFFT_bin_length: IFFT和FFT的点数

%carrier_count: 子载波个数

%bits_per_symbol: 每符号上的比特数

%symbols_per_carrier: 每桢的OFDM符号数

%Ｘ：欲发送的二进制比特流

clear all;

clc;

IFFT_bin_length=128;

carrier_count=100;

bits_per_symbol=2;

symbols_per_carrier=12;

LI=7 ; %导频之间的间隔

Np=ceil(carrier_count/LI)+1;%导频数 %加1的原因：使最后一列也是导频

N_number=carrier_count*symbols_per_carrier*bits_per_symbol;

carriers=1:carrier_count+Np;

GI=8; % guard interval length

N_snr=40; % 每比特信噪比

snr=8; %信噪比间隔

%------------------------------------------------------------

% vector initialization

X=zeros(1,N_number);

X1=[];

X2=[];

X3=[];

X4=[];

X5=[];

X6=[];

X7=[];

Y1=[];

Y2=[];

Y3=[];

Y4=[];

Y5=[];

Y6=[];

Y7=[];

XX=zeros(1,N_number);

dif_bit=zeros(1,N_number);

dif_bit1=zeros(1,N_number);

dif_bit2=zeros(1,N_number);

dif_bit3=zeros(1,N_number);

X=randint(1,N_number);%产生二进制随即序列（非0即1）

%--------------------------------------------------------

%QPSK调制：(1 1)->pi/4;(0 1)->3*pi/4;(0 0)->-3*pi/4;(1,0)->-pi/4;

s=(X.*2-1)/sqrt(2);

sreal=s(1:2:N_number);

simage=s(2:2:N_number);

X1=sreal+j.*simage;

%---------------------------------------------------------

%产生随机导频信号

%--------------------------------------------------------

train_sym=randint(1,2*symbols_per_carrier);

t=(train_sym.*2-1)/sqrt(2);

treal=t(1:2:2*symbols_per_carrier);

timage=t(2:2:2*symbols_per_carrier);

training_symbols1=treal+j.*timage;

training_symbols2=training_symbols1.';

training_symbols=repmat(training_symbols2,1,Np);

%disp(training_symbols)

pilot=1:LI+1:carrier_count+Np;

if length(pilot)~=Np

pilot=[pilot,carrier_count+Np];

end

%--------------------------------------------------------

%串并转换

X2=reshape(X1,carrier_count,symbols_per_carrier).';

%---------------------------------------------------------

%插入导频

signal=1:carrier_count+Np;

signal(pilot)=[];

X3(:,pilot)=training_symbols;

X3(:,signal)=X2;

%X3=cat(1,training_symbols,X2);

IFFT_modulation=zeros(symbols_per_carrier,IFFT_bin_length);

IFFT_modulation(:,carriers)=X3;

%IFFT_modulation(:,conjugate_carriers)=conj(X3);

X4=ifft(IFFT_modulation,IFFT_bin_length,2);

%X5=X4.';

%加保护间隔（循环前缀）

for k=1:symbols_per_carrier;

for i=1:IFFT_bin_length;

X6(k,i+GI)=X4(k,i);

end

for i=1:GI;

X6(k,i)=X4(k,i+IFFT_bin_length-GI);

end

%---------------------------------------------------------

%并串转换

X7=reshape(X6.',1,symbols_per_carrier*(IFFT_bin_length+GI));

%---------------------------------------------------------

%信道模型:带多普勒频移的瑞利衰落信道

fd=100; %多普勒频移

r=6; %多径数

a=[0.123 0.3 0.4 0.5 0.7 0.8]; %多径的幅度

d=[2 3 4 5 9 13]; %各径的延迟

T=1; %系统采样周期

th=[90 0 72 144 216 288]*pi./180;%相移

h=zeros(1,carrier_count);

hh=[];

for k=1:r

%deta=[zeros(1,d(k)-1),1,zeros(1,carrier_count-d(k))];

h1=a(k)*exp(j*((2*pi*T*fd*d(k)/carrier_count)));

%h1=a(k)*exp(j*((2*pi*T*fd*d(k)/carrier_count)));

hh=[hh,h1];

end

h(d+1)=hh;

%noise=randn(1,length(X7))+j.*randn(1,length(X7));

%--------------------------------------------------------

channel1=zeros(size(X7));

channel1(1+d(1):length(X7))=hh(1)*X7(1:length(X7)-d(1));

channel2=zeros(size(X7));

channel2(1+d(2):length(X7))=hh(2)*X7(1:length(X7)-d(2));

channel3=zeros(size(X7));

channel3(1+d(3):length(X7))=hh(3)*X7(1:length(X7)-d(3));

channel4=zeros(size(X7));

channel4(1+d(4):length(X7))=hh(4)*X7(1:length(X7)-d(4));

channel5=zeros(size(X7));

channel5(1+d(5):length(X7))=hh(5)*X7(1:length(X7)-d(5));

channel6=zeros(size(X7));

channel6(1+d(6):length(X7))=hh(6)*X7(1:length(X7)-d(6));

%---------------------------------------------------------------

Tx_data=X7+channel1+channel2+channel3+channel4;

%---------------------------------------------------------------

%----------------------------------------------------------------

%加高斯白噪声

Error_ber=[];%误比特率

Error_ber1=[];

Error_ber2=[];%误比特率

Error_ber3=[];

%Error_ser=[];%误符号率

for snr_db=0:snr:N_snr

code_power=0;

code_power=[norm(Tx_data)]^2/(length(Tx_data));%信号的符号功率

%bit_power=var(Tx_data);

bit_power=code_power/bits_per_symbol;%比特功率

noise_power=10*log10((bit_power/(10^(snr_db/10))));%噪声功率

noise=wgn(1,length(Tx_data),noise_power,'complex');%产生GAUSS白噪声信号

Y7=Tx_data+noise;

%-------------------------------------------------------

%串并变换

Y6=reshape(Y7,IFFT_bin_length+GI,symbols_per_carrier).';

%去保护间隔

for k=1:symbols_per_carrier;

for i=1:IFFT_bin_length;

Y5(k,i)=Y6(k,i+GI);

end

Y4=fft(Y5,IFFT_bin_length,2);

Y3=Y4(:,carriers);

%-------------------------------------------------------------

%LS信道估计

H=[];

Y2=Y3(:,signal);

Rx_training_symbols=Y3(:,pilot);

Rx_training_symbols0=reshape(Rx_training_symbols,symbols_per_carrier*Np,1);

training_symbol0=reshape(training_symbols,1,symbols_per_carrier*Np);

training_symbol1=diag(training_symbol0);

%disp(training_symbols)

training_symbol2=inv(training_symbol1);

Hls=training_symbol2*Rx_training_symbols0;

Hls1=reshape(Hls,symbols_per_carrier,Np);

HLs=[];

HLs1=[];

if ceil(carrier_count/LI)==carrier_count/LI

for k=1:Np-1

HLs2=[];

for t=1:LI

HLs1(:,1)=(Hls1(:,k+1)-Hls1(:,k))*(t-1)./LI+Hls1(:,k);

HLs2=[HLs2,HLs1];

end

HLs=[HLs,HLs2];

end

else

for k=1:Np-2

HLs2=[];

for t=1:LI

HLs1(:,1)=(Hls1(:,k+1)-Hls1(:,k))*(t-1)./LI+Hls1(:,k);

HLs2=[HLs2,HLs1];

end

HLs=[HLs,HLs2];

end

HLs3=[];

for t=1:mod(carrier_count,LI)

HLs1(:,1)=(Hls1(:,Np)-Hls1(:,Np-1))*(t-1)./LI+Hls1(:,Np-1);

HLs3=[HLs3,HLs1];

end;

HLs=[HLs,HLs3];

end

%Hls1=Hls.';

%H=repmat(Hls1,symbols_per_carrier,1);%将导频扩展成symbols_per_carrier*carrier_count矩阵

Y1=Y2./HLs;

%-------------------------------------------------------------------

%-------------------------------------------------------------

%并串变换

YY=reshape(Y2.',1,N_number/bits_per_symbol);

YY1=reshape(Y1.',1,N_number/bits_per_symbol);

%------------------------------------------------------------

%QPSK解调

y_real=sign(real(YY));

y_image=sign(imag(YY));

y_re=y_real./sqrt(2);

y_im=y_image./sqrt(2);

y_real1=sign(real(YY1));

y_image1=sign(imag(YY1));

y_re1=y_real1./sqrt(2);

y_im1=y_image1./sqrt(2);

r00=[];

r01=[];

r10=[];

r11=[];

for k=1:length(y_real);

r00=[r00,[y_real(k),y_image(k)]];

end;

for k=1:length(y_real1);

r10=[r10,[y_real1(k),y_image1(k)]];

end;

for k=1:length(y_re);

r01=[r01,[y_re(k),y_im(k)]];

end;

for k=1:length(y_re1);

r11=[r11,[y_re1(k),y_im1(k)]];

end;

XX(find(r01>0))=1;

%-------------------------------------------------------------

%计算在不同信噪比下的误比特率并作图

dif_bit=s-r01;

dif_bit1=s-r11;

ber_snr=0; %纪录误比特数

for k=1:N_number;

if dif_bit(k)~=0;

ber_snr=ber_snr+1;

end

end;

ber_snr1=0; %纪录误比特数

for k=1:N_number;

if dif_bit1(k)~=0;

ber_snr1=ber_snr1+1;

end

Error_ber=[Error_ber,ber_snr];

Error_ber1=[Error_ber1,ber_snr1];

end

BER=zeros(1,length(0:snr:N_snr));

BER1=zeros(1,length(0:snr:N_snr));

BER=Error_ber./N_number;

BER1=Error_ber1./N_number;

%-------------------------------------------------------------

i=0:snr:N_snr;

semilogy(i,BER,'-*r');

hold on;

semilogy(i,BER1,'-og');

hold on;

grid on;

legend('No Channel Estimation','LS Channel Estimation');

hold off

文件列表（点击上边下载按钮，如果是垃圾文件请在下面评价差评或者投诉）:

ofdm信道估计和均衡源码程序/
ofdm信道估计和均衡源码程序/ofdm_estimation.m
ofdm信道估计和均衡源码程序/ofdm信道估计和均衡.docx

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