OFDM仿真代码（完整）

#OFDM仿真代码（完整）

%DVB_T 2K Transmission
%The available bandwidth is 8 MHZ
%2K is intend for mobile services
clear all;
close all;

%DVB_T Parameters

Tu=224e-6; %useful OFDM symbol period
T=Tu/2048; %beceuse elementary period
G=0; %choice of 1/4,1/8,1/16,and 1/32
delta=GTu; %gaurd band duration
Ts=delta+Tu; %total OFDM symbol period
Kmax=1705; %number of subcarriers
Kmin=0;
FS=4096; %IFFT/FFT length
q=10; %carrier period to elementary period ratio
fc=q1/T; %carrier frequency
Rs=4*fc; %simultation period
t=0:1/Rs:Tu;

%Data generator (A)

M=Kmax+1;
rand(‘state’,0);
a=-1+2round(rand(M,1)).’+1i(-1+2*round(rand(M,1))).’;
A=length(a);
info=zeros(FS,1);
info(1:(A/2)) = [ a(1:(A/2)).’];%Zeros padding
info((FS-((A/2)-1)):FS) = [ a(((A/2)+1):A).’];

%Subcarriers generation (B)

carriers=FS.ifft(info,FS);
tt=0:T/2:Tu;
figure(1);
subplot(221);
stem(tt(1:20),real(carriers(1:20)));
subplot(212);
stem(tt(1:20),imag(carriers(1:20)));
figure(2);
f=(2/T)(1:(FS))/(FS);
subplot(211);
plot(f,abs(fft(carriers,FS))/FS);
subplot(212);
pwelch(carriers,[],[],[],2/T);

%D/A simulation

L = length(carriers);
chips = [ carriers.’;zeros((2q)-1,L)];
p=1/Rs:1/Rs:T/2;
g=ones(length§,1); %pulse shape
figure(3);
stem(p,g);
dummpy=conv(g,chips(?);
u=[dummpy(1:length(t))]; %©
figure(4);
subplot(211);
plot(t(1:400),real(u(1:400)));
subplot(212);
plot(t(1:400),imag(u(1:400)));
figure(5);
ff=(Rs)(1:(qFS))/(qFS);
subplot(211);
plot(ff,abs(fft(u,qFS))/FS);
subplot(212);
pwelch(u,[],[],[],Rs);
[b,a] = butter(13,1/20); %reconstruction filter
%[H,F] = FREQZ(b,a,FS,Rs);
[H,F] = freqz(b,a,FS,Rs);
figure(6);
plot(F,20log10(abs(H)));
uoft = filter(b,a,u); %baseband signal (D)
figure(7);
subplot(211);
plot(t(80:480),real(uoft(80:480)));
subplot(212);
plot(t(80:480),imag(uoft(80:480)));
figure(8);
subplot(211);
plot(ff,abs(fft(uoft,q*FS))/FS);
subplot(212);
pwelch(uoft,[],[],[],Rs);

%Upconverter

s_tilde=(uoft.’).exp(1i2pifc*t);
s=real(s_tilde); %passband signal (E)

figure(9);
plot(t(80:480),s(80:480));
figure(10);
subplot(211);
%plot(ff,abs(fft(((real(uoft).’).cos(2pifct)),qFS))/FS);
%plot(ff,abs(fft(((imag(uoft).’).sin(2pifct)),qFS))/FS);
plot(ff,abs(fft(s,qFS))/FS);
subplot(212);
%pwelch(((real(uoft).’).cos(2pifct)),[],[],[],Rs);
%pwelch(((imag(uoft).’).sin(2pifc*t)),[],[],[],Rs);
pwelch(s,[],[],[],Rs);

%DVB-T 2K Reception

clear all;
close all;

Tu=224e-6; %useful OFDM symbol period
T=Tu/2048; %baseband elementary period
G=0; %choice of 1/4,1/8,1/16,and 1/32
delta=GTu; %guard band duration
Ts=delta+Tu; %total OFDM symbol period
Kmax=1705; %number of subcarriers
Kmin=0;
FS=4096; %IFFT/FFT length
q=10; %carrier period to elementary period ratio
fc=q1/T; %carrier frequency
Rs=4*fc; %simulation period
t=0:1/Rs:Tu;
tt=0:T/2:Tu;

%Data generator
sM = 2;
[x,y] = meshgrid((-sM+1):2:(sM-1),(-sM+1):2:(sM-1));
alphabet = x(? + 1iy(?;
N=Kmax+1;
rand(‘state’,0);
a=-1+2round(rand(N,1)).’+1i*(-1+2*round(rand(N,1))).’;
A=length(a);
info=zeros(FS,1);
info(1:(A/2)) = [ a(1:(A/2)).’];
info((FS-((A/2)-1)):FS) = [ a(((A/2)+1):A).’ ];
carriers=FS.*ifft(info,FS);

%Upconverter
L = length(carriers);
chips = [ carriers.’;zeros((2q)-1,L)];
p=1/Rs:1/Rs:T/2;
g=ones(length§,1);
dummpy=conv(g,chips(?);
u=[dummpy; zeros(64,1)];
[b,aa] = butter(13,1/20);
uoft = filter(b,aa,u);
delay=64; %Reconstruction filter delay
s_tilde=(uoft(delay+(1:length(t))).’).exp(1i2pifct);
s=real(s_tilde);

%OFDM RECEPTION

%Downconversion
r_tilde=exp(-1i2pifct).s; %(F)
figure(1);
subplot(211);
plot(t,real(r_tilde));
axis([0e-7 12e-7 -60 60]);
grid on;
figure(1);
subplot(212);
plot(t,imag(r_tilde));
axis([0e-7 12e-7 -100 150]);
grid on;
figure(2);
ff=(Rs)(1:(qFS))/(qFS);
subplot(211);
plot(ff,abs(fft(r_tilde,q*FS))/FS);
grid on;
figure(2);
subplot(212);
pwelch(r_tilde,[],[],[],Rs);

%Carrier suppression

[B,AA] = butter(3,1/2);
r_info=2filter(B,AA,r_tilde); %Baseband signal continuous-time (G)
figure(3);
subplot(211);
plot(t,real(r_info));
axis([0 12e-7 -100 150]);
grid on;
figure(4);
f=(2/T)(1:(FS))/(FS);
subplot(211);
plot(ff,abs(fft(r_info,q*FS))/FS);
grid on;
subplot(212);
pwelch(r_info,[],[],[],Rs);

%Sampling

r_data=real(r_info(1:(2q):length(t)))… %Baseband signal ,disrete-time
+1iimag(r_info(1:(2q):length(t))); %(H)
figure(5);
subplot(211);
stem(tt(1:20),(real(r_data(1:20))));
axis([0 12e-7 -60 60]);
grid on;
figure(5);
subplot(212);
stem(tt(1:20),(imag(r_data(1:20))));
axis([0 12e-7 -100 150]);
grid on;
figure(6);
f=(2/T)(1:(FS))/(FS);
subplot(211);
f=(2/T)*(1:(FS))/(FS);
subplot(211);
plot(f,abs(fft(r_data,FS))/FS);
grid on;
subplot(212);
pwelch(r_data,[],[],[],2/T);

%FFT

info_2N=(1/FS).*fft(r_data,FS); %(I)
info_h=[info_2N(1:A/2) info_2N((FS-((A/2)-1)):FS)];

%Slicing

for k=1:N,
a_hat(k)=alphabet((info_h(k)-alphabet)==min(info_h(k)-alphabet)); %(J)
end;

figure(7)
plot(info_h((1:A)),’.k’);
title(‘info-h Received Constellation’)
axis square;
axis equal;
figure(8);
plot(a_hat((1:A)),‘or’);
title(‘a_hat 4-QAM’)
axis square;
axis equal;
grid on;
axis([-1.5 1.5 -1.5 1.5]);

%DVB-T 2K signal generation Eq. (2.1.4) vs. 2N-IFFT

clear all;
close all;

Tu=224e-6; %useful OFDM symbol period
T=Tu/2048; %beceuse elementary period
G=0; %choice of 1/4,1/8,1/16,and 1/32
delta=GTu; %gaurd band duration
Ts=delta+Tu; %total OFDM symbol period
Kmax=1705; %number of subcarriers
Kmin=0;
FS=4096; %IFFT/FFT length
q=10; %carrier period to elementary period ratio
fc=q1/T; %carrier frequency
Rs=4*fc; %simultation period

M=Kmax+1; %the value is from OFDM_Transmission
a=-1+2round(rand(M,1)).’+1i(-1+2round(rand(M,1))).’;
A=length(a);
info = [ a.’];
tt=0:1/Rs:Ts;
TT=length(tt);
k=Kmin:Kmax;
for t=0:(TT-1);
phi=a(k+1).exp((1j2(((t*(1/Rs))-delta))pi/Tu).((k-(Kmax-Kmin)/2)));
s(t+1)=real(exp(1j2pifc(t*(1/Rs))).*sum(phi));
end

infof=zeros(FS,1);
infof(1:(A/2)) = [ a(1:(A/2)).’];
infof((FS-((A/2)-1)):FS) = [ a(((A/2)+1):A).’];
carriers=FS.*ifft(infof,FS); %IFFT

%Upconverter
L = length(carriers);
chips = [ carriers.’;zeros((2q)-1,L)];
p=1/Rs:1/Rs:T/2;
g=ones(length§,1);
dummy=conv(g,chips(?);
u=[dummy(1:TT)];
[b,a] = butter(13,1/20);
uoft = filter(b,a,u);
s_tilde=(uoft.’).exp(1i2pifctt);
sf=real(s_tilde);
figure(1);
plot(tt,s,‘b’,tt,sf,‘g’);
figure(2);
pwelch(s,[],[],[],Rs);
hold on;
pwelch(sf,[],[],[],Rs);
hold off;

----------相关文章中文翻译：http://www.docin.com/p-1418270512.html
----------原文来自：Smart Antenna Research Laboratory