www.gusucode.com > MIMO与SISO仿真程序 > MIMO-OFDM/all code/results_MISO_OFDMA_v1.m
clc; clear all;close all; warning off
% simulate 2x1 OFDMA System with timing offsets
data = 2^16; % data points
n_fft = 128; % fft size
n_cp = 16; % cyclic prefix
snr = [0:2:30];
errors1 = zeros(size(snr));
ber1 = zeros(size(snr));
errors2 = zeros(size(snr));
ber2 = zeros(size(snr));
OFDM = n_fft+2*n_cp;
%% generate data
binary_data1 = round(rand(data,1)); % generate data
binary_data2 = round(rand(data,1));
bin1= binary_data1;
bin2= binary_data2;
% channel
h = [randn() + randn()*1i];
h = [h h];
%h = [randn()+randn()*1i , randn()+randn()*1i];
%% modulation
for mod_value = 1:3
% bits per symbol
if mod_value == 1
symbols = 2;
elseif mod_value == 2
symbols = 4;
else
symbols = 6;
while floor(length(binary_data1)/symbols) ~= length(binary_data1)/symbols
binary_data1 = [binary_data1; zeros(1,1)]; %padding for symbol mapping
end
while floor(length(binary_data1)/symbols/n_fft) ~= length(binary_data1)/symbols/n_fft
binary_data1 = [binary_data1; zeros(6,1)]; %padding for subcarriers mapping
end
while floor(length(binary_data2)/symbols) ~= length(binary_data2)/symbols
binary_data2 = [binary_data2; zeros(1,1)]; %padding for symbol mapping
end
while floor(length(binary_data2)/symbols/n_fft) ~= length(binary_data2)/symbols/n_fft
binary_data2 = [binary_data2; zeros(6,1)]; %padding for subcarriers mapping
end
end
mod_method = 2^symbols;
mod_data1 = qammod(binary_data1,mod_method,'unitaveragepower',true,'inputtype','bit');
mod_data2 = qammod(binary_data2,mod_method,'unitaveragepower',true,'inputtype','bit');
%% splitting data up between the transmitters
Tx1 = mod_data1;
Tx2 = mod_data2;
% allocating data onto each subcarrier
%% subcarriers
Xk1 = reshape(Tx1,n_fft/2,length(Tx1)/(n_fft/2)); % 64 sub carriers, per user
Xk2 = reshape(Tx2,n_fft/2,length(Tx2)/(n_fft/2));
%% ifft
% ofdm symbol
% ifft
Xn1 = ifft(Xk1);
Xn2 = ifft(Xk2);
% CP
Xn1_cp = [Xn1((end - n_cp + 1):end,:);Xn1];
Xn2_cp = [Xn2((end - n_cp + 1):end,:);Xn2];
Xn1_pad = [ Xn1_cp ; zeros(size(Xn1_cp)) ];
Xn2_pad = [ zeros( size(Xn2_cp)) ; Xn2_cp ];
% Parallel to Serial
xn1 = Xn1_pad(:);
xn2 = Xn2_pad(:);
%% channel
for k = 1:length(snr)
% channel gain
yn11 = xn1*h(1); % y time, receiver
yn21 = xn2*h(2);
db = snr(k);
%noise
yn11 = awgn(yn11,db,'measured');
yn21 = awgn(yn21,db,'measured');
% % delay
delay11 = 23;
delay21 = 0;
% tail of previous symbol added to front of next symbol - ISI
for i = 0:(length(yn11)/(OFDM))-2
if delay11 ~= 0
yn11(1+OFDM+OFDM*i:1+OFDM+delay11+OFDM*i) = yn11(1+OFDM+OFDM*i:1+OFDM+delay11+OFDM*i) ...
+ yn11(OFDM/2-delay11+OFDM*i:OFDM/2+OFDM*i);
end
if delay21 ~= 0
yn21(1+OFDM+OFDM*i:1+OFDM+delay21+OFDM*i) = yn21(1+OFDM+OFDM*i:1+OFDM+delay21+OFDM*i) ...
+ yn21(OFDM-delay21+OFDM*i:OFDM+OFDM*i);
end
end
if delay11 ~= 0
yn11(1:OFDM) = [zeros(delay11+1,1);yn11(1:OFDM-delay11-1)];
end
if delay21 ~= 0
yn21(OFDM+1:2*OFDM) = [zeros(delay21+1,1);yn21(OFDM+1:2*OFDM-delay21-1)];
end
% superposition
yn = yn11 + yn21;
%% receiver
%serial to parallel 128+CP streams
yn_sub = reshape(yn,n_fft+2*n_cp,length(Xn1));
% % users
Yn_sub1 = yn_sub(1:80,:); % higher order decision block
Yn_sub2 = yn_sub(81:160,:);
% % delay
% delay11 = 20;
% delay21 = 0;
%
% for i = 0:(length(yn11)/(OFDM))-2
% if delay11 ~= 0
% Yn11(1+OFDM+OFDM*i:1+OFDM+delay11+OFDM*i) = Yn11(1+OFDM+OFDM*i:1+OFDM+delay11+OFDM*i) ...
% + yn11(OFDM-delay11+OFDM*i:OFDM+OFDM*i);
% end
% if delay21 ~= 0
% yn21(1+OFDM+OFDM*i:1+OFDM+delay21+OFDM*i) = yn21(1+OFDM+OFDM*i:1+OFDM+delay21+OFDM*i) ...
% + yn21(OFDM-delay21+OFDM*i:OFDM+OFDM*i);
% end
%
% end
% if delay11 ~= 0
% yn11(1:OFDM) = [zeros(delay11+1,1);yn11(1:OFDM-delay11-1)];
% end
% if delay21 ~= 0
% yn21(1:OFDM) = [zeros(delay21+1,1);yn21(1:OFDM-delay21-1)];
% end
% remove CP
yn_sub_rcp1 = Yn_sub1((n_cp+1):end,:);
yn_sub_rcp2 = Yn_sub2((n_cp+1):end,:);
%% DFT convert back to freq domain
Yk_block1 = fft(yn_sub_rcp1);
Yk_block2 = fft(yn_sub_rcp2);
% P/S
Yk1_s = Yk_block1(:); % transform 64 subchannels back into 1 stream
Yk2_s = Yk_block2(:);
% delay = 0;
% Yk1_s = [zeros(delay,1); Yk1_s];
%% Channel estimation
% assume perfect channel estimation, so we know what h1 and h2 are
Xhat1 = Yk1_s./h(1);
Xhat2 = Yk2_s./h(2);
%% demodulate
X_demod1 = qamdemod(Xhat1,mod_method,'unitaveragepower',true,'outputtype','bit');
X_demod2 = qamdemod(Xhat2,mod_method,'unitaveragepower',true,'outputtype','bit');
output1 = X_demod1(:).';
output2 = X_demod2(:).';
%%
% binary_data1 = [bin1; zeros(delay,1)];
% binary_data2 = [bin2; zeros(delay,1)];
errors1(mod_value,k) = 0;
for i = 1:length(binary_data1)-n_fft*symbols
if output1(i+n_fft*symbols) ~= binary_data1(i+n_fft*symbols)
errors1(mod_value,k) = errors1(mod_value,k) + 1;
end
end
ber1(mod_value,k) = errors1(mod_value,k)/length(binary_data1);
errors2(mod_value,k) = 0;
for i = 1:length(binary_data2)-n_fft*symbols
if output2(i+n_fft*symbols) ~= binary_data2(i+n_fft*symbols)
errors2(mod_value,k) = errors2(mod_value,k) + 1;
end
end
ber2(mod_value,k) = errors2(mod_value,k)/length(binary_data2);
end
semilogy(snr-10*log10(symbols),ber1(mod_value,:),'-',snr-10*log10(symbols),ber2(mod_value,:),'-')
%semilogy(snr,ber2(mod_value,:),'o-');
title('Two users One receiver with Time Offset greater than CP by 50%'); legend('4QAM user1','4QAM user2','16QAM user1','16QAM user2','64QAM user1','64QAM user2');
xlabel('E_b/N_o (dB)'); ylabel('BER'); grid on;hold on
end
error = zeros(1,length(binary_data1));
for i = 1:length(binary_data1)
if output1(i) ~= binary_data1(i)
error(i) = 1;
end
end
% scatterplot(Yk_block1(:,1))
%
% scatterplot(Yk_block1(:,2))