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MMSE_detection_2x2.m
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MMSE_detection_2x2.m
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% MMSE_detection_2x2.m
%MIMO-OFDM Wireless Communications with MATLAB¢ç Yong Soo Cho, Jaekwon Kim, Won Young Yang and Chung G. Kang
%2010 John Wiley & Sons (Asia) Pte Ltd
clear all; close all; clc; tic
%%%%%%% option %%%%%%%
bits_option = 2; %% 0 : all zeros, 1 : all ones, 2: random binary
noise_option = 1; %% 0 : no noise addition, 1 : noise added
decision_scheme = 1;%% 0 : Hard decision, 1 : soft decision
b = 4; NT = 2;
SNRdBs =[0:2:25]; sq05=sqrt(0.5);
nobe_target = 500; BER_target = 1e-3;
raw_bit_len = 2592-6;
interleaving_num = 72; deinterleaving_num = 72;
N_frame = 1e8; %% maximum generated bits #
for i_SNR=1:length(SNRdBs)
sig_power=NT; SNRdB=SNRdBs(i_SNR);
sigma2=sig_power*10^(-SNRdB/10)*noise_option; sigma1=sqrt(sigma2/2);
rand('seed',1); randn('seed',1);
nobe = 0;
Viterbi_init
for i_frame=1:1:N_frame
%%%%%%%%%%%%%% Random data generation %%%%%%%%%%%%%%
switch (bits_option)
case {0}, bits=zeros(1,raw_bit_len);
case {1}, bits=ones(1,raw_bit_len);
case {2}, bits=randint(1,raw_bit_len);
end
%%% Convolutional encoding %%%%%
encoding_bits = convolution_encoder(bits);
% Interleaving %%
interleaved=[];
for i=1:interleaving_num
interleaved=[interleaved encoding_bits([i:interleaving_num:end])];
end
temp_bit =[];
for tx_time=1:648
tx_bits=interleaved(1:8);
interleaved(1:8)=[];
%%%%%%%%%%%%%% QAM16 modulation %%%%%%%%%%%%%%
QAM16_symbol = QAM16_mod(tx_bits, 2);
%%%%%%%%%%%%%% S/P %%%%%%%%%%%%%%
x(1,1) = QAM16_symbol(1); x(2,1) = QAM16_symbol(2);
%%%%% Channel H and received y %%%%%%%%%%%%
if rem(tx_time-1,81)==0
H = sq05*(randn(2,2)+j*randn(2,2));
end
y = H*x;
%%% AWGN addition %%%
noise = sqrt(sigma2/2)*(randn(2,1)+j*randn(2,1));
if noise_option==1, y = y + noise; end
%%%%%%%%%%%%% MMSE Detector %%%%%%%%%%%%%%%%%%
W = inv(H'*H+sigma2*diag(ones(1,2)))*H';
X_tilde = W*y;
%%%%%%%%%%%%% Hard decision %%%%%%%%%%%%%
if (decision_scheme == 0)
X_hat = QAM16_slicer(X_tilde, 2);
temp_bit = [temp_bit QAM16_demapper(X_hat, 2)];
%%%%%%%%%%%%% Soft decision %%%%%%%%%%%%%
else
soft_bits = Softoutput2x2(X_tilde); Ps=1;
SINR1=(Ps*(abs((W(1,:)*H(:,1)))^2)) / (Ps*( abs((W(1,:)*H(:,2)))^2 + W(1,:)*W(1,:)'*sigma2));
SINR2=(Ps*(abs((W(2,:)*H(:,2)))^2)) / (Ps*( abs((W(2,:)*H(:,1)))^2 + W(2,:)*W(2,:)'*sigma2));
soft_bits(1:4)=soft_bits(1:4)*SINR1;
soft_bits(5:8)=soft_bits(5:8)*SINR2;
temp_bit=[temp_bit soft_bits];
end
end
%% Deinterleaving
deinterleaved=[];
for i=1:deinterleaving_num
deinterleaved=[deinterleaved temp_bit([i:deinterleaving_num:end])];
end
%% Viterbi
received_bit=Viterbi_decode(deinterleaved);
%%%%% Error check %%%%%%
for EC_dummy=1:1:raw_bit_len,
if bits(EC_dummy)~=received_bit(EC_dummy), nobe=nobe+1; end
if nobe>=nobe_target, break; end
end
if (nobe>=nobe_target) break; end
end
%%%%%%%%%%%%% save BER data & Display %%%%%%%%%%%%%
BER(i_SNR) = nobe/((i_frame-1)*raw_bit_len+EC_dummy);
fprintf('\t%d\t\t%1.4f\n',SNRdB,BER(i_SNR));
if BER(i_SNR)<BER_target, break; end
end