www.gusucode.com > MIMO与SISO仿真程序 > MIMO-OFDM/all code/MIMO_v6_0_2x2.m
clc; clear all; close all data = 2^16; % data points n_fft = 64; % fft size n_cp = 16; % cyclic prefix snr = [0:1:35]; %% binary_data = round(rand(data,1)); % generate data %% mod_method = 4; mod_data = qammod(binary_data,mod_method,'unitaveragepower',true,'inputtype','bit'); %% STBC % [x1 -x2* ; x2 x1*] STBC = zeros(2*length(mod_data),1); for i = 0:(length(mod_data)/2-1) STBC(4*i+1) = mod_data(2*i+1); STBC(4*i+2) = mod_data(2*i+2); STBC(4*i+3) = -conj(mod_data(2*i+2)); STBC(4*i+4) = conj(mod_data(2*i+1)); end STBC = reshape(STBC.',2,length(mod_data)); %% splitting up the data between the transmitters Tx1 = STBC(1,:); Tx2 = STBC(2,:); %% IFFT Xk1 = reshape(Tx1,n_fft,length(Tx1)/n_fft); Xk2 = reshape(Tx2,n_fft,length(Tx2)/n_fft); Xn1 = ifft(Xk1); Xn2 = ifft(Xk2); %% Cyclic prefix Xn1_cp = [Xn1(:,(end - n_cp + 1):end),Xn1]; Xn2_cp = [Xn2(:,(end - n_cp + 1):end),Xn2]; %% Channel h = [randn()+randn()*1i, randn()+randn()*1i; randn()+randn()*1i, randn()+randn()*1i]; yn11 = Xn1_cp*h(1,1); % y time, receiver yn21 = Xn2_cp*h(2,1); yn12 = Xn1_cp*h(1,2); yn22 = Xn2_cp*h(2,2); % superposition of two received signals at receiver yn1 = yn11 + yn21; % y(1) = h1*x1 + h2*x2 ; y(2) = -h2* x1* + h1 * x2* yn2 = yn12 + yn22; %% remove cyclic prefix yn1_rcp = yn1(:,(n_cp + 1):end); yn2_rcp = yn2(:,(n_cp + 1):end); %% DFT Yk1_block = fft(yn1_rcp); Yk2_block = fft(yn2_rcp); Yk1 = reshape(Yk1_block, 1, length(Tx1)); % transform 64 subchannels back into 1 stream Yk2 = reshape(Yk2_block, 1, length(Tx2)); %% STBC decoding abs_h = sum(sum(abs(h).^2)); % assume perfect channel estimation H = [ conj(h(1,1)) , conj(h(1,2)), h(2,1), h(2,2) ; ... % pseudo inverse conj(h(2,1)), conj(h(2,2)), -h(1,1) , -h(1,2)]./ abs_h; X_hat1 = zeros(length(Yk1)/2,1); X_hat2 = zeros(length(Yk2)/2,1); X = zeros(length(binary_data)/2,1); for i = 0:length(Yk1)/2-1 Yk1(2*i+2) = conj(Yk1(2*i+2)); Yk2(2*i+2) = conj(Yk2(2*i+2)); X_hat1(i+1) = H(1,1)*Yk1(2*i+1) + H(1,2)*Yk2(2*i+1) + H(1,3)*Yk1(2*i+2) + H(1,4)*Yk2(2*i+2); X_hat2(i+1) = H(2,1)*Yk1(2*i+1) + H(2,2)*Yk2(2*i+1) + H(2,3)*Yk1(2*i+2) + H(2,4)*Yk2(2*i+2); X(2*i+1) = X_hat1(i+1); X(2*i+2) = X_hat2(i+1); end %% demodulate X_demod = qamdemod(X,4,'unitaveragepower',true,'outputtype','bit'); output = reshape(X_demod.',size(binary_data)); %% errors = 0; for i = 1:length(binary_data) if X_demod(i) ~= binary_data(i) errors = errors + 1; end end