基于matlab实现的空间调制的最大似然检测，借鉴他人的，性能比较好，仅供参考

%========================================================================== % Copywrite 2015 % Maximum Likelihood detector % for spatial Modulation (SM) MIMO transmission technique. % This Matlab code computes the BER of the SM for the case where the % channel coefficients are modeled as uncorrelated Rayleigh fading channel % M is the modulation order of M-QAM schemes. % Mt = number of transmit antennas.% Mr = number of receive antennas. %========================================================================== clear all; clc; mode = 1; % mode = 1 the channel is normalized, % mode = 2 the channel is not normalized M = 8;%4 Mt = 8; Mr = 4; bit_SMsym = log2(M*Mt); % number of bit per spatial modulation sysmbol Nbits = bit_SMsym*1e3; % Number of bits to be simulated. %4 Nt = log2(Mt); Nobit = log2(M); hmodem = modem.qammod('M',M, 'SymbolOrder', 'Gray','InputType', 'bit'); hdemodem = modem.qamdemod('M', M,'SymbolOrder','Gray','OutputType','bit'); Eac = (mean(hmodem.Constellation .* conj(hmodem.Constellation))); decimal = 0:M-1; % generate all possible transmitted symnols binary = de2bi(decimal(:), log2(M) ,'left-msb')'; % convert from binary to decimal binary = binary(:); all_sym = modulate(hmodem,binary); SNR = 0 : 2 :30; % signal-to-noise ratio in dB No= (Eac)*10.^(-SNR/10); % noise variance L_SNR=length(SNR); ber= zeros (L_SNR,1); bit_R=zeros(Nbits, 1); % ============================= Transmitter =============================== bit_T = randi([0 1],Nbits,1); % generate random bits x = reshape(bit_T,Nobit+Nt,[]); % grouping bits into blocks % =========== Spatial modulation mapping ============ ante = bi2de(x(1:Nt,:).' , 'left-msb') + 1;% Select the antenna index digMod = modulate(hmodem,x(Nt+1:end,:)); % Mapping the remaing bits mod_T = zeros(Mt , length(digMod)); for i = 1 : length(digMod) mod_T( ante(i) , i) = digMod(i); end for ii=1:L_SNR for j = 1 : size(mod_T ,2) ch = sqrt(.5)*( randn(Mr,Mt,1) + 1i*randn(Mr,Mt,1)); noise = sqrt(.5)*(randn(Mr , 1) + 1i*randn(Mr , 1))* sqrt(No(ii)); % =============================== Receiver ================================ y = (ch(:,ante(j)) )* mod_T(ante(j) ,j) + noise; % Received Signal yy = kron(y,ones(1,M)); ML=zeros(Mt,M); % In the following we find |y-hj.si|^2 for all possible symbol and % antenna index for k = 1:Mt ML(k,:) = sum(abs(yy - ch(:,k)*all_sym.').^2); end [temp1, temp2] = min(ML); [aaa, sym_num] = min(temp1); % findind index of estimating symbol ant_num = temp2(sym_num); % findind index of estimating antenna bi_ant = de2bi(ant_num - 1 , log2(Mt) ,'left-msb'); bi_mod = demodulate(hdemodem,all_sym(sym_num,1)); bit_R( (j-1)*bit_SMsym+1 : (j-1)*bit_SMsym+bit_SMsym ,1 ) = [bi_ant.' ; bi_mod]; end bit_R = bit_R(:); [bbb,ber(ii,1)] = biterr(bit_T(:,1),bit_R(:)); end semilogy(SNR,ber(:,1),'color',[0,0.75,0.75],'linestyle','-','LineWidth',1); grid on; xlabel('$$SNR$$','Interpreter','latex') ylabel('BER','Interpreter','latex') title('Bit Error Rate of SM using i-MRC detector') legend([num2str(M),'-QAM'] , 'Location','NorthEast')