脏纸编码和Tomlinson-Harashima预编码附matlab代码.zip

% Dirty_or_TH_precoding.m %MIMO-OFDM Wireless Communications with MATLAB�� Yong Soo Cho, Jaekwon Kim, Won Young Yang and Chung G. Kang %2010 John Wiley & Sons (Asia) Pte Ltd clear all; clf mode = 0; % Set to 0/1 for Dirty/TH precoding N_frame=10; % Number of frames in a packet, 1 frame=4 symbols N_packet=200; % Number of packets b=2; % Number of bits per QPSK symbol NT=4; N_user=10; N_act_user=4; I=eye(N_act_user,NT); N_pbits = N_frame*NT*b; % Number of bits in a packet N_tbits = N_pbits*N_packet; % Number of total bits SNRdBs=[0:2:20]; sq2=sqrt(2); for i_SNR=1:length(SNRdBs) SNRdB = SNRdBs(i_SNR); N_ebits = 0; rand('seed',1); randn('seed',1); sigma2 = NT*0.5*10^(-SNRdB/10); sigma = sqrt(sigma2); %------------- Transmitter ---------------- for i_packet=1:N_packet msg_bit = randint(1,N_pbits); % Bit generation symbol = QPSK_mapper(msg_bit).'; x = reshape(symbol,NT,N_frame); H = (randn(N_user,NT)+j*randn(N_user,NT))/sq2; %----- user selection ---------- Combinations = nchoosek([1:N_user],N_act_user)'; for i=1:size(Combinations,2) H_used = H(Combinations(:,i),:); [Q_temp, R_temp] = qr(H_used); %diagonal entries of R_temp are real minimum_l(i) = min(diag(R_temp)); end [max_min_l,Index] = max(minimum_l); H_used = H(Combinations(:,Index),:); [Q_temp,R_temp] = qr(H_used'); L=R_temp'; Q=Q_temp'; xp = x; if mode==0 % Dirty precoding for m=2:4 xp(m,:) = xp(m,:) - L(m,1:m-1)/L(m,m)*xp(1:m-1,:); end else % TH precoding for m=2:4 xp(m,:) = modulo(xp(m,:)-L(m,1:m-1)/L(m,m)*xp(1:m-1,:),sq2); end end Tx_signal = Q'*xp; % DPC/TH encoder %------------ Channel and Noise ---------------- Rx_signal = H_used*Tx_signal + ... sigma*(randn(N_act_user,N_frame)+j*randn(N_act_user,N_frame)); %------------ Receiver ---------------- y = inv(diag(diag(L)))*Rx_signal; symbol_hat = reshape(y,NT*N_frame,1); if mode==1 % in the case of TH precoding symbol_hat = modulo(symbol_hat,sq2); end symbol_sliced = QPSK_slicer(symbol_hat); demapped = QPSK_demapper(symbol_sliced); N_ebits = N_ebits + sum(msg_bit~=demapped); end BER(i_SNR) = N_ebits/N_tbits; end semilogy(SNRdBs,BER,'-x'), grid on