OFDM中LMMSE信道估計

clear all;
 close all;
 %=============== Some standard Hyperlan Params ==================
 T = 50e-9; % System sampling period 
 fs = 1/T; % System sampling freq = 20MHz 
 Tcp = 16*T; % CP period
 Tu = 64*T; % Useful symbol period
 Ts = Tu+Tcp; % OFDM Symbol period 80 samples
 delta_f = 0.3125e6; % Frequency spacingFFTLen = 64; % Length of FFT.
 CPLen = 16;  % Length of Cyclic Prefix
 M = 4;       % Bits encoded in a QAM symbol.
 Ns = 10;      % Number of Symbols/Carrier
 %F = 3;        % Order of the filter
 w = ones(FFTLen, 1);   % Filter coefficients, initialised to zero order 10 by default.
 SNRdB = 0;   % SNR of AWGN in channel in dBstore_input = zeros(Ns, FFTLen*M); % Used to calculate BER at the end.
 store_output = zeros(Ns, FFTLen*M);
 store_error = zeros(Ns, FFTLen);
 %=================== Simulation ===============================
 for sym=1:Ns
     %----------- Data genration ------------------
     input = rand(1,FFTLen*M) > 0.5; %transmits one symbol
     store_input(sym,:) = input;
     %----------- Transmit Data -------------------
     [signal_tx, input_symbols] = transmitter(input, FFTLen, CPLen, M);
     %----------- Channel the data ----------------
     signal_rx = channel(signal_tx, SNRdB);
     %-------------- Receiver ---------------------
     [signal_recovered, w, error_sym] = ...
         receiver_lmmse(signal_tx, signal_rx, input_symbols, FFTLen, CPLen, M, w, SNRdB);
     store_output(sym,:) = signal_recovered;
     store_error(sym,:) = error_sym.';
 end
 %=============== Simulation End ============================%==================== BER Calculation =========================
 errors = abs(store_input - store_output);
 num_errors = sum(sum(errors));
 BER = num_errors/(FFTLen*M*Ns)%=================== Plot Equlaizer Convergence ==================
 figure(10);
 error_samples = reshape(store_error.',1,(FFTLen)*Ns);
 semilogy(abs(error_samples.^2)), ...
     title('Zero Force Equalizer Error Over 10 Symbols') ...
     ,ylabel('Error Squared'), xlabel('OFDM Symbol');%==================== END FILE ===================================