ofdm_multisymbol_zf.m

OFDM信道估计和均衡的仿真程序

%+----------------------------------------------------------------+
%|                                                                |
%|  Name: ofdm_mutlisymbol_ZF.m                                                 |
%|  Author: James Shen                                            |
%|  Description: Basic OFDM model used for simulation purposes.   |    
%|  This model can transmit a specified number of symbols  .      |
%|                                                                |
%+----------------------------------------------------------------+
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 spacing

FFTLen = 64; % Length of FFT.
CPLen = 16;  % Length of Cyclic Prefix
M = 4;       % Bits encoded in a QAM symbol.
Ns = 10;     % Number of Symbols/Carrier
w = ones(FFTLen, 1);   % Filter coefficients, initialised to zero order 10 by default.
SNRdB = 100;   % SNR of AWGN in channel in dB

store_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_zf(signal_tx, signal_rx, input_symbols, FFTLen, CPLen, M, w);
    store_output(sym,:) = signal_recovered;
    store_error(sym,:) = error_sym.';
end
%=============== Simulation End ============================

%==================== BER Calculation =========================
errors_ext = abs(store_input - store_output);
errors = errors_ext(FFTLen+1:length(errors_ext));
num_errors = sum(sum(errors));
BER = num_errors/(FFTLen*M*(Ns-1))

%=================== 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 ===================================