ofdm.m

ofdm系统性能的仿真

clear all;

A = [1 1/exp(1) 1/exp(2)];  % power delay profile
N = 64;  % number of symbols in a single OFDM symbol
GI = 16;  % guard interval
Mt = 1;  % number of Tx antennas
Mr = 1;  % number of Rx antennas
sig2 = 1e-3;  % noise variance
M = 8;  % max constellation bit number
Mgap = 10.^(1:(1.7/10):2.7);  % gap
Btot = 100*Mt;  % total # bits per OFDM symbol
TransmitIter = 50; % # iterations of symbol transmissions for each channel instance
ChannelIter = 100; % # iterations of independent identically distributed channel instances
GapIter = length(Mgap);

load ENC2.mat
load ENC4.mat
load ENC16.mat
load ENC64.mat
load ENC256.mat

TotEbNo = [];
Errors =[];
EbNo = [];
for lGap = 1:GapIter
lGap
gap = Mgap(lGap);
totalErrors = 0;
for lChan = 1:ChannelIter
    
% create channel
[H h_f]=create_channel(Mt, Mr, A, N+GI);

% decompose each subchannel in the frequency domain
[U S V] = svd_decompose_channel(Mt, Mr, h_f, N);

% bitloading
[bits_alloc,energy_alloc] = BitLoad(S,Btot,Mt*N,gap,sig2,M);
%energy_alloc=energy_alloc/(mean(energy_alloc));
%energy_alloc=ones(1,128);

for lTrans = 1:TransmitIter

% bits to transmit
x = (randn(1,Btot)>0);

% modulate
x_mod = modulate(x,bits_alloc,energy_alloc, s2,s4,s16,s64,s256);

% precode modulated signal
x_pre = precode(Mt, x_mod, V, N);

% ifft, with cyclic prefix for each antenna
ofdm_symbol =[];
for i=1:Mt
    ofdm_symbol = [ofdm_symbol; ifft_cp_tx_blk(x_pre(i:Mt:Mt*(N-1)+i),N,GI)];
end
ofdm_symbol2 = reshape(ofdm_symbol,Mt*(N+GI),1);

% channel
y = transpose(channel(sig2, Mt, Mr, ofdm_symbol2, H, N+GI));

% fft
rec_symbol =[];
for i=1:Mt
    rec_symbol = [rec_symbol; fft_cp_rx_blk(y(i:Mt:Mt*(N+GI-1)+i),N,GI)];
end

rec_symbol2 = reshape(rec_symbol,1,Mt*N);

% shape received signal
shaped_vals = shape(rec_symbol2, Mr, U, N);

% demodulate
y_demod = demodulate(shaped_vals, bits_alloc, energy_alloc, S, s2,s4,s16,s64,s256, c2,c4,c16,c64,c256);

% comparison
totalErrors = totalErrors + sum(xor(y_demod,x));
end
EbNo = [EbNo sum(energy_alloc)/Btot/sig2];
end

Errors = [Errors totalErrors/Btot/ChannelIter/TransmitIter]
TotEbNo = [TotEbNo mean(EbNo)]
EbNo = [];
end

semilogx(TotEbNo, Errors);
xlabel('Eb/No');
ylabel('BER');
title('SISO link, adaptive rate and power')

save SISO_adaptive2.mat Errors EbNo