channel.m

OFDM系统

function [ GetData Channel ] = Channel( TransData, SNR )

global FLAG_AWGN;
global FLAG_MULTIPATH;
global Num_Channel;
global Channel_Est;
global Num_Train;
global Theta;

global Channel;


SNR = 10^(SNR/10);

% generate channel
ChanData = randn(1,Num_Channel) + randn(1,Num_Channel)*sqrt(-1);
ChanData = ChanData / sqrt(2*Num_Channel);
ChanData = [ ChanData , zeros(1,64-Num_Channel) ];

% add Multi-channel
if(FLAG_MULTIPATH == 1)
    RecData = conv(TransData, ChanData);     %length of RecData be 63 more 
else
    RecData = [ TransData , zeros(1,63) ];
end

% output the ture channel
Channel = ChanData ;

% % add frequency offset
% angle = 1:length(RecData);
% phase = exp(sqrt(-1) * Theta*angle);
% RecData = RecData .* phase;

% add gauss noise
Length_Rec = length( RecData ) - 16 - Num_Train*80;        
Gauss1 = randn(1,Length_Rec);
Gauss2 = randn(1,Length_Rec);
Gauss=Gauss1+Gauss2*sqrt(-1);

if(FLAG_AWGN == 1)
    GetData = [RecData(1:16+Num_Train*80), RecData(17+Num_Train*80 : end) + Gauss/sqrt(SNR*2)];
else
    GetData = RecData;
end