add_ofdm_prefix.m

国外大学的同志作出来的好程序

function ofdm_symbols=add_ofdm_prefix(timed_symbols, Nfft, Ncp);
%
%Add cyclic prefix to OFDM symbols
%
tx_num=size(timed_symbols, 2);
OFDMsymbols_num=size(timed_symbols, 1)/Nfft;


%declaration of time domain signals
ofdm_symbols=zeros((Nfft+Ncp)*OFDMsymbols_num, tx_num);

%Prefix index
index=[Nfft-Ncp+1: Nfft];

%add cyclic prefix for each antenna.
for ic_tx=1: tx_num,

    %resahpe into matrix
    symbols_mat=reshape(timed_symbols(:, ic_tx), Nfft, OFDMsymbols_num);
    prefix_mat=symbols_mat(index, :);

    %add prefix
    symbols_mat=[prefix_mat; symbols_mat];

    %make it a vector for each antenna
    ofdm_symbols(:, ic_tx)=symbols_mat(:);
end