de_fft_ofdm_basesignal_gen.m

PDCCH的实现过程及其遇见的问题应该遇见的问题

function designal = de_fft_ofdm_basesignal_gen(NDLRB,maxl,signal);
Ts = 1 / ( 15000 * 2048 ) ; % basic time unit ；
NRBSC = 12; % subcarriers in a resource block ；

if maxl == 7  % normal cyclic prefix ;
    dealtf = 15000; % subcarrier spacing 
    N = 2048 ; % a constant different with subcarrier spacing ；
    signal0 = zeros ( N , maxl );
    % discard cp
    for l = 1 : maxl
        if l == 1
            TCP = 160 ;
            signal0 ( 1 : N , l ) = signal ( ( TCP + 1 ) : ( TCP + N ) , l ) ;
        elseif l > 1
            TCP = 144 ;
            signal0 ( 1 : N , l ) = signal ( ( TCP + 1 ) : ( TCP + N ) , l ) ;
        end
    end
    % the coeffient for fft 
    for n = 1 : N ;
        e ( n ) = exp( j * 2 * pi / N * ( floor( NDLRB * NRBSC / 2 ) ) * ( n - 1 ) );
    end
    e = [e;e;e;e;e;e;e];
    e1 = e.' ;
    designal0 = e1 .* signal0;
    % fft
    designal = fft ( designal0 , N ) / N ;
    % discard the nonsense numbers ;
    designal ( ( NDLRB * NRBSC + 2 ) : N , : ) = [] ;
    designal ( ( NDLRB * NRBSC / 2 + 1 ) , : ) = [] ;
end

if maxl == 6 % extended cyclic prefix and subcarrier spacing of 15KHz
    dealtf = 15000; 
    N = 2048 ;
    TCP = 512 ;
    signal0 = zeros ( N , maxl );
    % discard cp
    for l = 1 : 6 
        signal0 ( 1 : N , l ) = signal ( ( TCP + 1 ) : ( TCP + N ) , l ) ;
    end
    % the coeffient of fft 
    for n = 1 : N ;
        e ( n ) = exp( j * 2 * pi / N * ( floor( NDLRB * NRBSC / 2 ) ) * ( n - 1 ) );
    end
    e = [e;e;e;e;e;e];
    e1 = e.';
    designal0 = e1 .* signal0;
    % fft 
    designal = fft ( designal0 , N ) / N ;
    % discard the nonsense numbers ;
    designal ( ( NDLRB * NRBSC + 2 ) : N , : ) = [] ;
    designal ( ( NDLRB * NRBSC / 2 + 1 ) , : ) = [] ;
end

if maxl == 3  % extended cyclic prefix and subcarrier spacing of 7.5KHz
    dealtf = 7500 ; 
    N = 4096 ;
    TCP = 1024 ;
    signal0 = zeros ( N , maxl );
    % discard cp
    for l = 1 : 3 
        signal0 ( 1 : N , l ) = signal ( ( TCP + 1 ) : ( TCP + N ) , l ) ;
    end
    % the coeffient of fft 
    for n = 1 : N ;
        e ( n ) = exp( j * 2 * pi / N * ( floor( NDLRB * NRBSC / 2 ) ) * ( n - 1 ) );
    end
    e = [e;e;e];
    e1 = e.';
    designal0 = e1 .* signal0;
    % fft ;
    designal = fft ( designal0 , N ) / N ;
    % discard the nonsense numbers ;
    designal ( ( NDLRB * NRBSC + 2 ) : N , : ) = [] ;
    designal ( ( NDLRB * NRBSC / 2 + 1 ) , : ) = [] ;
end