receive.asv

OFDM系统

function [ DeCodeBitData ] = Receive( RecData,ChanData )

global FLAG_AWGN;
global FLAG_MULTIPATH;
global Channel_Est;
global Num_Bit;
global Num_Train;
global Syn_Error;  
global Channel_fft;
global NSDEC;

% Channel estimation
if Channel_Est==1
    Channel = RecData(33+Syn_Error : 96+Syn_Error);
else
    Channel = ChanData;
end

if(FLAG_MULTIPATH == 1)
    Channel_fft = fft(Channel,64);
end

% GetData = RecData( Num_Train*80 +17 + Syn_Error : Num_Train*80 + Num_Bit*5/16 +Syn_Error );
GetData = [RecData( Num_Train*80 +17 + Syn_Error : end)];

Num_Sym_OFDM = 2*Num_Bit/4/64;
GetData_fft = zeros(1, 2*Num_Bit/4);

for i=1:Num_Sym_OFDM
    
    % fft
    Sym_OFDM_deletCP = GetData( 17+(i-1)*80 : i*80 );
    Sym_OFDM_fft = fft( Sym_OFDM_deletCP , 64 );
    
    % equalization
    if(FLAG_MULTIPATH == 1)
        % Sym_OFDM_fft = Sym_OFDM_fft .* (conj(Channel_fft)./abs(Channel_fft));
        Sym_OFDM_fft = Sym_OFDM_fft ./ Channel_fft;
    end
    
    GetData_fft(1+(i-1)*64 : i*64) = Sym_OFDM_fft;
    
end

t = poly2trellis(7, [131, 171]);
GetData_fft = sqrt(10)*GetData_fft / 8;

for i=1:length(GetData_fft)
    k = mod((i-1),64)+1;
    DeMapBitData( (i-1)*4+1 ) = -real(GetData_fft(i) );
    DeMapBitData( (i-1)*4+2 ) = abs( real(GetData_fft(i) ) ) - 2;%*abs(Channel_fft(k));
    DeMapBitData( (i-1)*4+3 ) = -imag(GetData_fft(i) );
    DeMapBitData( (i-1)*4+4 ) = abs( imag(GetData_fft(i) ) )-2;%*abs(Channel_fft(k)); 
end

% width = max(DeMapBitData) - min(DeMapBitData);
Thesh = max(abs(DeMapBitData));
width = Thesh*2;

if NSDEC==3
    PARTITION = -Thesh+width/8 : width/8 : -Thesh+7*width/8;
    [index, DeMapBitData] = quantiz(DeMapBitData,PARTITION,[7 6 5 4 3 2 1 0]); % Values in qcode are between 0 and 2^3-1.
elseif NSDEC==2
    PARTITION = -Thesh+width/4 : width/4 : -Thesh+3*width/4;
    [index, DeMapBitData] = quantiz(DeMapBitData,PARTITION,[3 2 1 0]);         % Values in qcode are between 0 and 2^2-1.
elseif NSDEC==8
    PARTITION = -Thesh+width/256 : width/256 : -Thesh+255*width/256;
    [index, DeMapBitData] = quantiz(DeMapBitData, PARTITION, 255:-1:0);          % Values in qcode are between 0 and 2^8-1.
end
    
% deinterleaving

for i=1: (2*Num_Bit/256)    
    DeInter1Out = DeMapBitData(1+(i-1)*256 : i*256);
    
    for k=1:256       
        j = 2*floor((k-1)/2) + mod((k+floor((k+15)/16)), 2);    %解高低位交织   
        DeInter2In(k) = DeInter1Out(j+1);   
    end
    
    for k=1:256              
        j = 16*(k-1) - 255*floor((k-1)/16);                     %解分组交织      
        DeInterOut(j+1+(i-1)*256) = DeInter2In(k);   
    end
end

DeCodeBitData = zeros(1, Num_Bit);
% DeCodeBitData = vitdec( DeInterOut, t, 35, 'term', 'unquant');
DeCodeBitData = vitdec( DeInterOut, t, 42, 'term', 'soft', NSDEC);