gsmsim_demo_bcch.m

小区初搜为GSM系统中的一个关键过程

function [] = GSMsim_demo_2(NumberOfBlocks,Lh,LogName)
% GSMSIM_DEMO:
%           This demonstrates the function of the GSMsim
%           package. Use this file as a starting point for building
%           your own simulations.
%
% SYNTAX:   GSMsim_demo_2(NumberOfBlocks,Lh,logname)
%
% INPUT:    NumberOfBlocks:
%                   The number of GSM code blocks to process, a block
%                   corresponds to four GSM bursts.
%
%           Lh:     The length of the channel impulse response
%                   minus one.
%           LogName:
%                   The basename of the file to which the simulation log is
%                   to be written. The simulation log is handy for
%                   evaluating the convergence og a simulation.
%
% OUTPUT:   To a file called: logname.NumberOfBlocks.Lh
%           Simulation statistics are constantly echoed to the screen for
%           easy reference.
%
% WARNINGS: Do not expect this example to be more than exactly that,
%           an example. This example is NOT scientifically correct.
%
% AUTHOR:   Arne Norre Ekstr鴐 / Jan H. Mikkelsen
% EMAIL:    [e-mail] / [e-mail]
%
% $Id: GSMsim_demo_2.m,v 1.6 1998/10/01 10:18:47 hmi Exp $

% This is an aid for the final screen report
%
tTotal=clock;
NumberOfBlocks = 1;
Lh= 3;


% There has, not yet, been observed any errors.
%
B_ERRS_Ia=0;
B_ERRS_Ib=0;
B_ERRS_II=0;
B_ERRS_II_CHEAT=0;

% gsm_set MUST BE RUN PRIOR TO ANY SIMULATIONS, SINCE IT DOES SETUP
% OF VALUES NEEDED FOR OPERATION OF THE PACKAGE.
%
gsm_set;

% PREPARE THE TABLES NEEDED BY THE VITERBI ALGORITHM.
%
[ SYMBOLS , PREVIOUS , NEXT , START , STOPS ] = viterbi_init(Lh);

% We need to initialize the interleaving routines, for that we need an so
% called first burst for the interleaver, this burst will not be fully
% received. Nor will bit errors be checked, hence there is no reason for
% encoding it...
%
tx_enc1=round(rand(1,456));

% Now we need a tx_data_matrix to start the deinterleaver thus get data
% for a burst. Bit errors will be checked for in this block.
%
tx_block2=data_gen(260);

% Do channel coding of data
%
tx_enc2=channel_enc(tx_block2);

% Interleave data
%
tx_data_matrix=interleave(tx_enc1,tx_enc2);

% Time goes by, and new become old, thus swap before entry of loop.
%
tx_enc1=tx_enc2;
tx_block1=tx_block2;

% Transmit and receive burst
%
rx_data_matrix1=tx_data_matrix;

% Sliding average time report aid.
%
A_Loop=0;

for N=2:NumberOfBlocks+1,

    % Time report aid.
    %
    t0=clock;

    % Get data for a new datablock, number two is the latest.
    %
    INIT_L = 184;
    tx_block2=data_gen(INIT_L);

    % Do channel coding of data
    %
    tx_enc2=channel_enc_BCCH(tx_block2);

    % tx_data_mnatrix contains data for four burst, generated from two blocks.
    %
    tx_data_matrix=interleave(tx_enc1,tx_enc1);
    %     a = 57;
    %     tx_enc= [tx_enc(1,1:a);tx_enc(1,a+1:2*a);tx_enc(1,2*a+1:3*a);tx_enc(1,3*a+1:4*a);tx_enc(1,4*a+1:5*a); ...
    %         tx_enc(1,5*a+1:6*a);tx_enc(1,6*a+1:7*a);tx_enc(1,7*a+1:8*a)];
    %     tx_data_matrix=reshape(  tx_enc, 8,57);
    %     tx_data_matrix = [tx_data_matrix(1,:),tx_data_matrix(2,:);tx_data_matrix(3,:),tx_data_matrix(4,:); ...
    %         tx_data_matrix(5,:),tx_data_matrix(6,:);tx_data_matrix(7,:),tx_data_matrix(8,:)];
    for n=1:4,

        % THIS IS ALL THAT IS NEEDED FOR MODULATING A GSM BUST, IN THE FORMAT
        % USED IN GSMsim. THE CALL INCLUDES GENERATION AND MODULATTION OF DATA.
        %
        [ tx_burst , I , Q ] = gsm_mod(Tb,OSR,BT,tx_data_matrix(n,:),TRAINING);

        % AT THIS POINT WE RUN THE CHANNEL SIMULATION. NOTE, THAT THE CHANNEL
        % INCLUDES TRANSMITTER FORNT-END, AND RECEIVER FRONT-END. THE CHANNEL
        % SELECTION IS BY NATURE INCLUDED IN THE RECEIVER FRONT-END.
        % THE CHANNEL SIMULATOR INCLUDED IN THE GSMsim PACKAGE ONLY ADDS
        % NOISE, AND SHOULD _NOT_ BE USED FOR SCIENTIFIC PURPOSES.
        %
        %     SNR =9;
        %     Speed = 0;
        %     r=channel_simulator(I,Q,OSR,SNR,Speed);

%         r(n,:) = I +Q*j;
       
        r(n,:) = BCCHDemodulation(n);
%                 z = r(n).';

%         N = 129;
%         % B = kaiser(N,9);
%         B = fir1(N,0.18);
%         h = dfilt.dffir(B);
%         % freqz(h);
%         I = real(r(n,:));
%         I = [I,zeros(1,(N-1)/2)];
%         
%         Q = imag(r(n,:));
%         Q= [Q, zeros(1,(N-1)/2)];
%         yI = filter(B,1,I);
%         yQ = filter(B,1,Q);
%         Z = yI(1,(N-1)/2+1:600+(N-1)/2) + yQ(1,(N-1)/2+1:600+(N-1)/2)*j;
%         r(n,:)= Z;

%         [mm,nn]=size(Z);
%         for kk = 1:nn/OSR
%             r(n,(kk-1)*OSR+1:kk*OSR) = r(n,(kk-1)*OSR+1:kk*OSR).*(-i).^kk;
%         end
%            r(n,:) = real(r(n,:));
        

        % RUN THE MATCHED FILTER, IT IS RESPONSIBLE FOR FILTERING SYNCRONIZATION
        % AND RETRIEVAL OF THE CHANNEL CHARACTERISTICS.
        %
        t_BCCH_gen=find_bcch;
        T_SEQ=t_BCCH_gen(6,:);
        [Y, Rhh,h_est] = mafi( r(n,:),Lh,T_SEQ,OSR);

        % HAVING PREPARED THE PRECALCULATABLE PART OF THE VITERBI
        % ALGORITHM, IT IS CALLED PASSING THE OBTAINED INFORMATION ALONG WITH
        % THE RECEIVED SIGNAL, AND THE ESTIMATED AUTOCORRELATION FUNCTION.
        %
%          rx_burst = viterbi_detectorzb(SYMBOLS,NEXT,PREVIOUS,START,STOPS,Y,Rhh);
 
        rx_burst = viterbi_detector(SYMBOLS,NEXT,PREVIOUS,START,STOPS,Y,Rhh);

        % RUN THE DeMUX
        %
        rx_data_matrix2(n,:)=DeMUX(rx_burst);

    end

    % This is for bypassing the channel, uncomment to use
    %
    % rx_data_matrix2=tx_data_matrix;

    % A block is regenerated using eight bursts.
    %
    %     rx_enc=deinterleave( [ rx_data_matrix1 ; rx_data_matrix2 ] )
    
    rx_enc=deinterleave_bcch( rx_data_matrix2 );
    
    %         rx_data_matrix2 = [rx_data_matrix2(1,:),rx_data_matrix2(2,:),rx_data_matrix2(3,:),rx_data_matrix2(4,:)];
    %         rx_enc=reshape(  rx_data_matrix2, 8,57  );
    %         a = 57;
    %         rx_enc= [rx_enc(1,:),rx_enc(2,:),rx_enc(3,:),rx_enc(4,:),rx_enc(5,:),rx_enc(6,:),rx_enc(7,:),rx_enc(8,:)];
    %     rx_block=channel_dec(rx_enc);
    
%     C = textread('.\data\456bitout.dat','%s');
% [m,nn]=size(C);
% rx_enc1 = hex2dec(C);
% rx_enc1= rx_enc1';
% xor(rx_enc,rx_enc1)

    trel = poly2trellis(5,[23 33]);  % Define trellis,    according to GSM0503.
    tblen = 228;
    rx_block1=vitdec(rx_enc,trel,tblen,'term','hard');
    rx_block= channel_dec_BCCH(rx_enc);
%     g = [1, 0,0, 1, zeros(1,13),1, zeros(1,5),1,  zeros(1,2),1,zeros(1,13),1];
    g = [1, zeros(1,13), 1, zeros(1,2),1, zeros(1,5),1,  zeros(1,13),1,0,0,1];
    d = [rx_block];
    [q,r] = deconv(d,g);
% ADJUST RESULT TO BINARY REPRESENTATION
    L = length(r);
    out = abs(r(L-39:L));
    for n = 1:length(out),
       if ceil(out(n)/2) ~= floor(out(n)/2)
         out(n) = 1;
       else
         out(n) = 0;
       end
    end
    
    
    out = addcrc(rx_block(1:184),g);
    crc = rx_block(185:224);
    crcre = out(185:224);

    crcerr = xor(crcre, crc)
end