orthosynchronization.m

这个程序主要是实现空时编码的matlab编解码仿真。

function [corr_max,sample_nr,sum_of_r_times_c1,sum_of_r_times_d2]=orthosynchronization(in_data_block, fs, T, train1, train2, model)

% 	[corr_max,sample_nr,sum_of_r_times_c1,sum_of_r_times_d2]=orthosynchronization(in_data_block, fs, T, train1, train2, model)
%
%	Output:
%	sample_nr               - Sample number, counted from first value in inphase_data_block
%                               where sampling is best performed.
%   corr_max                - Max value of the correlation 	
%   sum_of_r_times_c1       - Correlation vector for train1
%   sum_of_r_times_d2       - Correlation vector for train2
%
%   Input:
%	in_data_block 	        - Output from MF
%   fs                 	    - Sampling rate
%   T                  	    - Symboltime
%   train1           	    - Training_sequence1, same as concatenated in transmitter.
%   train2                  - Training_sequence2 (BOTH BINARY!)
%	model				    - Specifies if Alamouti-coding has been used.
%						        model = 0 : No Alamouti-coding in transm.
%						        model = 1 : Alamouti-coding in transm.
%   
%   Short Theoretical Background for the Function:
%
%   Slides the training-sequence over the recieved matched-filtered
%   inphase- or quadrature component and returns the number of the sample where the
%   first value of the train.-seq. has it's start.
%
%   The implentation can be compared to theory described in QPSK-lab
%   performed in the course of communication theory, year 2001 KTH.
%
%	 Assuming first part of data is training-sequence through antenna 1 and second
%    part is training-sequence through antenna2. If model = 0 only training-sequence one is used.
%	
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     
%%% Function part of simulation for Space-Time
%%% coding project, group Grey-2001.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%   Author: Stefan Uppg錼d
%   Date: 2001-03-20 and 21
%   Version: 1.0
%   Revision (Name & Date % Spec): 
%	 1.1 SU	2001-03-24	Adding the Alamouti-functioncall.
%   1.2 SU  2001-03-25  Decreased the slidingdistance to one train.seq.length.
%   1.3 SU  2001-03-27  Added the absolute function after for-loop.
%   1.4 SU  2001-03-28  Increased the slidingdistance to three train.seq.length
%   1.5 FH  2001-03-30  returns the maxvalue of the correlation 
%   2.0 FH  2001-04-02  correlate with trainingsequence two as well                  
%	 3.0 SU	2001-04-08	Perform synch. on two orthogonal train.sequences.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%
%%% Correlates the inphase-part with 
%%%

r = in_data_block;         % Rename variable to make the code easier to read.

c1 = bpsk(train1,model);
d2 = bpsk(train2,model);

L1 = length(c1);                  % Length of BPSK:ed training-sequence.
L2 = length(d2);

Q = fs*T;                      	% Number of samples per symbol.

%
% correlation for trainingsequence one
%

sum_of_r_times_c1 = [];

for(m=1:1*Q*L1)     % Lets m = sample_time slides one time the train.seq.distance.
    sum_of_r_times_c1 = [sum_of_r_times_c1 (r(m : Q: L1*Q+m-1) * c1')];
end
sum_of_r_times_c1 = abs(sum_of_r_times_c1);
figure(10), stem(sum_of_r_times_c1)
[corr_max1, sample_nr1] = max(sum_of_r_times_c1);

%
% correlation for trainingsequence two
%

if model==1
    sum_of_r_times_d2 = [];

    for(m=1:1*Q*L2)     % Lets m = sample_time slides one times the train.seq.distance.
        sum_of_r_times_d2 = [sum_of_r_times_d2 (r(m : Q: L2*Q+m-1) * d2')];
    end
    sum_of_r_times_d2 = abs(sum_of_r_times_d2);
    %figure(11), plot(sum_of_r_times_d2)
    [corr_max2, sample_nr2] = max(sum_of_r_times_d2); 

    % choose the one with the biggest maximum
    if corr_max1 > corr_max2
        corr_max = corr_max1;
        sample_nr = sample_nr1;
    else
        corr_max = corr_max2;
        sample_nr = sample_nr2;
     end % corr_max1>corr_max2
else %model!=1
    corr_max = corr_max1;
    sample_nr = sample_nr1;
    sum_of_r_times_d2 = 0;
end %model==1