st_trellis_dec_c.m

通信中常用的卷积码信道译码源码程序

function outputs = ...
   st_trellis_dec_C(Data_received,ST_NextState,Output_mod_1, ...
		    Output_mod_2,Lut_InfBits,...
		    alpha_channel,fading_gains,TerminateF,NRx);

%------------------------------------------------------------------------------
% Decode received space-time trellis coded data matrix.
%
% Format:
% -------
%
% outputs = ...
%   st_trellis_dec(Data_received,ST_NextState,ST_Output,Lut_InfBits,ModMap,...
%                  alpha_channel,fading_gains,TerminateF,NRx)
% 
% Author: MVe
% Date:   27.08.2002
%------------------------------------------------------------------------------

%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% -- Initialisations -- %%
%%%%%%%%%%%%%%%%%%%%%%%%%%%

% Length of the received symbol/data vector
LData = length(Data_received);

% Extract most used variables from struct 'Trellis'
% n = size(ST_Output{1,1},2);                % # of outputs/antenna
k_bits = log2(size(ST_NextState,2));       % # input bits to encoder
m_bits = log2(size(ST_NextState,1));       % encoder memory (in bits)
m = ceil(m_bits/k_bits);                   % encoder memory (in "symbols")
number_of_states = size(ST_NextState,1);

%% -- fading_gains = ('tx_antenna','time','rx_antenna') -- %%
%
% De-interleave data and fading (same interleaving assumed for all channels)
Data_received(:,alpha_channel) = Data_received;
fading_gains(:,alpha_channel) = fading_gains;

%keyboard

final_state_path = st_dec_CC(Data_received, ST_NextState, Output_mod_1,...
            			     Output_mod_2, fading_gains, m);
%keyboard

% Convert state path to info bit sequence
out_tmp = cell(1,length(final_state_path)-1);
for i1 = 1:length(out_tmp)
  out_tmp(i1) = ...
      Lut_InfBits(final_state_path(i1),final_state_path(i1+1));
end % for i1 = 1:2:length(Data_received)

outputs = [out_tmp{:}];

%keyboard

% Remove tail bits
if TerminateF
  outputs = outputs(1:end-k_bits*(ceil(log2(number_of_states)/k_bits)));
end % if TerminateF