conv_viterbi_simu.m

UWB viterbi decode matlab代码； 包括自己实现的matlat viterbi 译码和调用matlab内部模块的代码； 分硬判决和软判决两种情况； 严格按照MB-OFDM

% simulate the process of convolutional encoding and viterbi decoding
% using matlab functions
clear all;
clc;

% coding parameters
msg_len = 1494; 
L=7;      % constraint length
G=[133 165 171];  % generator polynomial for matlab
tblen=100;  % trace back length
soft_bit_len=4;  % bit length of soft input
tail_bit_len=L-1;  % length of tail bits

global g_soft_bit_len;   % soft decision input word length

g_soft_bit_len=2;

tail_bit=zeros(tail_bit_len,1);
len=msg_len+tail_bit_len;

t = poly2trellis(L,G); % Define trellis.


%random bit stream generation
msg = randint(msg_len,1,2,94384); % Random data
msg=[msg;tail_bit];  % appending by zeros tail bits

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%matlab%%%%%%%%%%%%%%%%
% convolutional encoding
code = convenc(msg,t); % Length is 2*len.


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%third party%%%%%%%%%%%%%%%%
 %对原信息编码 
k0=1;
G_3=[1 0 1 1 0 1 1;1 1 1 0 1 0 1;1 1 1 1 0 0 1];
code_3=cnv_encd(G_3,k0,msg');
code_3=code_3(1:end-18);

% logcial transfering
tcode = -2*code+1; % Transmit -1s and 1s.
nicode=tcode;
% % puncturing
% punctcode = tcode;
% punctcode(3:3:end)=[]; % Length is (2*len)*2/3.
% ncode=punctcode;
% 
% % depuncuring
% nicode = zeros(2*len,1); % Zeros represent inserted data.
% nicode(1:3:end) = ncode(1:2:end); % Write actual data.
% nicode(2:3:end) = ncode(2:2:end); % Write actual data.

% viterbi decoding for -1/1 logical input,hard decision
decoded = vitdec(nicode,t,tblen,'trunc','unquant'); % Decode.
% BER calculation
[number,ratio]=biterr(decoded,msg); % Bit error rate


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% matlab
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
%viterbi decoding for soft decision
   % transfer input into soft input bits, range [0,2~soft_bit_len-1]
   %nicode=nicode*(-1)+2;
%    for cn=1:length(nicode)
%        if(nicode(cn)==1)
%            nicode(cn)=0;
%        end;
%    end;

tcode=code*(2^g_soft_bit_len-1);
nicode=tcode;

decoded = vitdec(nicode,t,tblen,'term','soft',2); % Decode.
%decoded=decoded';
[number,ratio]=biterr(decoded,msg); % Bit error rate




% puncture
%data_temp=nicode;
for cn=1:(length(nicode)/15)
    data_temp((cn-1)*8+1:(cn-1)*8+2)=nicode((cn-1)*15+1:(cn-1)*15+2);
    data_temp((cn-1)*8+3:(cn-1)*8+5)=nicode((cn-1)*15+6:(cn-1)*15+8);
    data_temp((cn-1)*8+6:(cn-1)*8+8)=nicode((cn-1)*15+12:(cn-1)*15+14);
    
end;
nicode=data_temp';

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% depuncture
% puncture and depuncture
global g_phy_para;  % system  parameters for PHY

% PHY system parameters  initialization mannually
g_phy_para=[1                                 % TFC
 1                                 % band group
 0                                 % preamble mode; 0,standard; 1, burst
 0                                  % 53.3           80        106.7  200                                     
                                     % 320          400          480; [0,1,2,~6]
 0                                  % modulation mode; QPSK, 0; DCM,1;
 5/8                                % coding rate,index 6
 0                                   % FDS mode; 0, not using FDS;1, using FDS
 0                                    % TDS mode; 0,not using TDS; 1, using TDS
 00100                           % rate bits
 40                                  % length of PSDU by bytes
 01                                  % scrambler; 
 0                                    % preambler type bit, denotes the type used in next packet; 0, standard;1, burst;
 1                                    % burst mode bit
 128                                % FFT size, index 14
  100                                 % number of data subcarriers
  12                                    % number of pilot subcarriers
  10                                    % number of guard subcarriers
   ];



% depuncture and insert dummy bits
     dumy_bit=floor(2^(g_soft_bit_len-1));
     depunct_output=DEPUNCT(nicode,dumy_bit);


decoded = vitdec(depunct_output,t,tblen,'term','soft',2); % Decode.
decoded=decoded';
[number,ratio]=biterr(decoded,msg); % Bit error rate


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% third party
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
[decoder_output,survivor_state,cumulated_metric]=viterbi(G_3,k0,nicode');
[number,ratio]=biterr(decoded,msg); % Bit error rate