matlab_wan_ldpc.m

LDPC码在很多领域都将会有重要的应用

function wman1()

clear all;
fprintf('Start! Please waiting ...\n');

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%						Parameters for system configuration						%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
fc = 2.4e9;			%Carrier frequency
fs = 20e+6; 			%System bandwith is 5MHz
SubCarrNum = 256;	%size fourier transform to generate signal. It
					%is equal to the number of samples in the OFDM
					%symbol, and also it is the size of FFT.
GuardNum = 16;		%Total guard time in samples.
OfdmSize = (SubCarrNum + GuardNum);
ModType = 2;		%Allowable values are 1, 2, 3, 4, 6
					%BPSK,QPSK,8PSK,16QAM,64QAM respectely.
Mf = 16;			%Pilot space in frequency, continued in time direction.
NormFactor = sqrt(SubCarrNum);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%% Parameters for simulating the multipath channel and additive Gaussian noise %%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
PowerDelayProfile = [0,-1,-9,-10,-15,-20];
NonZeroPaths = [1,3,5,7,10,14];	%normalized by 1/fs
CHLen = max(NonZeroPaths);
InitTime = 0.14;			%channel simulator initial time.
v = 0;					%vehicle speed km/h
EbN0db = [20];		%Eb/N0

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%						Parameters for simulation number 						%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
SymbolNum = 2;%number of OFDM symbols,must be int
CalFrameNum = 1;	%according to the SNR the frame number is varying

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%					Parameters for pilot based channel estimation 				%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
PilotSymbol = (1-j)/sqrt(2);
PilotIndex = 1:Mf:SubCarrNum;
TmpIndex = zeros(1,SubCarrNum);
TmpIndex(PilotIndex) = PilotIndex;
DataIndex = find((1:SubCarrNum) ~= TmpIndex);
clear('TmpIndex');

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%  						Parameters for turbo code  or ldpc code							%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
puncture = 0;			%puncture = 0,rate=1/2;puncture = 1, puncture rate =1/3
CodeRate = 1/(2+puncture);
%the length of turbo coding,it should match the Mf=16,Mt=4, if others,it should use rate matching.
%CodeLen = length(DataIndex)*SymbolNum*ModType*CodeRate;  %CodeLen = 3328
%beta = interleave(CodeLen*(2+puncture),100)+1;%interleaver for frame.1~CodeLen*rate
fprintf('Interleaver generate successed\n');	%may be some bugs,see interleave.c
load 960.mat;
[H,inv_phi1,g]=ldpc_lintimeenc_parameter(H);
[m,n]=size(H)

beta = interleave(n,100)+1;
% Write some information about this program
fpname = strcat(mfilename, '.txt');
fp=fopen(fpname,'a+');
fprintf(fp,'**************************************************************************\n');
fprintf(fp,'+ + + +         OFDM simulator by XJ, NJUPT        + + + +\n');
fprintf(fp,'+ + + +     Please be patient. Wait a while to get the result.     + + + +\n');
fprintf(fp,'**************************************************************************\n\n');


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%% 		 						Start  										%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
tic

for nEN = 1:length(EbN0db)
	
	en = 10^(EbN0db(nEN)/10);
	sigma2 = 1/(2*ModType*CodeRate*en);
	
	errs0(nEN) = 0;
	
	t0 = InitTime;
    
     for nframe = 1:CalFrameNum
		nframe
		%The information bit that to transmit without the tail bit.
		TxBits = sparse(randint(1,n-m));
		%TxBits = randint(1,CodeLen ,2);
		%FEC channel coding, use Turbo code
        
        TxBitsCode=sparse(1,n);
        TxBitsCode = ldpc_linetime_encode(TxBits,H,inv_phi1,g);
        
       %Inter-frame interleave.
		TxBitsInter = full(TxBitsCode(beta));
        %TxSig_Repeat=kron(TxBitsInter,ones(1,SF));
        
        %Modulation by QPSK.
		ModData = 1/sqrt(2)*(TxBitsInter(1:2:end)+j*TxBitsInter(2:2:end));
        
        %Form the frame
		FreqSymbol = ones(SymbolNum,SubCarrNum);
        FreqSymbol(:,DataIndex) = vec2mat(ModData,length(DataIndex));
		FreqSymbol(:,PilotIndex) = FreqSymbol(:,PilotIndex)*PilotSymbol;
        
        %IFFT and then add CP
		OfdmSymbol = NormFactor*ifft(FreqSymbol,SubCarrNum,2);
		OfdmSymbol = [OfdmSymbol(:,SubCarrNum-GuardNum+1:SubCarrNum) OfdmSymbol];
		%parallel to serial convertion
		TransSignal = reshape(OfdmSymbol.',1,prod(size(OfdmSymbol)));
        
        % Pass through the multipath Rayleigh fading channel and AWGN
		ChannelOutput = MultiPath0(fc, v, fs, t0, length(TransSignal), PowerDelayProfile, NonZeroPaths, TransSignal, sigma2);
		t0 = t0 + length(TransSignal)/fs;
        
        
        % convert vector to matrix
		ChannelOutput = vec2mat(ChannelOutput,OfdmSize);
		%removal of CP and FFT
		ChannelOutput = ChannelOutput(:,GuardNum+1:OfdmSize);
		RecSymbol = 1/NormFactor * fft(ChannelOutput,SubCarrNum,2);
        
        %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
        %%%%%%%%%%%%%%%%%%%%%%%%%%%% 	  channel estimation	%%%%%%%%%%%%%%%%%%%%%%%%%%
        %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
        
        %one dimension channel estimation algorithm via LS to get the pilot estimation
		PilotFreqEst = RecSymbol(:,PilotIndex)./PilotSymbol;
		%estimation based on FFT
		%EstInTime = sqrt(size(PilotFreqEst,2))*ifft(PilotFreqEst,size(PilotFreqEst,2),2);
		EstInTime = ifft(PilotFreqEst,size(PilotFreqEst,2),2);
		
		%transform to frequency domain,get the final estimation
		FreqEst = fft(EstInTime(:,1:CHLen),SubCarrNum,2);
        
         % coherent demodulation
        EstData = RecSymbol(:,DataIndex).*conj(FreqEst(:,DataIndex))./abs(FreqEst(:,DataIndex));
        % EstData = RecSymbol(:,DataIndex)./FreqEst(:,DataIndex);
        
        %convert matrix to vector
		EstData0 = reshape(EstData.',1,prod(size(EstData)));
        
        % Demodulate the data with soft demodulation
		DemodData0 = zeros(1,length(EstData0)*ModType);
		DemodData0(1:2:end) = real(EstData0);
		DemodData0(2:2:end) = imag(EstData0);
        
        % Deinterleave
		DemodDataDeInter0(beta) = DemodData0;
        
        % Decode the data by Sova algorithm for turbo code.
        
		[Decodedata,success,kk]=ldpc_decode_logforOFDM1(DemodDataDeInter0,sqrt(sigma2),H);
		%kk
        DecodeData0=Decodedata(1:n-m);
        % Number of bit errors in current EbN0
        
         errs0(nEN) = errs0(nEN) + sum(DecodeData0 ~= TxBits);
         
          end
        
       errs0(nEN) = errs0(nEN)/(CodeLen*CalFrameNum(nEN));
	
       save errs1 errs0
       
    fprintf(fp,'%f	%8.6e	%8.6e\n', EbN0db(nEN),errs0(nEN));
	fprintf('****** Eb/N0 = %f dB     BER = %8.6e  ********\n', EbN0db(nEN),errs0(nEN));
	fclose(fp);
	fp=fopen(fpname,'a+');
end

TimeElapse = toc/3600;	% Simulation time (hour)
fprintf('****** The total time that used is : %3.1f hour ********', TimeElapse);
fprintf(fp,'\n\n****** The total time that used is : %3.1f hour ********\n', TimeElapse);
fclose(fp);