main.cpp

介绍了一种串行LDPC码的编码器和译码器的实现形式 C++环境下编写。有些地方还需完善

#include "main.h"
#include "sparse.h"
#include  "decoder.h"

void input(int *message,int seed);
void transmit(int *codedbit,double *receive,double *lratio,double n0);
void Read_Matrix(int S[][EncodedLength],int T[][H_ColNum],int infoBitsLocation[]);
void encoder(int S[][EncodedLength],int info[],int coded[]);

double  startsnr=2.0;
double	endsnr=2.75;
double	snrstep=0.25;
    
int Gen[G_RowNum][EncodedLength];    //generation matrix
int infoBitsLocation[InfoLength];    //information position
int InfoBit[InfoLength];             //vector stores information
int CodedWords[EncodedLength];       //vector stores code encoded
int Parity[ParityCheckNum][H_ColNum];//check matrix in given sparse term
int ERR[max_iter];                   //vector stores errors of each iteration
//int DERR[max_iter];					//vector stores detected errors of each iteration
char DecodedData[EncodedLength];     //vector stores code decoded
mod2sparse *H;                       //pointer point to a sparse matrix with the link structure

/*function: fist read the generation check and informationlocation matrix from given files
            second generate link table of given LDPC matrix
            third  simulating the process of the encoding  transforming and deconding*/
void main()
{ 	
	Read_Matrix(Gen,Parity,infoBitsLocation);
	H=Make_LDPC(Parity, 0,ParityCheckNum,EncodedLength);
    simulation();
}

/*function: simulating the process of the encoding transforming and decoding
            calculating the BER after each iteration.
*/
void simulation()
{	
	double snr,realsnr,N0;
    double BER[max_iter];
    double Receive[EncodedLength],lratio[EncodedLength],BitProb[EncodedLength];
    char   filename[20];
    int    i,TotalNum;
	FILE *file;

	//open file "SimResult.dat" to recode the results
	sprintf(filename,"SimResult.txt");
	if( ( file = fopen( filename, "w" ) ) == NULL )
	{
		printf( "can't open the file\n" );
		exit( 1 );
	}

	//from statrsnr to endsnr, calculate the bit error rate for each snr
	for(snr = startsnr;snr <= endsnr;snr += snrstep)
	{ 
		TotalNum = 0;
		srand( (unsigned) time(NULL) );

		//calculate the single side noise spectrum density N0
		realsnr = pow( 10, -snr/10.);
		N0 = realsnr/CodeRate;

		for(i=0;i<max_iter;i++)
			ERR[i]=0;
		
		//for each snr simulate codewords the number of Totalblock
		while( TotalNum< Totalblock )
		{
			//produce the information bits for a codeword
			input( InfoBit, rand() );
			//encode the information bits to a codeword
 	        encoder( Gen, InfoBit, CodedWords);
			//simulate a codeword being transmitted through AWGN channel
		 	transmit( CodedWords, Receive, lratio, N0 );
			//decode the received codeword using sum-product algorithm
			prprp_decode( H,lratio, DecodedData,BitProb);
  		    
			TotalNum++;

			//display the result on the screen
			if( TotalNum%10 == 0 )
			{
				for(i=0;i<max_iter;i++)
				{
					BER[i] = (double)ERR[i]/(double)(TotalNum*InfoLength);
					printf("snr=%f  iterater=%4d TotalNum=%4d errors=%d ber=%1.8f\n",snr,i+1,TotalNum,ERR[i],BER[i]);
				}
				if( TotalNum%1000 == 0 )
				{
					fprintf(file, "TotalNum=%d\n", TotalNum);
					for(i=0;i<max_iter;i++)
					{
						fprintf(file,"snr=%f  iterater=%4d errors=%d  ber=%1.8f\n",snr,i+1,ERR[i],BER[i]);
						fflush(file);
					}
				}
			}
		}

		//recode in the file the result for each iteration at a certain snr condition
      	for(i=0;i<max_iter;i++)
		{   
			fprintf(file,"snr=%f  iterater=%4d errors=%d  ber=%1.8f\n",snr,i+1,ERR[i],BER[i]);
	        fflush(file);
		}
	
	}
}