📄 ldpc.c
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#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>
#define HROW 640 //校验矩阵行数行数 未知
#define M 960 //列数 未知
#define K 320 //生成矩阵行数 未知
#define ROWLEN sizeof(struct rownode)
#define COLLEN sizeof(struct colnode)
#define BLOCKNUMBER 1000
#define PI 3.1415926f
#define ITERATIMES 5
struct rownode
{
int rownum,colnum;
double q;
struct rownode * rownext;
};
struct colnode
{
int rownum,colnum;
double r;
struct colnode * colnext;
};
double snr[10]={1.3,1.4,1.5,1.6,1.7,1.8,1.9,2.0,2.1,2.2}; //设定信噪比
int l;
int hmatrix[HROW][M]={0}; //定义为全局变量
int gmatrix[K][M]={0};
struct rownode * rowhead[HROW];
struct colnode * colhead[M];
void main()
{
void generate(int gseq[]);
void addgaussnoise(double addcode[]);
void decoder(double designal[]);
int bercounter(int array1[],int array2[]);
int percounter(int array1[],int array2[]);
double Gauss_rand();
double contanh(double y);
int i,j,n;
int benum=0;
int penum=0;
double ber[10]={0};
double per[10]={0};
int trancode[M]; //传送的双极性序列
int decode[M]; //译码得出的0-1序列，就是将译码器返回的double型的signal序列转成int型
double signal[M]; //传送和接受的实际信号
struct rownode * p1,* p2;
struct colnode * q1,* q2;
FILE * fph,* fpg,* fp_ber,* fp_per;
//****************************从文件读入生成矩阵和校验矩阵*******************************************//
fpg=fopen("Matrix_g2.txt","r");
//fpg=fopen("gmatrix.txt","r");
fph=fopen("Matrix_h2.txt","r");
//fph=fopen("hmatrix.txt","r");
fp_ber=fopen("ber.txt","w");
fp_per=fopen("per.txt","w");
if(fpg==NULL)
{
printf("生成矩阵不在指定的文件中!\n");
exit(0);
}
if(fph==NULL)
{
printf("校验矩阵不在指定的文件中!\n");
exit(0);
}
for (i=0;i<K;i++)
{
for (j=0;j<M;j++)
{
fscanf(fpg,"%d",&gmatrix[i][j]);
}
}
for (i=0;i<HROW;i++)
{
for (j=0;j<M;j++)
{
fscanf(fph,"%d",&hmatrix[i][j]);
}
}
for (j=0;j<HROW;j++) //根据行建立链表
{
n=0;
p1=(struct rownode *)malloc(ROWLEN);
p2=p1;
for (i=0;i<M;i++)
{
if (hmatrix[j][i]==1)
{
p1->rownum=j;
p1->colnum=i;
//p1->q=p[i]; //初始化信息
n=n+1;
if (n==1)rowhead[j]=p1;
else p2->rownext=p1;
p2=p1;
p1=(struct rownode *)malloc(ROWLEN);
}
}
p2->rownext=NULL;
free(p1);
} //建立行链表，第j行的头指针为rowhead[j]
for (i=0;i<M;i++) //按列建立链表
{
n=0;
q1=(struct colnode *)malloc(COLLEN);
q2=q1;
for (j=0;j<HROW;j++)
{
if (hmatrix[j][i]==1)
{
q1->rownum=j;
q1->colnum=i;
n=n+1;
if (n==1)colhead[i]=q1;
else q2->colnext=q1;
q2=q1;
q1=(struct colnode *)malloc(COLLEN);
}
}
q2->colnext=NULL;
free(q1);
} //建立列链表，第i列的头指针为colhead[i]
srand((int)time(0)); //产生随机数种子
for (l=0;l<10;l++)
{
benum=0;
penum=0;
for(j=0;j<BLOCKNUMBER;j++)
{
//************************产生一组随机的发送码序列bpsk调制信号***************************************//
if ((j%20)==0)
{
printf("haha!");
}
generate(trancode);
for (i=0;i<M;i++)
{
trancode[i]=trancode[i]*2-1; //bpsk
signal[i]=(double)trancode[i]; //将信号转成double型
//printf("%f ",signal[i]);
}
//printf("\n以上是产生的bpsk信号.\n");
//********************************add gaussnoise******************************************//
addgaussnoise(signal);
/*for (i=0;i<M;i++)
{
printf("%f ",signal[i]);
}
printf("\n以上是加上高斯白噪声后的信道信息\n");*/
//*************************************decode*********************************************//
decoder(signal);
//***********************************count BER and PER************************************//
//for (i=0;i<M;i++)
//{
// printf("%f ",signal[i]);
//}
//printf("\n");
for (i=0;i<M;i++)
{
decode[i]=(int)signal[i];//译码结果转成整型
}
/*for (i=0;i<M;i++)
{
printf("%d",decode[i]);
}
printf("\n以上是译码比特\n");*/
benum=benum+bercounter(trancode,decode);
penum=penum+percounter(trancode,decode);
//printf("\nbenum=%d, penum=%d\n",benum,penum);
//printf("\n");
}
ber[l]=(double)benum/(double)(BLOCKNUMBER*M);
per[l]=(double)penum/(double)BLOCKNUMBER;
//printf("\n误比特率为：%f\n误分组率为：%f\n",ber,per);
fprintf(fp_ber,"%f,%f ",ber[l],snr[l]);
fprintf(fp_per,"%f,%f ",per[l],snr[l]);
//printf("%d\n",l);
}
fclose(fpg);
fclose(fph);
fclose(fp_ber);
fclose(fp_per);
}
void generate(int gseq[])
{
int ranseq[K]={0};
int i,j;
for (i=0;i<K;i++)
{
ranseq[i]=rand()%2;
//printf("%d",ranseq[i]);
}
//printf("\n以上是产生的随机信源序列:\n");
for (i=0;i<M;i++)
{
gseq[i]=0;
for (j=0;j<K;j++)
{
gseq[i]=gseq[i]+ranseq[j]*gmatrix[j][i];
}
gseq[i]=gseq[i]%2;
//transeq[i]=gseq[i]*2-1;//pam to bpsk
//printf("%d",gseq[i]);
}
/*printf("\nNow here are the bpsk signal:\n");
for (i=0;i<M;i++)
{
printf("%d ",transeq[i]);
}*/
//printf("\n以上是生成的码字\n");
}
void addgaussnoise(double addcode[])
{
int i;
double var=1/snr[l];
double noise;
for (i=0;i<M;i++)
{
noise=(double)sqrt(var)*Gauss_rand(); //产生均值为0，方差为var的白噪声
addcode[i]=addcode[i]+noise; //加上高斯白噪声
}
}
void decoder(double designal[])
{
int n,k,j,i;
double temp=1;
double var=1/snr[l];
double p[M];
double deq[M];
struct rownode * p1;
struct colnode * q1;
//int check[HROW][M]={0};
//double rcheck[HROW][M]={0};
//for (i=0;i<5;i++)
//{
// var[i]=1/snr[i]; //由于这里是双极性，不考虑调制波形
//}
for (i=0;i<M;i++)
{
p[i]=0-2*designal[i]/var; //信道信息
//printf("%f ",p[i]);
}
for (i=0;i<HROW;i++) //初始化信息
{
p1=rowhead[i];
while(p1!=NULL)
{
p1->q=p[p1->colnum];
p1=p1->rownext;
}
}
/*for (j=0;j<HROW;j++) //检验校验矩阵是否构造正确
{
p1=rowhead[j];
while(p1!=NULL)
{
check[p1->rownum][p1->colnum]=1;
p1=p1->rownext;
}
}
printf("\n");
for (j=0;j<HROW;j++)
{
for (i=0;i<M;i++)
{
printf("%d ",check[j][i]);
}
printf("\n");
}*/
/*for (i=0;i<M;i++) //输出校验矩阵，检验校验矩阵是否构造正确
{
q1=colhead[i];
while (q1!=NULL)
{
check[q1->rownum][q1->colnum]=1;
q1=q1->colnext;
}
}
printf("\n");
for (j=0;j<HROW;j++)
{
for (i=0;i<M;i++)
{
printf("%d ",check[j][i]);
}
printf("\n");
}*/
/******************开始迭代处理****************************/
for (k=0;k<ITERATIMES;k++)
{
for (i=0;i<M;i++) //校验节点消息处理
{
q1=colhead[i];
while (q1!=NULL)
{
p1=rowhead[q1->rownum];
temp=1;
while (p1!=NULL)
{
if (p1->colnum!=i)
{
temp=temp*tanh(0.5*(p1->q));
}
p1=p1->rownext;
}
q1->r=2*contanh(temp);
q1=q1->colnext;
}
} //校验节点消息处理完成
/* for (i=0;i<M;i++) //显示各个节点的r值
{
q1=colhead[i];
while (q1!=NULL)
{
rcheck[q1->rownum][q1->colnum]=q1->r;
q1=q1->colnext;
}
}
printf("\n");
for (j=0;j<HROW;j++)
{
for (i=0;i<M;i++)
{
printf("%f ",rcheck[j][i]);
}
printf("\n");
}
*/
for (j=0;j<HROW;j++) //变量节点消息处理
{
p1=rowhead[j];
while (p1!=NULL)
{
q1=colhead[p1->colnum];
temp=0;
while (q1!=NULL)
{
if (q1->rownum!=j)
{
temp=temp+(q1->r);
}
q1=q1->colnext;
}
p1->q=p[p1->colnum]+temp;
p1=p1->rownext;
}
} //变量节点消息处理完成
//printf("\n");
for (i=0;i<M;i++) //译码判决
{
q1=colhead[i];
temp=0;
while (q1!=NULL)
{
temp=temp+(q1->r);
q1=q1->colnext;
}
deq[i]=p[i]+temp;
//printf("%f ",deq[i]);
if (deq[i]>0)
{
designal[i]=0;
}
else
{
designal[i]=1;
}
} //译码判决完成
n=0;
for (j=0;j<HROW;j++)
{
temp=0;
for (i=0;i<M;i++)
{
temp=temp+hmatrix[j][i]*designal[i];
}
if (temp)
{
n=n+1;
}
}
if(n==0)break; //如果校正子都为0，则译码结束，跳出迭代
}
}
/*void decoder(double designal[])
{
int i,j,k;
int n,m;
double temp1=1;
double temp2=1;
double snr=2;
double var=1/snr;
int hmatrix[15][15]={0,0,0,0,0,0,0,1,1,0,1,0,0,0,1,1,0,0,0,0,0,0,0,1,1,0,1,0,0,0,0,1,0,0,0,0,0,0,0,1,1,0,1,0,0,0,0,1,0,0,0,0,0,0,0,1,1,0,1,0,0,0,0,1,0,0,0,0,0,0,0,1,1,0,1,1,0,0,0,1,0,0,0,0,0,0,0,1,1,0,0,1,0,0,0,1,0,0,0,0,0,0,0,1,1,1,0,1,0,0,0,1,0,0,0,0,0,0,0,1,1,1,0,1,0,0,0,1,0,0,0,0,0,0,0,0,1,1,0,1,0,0,0,1,0,0,0,0,0,0,0,0,1,1,0,1,0,0,0,1,0,0,0,0,0,0,0,0,1,1,0,1,0,0,0,1,0,0,0,0,0,0,0,0,1,1,0,1,0,0,0,1,0,0,0,0,0,0,0,0,1,1,0,1,0,0,0,1,0,0,0,0,0,0,0,0,1,1,0,1,0,0,0,1,0};
double q0[15][15];
double q1[15][15];
double r0[15][15];
double r1[15][15];
double p0[15],p1[15];
double deq0[15],deq1[15];
printf("\n");
for (i=0;i<15;i++)
{
for (j=0;j<15;j++)
{
printf("%d ",hmatrix[i][j]);
}
printf("\n");
}
printf("\n");
for (i=0;i<15;i++) //初始化
{
//p0[i]=1/(1+exp(2*designal[i]/var));
//p1[i]=1-p0[i];
p0[i]=1/(exp((designal[i]+1)*(designal[i]+1)/(2*var))*sqrt(2*PI*var));
p1[i]=1/(exp((designal[i]-1)*(designal[i]-1)/(2*var))*sqrt(2*PI*var));
p0[i]=p0[i]/(p0[i]+p1[i]);
p1[i]=1-p0[i];
printf("%f %f ",p0[i],p1[i]);
for (j=0;j<15;j++)
{
q0[i][j]=p0[i];
q1[i][j]=p1[i];
}
}
printf("\n");
for (j=0;j<15;j++)
{
for (i=0;i<15;i++)
{
if (hmatrix[j][i]==0)
{
q0[i][j]=0;
q1[i][j]=0;
r0[j][i]=1;
r1[j][i]=1;
}
}
}
for (k=0;k<ITERATIMES;k++)
{
for (j=0;j<15;j++) //校验节点处理开始
{
for (i=0;i<15;i++)
{
if ((r0[j][i]!=1)&&(r1[j][i]!=1))
{
temp1=1;
for (m=0;m<15;m++)
{
if (m!=i)
{
temp1=temp1*(1-2*q1[m][j]);
}
}
r0[j][i]=0.5*temp1+0.5;
r1[j][i]=1-r0[j][i];
}
}
} //校验节点处理完成
for (i=0;i<15;i++) //变量节点处理开始
{
for (j=0;j<15;j++)
{
if ((q0[i][j]!=0)&&(q1[i][j]!=0))
{
temp1=1;
temp2=1;
for (m=0;m<15;m++)
{
if (m!=j)
{
temp1=temp1*r0[m][i];
temp2=temp2*r1[m][i];
}
}
q0[i][j]=p0[i]*temp1;
q1[i][j]=p1[i]*temp2;
q0[i][j]=q0[i][j]/(q0[i][j]+q1[i][j]);
q1[i][j]=1-q0[i][j];
}
}
} //变量节点处理完成
for (i=0;i<15;i++) //译码判决
{
temp1=1;
temp2=1;
for (j=0;j<15;j++)
{
temp1=temp1*r0[j][i];
temp2=temp2*r1[j][i];
}
deq0[i]=p0[i]*temp1;
deq1[i]=p1[i]*temp2;
deq0[i]=deq0[i]/(deq0[i]+deq1[i]);
deq1[i]=1-deq0[i];
}
printf("\n");
for (i=0;i<15;i++)
{
printf("%f %f ",deq0[i],deq1[i]);
}
printf("\n以上是硬判决信息，左为0右为1\n");
for (i=0;i<15;i++)
{
if (deq1[i]>deq0[i])
{
designal[i]=1;
}
else
designal[i]=0;
}
n=0;
for (i=0;i<15;i++)
{
temp1=0;
for (j=0;j<15;j++)
{
temp1=temp1+hmatrix[i][j]*designal[j];
}
if (temp1)
{
n=n+1;
}
}
if (n==0)break; //如果校正子都为0，则译码结束，跳出迭代
}
}*/
int bercounter(int array1[],int array2[])
{
int n=0;
int i;
for (i=0;i<M;i++)
{
array1[i]=(array1[i]+1)/2;
if (array1[i]!=array2[i])
{
n=n+1;
}
}
return n;
}
int percounter(int array1[],int array2[])
{
int n=0;
int i;
for (i=0;i<M;i++)
{
if (array1[i]!=array2[i])
{
n=1;
}
}
return n;
}
double Gauss_rand()
{
double random_num;
double u1,u2;
u1=((double)rand()+1.f)/32768.f;
u2=((double)rand()+1.f)/32768.f;
random_num=(double)(sqrt(-2.*log(u1))*cos(2*PI*u2));
return random_num;
}
double contanh(double y)
{
double value;
value=0.5*log((1+y)/(1-y));
return value;
}
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