awgn_channel.c

在无线网络的接收机端

#include"AWGN.h"
#include"math.h"


#define PI 3.14159


double random_u(struct AWGN *gauss)
{ 
    double temp;

    gauss->ix = (gauss->ix*249) % 61967; 
    gauss->iy = (gauss->iy*251) % 63443;
    gauss->iz = (gauss->iz*252) % 63599;
    temp= ( (double)gauss->ix/(double)61967 + (double)gauss->iy/(double)63443+ (double)gauss->iz/(double)63599 )
	   -(int)( (double)gauss->ix/(double)61967+ (double)gauss->iy/(double)63443+(double)gauss->iz/(double)63599 );
    
	return(temp);     
}

double gauss_generate(struct AWGN *gauss)
{
	double temp;
	double u1,u2;
	u1=random_u(gauss);
	u2=random_u(gauss);
	temp=(double)sqrt((double)(-2)*log((double)1-u1))*(double)cos((double)2*(double)PI*u2);
	temp=(double)temp*gauss->sigma;
	return (temp);
}

double random_source()
{
	long z,k;
	
	k = s1 / 53668L;
	s1 = 40014L * (s1 - k * 53668L) - k * 12211L;
	if(s1 < 0)
		s1 = s1 + 2147483563L;
	k = s2 / 52774;
	s2 = 40692L * (s2 - k * 52774L) - k * 3791L;
	if(s2 < 0)
		s2 = s2 + 2147483399L;
	z = s1 - s2;
	if(z < 1)
		z = z + 2147483562L;
	
	return (double) z / (double) 2147483563.0;
}

int generate_binary_source()
{
	if(random_source() < 0.5)
		return 0;
	else
		return 1;
} 
 

void awgn_channel(double *input,double *output,struct AWGN *gauss,int len)
{
	double awgn;
	int i;
	for(i=0;i<=len-1;i++)
	{
		awgn=gauss_generate(gauss);
		output[i]=input[i]+awgn;
	}
}