waterfill.c

ofdm project for Tms320C6000,完整

#include <stdio.h>
#include <math.h>
#include "receiver.h"

/* function which computes the bit allocation from the channel estimation.
The function uses the so called waterfilling algorithm.  */

// inputs: Hreal, Himag, Noise_var
// outputs: bn, en, btot

/**************waterfill***********/

#define SUBCARSIZE 124

//bit allocation function
void waterfill_simple(float *h_hat, float Noise_var, short *bn, float *en, float *gn) //, int *btot)
{

	
	// initialization
//	float gn[SUBCARSIZE];
	int i;
	float gap = 10;  //10;
	float K;
	float sum = 0;
//	float En_min;
	float inv_Noise_var = 1/Noise_var;		//1*_rcpsp(Noise_var);
	float inv_subcar=1*_rcpsp(SUBCARSIZE);
	
	// dB into normal scale
	gap = pow(10,gap/10);

	// find gn for multitone
	for(i= 0; i<SUBCARSIZE; i++)
	{	
		gn[i] = (h_hat[2*i]*h_hat[2*i] + h_hat[2*i+1]*h_hat[2*i+1]) * inv_Noise_var;
		sum = sum + 1/(gn[i]);
	}
	
	K = (Ex*SUBCARSIZE + gap*sum)* inv_subcar;
	
	
		
	for(i= 0; i<SUBCARSIZE; i++)
	{
		en[i] = K - gap / gn[i];
		bn[i] = ceil(0.5 * log10(K * gn[i] / gap)/log10(2));	
		if(bn[i]>6 && bn[i]<=12) 
			bn[i]=6;
		if(bn[i]>12)
			bn[i]=6;
		if (fmod(bn[i],2)!=0) 
			bn[i]=bn[i]-1;
		if(bn[i]<1) 
			bn[i]=0;
		
//		btot = btot + bn[i];
			
	} 
	
}




/*



void main(void)
{
	float Hreal[Ntot], Himag[Ntot];
	float en[Ntot];
	int bn[Ntot];
	int btot;
	int i;

	for(i= 0; i<2; i++)
	{
		Hreal[i] = 5;
		Himag[i] = 0;
	}
		for(i= 2; i<Ntot; i++)
	{
		Hreal[i] = 0.1;
		Himag[i] = 0;
	}
	waterfill(Hreal, Himag, bn, en, btot);

	for(i= 0; i<Ntot; i++)
	{
		printf("Output=%d, %f \n",bn[i], en[i]);	
	}
	
}


*/