rxpll.c

MIMO 2x2接收端选择全系统仿真代码

/*****************************************************************************
  Module     : Phase Locked Loop
******************************************************************************

  Function   : 

  Procedures : none

  Author     : $Author: Jinfeng $

  Revision   : $Revision: 6 $

  Modified   : $Modtime: 05-05-24 14:10 $

  File       : $Workfile: rxpll.c $

******************************************************************************
 KTH, Royal Institute of Technology, S3, Stockholm
*****************************************************************************/

/*--- Include files --------------------------------------------------------*/

/* import */
#include <csl_stdinc.h>
#include "../common/commondef.h"

/* export */
#include "rxpll.h"

/*=== End of include files =================================================*/


/*--- Global variables definition ------------------------------------------*/

typRX_PLLPARAM PLLparam;

/*=== End of global variables definition ===================================*/


/*--- Global constants definition ------------------------------------------*/
/*=== End of global constants definition ===================================*/


/*--- Local defines --------------------------------------------------------*/
#define LPFFILTERLEN 16
/*=== End of local defines =================================================*/


/*--- Local types declaration ----------------------------------------------*/
/*=== End of local types declaration =======================================*/


/*--- Local variables definition -------------------------------------------*/

extern float cos_table[COS_TAB_SIZE];

/*=== End of local variables definition ====================================*/


/*--- Local constants definition -------------------------------------------*/
const float lpf_coeff[LPFFILTERLEN] = 
		{-0.001920, -0.000316,  0.006319,  0.024859,
		  0.058182,  0.101516,  0.142955,  0.168405,
	      0.168405,  0.142955,  0.101516,  0.058182,
		  0.024859,  0.006319, -0.000316, -0.001920};
const float K0 = (2*PI*INTERFREQ/SAMPFREQ);
const Int16 AVG_LEN = 64; // the length of the domain carrying out average
/*=== End of local constants definition ====================================*/


/*--- Local functions definition -------------------------------------------*/
/*=== End of local functions definition ====================================*/


/*--- Global functions definition ------------------------------------------*/

/****************************************************************************
  Function   : lock_phase
 ****************************************************************************

  Description : find the frequency offset

  Inputs      : sinusoid signal and parameters of estimation

  Outputs     : Frequency offset

  By          : 2005-05-05 Jinfeng Du

 ****************************************************************************/
void lock_phase(typRX_PLLPARAM *pPLLparam, float *pSampBuff, const unsigned int uiBuffLen)
{
	
	unsigned int i, k;
	Int16 pos_i;
	Int16 pos = 0;
	Int16 lookup_index,index_sin;
	float a, interval;
	float phase_diff, out_seq;
	float I_filtered, Q_filtered;
//	float delta_x;
	float cos_n, sin_n;
	
	float loop_filter_output;
	float Ileft[LPFFILTERLEN]={0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
    float Qleft[LPFFILTERLEN]={0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

	float factor_1 = COS_TAB_SIZE*_rcpsp(2*PI);
//	float factor_2 = 2*PI*_rcpsp((float)COS_TAB_SIZE);
	
	loop_filter_output = pPLLparam->theta;


	for(i = 0; i < uiBuffLen; i++)
	{
		a = pSampBuff[i];

		interval = pPLLparam->theta*factor_1;
		lookup_index = (Int16)interval;
		index_sin = (lookup_index + 3*COS_TAB_SIZE/4) & (COS_TAB_SIZE - 1);
	//	index_sin = (index_sin>COS_TAB_SIZE) ? (index_sin-COS_TAB_SIZE):index_sin;
	//	delta_x = pPLLparam->theta - lookup_index*factor_2;
	//	cos_n = (1-0.5*delta_x*delta_x)*cos_table[lookup_index] - delta_x*cos_table[index_sin];
	//	sin_n = (1-0.5*delta_x*delta_x)*cos_table[index_sin] + delta_x*cos_table[lookup_index];
		
		cos_n = cos_table[lookup_index];
		sin_n = cos_table[index_sin];


		Ileft[pos] = a*cos_n;
		Qleft[pos] = a*sin_n;

		I_filtered = 0;
		Q_filtered = 0;
		
		#pragma MUST_ITERATE (LPFFILTERLEN, LPFFILTERLEN)
		for (k = 0; k<LPFFILTERLEN; k++)
		{
			pos_i = (pos - k +LPFFILTERLEN) & (LPFFILTERLEN - 1); // index in normal array
			// to find the index in the cyclic array
		//	pos_i = (pos_i<0) ? (pos_i+LPFFILTERLEN):pos_i; //constrain index within LPFFILTERLEN
			I_filtered += lpf_coeff[k]*Ileft[pos_i]; //-> working version
			Q_filtered += lpf_coeff[k]*Qleft[pos_i]; //->
		}
		
		pos++;
		pos = pos & (LPFFILTERLEN - 1);//save in cyclic array

		if (I_filtered != 0)
			phase_diff = -Q_filtered*_rcpsp(I_filtered);

		// Loop filter		
    	out_seq = loop_filter_output*pPLLparam->alpha + phase_diff*pPLLparam->beta ;
    	loop_filter_output = out_seq * pPLLparam->loop_gain;
    	
    	if (i>= uiBuffLen-AVG_LEN && i< uiBuffLen) pPLLparam->delta_avg += loop_filter_output;
    	

		pPLLparam->theta += K0 + loop_filter_output;

		while(pPLLparam->theta >= 2*PI)
		{
			pPLLparam->theta -= 2*PI;
		}
		
		while(pPLLparam->theta < 0)
		{
			pPLLparam->theta += 2*PI;
		}
		

	}

	pPLLparam->delta = (pPLLparam->delta_avg)/AVG_LEN;
}

/*=== End of global functions definition ===================================*/

/*--- AUTOMATICALLY GENERATED VERSION HISTORY --------------------------------

$Log: /MIMO/Receiver/rxpll.c $ 
 * 
 * 6     05-05-24 14:24 Jinfeng
 * shorten filter length to 16. use #pragma MUST_ITERATE(16,16)
 * 
 * 5     05-05-23 10:41 Jinfeng
 * remove modification of cos lookup table, need to be optimized.
 * 
 * 4     05-05-19 12:20 Jinfeng
 * introduce cyclic array to release most of the memory used to be
 * occupied.
 * 
 * 3     05-05-18 23:45 Jinfeng
 * correct for more than 70 steps debug, but cup error when run it
 * through.
 * 
 * 2     05-05-18 15:18 Jinfeng
 * need to be verified with MATLAB
 * 
 * 1     05-05-11 17:00 Adrian
 * created and added to VSS

===== END OF AUTOMATICALLY GENERATED VERSION HISTORY =======================*/

/**** End of file ***********************************************************/