spreading.c

这是一个c＋＋编写的WCDMA链路采用RAKE接收的方针源代码

/*
 |
 | Copyright disclaimer:
 |   This software was developed at the National Institute of Standards
 |   and Technology by employees of the Federal Government in the course
 |   of their official duties. Pursuant to title 17 Section 105 of the
 |   United States Code this software is not subject to copyright
 |   protection and is in the public domain.
 |
 |   We would appreciate acknowledgement if the software is used.
 |
*/

/*
 | Project:	WCDMA simulation environment
 | Module:      Spreading and despreading 
 | Author:      Tommi Makelainen, Nokia/NIST
 | Date:        January 5, 1999
 |
 | History:
 |              January 5, 1999 Tommi Makelainen
 |                      Initial version.
 |		January 7, 1999 Tommi Makelainen
 |			Spreading code can be longer than one input symbol.
 |			Now it can be any multiple of data
 |			symbols times spreading factor.
 |
 |		January 9, 1999 Tommi Makelainen
 |			Data types changed from char to int.
 |
 |		April 6, 1999 Tommi Makelainen
 |                      Added soft despreader function.
 */

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


/*
 * Function:	wcdma_spread
 * Desc.:	Spreads each data bit from vector 'data' by code
 *              in vector 'code'. The code has length 'code_len'.
 *
 * Note:	
 *		Both input data and spreading code are expected
 *		to given in antipodal (-1,1) presentation.
 *		The length of data, 'data_len', must be
 *		multiple of the code length 'code_len'.
 */
int wcdma_spread(
	   int data[],		/* IN: input data bit vector */
           int data_len,	/* IN: length of input data vector */
           int code[],		/* IN: spreading code vector */
           int code_len,	/* IN: length of spreading code */
           int sf,		/* IN: Chip/data rate, i.e. spreading factor */
           int out[])		/* OUT: spreaded output symbol vector */
{ 
    int i, out_index, j, k;
    int data_symbols_per_code_seq;

    data_symbols_per_code_seq = code_len / sf;

#ifndef I_KNOW_WHAT_I_DO
    if (data_symbols_per_code_seq == 0) {
        if ( ((sf / code_len) != 0) && ((data_len / code_len) != 0) ) {
            printf("spread: Data length must be multiple of code length divided by spreading factor.\n");
            return(-1);
        }
    } else 
    if ( ( data_len % data_symbols_per_code_seq ) != 0 ) {
      printf("spread: Data length must be multiple of code length divided by spreading factor.\n");
      return(-1);
    }
#endif /* I_KNOW_WHAT_I_DO */

    out_index = i = 0;
    while (i < data_len) {
        for (j=0; j < data_symbols_per_code_seq; j++) {
          for (k=j*sf; k < sf; k++) {
            out[out_index++] = data[i] * code[k];
          }
          i++;
        } /* for */
    } /* while */

    return(0);
} /* wcdma_spread */


/*
 * Function:	wcdma_hard_despread
 * Desc.:	Despreads data symbols from vector 'in_data' by code
 *              in vector 'code'. The code has length 'sf'.
 *
 * Note:	
 *		Both input data and spreading code are expected
 *		to given in antipodal (-1,1) presentation.
 */
int wcdma_hard_despread(
	     int in_data[],	/* IN: input data symbol vector */
             int in_len,	/* IN: length of input data vector */
             int code[],	/* IN: spreading code vector */
             int code_len,	/* IN: length of spreading code */
             int sf,		/* IN: Chip/data rate, i.e. spreading factor */
             int out_data[])	/* OUT: despreaded output symbol vector */
{ 
    int i, data_length, out_index, j, new_out_index, k;
    int antipodal_data, outer_loop_count;
    int temp_data = 0;
    int data_symbols_per_code_seq;

    data_symbols_per_code_seq = code_len / sf;

#ifndef I_KNOW_WHAT_I_DO
    if ( (in_len % data_symbols_per_code_seq ) != 0) {
      printf("despread: Data length must be multiple of ratio between code length and spreading factor.\n");
      return(-1);
    }
#endif /* I_KNOW_WHAT_I_DO */

    out_index = i = 0;
    outer_loop_count = in_len / sf;
    while (out_index < outer_loop_count) 
    {
        for (j=0; j < data_symbols_per_code_seq; j++) {
          temp_data = 0;
          for (k=j*sf; k < sf; k++, i++) {
            temp_data += in_data[i] * code[k];
          }
          out_data[out_index] = (temp_data > 0) ? 1 : -1;
          out_index++;
        } /* for */
    } /* while */

    return(0);
} /* wcdma_hard_despread */


/*
 * Function:	wcdma_soft_despread
 * Desc.:	Despreads data symbols from vector 'in_data' by code
 *              in vector 'code'. The code has length 'sf'.
 *		Output soft decision is normalized with  'code_len'.
 *
 * Note:	
 *		Both input data and spreading code are expected
 *		to given in antipodal (-1,1) presentation.
 */
int wcdma_soft_despread(
	     double in_data[],	/* IN: input data symbol vector */
             int in_len,	/* IN: length of input data vector */
             int code[],	/* IN: spreading code vector */
             int code_len,	/* IN: length of spreading code */
             int sf,		/* IN: Chip/data rate, i.e. spreading factor */
             double out_data[],	/* OUT: despreaded output symbol vector */
             int add_index,     /* IN: index to add next output */
             int ringBufLen)    /* IN: ringbuffer length */
{ 
    int i, data_length, out_index, j, new_out_index, k;
    int antipodal_data, outer_loop_count;
    double temp_data = 0;
    int data_symbols_per_code_seq;

    data_symbols_per_code_seq = code_len / sf;

#ifndef I_KNOW_WHAT_I_DO
    if ( (in_len % data_symbols_per_code_seq ) != 0) {
      printf("despread: Data length must be multiple of ratio between code length and spreading factor.\n");
      return(-1);
    }
#endif /* I_KNOW_WHAT_I_DO */

    out_index = i = 0;
    outer_loop_count = in_len / sf;
    while (out_index < outer_loop_count) 
    {
        for (j=0; j < data_symbols_per_code_seq; j++) {
          temp_data = 0;
          for (k=j*sf; k < code_len; k++, i++) {
            temp_data += in_data[i] * code[k];
          }
          out_data[add_index] = temp_data / code_len;
          add_index = (add_index + 1) % ringBufLen;
        } /* for */
        out_index++;
    } /* while */

    return(0);
} /* wcdma_soft_despread */