qpsk.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:      QPSK data modulation and demodulation
 | Author:      Tommi Makelainen, Nokia/NIST
 | Date:        January 6, 1999
 |
 | History:
 |              January 6, 1999 Tommi Makelainen
 |                      Initial version.
 |
 */

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

/*
 * Function:    wcdma_dl_qpsk_mod
 * Desc.:       QPSK downlink data modulation
 *
 * Note:
 *		Incoming data have to be a multiple of full bytes.
 *		Output vectors must be 4 times longer than input vector.
 */
int wcdma_dl_qpsk_mod(
	char data[],	/* input data bit vector */
        int data_len,	/* length of input data vector, in bytes */
        char I_out[],	/* output I parts of complex symbol vector */
        char Q_out[],	/* output Q parts of complex symbol vector */
        int *out_len)	/* output length of complex symbol vector */
{ 
    int I_out_index, Q_out_index, i, j;

    I_out_index = 0;
    Q_out_index = 0;
    for (i=0; i < data_len; i++)
    {
      /* get I branch bits from a byte */
      for (j=7; j > 0; j -= 2) {
        I_out[I_out_index] = extract_bit_from_byte(data[i], j);
        I_out_index++;
      }
      /* get Q branch bits from a byte */
      for (j=6; j > -1; j -= 2) {
        Q_out[Q_out_index] = extract_bit_from_byte(data[i], j);
        Q_out_index++;
      }
    }

    *out_len = I_out_index;

    return(0);
}

/*
 * Function:    wcdma_dl_qpsk_demod
 * Desc.:       QPSK data demodulation
 *
 * Note:
 */
int wcdma_dl_qpsk_demod(
	char I_in[],	/* IN: input I part of complex symbol vector */
        char Q_in[],	/* IN: input Q part of complex symbol vector */
        int in_len,	/* IN: length of input symbol vectors */
        char out_data[],/* OUT: output symbol vector */
        int *out_len)	/* OUT: length of output symbol vector */

{ 
    int i, out_index, j, I_index, Q_index;
    int antipodal_data, outer_loop_count;
    char temp_byte;

    I_index = 0;
    Q_index = 0;
    out_index = 0;
    
    /* Construct one byte per round */
    while (I_index < in_len) { 
      temp_byte = 0;
      /* Set bits from I branch */
      for (j=7; j > 0; j -= 2) {
        set_bit_in_byte(I_in[I_index], j, &temp_byte);
        I_index++;
      }
      /* Set bits from Q branch */
      for (j=6; j > -1; j -= 2) {
        set_bit_in_byte(Q_in[Q_index], j, &temp_byte);
        Q_index++;
      }
      out_data[out_index] = temp_byte;
      out_index++;
    };

    *out_len = out_index;

    return(0);
}