www.pudn.com > qpsk_rm31.rar > qpsk_rm31.c

// ------------------------------------------------------------------------ 
//        File: qpsk_rm31.c 
//        Date: April 2, 2002 
// Description: Simulation of coded QPSK with an extended Hamming (8,4,4) code 
// ------------------------------------------------------------------------ 
// This program is complementary material for the book: 
// 
// R.H. Morelos-Zaragoza, The Art of Error Correcting Coding, Wiley, 2002. 
// 
// ISBN 0471 49581 6 
// 
// This and other programs are available at http://the-art-of-ecc.com 
// 
// You may use this program for academic and personal purposes only.  
// If this program is used to perform simulations whose results are  
// published in a journal or book, please refer to the book above. 
// 
// The use of this program in a commercial product requires explicitely  
// written permission from the author. The author is not responsible or  
// liable for damage or loss that may be caused by the use of this program.  
// 
// Copyright (c) 2002. Robert H. Morelos-Zaragoza. All rights reserved. 
// ------------------------------------------------------------------------ 
 
#include  
#include  
#include  
#include  
 
#define MAX_RANDOM LONG_MAX    /* Maximum value of random() */ 
#define RATE 0.5               /* Coding rate = 4/8 */ 
#define INIT_SNR   0.0         /* Initial value of Eb/N0 */ 
#define FINAL_SNR 10.0         /* Final value of Eb/N0 */ 
#define SNR_INCREMENT 1.0      /* Increment in Eb/N0 */ 
#define NUMSIM  100000         /* Number of simulations (one per 4 bits) */ 
 
int wh[16] = { 0, 1, 1, 2, 1, 2, 2, 3,       /* Hamming weight function: */ 
               1, 2, 2, 3, 2, 3, 3, 4 };     /* wh[i] = weight of i      */ 
int n = 8;  
int k = 4; 
 
int G[4][8] = { 1,1,1,1,1,1,1,1, 
                0,1,0,1,0,1,0,1, 
                0,0,1,1,0,0,1,1, 
                0,0,0,0,1,1,1,1 }; 
 
double sim, block_error; 
double ber; 
double amp; 
double seed; 
int error; 
int data[4], codeword[8]; 
int data_int; 
double snr; 
double transmitted_I[4],transmitted_Q[4]; 
double received_I[4],received_Q[4]; 
 
double max, metric; 
int winner; 
 
void initialize(void); 
double awgn(void); 
void encode(void); 
 
main() 
{ 
  int i,j,code_index[4]; 
 
  double qpsk_I[4] = { M_SQRT1_2,  M_SQRT1_2, -M_SQRT1_2, -M_SQRT1_2}; 
  double qpsk_Q[4] = { M_SQRT1_2, -M_SQRT1_2,  M_SQRT1_2, -M_SQRT1_2}; 
 
  int message[16][4] = { 
    0,0,0,0, 
    1,0,0,0, 
    0,1,0,0, 
    0,0,1,0, 
    0,0,0,1, 
    1,1,0,0, 
    1,0,1,0, 
    1,0,0,1, 
    0,1,1,0, 
    0,1,0,1, 
    0,0,1,1, 
    1,1,1,0, 
    1,1,0,1, 
    1,0,1,1, 
    0,1,1,1, 
    1,1,1,1, 
  }; 
 
  double reference_I[16][4] = {  
    qpsk_I[0], qpsk_I[0], qpsk_I[0], qpsk_I[0], 
    qpsk_I[3], qpsk_I[3], qpsk_I[3], qpsk_I[3], 
    qpsk_I[2], qpsk_I[2], qpsk_I[2], qpsk_I[2], 
    qpsk_I[0], qpsk_I[3], qpsk_I[0], qpsk_I[3], 
    qpsk_I[0], qpsk_I[0], qpsk_I[3], qpsk_I[3], 
    qpsk_I[1], qpsk_I[1], qpsk_I[1], qpsk_I[1], 
    qpsk_I[3], qpsk_I[0], qpsk_I[3], qpsk_I[0], 
    qpsk_I[3], qpsk_I[3], qpsk_I[0], qpsk_I[0], 
    qpsk_I[2], qpsk_I[1], qpsk_I[2], qpsk_I[1], 
    qpsk_I[2], qpsk_I[2], qpsk_I[1], qpsk_I[1], 
    qpsk_I[0], qpsk_I[3], qpsk_I[3], qpsk_I[0], 
    qpsk_I[1], qpsk_I[2], qpsk_I[1], qpsk_I[2], 
    qpsk_I[1], qpsk_I[1], qpsk_I[2], qpsk_I[2], 
    qpsk_I[3], qpsk_I[0], qpsk_I[0], qpsk_I[3], 
    qpsk_I[2], qpsk_I[1], qpsk_I[1], qpsk_I[2], 
    qpsk_I[1], qpsk_I[2], qpsk_I[2], qpsk_I[1]  
  }; 
 
  double reference_Q[16][4] = {  
    qpsk_Q[0], qpsk_Q[0], qpsk_Q[0], qpsk_Q[0], 
    qpsk_Q[3], qpsk_Q[3], qpsk_Q[3], qpsk_Q[3], 
    qpsk_Q[2], qpsk_Q[2], qpsk_Q[2], qpsk_Q[2], 
    qpsk_Q[0], qpsk_Q[3], qpsk_Q[0], qpsk_Q[3], 
    qpsk_Q[0], qpsk_Q[0], qpsk_Q[3], qpsk_Q[3], 
    qpsk_Q[1], qpsk_Q[1], qpsk_Q[1], qpsk_Q[1], 
    qpsk_Q[3], qpsk_Q[0], qpsk_Q[3], qpsk_Q[0], 
    qpsk_Q[3], qpsk_Q[3], qpsk_Q[0], qpsk_Q[0], 
    qpsk_Q[2], qpsk_Q[1], qpsk_Q[2], qpsk_Q[1], 
    qpsk_Q[2], qpsk_Q[2], qpsk_Q[1], qpsk_Q[1], 
    qpsk_Q[0], qpsk_Q[3], qpsk_Q[3], qpsk_Q[0], 
    qpsk_Q[1], qpsk_Q[2], qpsk_Q[1], qpsk_Q[2], 
    qpsk_Q[1], qpsk_Q[1], qpsk_Q[2], qpsk_Q[2], 
    qpsk_Q[3], qpsk_Q[0], qpsk_Q[0], qpsk_Q[3], 
    qpsk_Q[2], qpsk_Q[1], qpsk_Q[1], qpsk_Q[2], 
    qpsk_Q[1], qpsk_Q[2], qpsk_Q[2], qpsk_Q[1]  
  }; 
 
  snr = INIT_SNR; 
  while ( snr < (FINAL_SNR+0.001) ) 
    { 
      initialize(); 
      while (sim < NUMSIM)  
      {  
        for (i=0; i>10) & 0x01; 
 
        /* convert data[] to integer for error computation purposes */ 
        data_int = 0; 
        for (i=0; i max) { 
            max = metric; 
            winner = i; 
          } 
        } 
 
	i =  (message[winner][3]   + message[winner][2]*2); 
	i += (message[winner][1]*4 + message[winner][0]*8); 
 
        error = i ^ data_int; 
 
        ber += (float) wh[error]; 
 
        sim+=1.0; 
      } 
    printf("%f %13.8e\n", snr, (ber/(sim*4.0))); /* 1 sim = 4 bits! */ 
    fflush(stdout); 
    snr += SNR_INCREMENT; 
  } 
} 
 
 
void encode() 
{ 
  int i,j; 
  for (j=0; j= 1); 
  noise = (u1 * sqrt( (-2.0*log(s))/s ))/(amp*sqrt(2.0)); 
  return(noise); 
} 
 
void initialize() 
{ 
  time(&seed); 
  srandom(seed); 
  amp = sqrt(2.0*RATE*pow(10.0,(snr/10.0))); 
  block_error = 0.0; 
  ber = 0.0; 
  sim = 0.0; 
}