mapper.c

This model is just testing an idea of MIMO, which IEEE802.11n will have. But I havo not seen the s

/*****************************************************************************/
/*   FIle Name : mapper.c                                                    */
/*   Description : WLAN OFDM Subcarrier modulation mapper for Encoder        */
/*   author : miffie                                                         */
/*   Date   : aug/08/05                                                      */
/*   Copyright (c) 2005 miffie   All rights reserved.                          */
/*****************************************************************************/
struct complexset mapper (struct binaryset datain, 
                          char Nbpsc,
                          char *pilot_shifter ) {
int 	ii , pp ;
char 	shifter ;
char 	tmp1 ;
char    pilot_polarity ;
struct 	complexset cset ;
struct  complex    *top ;
char    *p ;
static  char  bpsk_map[] = {-1, 1 } ;
static  char  qpsk_map[] = {-1, 1 } ;
static  char  qam16_map[] = {-3, -1, 3, 1 } ; //Gray coded
static  char  qam64_map[] = {-7, -5, -1, -3, 7, 5, 1, 3 } ; //Gray coded
static  double Kmod_bpsk = 1 ;	
static  double Kmod_qpsk = 0.70710678 ; //1/(sqrt (2)) ;	
static  double Kmod_qam16 = 0.31622777 ;
static  double Kmod_qam64 = 0.15430335 ;

  //Main 
    if ((top = (struct complex *)malloc(64*sizeof(struct complex)) ) == NULL) {
        PRINTF( " malloc failed in mapper.c\n") ;
    } //fail
    else { //allocated
     //OFDM randomizer
     *pilot_shifter = pilot_randomizer( *pilot_shifter ) ;
     pilot_polarity = *pilot_shifter & 0x1 ;
     if ( pilot_polarity ==1) pilot_polarity = -1 ;
     else pilot_polarity =1 ;
     PRINTF("mapper size=%d pilot_polarity=%d\n", datain.size, pilot_polarity ) ;

     p= datain.data ;
     switch ( Nbpsc ) { //switch
       case 1: { //BPSK
            for(ii=-26;ii<=26;ii++) { //each subcarrier
               //pilot
              if ((ii!=-21)&(ii!=-7)&(ii!=0)&(ii!=7)&(ii!=21)) { //not pilot
                 tmp1 = (*p++) ;
                 top[ii+32].realp = bpsk_map[ tmp1 ] * Kmod_bpsk;
                 top[ii+32].image = 0 ;
              }//not pilot
            } //each subcarrier
            break ;
       } //BPSK
       case 2: { //QPSK
            for(ii=-26;ii<=26;ii++) { //each subcarrier
               //pilot
              if ((ii!=-21)&(ii!=-7)&(ii!=0)&(ii!=7)&(ii!=21)) { //not pilot
                 //tmp1 = (*p++<<1) + (*p++) ;
                 tmp1 = (*p++) ;
                 top[ii+32].realp = qpsk_map[ tmp1 ] * Kmod_qpsk;
                 tmp1 = (*p++) ;
                 top[ii+32].image = qpsk_map[ tmp1 ] * Kmod_qpsk;
              }//not pilot
            } //each subcarrier
            break ;
       } //QPSK
       case 4: { //16QAM
            for(ii=-26;ii<=26;ii++) { //each subcarrier
               //pilot
              if ((ii!=-21)&(ii!=-7)&(ii!=0)&(ii!=7)&(ii!=21)) { //not pilot
                 tmp1 = (*p++<<1)  ;
                 tmp1 += (*p++) ;
                  //printf("subcarrier (%d) %d ", ii, tmp1 ) ;
                 top[ii+32].realp = qam16_map[ tmp1 ] * Kmod_qam16 ;
                 tmp1 = (*p++<<1)  ;
                 tmp1 += (*p++) ;
                  //printf(" %d\n", tmp1 ) ;
                 top[ii+32].image = qam16_map[ tmp1 ] * Kmod_qam16 ;
              }//not pilot
            } //each subcarrier
            break ;
       } //16QAM
       default: { //64QAM
            for(ii=-26;ii<=26;ii++) { //each subcarrier
               //pilot
              if ((ii!=-21)&(ii!=-7)&(ii!=0)&(ii!=7)&(ii!=21)) { //not pilot
                 tmp1 = (*p++<<2)  ;
                 tmp1 += (*p++<<1)  ;
                 tmp1 += (*p++) ;
                 top[ii+32].realp = qam64_map[ tmp1 ] * Kmod_qam64 ;
                 tmp1 = (*p++<<2)  ;
                 tmp1 += (*p++<<1)  ;
                 tmp1 += (*p++) ;
                 top[ii+32].image = qam64_map[ tmp1 ] * Kmod_qam64 ;
              }//not pilot
            } //each subcarrier
            break ;
       } //64QAM
     }//switch

     //Blank subcarriers
     for(ii=-32;ii<=-27;ii++) { //each subcarrier
       top[ii+32].realp = 0 ;
       top[ii+32].image = 0 ;
     } //each subcarrier

     for(ii=27;ii<=31;ii++) { //each subcarrier
       top[ii+32].realp = 0 ;
       top[ii+32].image = 0 ;
     } //each subcarrier

     //pilot subcarriers
     top[ -21 + 32 ].realp =  pilot_polarity ;
     top[ -21 + 32 ].image =  0 ;
     top[ -7 + 32 ].realp =  pilot_polarity ;
     top[ -7 + 32 ].image =  0 ;
     top[ 7 + 32 ].realp =  pilot_polarity ;
     top[ 7 + 32 ].image =  0 ;
     top[ 21 + 32 ].realp =  -pilot_polarity ;
     top[ 21 + 32 ].image =  0 ;

     cset.size = 64 ;
     cset.data = top ;
    }//allocated
    free( datain.data ) ;
    return ( cset ) ;
} //mapper