constellation.c

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

/*****************************************************************************/
/*   FIle Name : constellation.c                                             */
/*   Description : WLAN OFDM Subcarrier modulation constellation Decoder     */
/*   author : miffie                                                         */
/*   Date   : aug/11/05                                                      */
/*   Copyright (c) 2005 miffie   All rights reserved.                          */
/*****************************************************************************/
struct binaryset constellation (struct complexset datain, 
                          char Nbpsc ) {
int 	ii ;
char 	shifter ;
double 	realp, image ;
char    pilot_polarity ;
struct 	binaryset bset ;
char  	*top ;
char    *pp ;
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 = (char *)malloc(48*Nbpsc*sizeof(char)) ) == NULL) {
        PRINTF( " malloc failed in constellation.c\n") ;
    } //fail
    else { //allocated
     PRINTF("constellation size=%d \n", datain.size ) ;

     pp= top ;
     for(ii=-26;ii<=26;ii++) { //each subcarrier
        realp = datain.data[ii+32].realp ;
        image = datain.data[ii+32].image ;
        if ((ii!=-21)&(ii!=-7)&(ii!=0)&(ii!=7)&(ii!=21)) { //not pilot
          switch ( Nbpsc ) { //switch
            case 1: { //BPSK
               //-1:0 0:8 1:f
                 *pp = (realp +1) * 8 ;
                 if( *pp > 0xf ) *pp = 0xf ;
                 else if (*pp <0 ) *pp = 0 ;
                 //printf("%d realp=%6.3f  %x\n", ii, realp, *pp );
                 pp++ ;
                 break ;
                } //BPSK
            case 2: { //QPSK
                 *pp = ((realp + Kmod_qpsk) * 16)/(2*Kmod_qpsk) ;
                 if( *pp > 0xf ) *pp = 0xf ;
                 else if (*pp <0 ) *pp = 0 ;
                 pp++ ;
                 *pp = ((image + Kmod_qpsk) * 16)/(2*Kmod_qpsk) ;
                 if( *pp > 0xf ) *pp = 0xf ;
                 else if (*pp <0 ) *pp = 0 ;
                 pp++ ;
                 break ;
                } //QPSK
            case 4: { //16QAM
                 *pp = ((realp + Kmod_qam16) * 16)/(2*Kmod_qam16) ;
                 if( *pp > 0xf ) *pp = 0xf ;
                 else if (*pp <0 ) *pp = 0 ;
                 pp++ ;
                 *pp = (( Kmod_qam16*3 - fabs(realp) ) * 16)/(2*Kmod_qam16) ;
                 if( *pp > 0xf ) *pp = 0xf ;
                 else if (*pp <0 ) *pp = 0 ;
                 pp++ ;

                 *pp = ((image + Kmod_qam16) * 16)/(2*Kmod_qam16) ;
                 if( *pp > 0xf ) *pp = 0xf ;
                 else if (*pp <0 ) *pp = 0 ;
                 pp++ ;
                 *pp = (( Kmod_qam16*3 - fabs(image) ) * 16)/(2*Kmod_qam16) ;
                 if( *pp > 0xf ) *pp = 0xf ;
                 else if (*pp <0 ) *pp = 0 ;
                 pp++ ;
                 break ;
                } //16QAM
            default: { //64QAM
                 *pp = ((realp + Kmod_qam64) * 16)/(2*Kmod_qam64) ;
                 if( *pp > 0xf ) *pp = 0xf ;
                 else if (*pp <0 ) *pp = 0 ;
                 pp++ ;
                 *pp = (( Kmod_qam64*5 - fabs(realp) ) * 16)/(2*Kmod_qam64) ;
                 if( *pp > 0xf ) *pp = 0xf ;
                 else if (*pp <0 ) *pp = 0 ;
                 pp++ ;
                 *pp = (( Kmod_qam64*3 - fabs(fabs(realp)-4*Kmod_qam64) ) * 16)/
                      (2*Kmod_qam64) ;
                 if( *pp > 0xf ) *pp = 0xf ;
                 else if (*pp <0 ) *pp = 0 ;
                 pp++ ;

                 *pp = ((image + Kmod_qam64) * 16)/(2*Kmod_qam64) ;
                 if( *pp > 0xf ) *pp = 0xf ;
                 else if (*pp <0 ) *pp = 0 ;
                 pp++ ;
                 *pp = (( Kmod_qam64*5 - fabs(image) ) * 16)/(2*Kmod_qam64) ;
                 if( *pp > 0xf ) *pp = 0xf ;
                 else if (*pp <0 ) *pp = 0 ;
                 pp++ ;
                 *pp = (( Kmod_qam64*3 - fabs(fabs(image)-4*Kmod_qam64) ) * 16)/
                      (2*Kmod_qam64) ;
                 if( *pp > 0xf ) *pp = 0xf ;
                 else if (*pp <0 ) *pp = 0 ;
                 pp++ ;
                 break ;
                } //64QAM
          }//switch
        }//not pilot
     } //each subcarrier

     bset.size = 48*Nbpsc ;
     bset.format = 1 ;
     bset.data = top ;
    }//allocated
    free ( datain.data ) ;
    return ( bset ) ;
} //constellation