signal_enc.c

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

/*****************************************************************************/
/*   FIle Name : signal_enc.c                                                */
/*   Description : WLAN FEC SIGNAL Field Encoder                             */
/*   author : miffie                                                         */
/*   Date   : aug/10/05                                                      */
/*   Copyright (c) 2005 miffie   All rights reserved.                        */
/*****************************************************************************/
///////////////////////////////////////////////////////////////////////////////

struct complexset signal_enc( char RATE , short LENGTH , char *pilot_shifter) { // 
struct	binaryset bset0,bset1 ;
struct  complexset cset0, cset1 ;
struct  complexset ctop ;
struct  complex  ctmp1, ctmp2 ;
char 	*tmp1 , *tmp2 ;
char	parity ;
int	ii ;

// Rate(Mbps)   RATE(R1-R4) Coding_Rate Modulation Nbpsc Ncbps Ndbps
//     6          1101        0:1/2        BPSK     1     48    24 

  //Make SIGNAL bits
  //SERVICE field
    if ((tmp1 = (char *)malloc(3*sizeof(char)) ) == NULL) {
        PRINTF( " malloc failed in SIGNAL\n") ;
    } //fail
    else { //allocated
       //bset1 for SERVICE field
       PRINTF("SIGNAL Encoder RATE=%x LENGTH=%x\n" ,RATE, LENGTH) ;
       bset1.format = 1 ; //a byte octet
       bset1.size = 3 ; //a byte octet
       bset1.data = tmp1 ; //
       tmp2 = tmp1 ;
       parity = 0 ;
       //first byte
       *tmp2   = ((LENGTH &0x7) <<5)  //first byte
               + (0x0<<4)             //Reserved
               + RATE ;             //RATE
       for (ii=0;ii<8;ii++) parity ^= (*tmp2>>ii) &0x1 ; 
       tmp2++ ;

       //second byte
       *tmp2   = (LENGTH &0x7f8)>>3 ; //second byte
       for (ii=0;ii<8;ii++) parity ^= (*tmp2>>ii) &0x1 ; 
       tmp2++ ;

       //third byte
       parity ^= (LENGTH>>11) &0x1 ; 
       *tmp2 = ((LENGTH &0x800)>>11)  //third byte
             + ((parity &0x1) <<1) ;
    } //allocated
    bset0 = byte2binary(bset1) ;
    print_binaryset( bset0 ) ;
 
  //No Scrambler in SIGNAL

  //Convolution encoder
    bset0 = convolution_encoder(bset0 , 0 ) ; //rate 0:1/2
    //Compare with Table G.8 for convolution encoder
    print_binaryset( bset0 ) ;
    
    //interleaver
    bset0 = interleaver(bset0 , 1 ) ; //Nbpsc=1
    //Compare with Table G.9 for interleaved bits
    print_binaryset( bset0 ) ;

    //OFDM mapper
    cset0 = mapper (bset0, 1, pilot_shifter) ; 
    //Compare with Table G.11 for Frequency Domain data
    print_complexset( cset0 ) ;
    
    //OFDM IFFT
    cset0 = idft64 ( cset0 ) ;
    //Compare with Table G.12 for Frequency Domain data
    print_complexset( cset0 ) ;

    //build a DATA symbol
    cset1 = extract_complexset(cset0 , 48 , 16 ) ; //Guard Interval
    cset1 = cat_complexset(cset1 , cset0 ) ;
    ctop = cset1 ;
    return( ctop ) ;
} //signal_enc