preamble.c

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

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/*   FIle Name : preamble.c                                                  */
/*   Description : WLAN Preamble of PPDU Encoder                             */
/*   author : miffie                                                         */
/*   Date   : aug/10/05                                                      */
/*   Copyright (c) 2005 miffie   All rights reserved.                        */
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///////////////////////////////////////////////////////////////////////////////

struct complexset preamble( ) { // 
struct  complexset cset0, cset1 ;
struct  complexset ctop ;
struct  complex  *ctmp1, *ctmp2 ;
int	ii ;
static  char   longseq[] = { 0 , 0 , 0 , 0 , 0 , 0 , 1 , 1 ,    //-32 -25
                            -1 ,-1 , 1 , 1 ,-1 , 1 ,-1 , 1 ,    //-24 -17
                             1 , 1 , 1 , 1 , 1 ,-1 ,-1 , 1 ,    //-16 -9
                             1 ,-1 , 1 ,-1 , 1 , 1 , 1 , 1 ,    //-8 -1
                             0 , 1 ,-1 ,-1 , 1 , 1 ,-1 , 1 ,    // 0  7
                            -1 , 1 ,-1 ,-1 ,-1 ,-1 ,-1 , 1 ,    // 8  15
                             1 ,-1 ,-1 , 1 ,-1 , 1 ,-1 , 1 ,    //16  23
                             1 , 1 , 1 , 0 , 0 , 0 , 0 , 0 } ;  //24  31
static double short_realp[] = {  0.046 , -0.132 , -0.013 ,  0.143, 
                                 0.092 ,  0.143 , -0.013 , -0.132,
                                 0.046 ,  0.002 , -0.079 , -0.013,
                                 0.000 , -0.013 , -0.079 ,  0.002 } ;

static double short_image[] = {  0.046 ,  0.002 , -0.079 , -0.013, 
                                 0.000 , -0.013 , -0.079 ,  0.002,
                                 0.046 , -0.132 , -0.013 ,  0.143,
                                 0.092 ,  0.143 , -0.013 , -0.132 } ;



  //Make LONG sequence
    if (((ctmp1 = (struct complex *)malloc(160*sizeof(struct complex))) == NULL) |
        ((ctmp2 = (struct complex *)malloc(64*sizeof(struct complex))) == NULL)) {
        PRINTF( " malloc failed in preamble\n") ;
    } //fail
    else { //allocated
      //SHORT Sequence
      cset0.size = 160 ;
      cset0.data = ctmp1 ;
      for (ii=0;ii<160;ii++) { //shortseq
         ctmp1[ ii ].realp  = short_realp[ ii %16 ] ; 
         ctmp1[ ii ].image  = short_image[ ii %16 ] ; 
      } //shortseq
      ctop = cset0 ;
      //short seq boundary
      ctmp1[ 0 ].realp = ctmp1[ 0 ].realp/2 ;
      ctmp1[ 0 ].image = ctmp1[ 0 ].image/2 ;
 
      //LONG  Sequence OFDM mapper
      cset1.size =64 ;
      cset1.data = ctmp2 ;
      for (ii=0;ii<64;ii++) {//long map
         cset1.data[ ii ].realp = longseq[ ii ] ;
         cset1.data[ ii ].image = 0 ;
      }//long map
      //Compare with Table G.11 for Frequency Domain data
      print_complexset( cset1 ) ;
      
    
      //OFDM IFFT
      cset1 = idft64 ( cset1 ) ;
      //Compare with Table G.12 for Frequency Domain data
      print_complexset( cset1 ) ;

      //build a preamble
      cset0 = extract_complexset(cset1 , 32 , 32 ) ; //Guard Interval2
      ctop = cat_complexset(ctop , cset0 )  ;
      ctop = cat_complexset(ctop , cset1 ) ;
      ctop = cat_complexset(ctop , cset1 ) ;
      //short seq & longseq boundary
      ctop.data[160].realp = (ctop.data[160].realp + ctop.data[16].realp) /2 ;
      ctop.data[160].image = (ctop.data[160].image + ctop.data[16].image) /2 ;
    } //allocated
    return( ctop ) ;
} //preamble