[Discuss-gnuradio] about ofdm

[bin zan]

Hi all,
       I was trying to cut a packet into several pieces and send them through ofdm. I force the transmitter use only certain sub-carriers, for example first 64 sub-carriers. However, at the receiver side, I found it only can receive first piece of packet correct, and never receive the remaining piece correctly. Any help?

Thanks,
Bin

=========================== 
        The only places I modified are in gr_ofdm_mapper_bcv::work 
...
 memset(out, 0, d_fft_length*sizeof(gr_complex));
  i = 0;
  unsigned char bits = 0;
  //while((d_msg_offset < d_msg->length()) && (i < d_occupied_carriers)) {      
  //while((d_msg_offset < d_msg->length()) && (i < d_subcarrier_map.size())) {
  while((d_msg_offset < d_msg->length()) && (i<64))  //so only use first 64 subcarriers
....
at transmitter side.
 And: in gr_ofdm_frame_sink::demapper
...
 if(d_byte_offset == 8) {
      //printf("demod byte: %x \n\n", d_partial_byte);                          
      if(bytes_produced<8)         //this will match the first 64 carriers for bpsk
           out[bytes_produced++] = d_partial_byte;                                                        
       d_byte_offset = 0;
       d_partial_byte = 0;
  }
...
at the receiver side.