[Discuss-gnuradio] Re: Discuss-gnuradio Digest, Vol 65, Issue 45

[CHIN-YA HUANG]

> Message: 6
> The OFDM system uses fft_length number of subcarriers and 
> occupied_tones 
> number of used subcarriers. The used subcarriers are mapped to the 
> middle of the fft_length subcarriers leaving the same number of 
> guardband subcarriers on either side. The middle two subcarriers are 
> also nulled to avoid DC affects.
> 
> The mapping is done in gr_ofdm_mapper_bcv.cc. If you want to play with 
> 
> this, I'd make a copy of this one as a different version of the mapping.
> 
> Tom
> 

Thanks Tom.

Do you mean mapping to the fft_length?

But, my questions is when received a packet, I saw the code in 
gr_ofdm_mapper_bcv.cc that
the bits in the packet is sequentially to the subcarrier in order, and then do 
modulation according to desired constellation. Do I misunderstand anything?

Regards.

Yaya