Re: [Discuss-gnuradio] OFDM serial to parallel mappping

[Tom Rondeau]

CHIN-YA HUANG wrote:
> Hi,
>
> Does anyone have clear idea about how gunradio implements serial to parallel 
> mapping since 802.11 has 52 channels?
> I check the gr_ofdm_mapper_bcv.cc , but still have no idea about it.  
> In further, I want to apply an array mapping to implement that different channels use different constellation. Does anyone have another comments if I apply an array in the gr_ofdm_mapper_bcv.cc file? 
>
> Thanks.
>
> Yaya
>   

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