Dual carrier modulation / signal space diversity : demapping/detection

Hi folks,
  Can anyone give me some idea about demapping/detection algorithm for
Dual carrier modulation . its used in OFDM based UWB systems.

DCM is like mapping same databits into different constellation points
from different constellation diagrams. In OFDM UWB 4databits are mapped
into 2 I/Q points in (16 QAM like constellation) from 2 different
constellation digrams.


http://www.wimedia.org/imwp/idms/popups/pop_download.asp?ContentID=6394

Any idea how to detect/demodulate?

Thanks
John.

Hi,
You can use ML & LLR decoding.
ML based on symbol decision use minimum distance from two constellations.
LLR based on bit dicision use log-likelihood functions.
I knew that ML & LLR should show same performance. they show same
performance in case of 16QAM with 1 constellation.
But, when I simulated both in DCM, they were different, ML was better than
LLR. I'm still wondering why....



>Hi folks,
>  Can anyone give me some idea about demapping/detection algorithm for
>Dual carrier modulation . its used in OFDM based UWB systems.
>
>DCM is like mapping same databits into different constellation points
>from different constellation diagrams. In OFDM UWB 4databits are mapped
>into 2 I/Q points in (16 QAM like constellation) from 2 different
>constellation digrams.
>
>
>http://www.wimedia.org/imwp/idms/popups/pop_download.asp?ContentID=6394
>
>Any idea how to detect/demodulate?
>
>Thanks
>John.
>
>