researResearch - Télécom Bretagne

h Research
9
RESEARCH
Main achievements of the project
In 2008, the activity related to the analog
embedding of channel decoders was
characterised principally by continued integration
in BiCMOS 0.25micro.m of an analog turbo
decoder using a patented technique [ARZ05]. The
circuit in question requires a technique known as
“wheel decoding” and processes a 64 symbol
double binary frame. Four wheels are used to
decode 128 binary symbols of information as well
as 128 redundant symbols which were previously
produced by the encoding. This project, in
partnership with Orange Labs, is expected to lead
to the production, in 2009, of an operational
prototype. Improving the calculation cells is also a
priority for the group. Thus, notable advances
have been obtained in the determination of the
parasitic elements which lowered performance
levels (precision, speed …etc). Whether they are
embedded with bipolar or Mos transistors below
the threshold, the operations linked to decoding
algorithms (sum- product) have been improved
significantly. In the same way, a study of Cortex
codes was carried out and has produced some
promising perspectives. Indeed, a modular and
systematic construction method for these codes
was invented and has led to obtaining short codes
with a high value minimum distance. Finally, the
first technique for the decoding of these codes has
also been developed. Currently, it is the only
technique which demonstrates the feasability of
Cortex code decoding. In this way, a Hamming
(8,4,4)code Cortex decoder prototype has been
integrated into CMOS 0.25micro.m technology.
These results have been the subject of the writing
of a patent and several publications.
Publications
Articles in peer-review journals
Nicolas Duchaux, Cyril Lahuec, Fabrice Séguin, Michel Jézéquel,
Matthieu Arzel. Effect of BJT’s parasitics on computing cells for
analog decoders. NEWCAS-TAISA, 22-25 juin 2008, Montréal,
Québec, Canada, 2008
HDR
Michel Jézéquel. Une contribution dans le domaine de l'interaction
algorithme - silicium. HDR : Institut Télécom ; Télécom Bretagne :
2008, 103 p.
41