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On the Equivalence of TCM Encoders

Alex Alvarado ; Alexandre Graell i Amat (Institutionen för signaler och system, Kommunikationssystem) ; Fredrik Brännström (Institutionen för signaler och system, Kommunikationssystem) ; Erik Agrell (Institutionen för signaler och system, Kommunikationssystem)
2012 IEEE International Symposium on Information Theory, ISIT 2012. Cambridge, MA, 1 - 6 July 2012 p. 2401-2405. (2012)
[Konferensbidrag, refereegranskat]

Optimal trellis-coded modulation (TCM) schemes are obtained by jointly designing the convolutional encoder and the binary labeling of the constellation. Unfortunately this approach is infeasible for large encoder memories or constellation sizes. Traditional TCM designs circumvent this problem by using a labeling that follows the set-partitioning principle and by performing an exhaustive search over the encoders. Therefore, traditional TCM schemes are not necessarily optimal. In this paper, we study binary labelings for TCM and show how they can be grouped into classes, which considerably reduces the search space in a joint design. For the particular case of 8-ary modulation the search space is reduced from 40320 to 240. Using this classification, we formally prove that for any channel it is always possible to design a TCM system based on the binary-reflected Gray code with identical performance to the one proposed by Ungerboeck in 1982. Moreover, the classification is used to tabulate asymptotically optimal TCM schemes.

Nyckelord: Asymptotically optimal, Constellation sizes, Convolutional encoders, Exhaustive search, Gray codes, Joint designs, Labelings, Search spaces, Trellis coded modulation, Ungerboeck



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Denna post skapades 2012-04-28. Senast ändrad 2016-04-28.
CPL Pubid: 157189

 

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Institutioner (Chalmers)

Institutionen för signaler och system, Kommunikationssystem (1900-2017)

Ämnesområden

Informations- och kommunikationsteknik
Telekommunikationsteori
Datatransmission

Chalmers infrastruktur