Iterative detectors for trellis-code multiple-access
Artikel i vetenskaplig tidskrift, 2002

Trellis-code multiple-access (TCMA) is a narrowband multiple-access scheme based on trellis-coded modulation. There is no bandwidth expansion, so K users occupy the same bandwidth as one single user. The load of the system, in number of bits per channel use, is therefore much higher than the load in, for example, conventional code-division multiple-access systems. Interleavers are introduced as a new feature to separate the users. This implies that the maximum-likelihood sequence detector (MLSD) is now too complex to implement. Iterative detectors are therefore suggested as an alternative to the joint MLSD. The conventional interference cancellation (IC) detector has lower complexity than the MLSD, but its performance is shown to be far from acceptable. Even after a novel improvement of the IC detector, the performance is unsatisfactory. Instead of using IC, another iterative detector is suggested. This detector updates the branch metric for every iteration, and avoids the standard Gaussian approximation. Simulations show that the performance of this detector can be close to single-user performance, even when the interleaver and the phase offset are the only user-specific features in the TCMA system.

trellis-coded modulation.

Interference cancellation

iterative methods

trellis-code multiple-access

multiple-access technique


Fredrik Brännström

Chalmers, Institutionen för datorteknik

Tor Aulin

Chalmers, Institutionen för datorteknik, Telekommunikationsteori

Lars K. Rasmussen

IEEE Transactions on Communications

Vol. 50 9 1478–-1485


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