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Proceedings Paper

Turbo-coded modulation as an alternative to space-time codes: the case of a large number of transmit-and-receive antennas
Author(s): Andrej Stefanov; Tolga M. Duman
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Paper Abstract

In a recent paper we have shown that a simple turbo coded modulation scheme provides significant performance improvement with respect to the properly interleaved space- time trellis codes for block Rayleigh fading channels. The turbo coded modulation scheme for the multiple antenna system is based on a simple encoding procedure which uses the encoder for a binary turbo code and maps the encoded bits to a certain constellation, and a simple decoding procedure which is based on a log-likelihood computation of the transmitted bits and the use of these log-likelihoods in a sub-optimal iterative decoding algorithm. Although the computation of log-likelihoods is not a problem for small number of transmit antennas, the computational complexity at the receiver is too high for the case of large number of transmit antennas. In this paper we present a practical method for handling this problem. In particular, we present a new decoding algorithm which does not suffer from the same computational complexity. Our method is similar to the array processing/group interference suppression scheme developed for space-time trellis coding. We present examples for the case of four transmit-four receive antennas and for the case of eight transmit-eight receiver antennas over block fading channels. We observe gains of around 3 dB at a bit error rate of 10-5 over the multi-layered space-time trellis coding with symbol interleaving. We also observe that although the current approach is computationally efficient, it results in a considerable performance degradation compared to the original (more complex) approach.

Paper Details

Date Published: 26 July 2000
PDF: 8 pages
Proc. SPIE 4045, Digital Wireless Communication II, (26 July 2000); doi: 10.1117/12.394098
Show Author Affiliations
Andrej Stefanov, Arizona State Univ. (United States)
Tolga M. Duman, Arizona State Univ. (United States)

Published in SPIE Proceedings Vol. 4045:
Digital Wireless Communication II
Raghuveer M. Rao; Soheil A. Dianat; Michael D. Zoltowski, Editor(s)

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