Performance evaluation of superorthogonal turbo codes in AWGN and flat Rayleigh fading channels

Document Type

Article

Publication Date

1-1-1998

Abstract

Turbo codes are parallel concatenated codes whose performance in the additive white Gaussian noise (AWGN) channel has been shown to be near the theoretical limit. In this paper, we describe a low-rate superorthogonal turbo code that combines the principles of low-rate convolutional coding and that of parallel concatenation. Due to the bandwidth expansion, this code outperforms the ordinary turbo code both in AWGN and especially in fading channels. Thus, superorthogonal turbo codes are suited mainly for spread-spectrum applications. For the purposes of iterative decoding, we concisely describe the connection between the optimal maximum a posteriori symbol estimation and suboptimal soft-output decoding based on sequence estimation. The suboptimal decoder produces outputs that can directly be used as additive metrics at successive decoding iterations, without the need for estimating channel noise variance. Simulation results in AWGN and flat Rayleigh fading channels are also presented, along with analytical upper bounds of bit- and frame-error probabilities.

Identifier

0031999040 (Scopus)

Publication Title

IEEE Journal on Selected Areas in Communications

External Full Text Location

https://doi.org/10.1109/49.661108

ISSN

07338716

First Page

196

Last Page

205

Issue

2

Volume

16

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