Improvement of Turbo Trellis-Coded Modulation System

Haruo OGIWARA; Masaaki YANO

Improvement of Turbo Trellis-Coded Modulation System

Haruo OGIWARA, Masaaki YANO

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A structure and an iterative decoding algorithm of a turbo trellis-coded modulation system, proposed by Robertson and et al. , are improved. For the encoder, removal of the odd-even constraint of an interleaver is discussed and a structure which removes a serial connection of an interleaver and a deinterleaver is proposed. The latter makes encoding delay nearly half. A decoding algorithm which is a natural extension of the standard decoding algorithm to TCM is proposed. In the proposed algorithm, logarithm of an a posteriori probability ratio is divided into three component values: an a priori value, a channel value and an extrinsic information. The extrinsic information is transferred to the next decoding stage as an a priori value. The proposed algorithm is easier to understand than the Robertson's algorithm in which a combination of the channel value and the extrinsic information is transferred to the next stage. Simulation results show the proposed algorithm realizes equivalent or better performance than the Robertson's algorithm. The removal of the odd-even constraint gives a little better performance than that with odd-even constraint in some conditions. By this improvement, bit error rate of 10^-5 is obtained at E_b/N₀ 0. 4 dB from the Shannon limit for 2 bit/symbol transmission with 8-PSK modulation.

Publication: IEICE TRANSACTIONS on Fundamentals Vol.E81-A No.10 pp.2040-2046

Publication Date: 1998/10/25

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Type of Manuscript: Special Section PAPER (Special Section on Information Theory and Its Applications)

Category: Coded Modulation

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Haruo OGIWARA, Masaaki YANO, "Improvement of Turbo Trellis-Coded Modulation System" in IEICE TRANSACTIONS on Fundamentals, vol. E81-A, no. 10, pp. 2040-2046, October 1998, doi: .
Abstract: A structure and an iterative decoding algorithm of a turbo trellis-coded modulation system, proposed by Robertson and et al. , are improved. For the encoder, removal of the odd-even constraint of an interleaver is discussed and a structure which removes a serial connection of an interleaver and a deinterleaver is proposed. The latter makes encoding delay nearly half. A decoding algorithm which is a natural extension of the standard decoding algorithm to TCM is proposed. In the proposed algorithm, logarithm of an a posteriori probability ratio is divided into three component values: an a priori value, a channel value and an extrinsic information. The extrinsic information is transferred to the next decoding stage as an a priori value. The proposed algorithm is easier to understand than the Robertson's algorithm in which a combination of the channel value and the extrinsic information is transferred to the next stage. Simulation results show the proposed algorithm realizes equivalent or better performance than the Robertson's algorithm. The removal of the odd-even constraint gives a little better performance than that with odd-even constraint in some conditions. By this improvement, bit error rate of 10^-5 is obtained at E_b/N₀ 0. 4 dB from the Shannon limit for 2 bit/symbol transmission with 8-PSK modulation.
URL: https://global.ieice.org/en_transactions/fundamentals/10.1587/e81-a_10_2040/_p

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@ARTICLE{e81-a_10_2040,
author={Haruo OGIWARA, Masaaki YANO, },
journal={IEICE TRANSACTIONS on Fundamentals},
title={Improvement of Turbo Trellis-Coded Modulation System},
year={1998},
volume={E81-A},
number={10},
pages={2040-2046},
abstract={A structure and an iterative decoding algorithm of a turbo trellis-coded modulation system, proposed by Robertson and et al. , are improved. For the encoder, removal of the odd-even constraint of an interleaver is discussed and a structure which removes a serial connection of an interleaver and a deinterleaver is proposed. The latter makes encoding delay nearly half. A decoding algorithm which is a natural extension of the standard decoding algorithm to TCM is proposed. In the proposed algorithm, logarithm of an a posteriori probability ratio is divided into three component values: an a priori value, a channel value and an extrinsic information. The extrinsic information is transferred to the next decoding stage as an a priori value. The proposed algorithm is easier to understand than the Robertson's algorithm in which a combination of the channel value and the extrinsic information is transferred to the next stage. Simulation results show the proposed algorithm realizes equivalent or better performance than the Robertson's algorithm. The removal of the odd-even constraint gives a little better performance than that with odd-even constraint in some conditions. By this improvement, bit error rate of 10^-5 is obtained at E_b/N₀ 0. 4 dB from the Shannon limit for 2 bit/symbol transmission with 8-PSK modulation.},
keywords={},
doi={},
ISSN={},
month={October},}

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TY - JOUR
TI - Improvement of Turbo Trellis-Coded Modulation System
T2 - IEICE TRANSACTIONS on Fundamentals
SP - 2040
EP - 2046
AU - Haruo OGIWARA
AU - Masaaki YANO
PY - 1998
DO -
JO - IEICE TRANSACTIONS on Fundamentals
SN -
VL - E81-A
IS - 10
JA - IEICE TRANSACTIONS on Fundamentals
Y1 - October 1998
AB - A structure and an iterative decoding algorithm of a turbo trellis-coded modulation system, proposed by Robertson and et al. , are improved. For the encoder, removal of the odd-even constraint of an interleaver is discussed and a structure which removes a serial connection of an interleaver and a deinterleaver is proposed. The latter makes encoding delay nearly half. A decoding algorithm which is a natural extension of the standard decoding algorithm to TCM is proposed. In the proposed algorithm, logarithm of an a posteriori probability ratio is divided into three component values: an a priori value, a channel value and an extrinsic information. The extrinsic information is transferred to the next decoding stage as an a priori value. The proposed algorithm is easier to understand than the Robertson's algorithm in which a combination of the channel value and the extrinsic information is transferred to the next stage. Simulation results show the proposed algorithm realizes equivalent or better performance than the Robertson's algorithm. The removal of the odd-even constraint gives a little better performance than that with odd-even constraint in some conditions. By this improvement, bit error rate of 10^-5 is obtained at E_b/N₀ 0. 4 dB from the Shannon limit for 2 bit/symbol transmission with 8-PSK modulation.
ER -