Iterative MAP Receiver Employing Forward Channel Estimation via Message Passing for OFDM over Fast Fading Channels

Kazushi MURAOKA; Kazuhiko FUKAWA; Hiroshi SUZUKI; Satoshi SUYAMA

doi:10.1587/transcom.E95.B.1770

Iterative MAP Receiver Employing Forward Channel Estimation via Message Passing for OFDM over Fast Fading Channels

Kazushi MURAOKA, Kazuhiko FUKAWA, Hiroshi SUZUKI, Satoshi SUYAMA

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This paper proposes an iterative maximum a posteriori (MAP) receiver for orthogonal frequency division multiplexing (OFDM) mobile communications under fast-fading conditions. The previous work in [21] developed a MAP receiver based on the expectation-maximization (EM) algorithm employing the differential model, which can allow correlated time-variation of channel impulse responses. In order to make such a MAP receiver more robust against time-variant channels, this paper proposes two new message-passing algorithms derived from factor graphs; subcarrier removal and partial turbo processing. The subcarrier removal estimates the channel frequency response by using all subcarriers other than the targeted subcarrier. Such channel estimate can be efficiently calculated by removing information on the targeted subcarrier from the estimate of the original EM algorithm that uses all the subcarriers. This modification can avoid the repetitive use of incorrectly detected signals for the channel estimation. On the other hand, the partial turbo processing performs symbol-by-symbol channel decoding by using a symbol interleaver. Owing to this process, the current channel estimate, which is more accurate due to the decoding gain, can be used as the initial channel estimate for the next symbol. Computer simulations under fast multipath fading conditions demonstrate that the subcarrier removal and the partial turbo processing can improve the error floor and the convergence speed, respectively, compared to the conventional MAP receiver.

Publication: IEICE TRANSACTIONS on Communications Vol.E95-B No.5 pp.1770-1783

Publication Date: 2012/05/01

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Online ISSN: 1745-1345

DOI: 10.1587/transcom.E95.B.1770

Type of Manuscript: PAPER

Category: Wireless Communication Technologies

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Kazushi MURAOKA, Kazuhiko FUKAWA, Hiroshi SUZUKI, Satoshi SUYAMA, "Iterative MAP Receiver Employing Forward Channel Estimation via Message Passing for OFDM over Fast Fading Channels" in IEICE TRANSACTIONS on Communications, vol. E95-B, no. 5, pp. 1770-1783, May 2012, doi: 10.1587/transcom.E95.B.1770.
Abstract: This paper proposes an iterative maximum a posteriori (MAP) receiver for orthogonal frequency division multiplexing (OFDM) mobile communications under fast-fading conditions. The previous work in [21] developed a MAP receiver based on the expectation-maximization (EM) algorithm employing the differential model, which can allow correlated time-variation of channel impulse responses. In order to make such a MAP receiver more robust against time-variant channels, this paper proposes two new message-passing algorithms derived from factor graphs; subcarrier removal and partial turbo processing. The subcarrier removal estimates the channel frequency response by using all subcarriers other than the targeted subcarrier. Such channel estimate can be efficiently calculated by removing information on the targeted subcarrier from the estimate of the original EM algorithm that uses all the subcarriers. This modification can avoid the repetitive use of incorrectly detected signals for the channel estimation. On the other hand, the partial turbo processing performs symbol-by-symbol channel decoding by using a symbol interleaver. Owing to this process, the current channel estimate, which is more accurate due to the decoding gain, can be used as the initial channel estimate for the next symbol. Computer simulations under fast multipath fading conditions demonstrate that the subcarrier removal and the partial turbo processing can improve the error floor and the convergence speed, respectively, compared to the conventional MAP receiver.
URL: https://global.ieice.org/en_transactions/communications/10.1587/transcom.E95.B.1770/_p

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@ARTICLE{e95-b_5_1770,
author={Kazushi MURAOKA, Kazuhiko FUKAWA, Hiroshi SUZUKI, Satoshi SUYAMA, },
journal={IEICE TRANSACTIONS on Communications},
title={Iterative MAP Receiver Employing Forward Channel Estimation via Message Passing for OFDM over Fast Fading Channels},
year={2012},
volume={E95-B},
number={5},
pages={1770-1783},
abstract={This paper proposes an iterative maximum a posteriori (MAP) receiver for orthogonal frequency division multiplexing (OFDM) mobile communications under fast-fading conditions. The previous work in [21] developed a MAP receiver based on the expectation-maximization (EM) algorithm employing the differential model, which can allow correlated time-variation of channel impulse responses. In order to make such a MAP receiver more robust against time-variant channels, this paper proposes two new message-passing algorithms derived from factor graphs; subcarrier removal and partial turbo processing. The subcarrier removal estimates the channel frequency response by using all subcarriers other than the targeted subcarrier. Such channel estimate can be efficiently calculated by removing information on the targeted subcarrier from the estimate of the original EM algorithm that uses all the subcarriers. This modification can avoid the repetitive use of incorrectly detected signals for the channel estimation. On the other hand, the partial turbo processing performs symbol-by-symbol channel decoding by using a symbol interleaver. Owing to this process, the current channel estimate, which is more accurate due to the decoding gain, can be used as the initial channel estimate for the next symbol. Computer simulations under fast multipath fading conditions demonstrate that the subcarrier removal and the partial turbo processing can improve the error floor and the convergence speed, respectively, compared to the conventional MAP receiver.},
keywords={},
doi={10.1587/transcom.E95.B.1770},
ISSN={1745-1345},
month={May},}

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TY - JOUR
TI - Iterative MAP Receiver Employing Forward Channel Estimation via Message Passing for OFDM over Fast Fading Channels
T2 - IEICE TRANSACTIONS on Communications
SP - 1770
EP - 1783
AU - Kazushi MURAOKA
AU - Kazuhiko FUKAWA
AU - Hiroshi SUZUKI
AU - Satoshi SUYAMA
PY - 2012
DO - 10.1587/transcom.E95.B.1770
JO - IEICE TRANSACTIONS on Communications
SN - 1745-1345
VL - E95-B
IS - 5
JA - IEICE TRANSACTIONS on Communications
Y1 - May 2012
AB - This paper proposes an iterative maximum a posteriori (MAP) receiver for orthogonal frequency division multiplexing (OFDM) mobile communications under fast-fading conditions. The previous work in [21] developed a MAP receiver based on the expectation-maximization (EM) algorithm employing the differential model, which can allow correlated time-variation of channel impulse responses. In order to make such a MAP receiver more robust against time-variant channels, this paper proposes two new message-passing algorithms derived from factor graphs; subcarrier removal and partial turbo processing. The subcarrier removal estimates the channel frequency response by using all subcarriers other than the targeted subcarrier. Such channel estimate can be efficiently calculated by removing information on the targeted subcarrier from the estimate of the original EM algorithm that uses all the subcarriers. This modification can avoid the repetitive use of incorrectly detected signals for the channel estimation. On the other hand, the partial turbo processing performs symbol-by-symbol channel decoding by using a symbol interleaver. Owing to this process, the current channel estimate, which is more accurate due to the decoding gain, can be used as the initial channel estimate for the next symbol. Computer simulations under fast multipath fading conditions demonstrate that the subcarrier removal and the partial turbo processing can improve the error floor and the convergence speed, respectively, compared to the conventional MAP receiver.
ER -