Variational Soft Symbol Decoding for Sweep Spread Carrier Based Underwater Acoustic Communications

Arunkumar, KP and Murthy, CR (2019) Variational Soft Symbol Decoding for Sweep Spread Carrier Based Underwater Acoustic Communications. In: 20th IEEE International Workshop on Signal Processing Advances in Wireless Communications, SPAWC 2019, 2 July 2019 - 5 July 2019, Cannes.

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Abstract

We present a scheme for data detection in sweep spread carrier (S2C) based point-to-point communication over doubly-spread underwater acoustic (UWA) channels. The existing schemes for data detection-based on the gradient heterodyne receiver-are only effective when the path delay and Doppler spread are moderate. Based on the principle of variational Bayes' inference, we develop a new variational soft symbol decoding (VSSD) algorithm for a general linear channel model. We show that, in benign underwater channels with moderate delay and Doppler spreads, the VSSD algorithm is equivalent to the existing receivers for S2C communications. We apply the VSSD algorithm to the i.i.d. Gaussian multiple-input multiple-output (MIMO) channel and show, through numerical simulations, that it far outperforms the minimum mean squared error (MMSE) data detection in both uncoded and coded communications. Further, even with channel estimation errors, the VSSD retains its performance advantage over the MMSE receiver. In UWA channels where the existing S2C receivers completely fail, or must compromise on the data rate to maintain the bit error rate (BER) performance, the proposed VSSD algorithm recovers the data symbols at a signal-to-noise ratio (SNR) which is at least 10 dB (8 dB) lower than the MMSE decoder for uncoded (rate 2/3 LDPC coded) communications. © 2019 IEEE.

Item Type:	Conference Paper
Publication:	IEEE Workshop on Signal Processing Advances in Wireless Communications, SPAWC
Publisher:	Institute of Electrical and Electronics Engineers Inc.
Additional Information:	The copyright for this article belongs to Institute of Electrical and Electronics Engineers Inc.
Keywords:	Bit error rate; Carrier communication; Channel coding; Convolutional codes; Decoding; Errors; Inference engines; Mean square error; MIMO systems; Radio receivers; Signal processing; Trellis codes; Underwater acoustics, Bit error rate (BER) performance; Channel estimation errors; Heterodyne receivers; Minimum mean squared error; Multiple-input multiple-output channels; Point-to-point communication; Underwater acoustic communications; Variational bayes, Signal to noise ratio
Department/Centre:	Division of Electrical Sciences > Electrical Communication Engineering
Date Deposited:	19 Dec 2022 07:21
Last Modified:	19 Dec 2022 07:21
URI:	https://eprints.iisc.ac.in/id/eprint/78505

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