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A finite input alphabet perspective on the rate-energy tradeoff in SWIPT over parallel Gaussian channels

A finite input alphabet perspective on the rate-energy tradeoff in SWIPT over parallel Gaussian channels
A finite input alphabet perspective on the rate-energy tradeoff in SWIPT over parallel Gaussian channels
Simultaneous wireless information and power transfer (SWIPT) has gained significant popularity in the recent past owing to its applications in a wide range of use-cases. Although SWIPT has been fairly well investigated in the literature, the existing work has mainly focused on attaining the optimal rate energy (RE) trade-off assuming Gaussian input alphabet. However, practical systems operate with finite input alphabets such as QAM/PSK. We characterise the attainable RE trade-off in SWIPT systems employing finite input alphabet for transmission over parallel Gaussian channels of say orthogonal frequency division multiplexing subcarriers or multiple-input multiple-output streams. Some of the key results in the literature that assume Gaussian input alphabet are shown to be special cases of our results. Furthermore, we provide insights into our results with the aid of graphical illustrations, which throw light on the optimal power allocation policy for various energy harvesting constraints. Furthermore, we consider practically relevant time sharing and power splitting schemes operating with finite input alphabet and characterise their RE trade-off. Their optimal solutions in the asymptotic regime are obtained, which serve as low-complexity solutions suitable for practical implementation. Our simulation studies have demonstrated that the Gaussian input assumption significantly over-estimates the attainable RE trade-off, especially when the signal set employed is small. Furthermore, it is observed through numerical simulations that the proposed optimal power allocation performs significantly better than the power allocation based on the Gaussian input assumption. Specifically, as much as 30\% rate improvement is observed when employing the classic 4-QAM signal set.
0733-8716
Mysore Rajashekar, Rakshith
d2fbbb04-57c5-4165-908f-600fc1fbdeab
Renzo, Marco Di
851ec05a-0f5d-49b1-aaf6-563604f8b809
Yang, Lieliang
ae425648-d9a3-4b7d-8abd-b3cfea375bc7
Hari, K.V.S.
2da50d38-1324-4f2a-ab9e-622b8236dee6
Hanzo, Lajos
66e7266f-3066-4fc0-8391-e000acce71a1
Mysore Rajashekar, Rakshith
d2fbbb04-57c5-4165-908f-600fc1fbdeab
Renzo, Marco Di
851ec05a-0f5d-49b1-aaf6-563604f8b809
Yang, Lieliang
ae425648-d9a3-4b7d-8abd-b3cfea375bc7
Hari, K.V.S.
2da50d38-1324-4f2a-ab9e-622b8236dee6
Hanzo, Lajos
66e7266f-3066-4fc0-8391-e000acce71a1

Mysore Rajashekar, Rakshith, Renzo, Marco Di, Yang, Lieliang, Hari, K.V.S. and Hanzo, Lajos (2018) A finite input alphabet perspective on the rate-energy tradeoff in SWIPT over parallel Gaussian channels. IEEE Journal on Selected Areas in Communications. (doi:10.1109/JSAC.2018.2872312).

Record type: Article

Abstract

Simultaneous wireless information and power transfer (SWIPT) has gained significant popularity in the recent past owing to its applications in a wide range of use-cases. Although SWIPT has been fairly well investigated in the literature, the existing work has mainly focused on attaining the optimal rate energy (RE) trade-off assuming Gaussian input alphabet. However, practical systems operate with finite input alphabets such as QAM/PSK. We characterise the attainable RE trade-off in SWIPT systems employing finite input alphabet for transmission over parallel Gaussian channels of say orthogonal frequency division multiplexing subcarriers or multiple-input multiple-output streams. Some of the key results in the literature that assume Gaussian input alphabet are shown to be special cases of our results. Furthermore, we provide insights into our results with the aid of graphical illustrations, which throw light on the optimal power allocation policy for various energy harvesting constraints. Furthermore, we consider practically relevant time sharing and power splitting schemes operating with finite input alphabet and characterise their RE trade-off. Their optimal solutions in the asymptotic regime are obtained, which serve as low-complexity solutions suitable for practical implementation. Our simulation studies have demonstrated that the Gaussian input assumption significantly over-estimates the attainable RE trade-off, especially when the signal set employed is small. Furthermore, it is observed through numerical simulations that the proposed optimal power allocation performs significantly better than the power allocation based on the Gaussian input assumption. Specifically, as much as 30\% rate improvement is observed when employing the classic 4-QAM signal set.

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Accepted/In Press date: 7 September 2018
e-pub ahead of print date: 3 October 2018

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Local EPrints ID: 423251
URI: http://eprints.soton.ac.uk/id/eprint/423251
ISSN: 0733-8716
PURE UUID: d495e105-b70b-475c-8d49-8dcbe96ecc8d
ORCID for Rakshith Mysore Rajashekar: ORCID iD orcid.org/0000-0002-7688-7539
ORCID for Lieliang Yang: ORCID iD orcid.org/0000-0002-2032-9327
ORCID for Lajos Hanzo: ORCID iD orcid.org/0000-0002-2636-5214

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Date deposited: 19 Sep 2018 16:31
Last modified: 07 Oct 2020 01:42

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Contributors

Author: Rakshith Mysore Rajashekar ORCID iD
Author: Marco Di Renzo
Author: Lieliang Yang ORCID iD
Author: K.V.S. Hari
Author: Lajos Hanzo ORCID iD

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