University of Oulu

F. A. Monteiro, O. L. A. López and H. Alves, "Massive Wireless Energy Transfer With Statistical CSI Beamforming," in IEEE Journal of Selected Topics in Signal Processing, vol. 15, no. 5, pp. 1169-1184, Aug. 2021, doi: 10.1109/JSTSP.2021.3090962

Massive wireless energy transfer with statistical CSI beamforming

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Author: Monteiro, Francisco A.1; López, Onel L. A.2; Alves, Hirley2
Organizations: 1Instituto de Telecomunicações, and ISCTE - Instituto Universitário de Lisboa, Lisbon, Portugal
2Centre for Wireless Communications, University of Oulu, Oulu, Finland
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 2.2 MB)
Persistent link: http://urn.fi/urn:nbn:fi-fe2021122162548
Language: English
Published: Institute of Electrical and Electronics Engineers, 2021
Publish Date: 2021-12-21
Description:

Abstract

Wireless energy transfer (WET) is a promising solution to enable massive machine-type communications (mMTC) with low-complexity and low-powered wireless devices. Given the energy restrictions of the devices, instant channel state information at the transmitter (CSIT) is not expected to be available in practical WET-enabled mMTC. However, because it is common that the terminals appear spatially clustered, some degree of spatial correlation between their channels to the base station (BS) is expected to occur. The paper considers a massive antenna array at the BS for WET that only has access to i) the first and second order statistics of the Rician channel component of the multiple-input multiple-output (MIMO) channel and also to ii) the line-of-sight MIMO component. The optimal precoding scheme that maximizes the total energy available to the single-antenna devices is derived considering a continuous alphabet for the precoders, permitting any modulated or deterministic waveform. This may lead to some devices in the clusters being assigned a low fraction of the total available power in the cluster, creating a rather uneven situation among them. Consequently, a fairness criterion is introduced, imposing a minimum amount of power allocated to the terminals. A piece-wise linear harvesting circuit is considered at the terminals, with both saturation and a minimum sensitivity, and a constrained version of the precoder is also proposed by solving a non-linear programming problem. A paramount benefit of the constrained precoder is the encompassment of fairness in the power allocation to the different clusters. Moreover, given the polynomial complexity increase of the proposed unconstrained precoder, and the observed linear gain of the system's available sum-power with an increasing number of antennas at the ULA, the use of massive antenna arrays is desirable.

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Series: IEEE journal of selected topics in signal processing
ISSN: 1932-4553
ISSN-E: 1941-0484
ISSN-L: 1932-4553
Volume: 15
Issue: 5
Pages: 1169 - 1184
DOI: 10.1109/JSTSP.2021.3090962
OADOI: https://oadoi.org/10.1109/JSTSP.2021.3090962
Type of Publication: A1 Journal article – refereed
Field of Science: 113 Computer and information sciences
Subjects:
WET
Funding: Francisco Monteiro was supported by a joint scholarship from Fundacion Carolina and Fundaci on Endesa (both from Spain) and funded by FCT/MCTES (Portugal) through national funds and when applicable co-funded EU funds under the project UIDB/50008/2020. This work was also supported by Academy of Finland (Aka) (Grants n.307492, n.318927 (6Genesis Flagship), n.319008 (EE-IoT)).
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