University of Oulu

O. L. A. López, N. H. Mahmood, H. Alves and M. Latva-aho, "CSI-Free vs CSI-Based Multi-Antenna WET for Massive Low-Power Internet of Things," in IEEE Transactions on Wireless Communications, vol. 20, no. 5, pp. 3078-3094, May 2021, doi: 10.1109/TWC.2020.3047355

CSI-free vs CSI-based multi-antenna WET for massive low-power Internet of Things

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Author: López, Onel L. A.1; Mahmood, Nurul Huda1; Alves, Hirley1;
Organizations: 1Centre for Wireless Communications (CWC), University of Oulu, 90570 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.1 MB)
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Language: English
Published: Institute of Electrical and Electronics Engineers, 2021
Publish Date: 2021-06-10


Wireless Energy Transfer (WET) is a promising solution for powering massive Internet of Things deployments. An important question is whether the costly Channel State Information (CSI) acquisition procedure is necessary for optimum performance. In this paper, we shed some light into this matter by evaluating CSI-based and CSI-free multi-antenna WET schemes in a setup with WET in the downlink, and periodic or Poisson-traffic Wireless Information Transfer (WIT) in the uplink. When CSI is available, we show that a maximum ratio transmission beamformer is close to optimum whenever the farthest node experiences at least 3 dB of power attenuation more than the remaining devices. On the other hand, although the adopted CSI-free mechanism is not capable of providing average harvesting gains, it does provide greater WET/WIT diversity with lower energy requirements when compared with the CSI-based scheme. Our numerical results evidence that the CSI-free scheme performs favorably under periodic traffic conditions, but it may be deficient in case of Poisson traffic, specially if the setup is not optimally configured. Finally, we show the prominent performance results when the uplink transmissions are periodic, while highlighting the need of a minimum mean square error equalizer rather than zero-forcing for information decoding.

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Series: IEEE transactions on wireless communications
ISSN: 1536-1276
ISSN-E: 1558-2248
ISSN-L: 1536-1276
Volume: 20
Issue: 5
Pages: 3078 - 3094
Article number: 9316281
DOI: 10.1109/TWC.2020.3047355
Type of Publication: A1 Journal article – refereed
Field of Science: 213 Electronic, automation and communications engineering, electronics
Funding: This work was supported in part by the Academy of Finland (Aka) under Grant n.307492, Grant n.318927 (6Genesis Flagship), and Grant n.319008 (EE-IoT).
Academy of Finland Grant Number: 307492
Detailed Information: 307492 (Academy of Finland Funding decision)
318927 (Academy of Finland Funding decision)
319008 (Academy of Finland Funding decision)
Copyright information: © The Authors 2021. This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see