Abstract
Wireless energy transfer (WET) is emerging as an enabling green technology for Internet of Things (IoT) networks. WET allows the IoT devices to wirelessly recharge their batteries with energy from external sources such as dedicated radio frequency transmitters called power beacons (PBs). In this paper, we investigate the optimal deployment of PBs that guarantees a network-wide energy outage constraint. Optimal positions for the PBs are determined by maximizing the average incident power for the worst location in the service area since no information about the sensor deployment is provided. Such network planning guarantees the fairest harvesting performance for all the IoT devices. Numerical simulations evidence that our proposed optimization framework improves the energy supply reliability compared to benchmark schemes. Additionally, we show that although both, the number of deployed PBs and the number of antennas per PB, introduce performance improvements, the former has a dominant role. Finally, our proposal allows to extend the coverage area while keeping the total power budget fixed, which additionally reduces the level of electromagnetic radiation in the vicinity of PBs.
Highlights
T HE BROAD range of today’s Internet-of-Things (IoT) applications demands a massive deployment of lowcost devices, powered by small batteries, and with different Quality-of-Service (QoS) requirements
The optimal positions after solving P2 are represented in Fig. 6 for different number of power beacons (PBs); while we show the corresponding average power along the circle area as a heatmap
The optimization is limited to 15 PBs due to the poor convergence of genetic algorithms (GAs) compared with the Interior-point methods (IPMs) method
Summary
T HE BROAD range of today’s Internet-of-Things (IoT) applications demands a massive deployment of lowcost devices, powered by small batteries, and with different Quality-of-Service (QoS) requirements. The use of multiple antennas provides diversity over the space as well as additional degrees of freedom, suitable to tackle the impairments caused by small-scale fading This applies to wireless-powered communication networks (WPCNs), where beamforming techniques can be implemented to increase the coverage area due to the directionality in transmission [7]. Zhou et al [13] proposed a charge scheduling scheme using battery-powered PBs that harvest energy from a central PB They exploit the benefits of beamforming in order to maximize the energy efficiency while satisfying QoS constraint of the sensor network. In an attempt to fill this gap, the authors of [16], [17] study a WET setup where a multiantenna PB operates without CSI for powering massive low-power IoT deployments They analyze the statistics of the harvested energy under the sensitivity and saturation phenomena, and compare it with that experienced when using CSI-based schemes. Therein, the authors investigate the area that should be covered by the centered BS to minimize the average power consumption so that the uplink rate is above a certain threshold with probability given by the QoS requirement of all devices in the network
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