Optimizing Charging Direction Set for Directional Mobile Chargers With Multi-Sectorial Energy Beams

Document Type

Article

Publication Date

1-1-2026

Abstract

Leveraging breakthroughs in wireless power transfer technology, deploying Mobile Chargers (MCs) to charge sensor nodes can significantly prolong the operational lifetime of wireless sensor networks. Directional Mobile Chargers (DMCs), which integrate directional antennas, can focus radio frequency energy along designated directions, thereby boosting charging efficiency. Most existing works assume that DMCs emit a single energy beam; however, in practice, some DMC platforms can generate multiple sectorial- like energy beams, enabling a novel Multi-Beam DMC (MB-DMC)-based charging paradigm for Wireless Rechargeable Sensor Networks (WRSNs). This paradigm introduces a critical challenge: determining a minimum-size antenna direction set for the DMC while assuring that it is functionally equivalent to the infinite [0,2π) direction space in maintaining charging schedules with minimal energy loss. This paper systematically investigates the Multi-Sectorial-Beam DMC Charging Scheduling (MSBDCS) problem in MB-DMC-enhanced WRSNs (MB-WRSNs) and proves its NP-hardness. Furthermore, to address this challenge, we propose a Multi-Sectorial Beam Antenna Direction Selection (MSBADS) algorithm by efficiently exploiting geometric properties of local node set distribution, and theoretically prove its optimality in generating a minimum-size charging direction set that is functionally equivalent to the [0,2π) space. By integrating MSBADS into a four-step charging scheduling framework, we develop our MSBADS-based four-step Charging Scheduling (MSB-4S) algorithm to address the MSBDCS problem in MB-WRSNs. Extensive simulations and testbed experiments demonstrate that MSB-4S outperforms state-of-the-art baseline schemes by over 22% in energy efficiency improvement and more than 14% in scheduling time reduction.

Publication Title

IEEE Transactions on Mobile Computing

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