Multiuser MIMO Wireless Energy Transfer With Coexisting Opportunistic Communication

TL;DR

This paper analyzes spectrum sharing between multiuser MIMO wireless energy transfer and coexisting MIMO information transmission, proposing a single-beam energy transmission scheme to minimize interference and preserve system performance.

Contribution

It introduces a novel single-beam energy transmission scheme based on time sharing to reduce interference in spectrum sharing between WET and WIT systems.

Findings

Interference causes DoF loss proportional to energy beams.

Single-beam time sharing scheme maintains WET performance.

Proposed scheme minimizes interference impact on WIT.

Abstract

This letter considers spectrum sharing between a primary multiuser multiple-input multiple-output (MIMO) wireless energy transfer (WET) system and a coexisting secondary point-to-point MIMO wireless information transmission (WIT) system, where WET generates interference to WIT and degrades its throughput performance. We show that due to the interference, the WIT system suffers from a loss of the degrees of freedom (DoF) proportional to the number of energy beams sent by the energy transmitter (ET), which, in general, needs to be larger than one in order to optimize the multiuser WET with user fairness consideration. To minimize the DoF loss in WIT, we further propose a new single-beam energy transmission scheme based on the principle of time sharing, where the ET transmits one of the optimal energy beams at each time. This new scheme achieves the same optimal performance for the WET system, and minimizes the impact of its interference to the WIT system.