Latency-Aware Multi-antenna SWIPT System with Battery-Constrained Receivers

TL;DR

This paper develops a dynamic resource allocation framework for latency-aware multi-antenna SWIPT systems with battery-constrained receivers, optimizing energy transfer and information decoding under complex constraints.

Contribution

It introduces a Lyapunov optimization-based algorithm for joint beamforming and power splitting, addressing battery constraints and latency in SWIPT systems, with novel solution approaches.

Findings

The proposed algorithm effectively minimizes transmit energy while satisfying latency and energy harvesting needs.

The low-complexity iterative algorithm performs well in scenarios with delay-bounded batteryless receivers.

Numerical results demonstrate robustness and energy efficiency of the proposed system design.

Abstract

Power splitting (PS) based simultaneous wireless information and power transfer (SWIPT) is considered in a multi-user multiple-input-single-output broadcast scenario. Specifically, we focus on jointly configuring the transmit beamforming vectors and receive PS ratios to minimize the total transmit energy of the base station under the user-specific latency and energy harvesting (EH) requirements. The battery depletion phenomenon is avoided by preemptively incorporating information regarding the receivers' battery state and EH fluctuations into the resource allocation design. The resulting time-average sum-power minimization problem is temporally correlated, non-convex (including mutually coupled latency-battery queue dynamics), and in general intractable. We use the Lyapunov optimization framework and derive a dynamic control algorithm to transform the original problem into a sequence of deterministic and independent subproblems, which are then solved via two alternative approaches: i) semidefinite relaxation combined with fractional programming, and ii) successive convex approximation. Furthermore, we design a low-complexity closed-form iterative algorithm exploiting the Karush-Kuhn-Tucker optimality conditions for a specific scenario with delay bounded batteryless receivers. Numerical results provide insights on the robustness of the proposed design to realize an energy-efficient SWIPT system while ensuring latency and EH requirements in a time dynamic mobile access network.