Latency-Aware Joint Transmit Beamforming and Receive Power Splitting for SWIPT Systems

This paper considers a multi-user multiple-input-single-output (MU-MISO) broadcast scenario with power splitting (PS) based simultaneous wireless information and power transfer (SWIPT). Specifically, we propose a novel joint transmit beamforming and receive PS strategy aiming to minimize the total transmit power of the base station (BS) under user-specific latency constraints. We use the Lyapunov optimization framework and derive a dynamic control algorithm to transform the long-term time-average sum-power minimization problem into a sequence of deterministic and independent subproblems. Furthermore, the combinations of coupled and non-convex constraints are handled using semidefinite relaxation (SDR) and fractional programming (FP) techniques. The numerical examples illustrate the trade-offs between average transmit power and harvested power while ensuring the user-specific latency requirements.