MISO interference channel with QoS and RF energy harvesting constraints

This paper deals with a multiple-input single-output (MISO) network where the receivers are characterized by both quality-of-service (QoS) and radio-frequency (RF) energy harvesting (EH) constraints. We consider the power splitting RF-EH technique where each receiver divides the received signal into two parts a) the first part for information decoding and b) the second part for battery charging. The minimum required energy that supports both the QoS and the RF-EH constraints at each receiver is formulated by an optimization problem and is discussed for two standard beamforming designs, the zero-forcing (ZF) and the maximum ratio transmission (MRT). The optimal solution for ZF beamforming is derived in closed-form, while optimization algorithms based on second-order cone programming (SOCP) and Linear Programming (LP) are developed for MRT beamforming to solve the problem. Numerical results indicate that MRT significantly outperforms ZF in terms of transmitted power, as the associated cross-interference becomes beneficial from an EH standpoint, while ZF always ensures the existence of a solution for the optimization problem considered.