Scaling Laws For Wireless Energy Transmission In Mmwave Massive Mimo Systems

In this paper, the performance of wireless energy transfer (WET) in millimeter wave (mmWave) massive multiple-input multiple-output (MIMO) systems is analyzed. By accounting for rainfall effects, path loss and small-scale fading, a comprehensive MIMO channel model is first developed, which is suitable for modeling the energy propagation in WET mmWave massive MIMO systems operating in rainy or clear conditions. Based on this model, a framework for the channel estimation at the hybrid data-and-energy access point (HAP) is presented. Starting from the law of energy conservation, the downlink energy transferred by the HAP and harvested by the user equipments (UEs) is assessed, for several important scenarios. In particular, the results show that the asymptotic harvested energy increases linearly with the number of HAP antennas and the number of UEs, but decreases exponentially with the raining parameters which monotonically increase with the operating frequency.