Throughput and Energy Efficiency of Wireless Powered Multi-tier MIMO HetNets

Wireless powered communications have been recently proposed as a variable power solution for the heterogeneous networks (HetNets) with small and flexible deployments of low-power base stations (BSs). In this paper, we consider the wireless powered multi-tier multi-input multi-output (MIMO) HetNets, where the multi-antenna BSs perform downlink transmission. In particular, we consider two cases of interests, i.e., 1) energy harvesting (EH) without energy beamforming (EB) tier and 2) EH with EB tier. Using tools of stochastic geometry, we perform analysis on the throughput and energy efficiency (EE) of the considered network. Closed-form and tractable results are obtained to reveal interesting insights that the proposed wireless-powered MIMO HetNets can achieve higher EE as compared to the conventional HetNets without EH, and the EE performance can be further improved by introducing well-designed EB across tiers.