Downlink Energy Transfer and Pilot Contamination Analysis in Multi-Cell Massive MIMO Systems

This paper is about analysis of wireless energy transfer (WET) in multi-cell massive multi-input-multi-output (MIMO) systems. It considers imperfect channel state information (CSI) with energy beamforming at base station (BS) in downlink. It presents an analytical expression for downlink harvested energy and uplink throughput rate in multi-cell massive MIMO. The effect of pilot contamination on harvested energy in multi-cell massive MIMO system has also been studied in this paper. Energy and information data transmission is frame based time division duplex (TDD) mode. Firstly, base station estimates the channel using training pilots and then transfers energy by energy beamforming. User terminals transmit uplink data utilizing energy, harvested in downlink transmission. It considers user has infinite capacity to store energy and has no other source of energy. So, a harvest-then-transmit protocol is considered. All cells are using same orthogonal training sequences which cause pilot contamination. It also discusses the effect of pilot contamination on harvested energy and throughput uplink rate.