Dynamic RF Combining for Multi-Antenna Ambient Energy Harvesting

TL;DR

This paper introduces a dynamic RF combining architecture for ambient RF energy harvesting, demonstrating that sequential testing offers a good balance of performance and power efficiency, especially as antenna count and transmitter density increase.

Contribution

The paper proposes a novel dynamic RF combining architecture with three phase shift mechanisms, highlighting the advantages of sequential testing over brute force and codebook methods.

Findings

Sequential testing outperforms other mechanisms in power efficiency.

Performance gains increase with more antennas and transmitters.

Dynamic combining improves ambient RF energy harvesting reliability.

Abstract

Ambient radio frequency (RF) energy harvesting (EH) technology is key to realize self-sustainable, always-on, low-power, massive Internet of Things networks. Typically, rigid (non-adaptable to channel fluctuations) multi-antenna receive architectures are proposed to support reliable EH operation. Herein, we introduce a dynamic RF combining architecture for ambient RF EH use cases, and exemplify the attainable performance gains via three simple phase shifts' exploration mechanisms, namely, brute force (BF), sequential testing (ST) and codebook based (CB). Among the proposed mechanisms, BF demands the highest power consumption, while CB requires the highest-resolution phase shifters, thus tipping the scales in favor of ST. Finally, we show that the performance gains of ST over a rigid RF combining scheme increase with the number of receive antennas and energy transmitters' deployment density.