Dynamic RF Combining for Multi-Antenna Ambient Energy Harvesting
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.