Information and Energy Beamforming Optimization for Symbiotic AmBC and SWIPT Networks

This letter develops a symbiotic network comprising an ambient backscatter communication network and a simultaneous wireless information and power transfer (SWIPT) network. Specifically, passive tags leverage the primary signal from the full-duplex (FD) base station (BS) for energy harvesting (EH) and data transmission to the FD BS, while delivering more power to the downlink SWIPT users. To enhance the symbiosis benefits and suppress the harms between the two networks, we design uplink zero-forcing reception filters and downlink optimal energy and information beamforming at the FD BS, and optimal power splitting factor at users to maximize the tag sum signal-to-interference-plus-noise ratio, subject to the minimum rate and power requirements of the users, tags' EH requirement and the residual self-interference constraints. Compared to random, maximum ratio transmission, and zero-forcing beamforming, our approach yields significant improvements.