Linear Transceiver Design for Multi-Tag Symbiotic Radio Systems With Max-Min Fairness

This letter considers a multi-tag symbiotic radio system, where a multi-antenna source node transmits its own message to a multi-antenna destination, while multiple backscatter tags transmit data to the destination by directly reflecting the incident signals from the source. We investigate the joint transmit/receive beamforming design for the purpose of maximizing the minimum signal-to-interference-plus-noise ratio (SINR) of the tags, subject to the SINR constraint for the source and the harvested power constraints for the tags. We propose an efficient beamforming design algorithm based on bisection search, semi-definite relaxation (SDR) and alternating optimization. A suboptimal beamforming design algorithm is also proposed to reduce the complexity. Numerical results show that the proposed beamforming designs outperform the counterpart scheme significantly.