Backscatter Based Bidirectional Full-Duplex Magnetic Induction Communications

Magnetic induction (MI) communications have gained substantial attention due to the advantages in special environments such as underground, underwater, and human body. MI wireless networks in such environments can enable important applications in future civil and public security fields. However, due to the particularity of application environments, it is challenging to guarantee the energy supply for MI devices. In this paper, we propose a backscatter based bidirectional full-duplex MI communication (BFMC), which can enhance the energy efficiency of MI communications. In BFMC, additional information is backscattered with the inherent backscatter property of MI channel and the backscatter device (BD) is free of self-interference (SI). For the BFMC based multi-user network, we formulate the joint magnetic beamforming and time allocation optimization problem, which aims to minimize the average energy consumption and guarantee the downlink signal to noise ratio (SNR), uplink signal to interference plus noise ratio (SINR), and energy harvesting requirements. The formulated problem is non-convex and transformed into magnetic beamforming and time allocation sub-problems. Based on block coordinate descent (BCD) method, the sub-problems are solved iteratively. Numerical results show that BFMC and the proposed joint beamforming and time allocation scheme can effectively reduce average energy consumption and enhance energy efficiency.