Power-efficient distributed beamforming for multiple full-duplex relays aided multiuser networks

Full-duplex relaying (FDR) is an efficient technique to serve remote users with low power consumption, however, careful interference suppression is needed to mitigate self interference (SI) and multi-user interference (MUI). When multiple FDRs are employed, inter-relay interference (IRI) emerges and degrades system performance severely by consuming excessive transmit power. In this paper, distributed interference suppression in multiple full-duplex relays aided multiuser networks is investigated. A general model addressing all the three types of interference is established first. To minimize the total transmit power of the system, a distributed beamforming algorithm is proposed to jointly mitigate the three types of interference under individual user rate constraints. The algorithm requires only local information exchange at the relays, hence evidently reducing the signaling overhead in large-scale networks. Furthermore, theoretical proof for the algorithm's convergence is provided, and an upper bound for the iterative stepsize guaranteeing convergence is also derived. Numerical simulations validate effectiveness and stability of our proposal.