Energy-Efficient Hybrid Duplexing Strategy for Bidirectional Distributed Antenna Systems

Abstract

We propose a bidirectional distributed antenna (DA) system where DAs are capable of working dynamically in hybrid duplex modes: full duplex (FD), half duplex, and sleep, which enables higher degree of freedom and hence much higher energy efficiency (EE) than DA sole-FD systems, with just marginal loss in spectral efficiency (SE). The proposed system also demonstrates significant EE and SE enhancement over FD colocated antenna systems. Compared to the above two benchmark systems, the proposed system also requires much simpler self-interference cancelation design for FD mode due to less cross talks between antennas. A low-complexity EE maximization scheme is proposed for the bidirectional DA system. A channel gain based DA clustering algorithm is first performed to activate/deactivate transmit/receive chains, which highlights the characteristics of DA deployment, and then a distributed hybrid duplexing algorithm is performed to optimize the downlink beamformer and the uplink transmission power. Various practical aspects are taken into account for system design, such as self-interference at DAs in FD mode, cochannel interference from uplink users to downlink users, and multiuser interference in both uplink and downlink. The effectiveness of the proposed system is verified by simulation results.