Performance Analysis of Full-Duplex Relaying Employing Fiber-Connected Distributed Antennas

Different from the previous studies on distributed-antenna (DA) systems (DASs) that mostly focused on the enhancement of downlink or uplink performance of cellular systems through cooperation of DAs, this paper proposes and investigates the performance of a novel fiber-connected DA relay system (DARS) that employs radio-over-fiber (RoF) techniques to interconnect a DAS to a central processor, which collectively form a relay node. Under the assumption that self-interference can be perfectly canceled in DARS, full-duplex (FD) operation is possible, by which some antennas receive from the source, whereas other antennas simultaneously transmit to the destination. The numbers of transmit and receive antennas can be controlled to achieve a balance between the transmissions of the source-relay (SR) and relay-destination (RD) links. Consequently, higher spectral efficiency can be achieved compared with half-duplex (HD) relaying systems. For Nakagami fading channels with no direct source-destination (SD) link, we show that DARS can obtain the optimal diversity-multiplexing tradeoff (DMT). Moreover, as the primary purpose of FD relaying is to increase the throughput, we also analyze the throughput performance of DARS. Numerical results show that the FD-DARS with a large number of antennas exhibits a much better throughput performance than HD relaying systems and in regions with high signal-to-noise ratios.