Full-duplex transmissions in fiber-connected distributed relay antenna systems

Distributed antenna systems (DAS) have been studied extensively to improve spectral efficiency and extend coverage. Different from the previous studies that focused mostly on the enhancement of downlink or uplink performance through cooperation of distributed antennas, this paper proposes and investigates a novel communication configuration in which a fiber-connected DAS is employed as a distributed relay antenna system (DRAS). We investigate that such a DRAS has a self-interference cancellation property that leads to the support of simultaneous transmissions and receptions. The DRAS also allows the number of transmit and receive antennas to be controlled to achieve a balance between the signal-to-noise ratios of the source-to-relay and relay-to-destination links. Consequently, a higher spectral efficiency can be achieved compared to conventional half-duplex relay systems. For Rayleigh fading channels, the throughput and the diversity order of the DRAS are analyzed and numerical results show that the full-duplex DRAS exhibits better throughput performance than half-duplex relay systems with large number of relay antennas and in high SNR regions.