ReFleX: Enabling Full Duplex Relay Cluster

Empowered by recent advances in in-band full duplex technique, it has been shown that full duplex capable relays are possible. Full duplex relays have been employed in many recent works to enlarge the communication range of WiFi system. However, most of these designs can only utilize one relay due to the potential inter-relay interference when multiple relays coexist. While there are recently proposed systems that can cope with the interference, these designs can hardly work with existing systems due to the large extra delay spread introduced. In this paper, we present ReFleX, a system that can employ multiple full duplex relays at the same time, while introducing only the same amount of extra delay as a one-relay system. To design such a system, we propose a novel inter-relay interference cancellation strategy, a practical channel estimation procedure, and an effective power amplification setting. To evaluate the real-world performance of ReFleX, we build a prototype and conduct experiments using software defined radios. We show that ReFleX can enlarge wireless coverage, provide link diversity, and achieve efficient multicasting compared with half duplex relays or single full duplex relay systems.