RCTC: Rapid concurrent transmission coordination in full DuplexWireless networks

With recent advances in wireless systems, wireless in-band full duplex is proven possible. Prior work primarily allows a full duplex receiver to either send back a packet (bi-directional mode) or to forward another packet to its neighbor (secondary transmission). In our work, we look beyond a node pair and explore how a network can best utilize the full duplex capability. When a full duplex receiver does not have any packets to send back, concurrent transmissions (exposed transmissions) can be initiated. In a distributed channel access protocol, rapid signaling is crucial to identify the best mode for a given pair of transmitter and receiver, and to inform potential exposed terminals of transmission opportunities. In this paper, we present, RCTC, a fast and low overhead signaling mechanism based on Pseudo-random Noise (PN) sequences to enable multi-modal operation of wireless links in a distributed channel access setting to support concurrent transmissions in the neighborhood. Our prototype with USRPs shows up to 78% throughput gain. Extensive simulations over larger networks show a throughput gain of up to 131% for RCTC over the native full duplex scheme and up to 111% over a scheme that enables secondary transmission.