Floor acquisition multiple access (FAMA) for packet-radio networks

TLDR

The paper specifies and analyzes a family of medium access control protocols for single‑channel packet radio networks. The authors introduce FAMA, a floor acquisition multiple access protocol that uses carrier sensing and a collision‑avoidance dialogue to grant exclusive channel access to one station, with control packet length tied to propagation delay, and analyze its throughput versus non‑persistent CSMA. They find that MACA and certain CSMA variants are special cases of FAMA when control packets are long enough, and that incorporating carrier sensing into floor acquisition yields MACA‑like benefits with hidden terminals and throughput that is comparable to or exceeds non‑persistent CSMA when hidden terminals are absent.

Abstract

A family of medium access control protocols for single-channel packet radio networks is specified and analyzed. These protocols are based on a new channel access discipline called floor acquisition multiple access (FAMA), which consists of both carrier sensing and a collision-avoidance dialogue between a source and the intended receiver of a packet. Control of the channel (the floor) is assigned to at most one station in the network at any given time, and this station is guaranteed to be able to transmit one or more data packets to different destinations with no collision with transmissions from other stations. The minimum length needed in control packets to acquire the floor is specified as a function of the channel propagation time. The medium access collision avoidance (MACA) protocol proposed by Karn and variants of CSMA based on collision avoidance are shown to be variants of FAMA protocols when control packets last long enough compared to the channel propagation delay. The throughput of FAMA protocols is analyzed and compared with the throughput of non-persistent CSMA. This analysis shows that using carrier sensing as an integral part of the floor acquisition strategy provides the benefits of MACA in the presence of hidden terminals, and can provide a throughput comparable to, or better than, that of non-persistent CSMA when no hidden terminals exist.