AM-MAC: an energy efficient, Adaptive Multi-hop MAC protocol for sensor networks

Sensor network MAC protocols use a duty cycling mechanism and a multi-hop transmission to create a good trade-off between their energy efficiency and latency. The nodes in duty cycling multi-hop MAC protocols such as RMAC periodically sleep/listen during the operational cycle to reduce their energy consumption by idle listening; and the listening period is usually long in order to support packets in reaching a multi-hop destination in a single cycle (multi-hop transmission). The traffic network in the wireless sensor network is otherwise very scarce, and keeping the radio on during such long listening periods when there is no data transmission in the network wastes energy. In addition, these protocols incur a large amount of control overhead, which is one of the main energy wasted sources. This paper proposes an adaptive low overhead MAC protocol we call AM-MAC (Adaptive Multi-hop MAC). It can reduce the wastage caused by long listening period and minimizes the control overhead. The nodes in AM-MAC use an adaptive method, and thus they can adjust the duration of the listening period according to the traffic load. To reduce the control overhead, a single packet has more than one role. During a multi-hop transmission, the new control packet replaces the RTS/CTS pair, and one DATA packet can play both DATA/ACK roles. An extended evaluation of AM-MAC has been conducted through simulation, against RMAC. The results illustrate that AM-MAC significantly reduces the energy consumption and notably lessens the end-to-end latency.