A TDMA-based MAC between gateway and devices in M2M networks

Machine-to-Machine (M2M) networks require more elaborate design of medium access control (MAC) due to their higher complexity in system management. In many applications of M2M networking, the major traffic pattern consists of data collected from several source nodes to a sink through a unidirectional tree. Earlier prevalence of Carrier-Sense Multiple Access (CSMA) has continuously been being switched to Time-Division Multiple Access (TDMA). The main drawback of CSMA is idle listening, which refers to the fact that the nodes have to unnecessarily wake up due to lack of schedule. Energy inefficiency of a network gets higher as the number of nodes committed to idle listening, which seriously limits the scalability of a network. Recent enhancement of hardware has been enabling sufficiently accurate synchronization while keeping energy consumption low enough, which mitigates the main drawback of TDMA. This paper proposes a TDMA-based MAC protocol that achieves higher energy efficiency in centralized M2M communications. As a TDMA-based protocol, the proposed protocol is fully scheduled and hence no idle listening occurs. Moreover, the protocol reduces the length of a multi-hop transaction which results in higher energy efficiency as well as lower latency. Simulation results show that the proposed MAC protocol outperforms the conventional CSMA and other popular MAC schemes, in terms of energy consumption, delay, and packet delivery ratio (PDR).