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A Novel Scalable Hybrid-MAC Protocol for Densely Deployed M2M Networks

In this paper, we propose a scalable hybrid-medium access control (MAC) protocol for inter-M2M communications, which combines the benefits of both contention-based and reservation-based medium access schemes. This protocol facilitates concurrent transmissions through spatial reuse. We assume that the contention and reservation portion of M2M devices is a frame structure, which is comprised of two sections: contention interval (CI) and transmission interval (TI). The CI duration follows p-persistent carrier sense multiple access (CSMA) mechanism, which allows M2M devices to contend for the transmission slots. After contention, only those devices, which have won time-slots, are allowed to transmit data packets during TI. In our proposed MAC scheme, the TI duration is basically a time division multiple access (TDMA) frame. Each M2M transmitter device and its corresponding one-hop distant receiver device communicate using MBAA-MAC protocol within each TDMA slot to facilitate concurrent transmissions, and to overcome the various limitations of TDMA mechanism. The simulation results demonstrate the effectiveness of the proposed hybrid-MAC protocol.