Reliable and Efficient Access for Alarm-Initiated and Regular M2M Traffic in IEEE 802.11ah Systems

IEEE 802.11ah is a novel WiFi-based protocol, aiming to provide an access solution for the machine-to-machine (M2M) communications. In this paper, we propose an adaptive access mechanism that can be seamlessly incorporated into IEEE 802.11ah protocol operation and that supports all potential M2M reporting regimes, which are periodic, on-demand, and alarm reporting. The proposed access method is based on a periodically reoccurring pool of time slots, whose size is proactively determined on the basis of the reporting activity in the cell. We show that it is possible to both efficiently and reliably resolve all reporting stations in the cell, within the limits of the allowed deadlines. As a side result, we also provide a rationale for modeling the interarrival time in alarm events by using the Beta distribution, a model that is considered in the 3GPP standardization.