Distributed beacon scheduling for IEEE 802.15.4 cluster-tree topology

The IEEE 802.15.4 standard provides a synchronization mechanism for devices connected in a star network topology using beacons. The lack of it in peer-to-peer network topology restricts its use to non-beacon mode. Addressing this issue, few protocols have been proposed based on either centralized or distributed approach. Irrespective of the approach, the three major criterion to evaluate different schemes are utilization of time slots, transmission count, and scalability. Centralized schemes are shown to incur high overhead and are not scalable. In this paper, we propose two distributed beacon scheduling mechanism that better utilize the available time slots, incur fewer transmissions and are highly scalable. In addition, the proposed works also lower the number of beacon frame collisions that otherwise leads to orphan nodes. The analytical study of both the mechanisms is presented along with proof of concept through simulation. A Markov chain model is defined to understand the different states of channel during transmission of frames.