Analysis of a Cooperative Beacon-Free MAC Layer for Body Area Networks

This paper discusses medium access control (MAC) issues for body area networks (BANs), relying on an Ultrawide Band Impulse radio (UWB-IR) physical layer. BANs are bound to be coordinated by a powerful device like a smart-phone, which manage the access of the nodes on a beaconed fashion. But in some particular situations, the coordinator may disappear and/or be not yet available. These transient situations shall be addressed and a beacon-free medium access control is desirable. We propose a beacon-free MAC layer, based on a collaborative version of the preamble sampling approach. This is designed to address the European regulatory low duty cycle (LDC) constraint, which UWB devices must comply to. A Markov chain model is given to describe the protocol. By means of simulations, we first show that the model is accurate and secondly that this protocol looks able to manage various BANs configurations.