Design of an ultra low power MAC for a heterogeneous in-body sensor network

This paper presents an ultra low power MAC designed for in-body implant network. We show how an in-body implant network, has its own unique set of requirements (priority, latency, throughput etc.) which are not addressed by generic BAN(body area network) protocols which are designed assuming identical sensors. By choosing a particular use case, we demonstrate how we can exploit disparities inherent in a typical implanted BAN to enable ultra low power operation which also meets other (often) competing requirements. We present a new MAC scheme, which allows ultra low power operation by handling the nodes in accordance to their power and latency requirements. We present a new scheme for deriving analytically the power-optimised TDMA frame parameters like beacon interval and discuss solutions to manage synchronisation overhead. Equations for deriving the duty-cycling efficiency are presented and the packet error rate is calculated for the in-body wireless channel. Our results and simulations show that the protocol outperforms best of reported MACs and for low data rate sensors (typical of BAN) our MAC allows close to standby limit power consumption.