Enhancing reliability of emergency traffic in IEEE 802.15.6 wireless body area networks

Emergency nodes, i.e, nodes with priority 7 as per 802.15.6 standard play a very important role in facilitating the immediate transfer of information during life threatening situations. These nodes should relay critical information with utmost reliability and in the shortest possible time. IEEE 802.15.6 provides the necessary functionality to these nodes by adapting the contention window sizes as well as the time duration over which it can transmit in a superframe. Although these methods solve problems when emergency nodes are few in number, simultaneous occurrence of emergency events in multiple nodes can create a situation where frames may not be transmitted within the stipulated response time or may be lost due to repeated collisions. This paper proposes two techniques using polling that can overcome such eventualities for emergency nodes. We evaluate the performance of the proposed schemes via analysis and simulation.