MEB MAC: Improved channel access scheme for medical emergency traffic in WBAN

Emergency data delivery is an important service for medical Wireless Body Area Networks. The successful dissemination of emergency messages can make a huge difference between life and death. The utmost importance of emergency message dissemination requires high reliability while the intermittent nature of alarms requires minimum channel access delay for almost instantaneous delivery. IEEE 802.15.6 beacon enabled networks have defined an adjustable superframe structure that consists of contention-free and contention access periods. Short superframes can satisfy the channel access delay requirements of emergency traffic but penalizes the energy efficiency of all devices in the network. On the other hand, long superframes increase the energy efficiency but the channel access delay is also increased. To balance this contradicting requirement of energy efficiency and Quality of Service, we propose the Medical Emergency Body (MEB) MAC protocol that inserts listening windows dynamically within the contention free periods. The frequency of listening window insertion is determined by the minimum delay tolerance. Furthermore, MEB MAC utilizes idle time slots to insert additional listening window opportunities for emergency traffic, without affecting the network throughput. Our analysis shows that MEB MAC is able to reduce channel access delay for emergency traffic especially for long superframe durations. Simulation results show the effectiveness of the MEB MAC scheme in serving emergency messages in medical body area networks.