Contention versus polling access in IEEE 802.15.6: Delay and lifetime analysis

Lifetimes and latencies of devices in wireless body area networks (WBANs) that monitor the health conditions of patients largely determine their utility under such a setup. It is seen that the medium access control (MAC) used in the WBAN can play a significant role in the network lifetime and the quality of service (QoS) it can provide. IEEE 802.15.6 standard for WBAN includes different MAC options: contention, scheduled, polling, or a combination of these techniques. In this paper, contention based on CSMA/CA and polling are investigated to assess their effectiveness in meeting the lifetime and QoS requirements of WBAN with multipriority traffic. We provide analytical models for the access delay and lifetime with contention access, and also for latency with polling access. The analytical results are compared with simulation for a typical configuration of medical devices. It is found that priority polling can give a combination of high lifetime and a low latency. Various other results offer important insights into the behaviour of these techniques under WBAN conditions.