A low overhead tree-based energy-efficient routing scheme for multi-hop wireless body area networks

Reliability and energy efficiency are key performance metrics for meeting the requirements of long-term and continuous health monitoring in Wireless Body Area Networks (WBANs). In this paper, we explore energy-efficient routing mechanisms for WBANs. We first present experimental results showing that wireless link quality changes rapidly in WBANs due to body shadowing, and a fixed transmission power results in either wasted energy or low reliability. Moreover, in multi-hop WBANs, as various vital signs are collected from sensors on different body parts, the traffic load among sensor nodes could be severely unbalanced, leading to uneven energy consumption. In this paper, we propose a scheme, we term the tree-based energy-efficient routing scheme (EERS), with low overhead to jointly address adaptive power control and routing in multi-hop WBANs. The proposed scheme can establish an energy-efficient end-to-end path as well as adaptively choose transmission power for sensor nodes. We conduct extensive experiments on a MicaZ WBAN testbed to compare the performance of EERS with the Collection Tree Protocol (CTP) in terms of packet reception ratio (PRR), collection delay, energy consumption, and energy balancing. Experimental results show that EERS outperforms CTP in terms of reliability, delay and energy consumption. In particular, EERS exhibits a mean delay 30% lower than the mean delay of CTP and an energy consumption 10% lower than CTP, while achieving at least 0.95 PRR.