Medium Access Control for Body Sensor Networks

H-MAC, a novel time division multiple access (TDMA) MAC protocol, aims to improve body sensor networks (BSNs) energy efficiency by exploiting heartbeat rhythm information to perform time synchronization. Heartbeat rhythm is inherent in every human body and observable in various biosignals. Biosensors in a BSN can extract the heartbeat rhythm from their own sensory data by detecting waveform peaks. Following the rhythm, biosensors can achieve time synchronization without having to turn on their radio to receive periodic timing information from a central controller, so that energy cost for time synchronization can be completely eliminated and the lifetime of network can be prolonged. An active synchronization recovery scheme is also developed, in which two resynchronization approaches can be triggered by detected abrupt peak interval changes. The algorithms are verified using real world data from MIT-BIH multi-parameter database MIMIC.