A plant-and-play wireless sensor network system for gate monitoring

We present a practical plant-and-play wireless sensor network system for entry-exit monitoring. Our system is easily configurable and robust, making it feasible to be deployed in a wide range of entry-exit monitoring applications. At the core of our system lies a novel MAC protocol that is self-synchronizing. Notably, our MAC protocol allows the nodes to maintain a very low duty cycle (the radios are in sleep mode 100% of the time in the absence of detections), while also enabling quick synchronization of the nodes (when needed) for a consistent classification of entry or exit events. We have deployed this system for monitoring a faculty parking lot at our university and integrated it with an SMS notification system to provide information on the availability of parking spots on demand. We present the parking lot occupancy trends obtained through this deployment and discuss some of the reliability issues encountered.