A Ubiquitous Publish/Subscribe Platform for Wireless Sensor Networks with Mobile Mules

Existing publish/subscribe architectures for wireless sensors networks only support stationary sensors interconnected with each other. They cannot handle mobile sensors or remote sensors that are sparsely deployed. In this paper, we propose a novel ubiquitous publish/subscribe system that supports data access from both mobile sensors and stationary sensors. Our system utilizes mobile phones as data mules to relay subscriptions and published data between broker and remote sensors. It provides content-based publish/subscribe services from sensors deployed anywhere without depending on any network infrastructure. We implement our publish/subscribe platform on real hardwares and test it in a hiking trail application. The application allows users to subscribe for sensing data from both stationary sensors and mobile sensors along hiking trails. Extensive experiments are conducted in an outdoor testbed to evaluate the system performances such data delay, number of data received and communication overhead.