GeoServ: A Distributed Urban Sensing Platform

Urban sensing where mobile users continuously gather, process, and share location-sensitive sensor data (e.g., street images, road condition, traffic flow) is emerging as a new network paradigm of sensor information sharing in urban environments. The key enablers are the smart phones (e.g., iPhones and Android phones) equipped with onboard sensors (e.g., cameras, accelerometer, compass, GPS), and various wireless devices (e.g., WiFi and 2/3G). The goal of this paper is to design a scalable sensor networking platform where millions of users on the move can participate in urban sensing and share location-aware information using always-on cellular data connections. We propose a two-tier sensor networking platform called GeoServ where mobile users publish/access sensor data via an Internet-based distributed P2P overlay network. The main contribution of this paper is two-fold: a location-aware sensor data retrieval scheme that supports geographic range queries, and a location-aware publish-subscribe scheme that enables efficient multicast routing over a group of subscribed users. We prove that GeoServ protocols preserve locality and validate their performance via extensive simulations.