Mobile Network Supported Wireless Sensor Network Services

Abstract

Wireless sensor networking research has been mainly focused on internal wireless sensor network issues such as MAC and routing protocols, energy saving, HW design and to some extent on the architecture of gateways that connect a wireless sensor network with the rest of the world. Wireless sensor networks have been seen as dedicated to one task by one owner. On the other hand, our research is focused on integration of wireless sensor networks into existing networks, primarily mobile ones, and provision of sensor based and/or enhanced services to remote users. Therefore, we have been working on designing an architecture that utilizes the existing infrastructure to interconnect independent wireless sensor networks and to provide data aggregation and actuator control services. In the proposed architecture, sensor networks (small or large, deployed for any purpose and by anyone) represented by their gateways are treated as leaf nodes hanging off a mobile or fixed network that use these networks to interact with remote and local users. Each gateway exposes the capabilities of its sensors, actuators and the sensor network as a whole. This information is used by sensor services middleware to query/command sensor ecosystems on behalf of applications and remote users interested in sensor measurements or actuator control. The details of the interaction between the gateways and its sensors/actuators are of no interest to the remote users. Further, we consider the whole wireless sensor networking landscape as an open market where the underlying mobile and fixed networks facilitate the interaction between the sensor networks and the consumers of the information they produce. Each sensor network is first of all a sensor information provider that offers specific sensor information defined by the type of available sensors and their spatial and temporal conditions to the interested users. Secondly, each sensor network provides actuation services that may potentially affect the information gathered by its sensors. Obviously, in such an environment, where many mobile users are acting as tiny information providers, service discovery, service composition, service provisioning and service authorization are very challenging problems. These problems are addressed in the proposed architecture by introducing a middle layer that aggregates information from all small information providers and provides higher level services to the end users. This layer provides the means to quickly add or remove sensors, actuators, sensor networks, sensor network providers, to modify and enhance the existing or add completely new services utilizing the underlying infrastructure. It could be thought of as a plug-and-play functionality for: (a) interconnecting different existing sensor networks; (b) adding new sensor networks which facilitate the expansion of the entire system; and (c) expanding the capability of individual sensor networks.