RESEARCH

Integrative Research

Middleware

Implication of science for proactive health systems

Enabling the home to provide medical assistance requires that the home be equipped with distributed, cooperative computation devices, physiological and environmental sensors, and both wired and wireless communication capabilities. Furthermore, applications that provide medical assistance require high reliability and must work with very energy-constrained, battery-operated devices that can be worn by the home’s occupants or placed discretely throughout the home. These specialized sensor networks are vital to obtain data about the home’s occupants as well as the external environment of the home.

Most sensor network research to date has focused on designing new network-level protocols (e.g., MAC layer, routing layer, topology control, etc.), without considering existing standards or how applications use the protocols. We believe that sensor network applications, especially those found in the home, may be built on top of existing protocols (e.g., IEEE 802.11, Bluetooth), and thus some coordination framework is needed to leverage the flexibility that exists in both standardized and non-standardized network protocols. However, to make these protocols more useful, application designers would benefit from a middleware that encapsulates the protocols, providing a high-level interface. We believe that savings can be achieved if the middleware varies the actual parameters of the network over time while simultaneously meeting the requirements of the application, thereby increasing the lifetime of the network.

We are developing a new middleware named MiLAN (Middleware Linking Applications and Networks) that receives a description of application requirements, monitors network conditions, and optimizes sensor and network configurations to maximize application lifetime. To accomplish these goals, applications represent their requirements to MiLAN through specialized graphs that incorporate state-based changes in application needs. Based on this information, MiLAN makes decisions about how to control the network as well as the sensors themselves to balance application QoS and energy efficiency, lengthening the lifetime of the application. A key feature of MiLAN is the separation of the policy for managing the network, which is defined by the application, from the mechanisms for implementing the policy, which is effected within MiLAN.

Unlike traditional middleware that sits between the application and the operating system, MiLAN has an architecture that extends into the network protocol stack. As MiLAN is intended to sit on top of multiple physical networks, an abstraction layer is provided that allows network specific plug-ins to convert MiLAN commands to protocol-specific commands that are passed through the usual network protocol stack. Therefore, MiLAN can continuously adapt to the specific features of whichever network is being used for communication (e.g., determining scatternet formations in Bluetooth networks, routers in IEEE 802.11 networks, etc.) in order to best meet the applications' needs over time.

Results

• W. Heinzelman, A. Murphy, H. Carvalho and M. Perillo,"Middleware to Support Sensor Network Applications," IEEE Network Magazine Special Issue. Jan. 2004.
• “Data- and Event-Centric Communication” by W. Heinzelman, A. Murphy and M. Perillo. To appear in Wireless Sensor Networks: A Systems Perspective, Artech House, 2005.
• "Sensor Management," by M. Perillo and W. Heinzelman. In Wireless Sensor Networks, Kluwer Academic Publishers, 2004.
• M. Perillo and W. Heinzelman, "DAPR: A Protocol for Wireless Sensor Networks Utilizing an Application-based Routing Cost," Proceedings of the IEEE Wireless Communications and Networking Conference (WCNC '04), March 2004.
• M. Perillo and W. Heinzelman, "Sensor Management Policies to Provide Application QoS," Elsevier AdHoc Networks Journal. Vol. 1, No. 2-3, 2003, pp. 235-246.
• H. Carvalho, W. Heinzelman, A. Murphy and C. Coelho, "A General Data Fusion Architecture," Proceedings of the 6th International Conference on Information Fusion (Fusion 2003) July 2003.
• H. Carvalho, A. Murphy, W. Heinzelman, and C. Coelho, "Network-Based Distributed Systems Middleware," Proceedings of the 1st International Workshop on Middleware for Pervasive and Ad-Hoc Computing. June 2003.
• M. Perillo and W. Heinzelman, "Providing Application QoS Through Intelligent Sensor Management," Proceedings of the 1st IEEE International Workshop on Sensor Network Protocols and Applications (SNPA '03). May 2003.
• M. Perillo and W. Heinzelman, "Optimal Sensor Management Under Energy and Reliability Constraints," Proceedings of the IEEE Wireless Communications and Networking Conference (WCNC '03). March 2003.
• A. Murphy and W. Heinzelman, "MiLAN: Middleware Linking Applications and Networks," TR-795, University of Rochester, Computer Science, Nov. 2002.