Wireless Sensor Networks (WSN) research in the Department of Computer Science at the University of New Orleans is a joint effort by two research laboratories, the Networking, Security, and Systems Administration Laboratory (NSSAL), directed by Dr. Golden G. Richard III, and the Wireless Network and Security Laboratory (WNSL), led by Dr. Jing Deng. Current research focus include service discovery, energy efficiency, network lifetime extension, data delivery, routing misbehavior detection and mitigation, and security provision in wireless sensor networks. Students in our research groups are working on interesting issues such as efficient data delivery, mobile data sink, cluster head selection, and multiple channel medium access control schemes in wireless sensor networks.

Service discovery is expected to become a key enabling technology for novel interaction among sensor nodes to build applications that have yet to be envisioned. Unfortunately, existing service discovery protocols are too resource intensive to be used in sensor networks. A sensor node provides services consisting of the sensed information, based on the types of sensors available, along with context, such as location, which makes that information useful. Taking the unified approach, in which a node in the sensor network is viewed as providing a set of location-based services, forms the basis of new location aware service discovery frameworks specifically tailored to sensor networks. Dr. Golden Richard, completed the first comprehensive book on service discovery, and has co-authored a new book on wireless networks. He is working with Loren Schwiebert of Wayne State University on a service discovery protocol specifically tailored for sensor networks, called TinySDP. TinySDP includes optimizations to reduce the cost of service advertisements in sensor networks and includes support for ultra-lightweight remote procedure calls (RPC, via our TinyRPC protocol) among sensor nodes. National Science Foundation funding for further development of TinySDP is pending.

Energy is a critical resource in wireless sensor networks because in most situations these network nodes are battery-operated. Compared with wired communication networks, wireless sensor networks have the following distinct properties: 1) energy availability varies for different kinds of nodes. For example, in sensor networks, the cluster heads and the data sink usually have more battery power while each sensor's power capability is limited; 2) it is beneficial to process the sensing data locally instead of sending it over long distance toward the data sink. The way in which the available energy is used in wireless sensor networks has profound effects on the lifetime and usability of sensor networks. Dr. Deng's research group is proposing novel techniques to conserve the limited on-board energy while maintaining the network functionality at the same time.

An example is the reduction of the overhead for service or destination discovery in wireless sensor networks. In order to reduce the number of rebroadcasts, it may be beneficial to broadcast the inquiry packet with a certain Time-To-Live (TTL) to search those nodes within a limited hop-count from the source node, hoping to locate the destination without using the network-wide broadcast. Such a technique is termed Expanding Ring Search (ERS). We have identified that, when the maximum hop-count of the network is known, a search strategy with three steps, instead of incrementing TTL after every failure, is the optimum.

When sensor networks are deployed in hostile environments, security becomes extremely important. These mostly autonomous sensor networks are prone to a number of types of malicious attacks: 1) An adversary can easily listen to the traffic. 2) An adversary can impersonate one of the network nodes, and intentionally provide incorrect information to other nodes. This attack can cause significant damage, especially in a battlefield situation. 3) An adversary can launch a denial of service attack against the communication channel to prevent nodes from sending their messages. 4) An adversary can launch attacks just to deplete the battery power of the network nodes.

Because of the unique properties of wireless sensor networks, such as energy-constrained, relatively slow CPU speed, and limited memory size, security mechanisms developed for general wired network computing cannot directly apply. Therefore, new security measures need to be developed to guard these networks and the information within. Dr. Deng's research group is investigating the following problems: Key distribution with high security connectivity, shared-secret delivery using multi-hop multi-path techniques, and sensor node misbehavior detection and mitigation in wireless sensor networks.

Dr. Deng's research lab has developed a Just Enough Redundancy Transmission (JERT) shared-secret delivery technique for wireless sensor networks. In the JERT scheme, the secret link key is encoded in (n, k) MDS (Maximum Distance Separable) code and transmitted through multiple multi-hop paths. To reduce the total information that needs to be transmitted, the redundant symbols of the MDS codes are transmitted only if the destination fails to decode the secret. We have shown that the JERT scheme is efficient and resilient against node capture.

Sample publications:

• W. Du, J. Deng, Y. S. Han, and P. K. Varshney, "A Key Pre-distribution Scheme for Sensor Networks Using Deployment Knowledge," IEEE Transactions on Dependable and Secure Computing, vol. 3, no. 1, pp. 62-77, January-March 2006.
• J. Deng, Y. S. Han, W. B. Heinzelman, and P. K. Varshney, "Balanced-energy Sleep Scheduling Scheme for High Density Cluster-based Sensor Networks," Elsevier Computer Communications Journal, Special Issue on ASWN '04, vol. 28, no. 14, pp. 1631-42, September 2005.
• W. Du, J. Deng, Y. S. Han, P. K. Varshney, J. Katz, and A. Khalili, "A Pairwise Key Pre-Distribution Scheme for Wireless Sensor Networks," ACM Transactions on Information and System Security, vol. 8, no. 2, pp. 228-58, May 2005.
• J. Deng, Y. S. Han, W. B. Heinzelman, and P. K. Varshney, "Scheduling Sleeping Nodes in High Density Cluster-based Sensor Networks," ACM/Kluwer Mobile Networks and Applications (MONET) Special Issue on "Energy Constraints and Lifetime Performance in Wireless Sensor Networks," April 2006, in press.
• X.-M. Huang, J. Deng, J. Ma, and Z. Wu, "Fault Tolerant Routing for Wireless Sensor Grid Networks," in Proc. of 2006 IEEE Sensors Applications Symposium (SAS '06), Houston, TX, USA, February 7-9, 2006, pp. 66-70.
• J. Deng and Y. S. Han, "Using MDS Codes for the Key Establishment of Wireless Sensor Networks," in Mobile Ad-hoc and Sensor Networks (MSN '05), Wuhan, P. R. China, December 13-15, 2005, X. Jia, J. Wu, and Y. He, Eds., vol. 3794 of Lecture Notes in Computer Science (LNCS), pp. 732-44, Springer-Verlag.
• X. Wang, J. Deng, and T. Berger, "GB: Distributed Reachability-Tunable Broadcast Algorithms for Wireless Sensor Networks," in Proc. of the 2nd IEEE International Conference on Mobile Ad-Hoc and Sensor Systems (MASS '05), Washington, DC, USA, November 7-10, 2005, pp. 733-42.
• D. Chen, J. Deng, and P. K. Varshney, "On the Forwarding Area of Contention-Based Geographic Forwarding for Ad Hoc and Sensor Networks," in Proc. of the 2nd IEEE International Conference on Sensor and Ad Hoc Communications and Networks (SECON '05), Santa Clara, CA, USA, September 26-29, 2005, pp. 130-41.
• J. Deng, "Locating Randomly Selected Destinations in Large Multi-hop Wireless Networks," in Proc. of 19th International Teletraffic Congress, Beijing, P. R. China, August 29 - September 2, 2005. Lecture Notes in Computer Science (LNCS), Springer-Verlag.
• K. Balakrishnan, J. Deng, and P. K. Varshney, "TWOACK: Preventing Selfishness in Mobile Ad Hoc Networks," in Proc. of IEEE Wireless Communications and Networking Conference (WCNC '05), New Orleans, LA, USA, March 13-17, 2005, vol. 4, pp. 2137-42.