NSF Sponsored Research Project:  Fault-Tolerant and Secure Infrastructure for Time Critical Embedded Systems


This file is available at the URL link




Research Group Webpage



Dr. Weili Wu  

Dr. Ping Deng

Dr. Yaochun Huang

Dr. Zhongnan Zhang

Dr. Zhao Zhang

Ms Jiaofei Zhong



Project Activities and Findings


In a distributed database system, multiple copies of data are stored at more than one locations of a network to achieve the high data availability in presence of link failure. This is referred as data replication problems, which has been extensively studied to improve system performance and enhance data reliability in distributed database.   Optimal placements of data replicas have been studied extensively in the literature for various protocols (e.g., read-only, write-dominant, majority voting, etc) with different kinds of network configurations. Our research focuses on studying the optimal placements in ring network for data replicas in distributed database with majority voting protocol.


We have been working on efficient optimal placements focusing on 1) even number of data replicas in ring network with majority voting protocol, 2) selecting the optimal number of data replicas, which is not too large compared to the number of data locations, 3) A complete showcase and theoretical prove of optimal placements of replicas in ring network with majority voting protocol. In addition, we have been continually working on efficient algorithms focusing on 1) identification of outlying sensors (i.e., outlying-reading sensors), 2) detection of the reach of events in sensor networks, 3) carrying out experimental evaluation to verify our algorithms.


Our research has generated several novel algorithms, some of which improve on the performance and accuracy of previous algorithms, theoretically prove and showcase the optimal placement of data replica to enhance the security in distributed database,   and provide an opportunity for the training of several graduate students. Most of our results have been published in various prestigious journals and conferences such as IEEE Transactions on Knowledge and Data Engineering (TKDE), ICDCS (The International Conference on Distributed Computing Systems) etc.




Training and Development

1). Techniques for theoretical prove of optimal placements fro data replica problems in distributed database.

2). Techniques for designing efficient algorithm and analyzing their complexities.

3). Design systematic tests using both simulated and real data to evaluate the performance of algorithms.

4). Knowledge of distributed database and sensor network.


Outreach Activities

We presented our new finding and results in some conferences and invited talks.


Zhao Zhang, Weili Wu, and Shashi Shekhar, Placements of Replicas in Ring Network with Majority Voting Protocol (pdf), Proceedings of the 28th International Conference on Distributed Computing Systems (ICDCS 2008), pp 387-394, June 17-20, 2008, Beijing China.


Ning Zhang, Incheol Shin, Feng Zou, Weili Wu, My T. Thai, Trade-off scheme for fault tolerant connected dominating sets on size and diameter (pdf), Proceedings of the 1st ACM International Workshop on Foundations of Wireless Ad Hoc and Sensor Networking and Computing, FOWANC 2008, pp 1-8, Hong Kong, China, May 26, 2008.


Guanfeng Li, Hui Ling, Taieb Znati, and Weili Wu, A Robust On-demand Path Key Establishment framework via Random Key Pre-distribution for Wireless Sensor Networks (pdf), EURASIP Journal on Wireless Communications and Networking, Vol 2006(2006): 1-10.


Weili Wu, Xiuzhen Cheng, Min Ding, Kai Xing, Fang Liu and Ping Deng, Localized Outlying and Boundary Data Detection in Sensor Networks, IEEE Transactions on Knowledge and Data Engineering (TKDE) (pdf), 19(8): 1145-1157 (2007).