A Fault-Tolerant Scheme for Mobility Management in PCS Networks

One of the most important and challenging issues in the design of personal communication service (PCS) systems is the management of location information. In this paper, we propose a new fault-tolerant location management scheme, which is based on the cellular quorum system. Due to quorum's salient set property, our scheme can tolerate the failures of one or more location server(s) without adding or changing the hardware of the systems in the two-tier networks. Meanwhile, with a region-based approach, our scheme stores/retrieves the MH location information in the location servers of a quorum set of the local region as much as possible to avoid long delays caused by the possible long-distance of VLR and HLR. Thus, it yields better connection establishment and update delay. Ming-Jeng Yang received the M.S. degree in computer science from the Syracuse University, New York, in 1991, and the Ph.D. degree in computer science from National Taiwan Normal University, Taiwan, in 2004. He is an associate professor in the Department of Information Technology, Takming College, Taiwan. His research interests include wireless networks, mobile computing, fault-tolerant computing, and distributed computing. He is a member of the IEEE Computer Society and the ACM. Yao-Ming Yeh received the B.S. degree in computer engineering from National Chiao-Tung University, Taiwan, in 1981, and the M.S. degree in computer science and information engineering from National Taiwan University, Taiwan, in 1983. In August 1991, he received the Ph.D. degree in the Department of Electrical and Computer Engineering, The Pennsylvania State University, Pa., U.S.A. He is a professor in the Department of Information and Computer Education, National Taiwan Normal University, Taiwan. His research interests include fault-tolerant computing, web and XML computing, and distributed computing.