Mobility management in PCS networks

We take the stance that a Universal Personal Identification (UPI) will become an integral part of future personal communication systems so as to better serve the ever increasing communication needs across heterogeneous networks and through diverse communication devices. Under such context, the relevant problem to be solved is how to locate a user given his UPI.; In general, the network keeps track of a user's location through an up-to-date user profile stored in various databases. Current standards (IS-41 and GSM) can not support UPI due to geographical numbering that ties a user's identification to a particular network and geographical location. Hierarchical mobility management techniques (MMTs) have been proposed to support UPI. A hierarchical structure not only scales better, but also exploits locality in user calling and mobility patterns. In addition to using a hierarchical structure, the performance of MMTs can be further enhanced by profile replication, which makes profile information more readily available, thus reducing lookup cost and latency. But to keep these replicas consistent and fresh, they must be updated whenever the user profile is updated.; Previously proposed profile replication algorithms are threshold-based. These algorithms treat requests as isolated events, and do not consider the network structure and communication link costs. Our optimal off-line replication algorithms minimize the network messaging cost based on the network structure, communication link costs, and user calling and mobility statistics. We develop optimal off-line replication algorithms for both unicast and multicast replica updates. Our on-line replication algorithms dynamically adjust replica placement according to user calling and mobility patterns. We not only generalize previously proposed on-line algorithms with a unified framework, but also effectively reduce the overhead incurred by these algorithms, hence making a family of on-line algorithms feasible in practice. We also propose two MMTs to support integrated personal communication services from heterogeneous networks using UPI. The performance of our proposed MMTs is studied via large scale computer simulations. Both our off-line and on-line replication algorithms are optimal and perform better than previously proposed threshold-based algorithms.