Jan Jannink

Efficient and flexible location management techniques for wireless communication systems

We consider the problem of managing the information required to locate users in a wireless communication system, with a focus on designing and evaluating location management techniques that are efficient, scalable, and flexible. The three key contributions of this paper are: (1) a family of location management techniques, HiPER (for Hierarchical ProfilE Replication), that efficiently provide life‐long (non‐geographic) numbering with fast location lookup; (2) Pleiades, a scalable event‐driven wireless system simulator with realistic calling and mobility patterns derived from several months of real traffic traces; and (3) multi‐day simulations comparing our proposed location management techniques with current and previously proposed techniques on a realistic geographical and network topology.

Per-user profile replication in mobile environments: algorithms, analysis, and simulation results

We consider per-user profile replication as a mechanism for faster location lookup of mobile users in a personal communications service system. We present a minimum-cost maximum-flow based algorithm to compute the set of sites at which a user profile should be replicated given known calling and user mobility patterns. We show the costs and benefits of our replication algorithm against previous location lookup approaches through analysis. We also simulate our algorithm against other location lookup algorithms on a realistic model of a geographical area to evaluate critical system performance measures. A notable aspect of our simulations is that we use well-validated models of user calling and mobility patterns.

Implementing deletion in B+-trees

This paper describes algorithms for key deletion in B+-trees. There are published algorithms and pseudocode for searching and inserting keys, but deletion, due to its greater complexity and perceived lesser importance, is glossed over completely or left as an exercise to the reader. To remedy this situation, we provide a well documented flowchart, algorithm, and pseudo-code for deletion, their relation to search and insertion algorithms, and a reference to a freely available, complete B+-tree library written in the C programming language.

Modeling location management in personal communications services

Location management refers to accessing and maintaining user information for call routing purposes. This paper presents a realistic modeling framework for evaluating the performance of location management schemes in PCS networks. The framework captures complex human behaviors and has been validated through analysis of actual call and mobility data. Simulation results, showing the performance of IS-41, are presented.

An Information Food Chain for Advanced Applications on the WWW

The growth of the WWW has resulted in amounts of information beyond what is suitable for human consumption. Automated information processing agents are needed. However, with the current technology it is difficult and expensive to build automated agents. To facilitate automated agents on the web we present an information food chain for advanced applications on the WWW. Every part of the food chain provides information that enables the existence of the next part.