Institute for Systems Research

The current plan in the modernization of the A/G communications is to migrate from analog voice only system to integrated digital voice and data system. The next generation satellite systems can be an alternative to the terrestrial A/G systems by their low propagation and transmission delays, global coverage, high capacity, and free flight suitable characteristics. In this paper, we give an overview of the current and the future ATC architectures, describe the systems and the communications issues in these systems, and develop a framework in which LEO/MEO next generation satellite systems can be integrated to the future ATC systems.

In this paper, we address the rate control problem for multirate multicast sessions,with the objective of maximizing the total receiver utility.This aggregate utility maximization problem not only takes into account the heterogeneityin user requirements, but also provides a unified framework for diverse fairness objectives.

We propose an algorithm for this problem and show, through analysis andsimulation, that it converges to the optimal rates.

In spite of the non-separability of the problem,the solution that we develop is completely decentralized, scalableand does not require the network to know the receiver utilities.Moreover, the algorithm requires very simple computations both forthe user and the network, and also has very low overhead of network congestionfeedback.

We propose a simple algorithm for achieving the optimal rates for this problem. The algorithm can be implemented in a distributed way and does not require the network to know the user utility functions.

In our algorithm, the network communicates to the user the number of congested links on the user's path, and the user (end-host) adjusts its rate accordingly, taking into account its utility function and the network congestion feedback.

We show through analysis and experimentation that our algorithm converges to the optimum rates.

In this paper, we address the problem of achieving rates that maximize the total receiver utility for multirate multicast sessions. This problem not only takes into account the heterogeneity in user requirements, but also provides a unified framework for diverse fairness objectives. We propose two algorithms and prove that they converge to the optimal rates for this problem.

The algorithms are distributed and scalable, and do not require the network to know the receiver utilities. We discuss how these algorithms can be implemented in a real network, and also demonstrate their convergence through simulation experiments.

This paper is organized as follows: Section I introduces the development of methods for wireless communication over multipath fading channel. Section II gives Turin's evaluation of the effects of multipath and fading on the performance of DS-CDMA systems. Section III gives Pursley's evaluation of this issue. Section IV explains the structure and performance of conventional RAKE receiver. Section V shows Sourour's work on Multicarrier DS-CDMA. Section VI is a proposal for a multicarrier DS-CDMA system and some numerical results I have gotten. Section VII is devoted to the conclusions and future work.

This paper presents a unique approach to conduct the systematic experimental research for the machinability of dental ceramics. A database management system is employed to perform the systematic data management and manipulation function. This database engine is then connected to the World Wide Web to take advantage of the information infrastructure provided by it.

Through user-friendly interface, this online database system provides guidance for the experiment design, data collection and data analysis. With the connection of the database to the World Wide Web, interactive web page can be generated to facilitate the information exchange and dissemination. This method utilizes new technologies to allow users to swiftly share information with anyone around the world.