Keywords: VoIP IP Telephony Voice quality Voice codecs Signaling protocols Call admission control Security a b s t r a c t The Internet has burgeoned into a worldwide information superhighway during the past few years, giving rise to a host of new applications and services. Among them, Voice over IP (VoIP) is the most prominent one. Beginning more as a… (More)
Low Earth Orbit (LEO) satellite networks are foreseen to complement terrestrial networks in future global mobile networks. Although space segment topology of a LEO network is characterized by periodic variations, connections of mobile stations (MS's) to the satellite backbone network alter stochastically. As a result the quality of service delivered to… (More)
The performance of a DMT system, which transmits information over channels with varying characteristics through the frequency zones, is improved when the subchannels of the system are loaded with variable data rate. In this study, we meet the bit loading problem of the subcarriers of a DMT system. We propose two new optimum-loading algorithms with low… (More)
A comparative study of routing techniques is carried out for LEO constellations interconnecting high speed terrestrial networks assuming Poison and Self-Similar input traffic. Shortest path routing as well as optimal routing (flow deviation) methods are applied for balanced and unbalanced traffic load and for uniform and non uniform distribution of the… (More)
Abstracg Two-dimensional traffic models for cellular mobile systems are formulated and the main performance measures are evaluated. System analysis in its general f m is rather complex but a solution is always attained in closed form or by numerical techniques.