Fotini-Niovi Pavlidou

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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)
Low earth orbit (LEO) satellite constellations could play an important role in future mobile communication networks due to their characteristics, such as global coverage and low propagation delays. However, because of the non-stationarity of the satellites, a call may be subjected to handovers, which can be cell or satellite handovers. Quite many techniques(More)
Game theory has been used for decades in fields of science such as economics and biology, but recently it was used to model routing and packet forwarding in wireless ad-hoc and sensor networks. However, the clustering problem , related to self-organization of nodes into large groups, has not been studied under this framework. In this work our objective is(More)
This article addresses several challenges related to the evolution towards seamless interworking of wireless LAN and 3G cellular networks. The main objective is to evaluate the conditions and restrictions under which seamless continuity of video sessions across the two networks is feasible. For this purpose, we formulate a number of practical interworking(More)
High Altitude platforms (HAPs) have gained a great interest in recent years. HAP systems will be globally in nature but nationally in service provision. They will deliver IMT-2000 mobile and fixed wireless access using the proposed IMT-2000 terrestrial component radio transmission technologies and protocols. Under the above considerations, in this paper the(More)
Notwithstanding the limited commercial success of the first narrowband Low Earth Orbit (LEO) satellite systems, the interest of the scientific community in this type of systems has been revived on the basis of the current trend toward the migration to all IP-based services. LEO systems can play a pivotal role in providing services to areas where there is no(More)