Mixed media cellular systems

Abstract-A voiceldata cellular system is studied in this work. Analytical methods are used based on generating functions techniques. An extended simulation analysis it was also carried out, defining the main performance parameters and their impact on system behaviour. The limits or analytical study are investigated and solutions through simulation methods are proposed. 1. INTRQDUCTION UTURE communication networks are expected to handle a variety of data traffic types, including digital voice, facsimile, video, file transfer and interactive information services. These services will be offered not only by stationary terininals but also by land mobile terminals which will be totally integrated into tlie public cominunications networks. Cellular mobile networks have been studied extensively last years. Frequency assignmelit techniques, cliaimel access models, transmission quality, standards for interfacing with the wired network as well as traffic management are some of the topics gained attention. Especially, referring to the last topic, a mathematical model has been developed [1]- [3] adequate Tor lrafFic analysis of mobile coniniunications systems. The important parameters of voice coiiimunication systems, i.e. blocking probability of new calls, handoff requirement probability, forced termination probability e.t.c, have been stated as functions of the system state probabilities. The cases of vehicular as well as portablc terminals havc becn covered. But as far as we know there is no analysis for mixed media cellular systems -voice, data, video-which will be widely used in the near future. In this work, we extend the mathematical model of [l] for the purpose of studying a voice-data cellular system. In the second section the mathematical model is presented and the main performance parameters are evaluated. Simulation analysis is carried out and results are presented in the third section. Conclusion and suggestions for fbrther analysis are finally staled. M~THEMATICAI, MODEL A. SYSTEM DESCFXPTION Without loss of generality we concentrate on the study of a highway cellular system

A VARIABLE REDUCTION ROUTING ALGORITHM FOR PACKET-SWITCHED COMPUTER NETWORKS

THE ROUTING PROBLEM IN PACKET-SWITCHED DISTRIBUTED-CONTROL COMPUTER NETWORKS ISCONSIDERED. THE MINIMISATION OF MEAN TIME DELAY OF PACKETS IS ATTAINED. LAGRANGE MULTIPLIERS METHOD IS STUDIED AND THE PROBLEMS ASSOCIATED WITH IT ARE EXAMINED. FURTHERMORE IT IS SHOWN THAT: 1) THE HESSIAN MATRIX OF THE OBJECTIVE FUNCTION IS NON-DIAGONAL AND SINGULAR. THE ELEMENTS OF THE MATRIX ARE EVALUATED. 2) THE VARIABLE REDUCTION METHOD IS PROPOSED FOR THE SOLUTION OF THE ROUTING PROBLEM AND A COMPARISON OF THE TWO TECHNIQUES IS GIVEN THROUGH VARIOUS NUMERICAL APPLICATION.ΜΕΛΕΤΑΤΑΙ ΤΟ ΠΡΟΒΛΗΜΑ ΔΡΟΜΟΛΟΓΗΣΗΣ ΜΗΝΥΜΑΤΩΝ ΣΕ ΔΙΚΤΥΟ ΥΠΟΛΟΓΙΣΤΩΝ ΜΕΤΑΓΩΓΗΣ ΠΑΚΕΤΩΝ ΚΑΙ ΔΙΑΝΕΜΗΜΕΝΟΥ ΕΛΕΓΧΟΥ. ΚΡΙΤΗΡΙΟ ΒΕΛΤΙΣΤΗΣ ΛΕΙΤΟΥΡΓΙΑΣ ΘΕΩΡΕΙΤΑΙ Η ΕΛΑΧΙΣΤΟΠΟΙΗΣΗ ΤΗΣ ΜΕΣΗΣ ΧΡΟΝΙΚΗΣ ΚΑΘΥΣΤΕΡΗΣΗΣ ΤΩΝ ΜΥΝΗΜΑΤΩΝ ΣΤΟ ΔΙΚΤΥΟ. ΓΙΝΕΤΑΙ ΣΥΝΤΟΜΗ ΙΣΤΟΡΙΚΗ ΑΝΑΔΡΟΜΗ ΣΤΙΣ ΤΕΧΝΙΚΕΣ ΠΟΥ ΕΦΑΡΜΟΣΘΗΚΑΝ ΓΙΑ ΤΗΝ ΕΠΙΛΥΣΗ ΤΟΥ ΠΡΟΒΛΗΜΑΤΟΣ ΔΡΟΜΟΛΟΓΗΣΗΣ. ΕΞΕΤΑΖΕΤΑΙ Η ΤΕΛΕΥΤΑΙΑ ΜΕΘΟΔΟΣ ΠΟΥ ΠΡΟΤΑΘΗΚΕ ΓΙΑ ΤΗΝ ΕΠΙΛΥΣΗ ΤΟΥ ΠΡΟΒΛΗΜΑΤΟΣ ΑΥΤΟΥ, Η ΜΕΘΟΔΟΣ ΠΟΛΛ/ΣΤΩΝ LAGRANGE ΠΟΥ ΒΑΣΙΖΕΤΑΙ ΣΕ ΤΕΧΝΙΚΕΣ ΜΗ ΓΡΑΜΜΙΚΟΥ ΠΡΟΓΡΑΜΜΑΤΙΣΜΟΥ (ΜΕΘΟΔΟΣ NEWTON). ΕΠΙΣΗΜΑΙΝΟΝΤΑΙ ΤΑ ΜΕΙΟΝΕΚΤΗΜΑΤΑ ΤΗΣ ΜΕΘΟΔΟΥ ΑΥΤΗΣ ΚΑΙ ΣΥΓΚΕΚΡΙΜΕΝΑ Η ΠΑΡΑΔΟΣΗ ΟΤΙ Η HESSIAN ΜΗΤΡΑ ΤΗΣ ΑΝΤΙΚΕΙΜΕΝΙΚΗΣ ΣΥΝΑΡΤΗΣΗΣ ΕΙΝΑΙ ΔΙΑΓΩΝΙΟΣ. ΣΤΗ ΣΥΝΕΧΕΙΑ ΑΠΟΔΕΙΚΝΥΕΤΑΙ: 1) ΟΤΙ Η HESSIAN ΔΕΝ ΕΙΝΑΙ ΔΙΑΓΩΝΙΟΣ, 2) ΥΠΟΛΟΓΙΖΕΤΑΙ Η ΠΛΗΡΗΣ ΜΗΤΡΑ ΚΑΙ ΕΥΡΙΣΚΕΤΑΙ ΜΗ ΑΝΑΣΤΡΕΨΙΜΗ , 3) ΠΡΟΤΕΙΝΕΤΑΙ ΚΑΙ ΕΦΑΡΜΟΖΕΤΑΙ Η ΜΕΘΟΔΟΣ ΜΕΙΩΣΗΣ ΜΕΤΑΒΛΗΤΩΝ, 4) ΓΙΝΕΤΑΙΣΥΓΚΡΙΣΗ ΤΩΝ ΔΥΟ ΜΕΘΟΔΩΝ ΚΑΙ ΣΧΟΛΙΑΖΟΝΤΑΙ ΤΑ ΑΠΟΤΕΛΕΣΜΑΤΑ ΕΦΑΡΜΟΓΩΝ ΤΟΥΣ

On call admission control and handover management in multimedia LEO satellite systems

Low earth orbit (LEO) satellite systems gained considerable interest in the past decade and were expected to be instrumental in future telecommunications systems. Nevertheless, the first two LEO satellite networks that are currently in operation have not come to fruition on account of the limited spectrum of services that they provide. In this context, future LEO satellite networks will be geared towards the provision of multimedia services. In this paper a novel call admission control and inter-satellite handover management scheme tailored for multimedia LEO satellite systems is proposed and evaluated. In addition, the proposed scheme is examined in satellite diversity based systems and two different satellite selection criteria, which can be applied to both new and handover requests, are assessed