Διαχείριση τηλεπικοινωνιακής κίνησης σε δορυφορικά συστήματα

Abstract

The subject of this doctoral dissertation is the study of tra#c management techniques in satellite systems. The study focuses on two kinds of systems, namely non-geostationary (non-GEO) satellite systems and High altitude platform (HAP) systems, which can play a pivotal and multifaceted role in future telecommunications networks. Tra#c management is of paramount importance, since bandwidth constitutes a resource at a premium in these systems. Initially, the problem of call admission control and call handover in non-GEO satellite systems is studied and ve new algorithms are proposed, which excel in e#ciently utilizing system resources. These algorithms exhibit very positive characteristics, outperforming other algorithms that have been proposed thus far. Moreover, an analytical model was devised that permits the performance assessment of certain algorithms, whose validity is corroborated by ample simulation experiments. Next, the issue of routing in non-GEO satellite systems is investigated. Routing in this type of systems constitutes a daunting challenge owing to variations in network topology. Two routing protocols are presented that introduce the concept of on-demand routing to this kind of systems. The positive characteristics of these protocols are revealed by means of comparison with the most well-known algorithms that have been proposed in the literature. The attention is then drawn towards HAP systems and speci cally to W-CDMA-based HAP systems. The capacity of this type of networks is estimated taking power control imperfections into account. Finally, a novel call admission control and handover technique is delineated and the results of its comparison with one of the most well-known techniques that have been proposed as yet are presented.