Future broadband satellite networks for multimedia will be seamlessly integrated into terrestrial broadband networks which often use asynchronous transfer mode (ATM) and recently also the less complex multi protocol label switching (MPLS) technique as transmission and switching protocol. In light of this, future broadband satellite networks may adopt the ATM transmission scheme and implement ATM or ATM-like switches on board the satellites. However, as compared to communication in fixed networks, satellite communication is characterized by special constraints (e.g. signal delay, channel quality, dynamic network topology) that require novel ATM-based communication technology for satellite systems. This paper presents results from the ATM-Sat project that aims to complete this technically challenging and important R&D task in the cooperation between DLR, Fraunhofer Gesellschaft and Tesat-Spacecom. In brief the following aspects have been addressed in the ATM-Sat project: development of the concept and communication technology for a multimedia satellite system with, non-geostationary orbit (NGSO) satellites; inter satellite links (ISLs); on-board ATM switching; fixed and mobile terminals; verification of the developed communication technology with a demonstrator. In particular the ATM-Sat R&D tasks cover the system and protocol architecture, on-board processing, ISL routing, up/downlink and on board ATM resource management (including medium access control), error control, IP over satellite-ATM, and active intelligent antennas. Copyright © 2005 John Wiley & Sons, Ltd.

Delivery of IP services is becoming increasingly important for wireless access networks, HeliNet being their representative based on high altitude platforms. Accordingly, new problems arise regarding quality of service (QoS) or class of service (CoS) provision and resource allocation. Traffic QoS/CoS should be managed on multiple communication layers such as application, network and radio interface layer. In the network layer, IP QoS models can offer various levels of QoS to the application layer, while the radio interface should provide mechanisms which can guarantee the required QoS level to IP. Mapping of QoS/CoS parameters between the network layer and radio interface can be performed in a suitable convergence sublayer. The paper addresses IP transmission over the HeliNet radio interface. Using a simulation model, it is shown that the introduction of scheduling algorithms, as part of the uplink medium access control (MAC) protocol, improves the ability of the radio interface to offer the required QoS/CoS to IP.

The aim of this paper is to present a suitable satellite multimedia network architecture and the results of simulated medium access control (MAC) protocols. The new generation of satellite multimedia networks is going to handle different types of traffic such as multimedia traffic. The ATM technology was developed for the integrated transmission of various types of traffic. The future networks protocols should be as much as possible compatible and that is one of the main reasons to think about the use of ATM technology for transmission over satellites. Satellite networks present a lot of challenges related to quality of services (QoS) provision and the medium access control access protocols are strongly related to QoS provision.

Within the next years, a large number of new satellite systems for broadband multimedia communications will be developed, mainly for fixed terminals, but to a lesser degree also for portable and mobile terminals. The most important systems will be based on low earth orbit (LEO) satellite constellations with inter satellite links (ISLs), and will be seamlessly integrated into the environment of terrestrial broadband networks. Since most of the terrestrial broadband networks will be based on the Asynchronous Transfer Mode ATM, it is advantageous for the satellite networks to adopt the ATM transmission scheme and implement ATM switches on board the satellites. However, compared to communication in fixed networks, satellite communication is characterised by special constraints (limited bandwidth, propagation delay, transmission errors, dynamic network topology) requiring the development of a new ATM-based communication technology. In the paper, an ISL-based LEO satellite network for multimedia communication will be considered. Several relevant aspects will be discussed, such as the system architecture, the system requirements, and the protocol architecture. Since the users access the satellite network via a radio interface, an error control scheme and a multiple access scheme suitable for multimedia communication must be implemented. The aspects of TDMA- and CDMA-based medium access control are discussed. Further issues are ATM resource management, radio resource management, and ISL routing. Finally, methods for terminal antenna steering are addressed, and the demonstration of aeronautical multimedia communication via the ITALSAT satellite is described.

In this paper we present and evaluate a hybrid-modular multiple access protocol for ATM transmission in a multiservice satellite system. Given appropriate synchronization and Doppler (shift) compensation, the protocol components can cope with the dynamics of the satellite constellation and are suitable to both mobile and fixed user environments. The general protocol framework is first given with an adaptive random-reservation protocol which can on principle support all ATM service classes over low earth orbit (LEO), medium earth orbit (MEO) and geostationary earth orbit (GEO) satellites while providing the required Quality of Service (QoS). In a second step, an optimized MAC protocol module for bandwidth-efficient support of rt-VBR traffic over LEO satellites is presented. The simulation based performance evaluation proves that the protocols allow to efficiently use statistical multiplexing of ATM traffic over the air interface, both for real-time and non-real-time bursty traffic.

The aim of this paper is to present a suitable satellite multimedia network architecture and the results of simulated medium access control (MAC) protocols. The new generation of satellite multimedia networks is going to handle different types of traffic such as multimedia traffic. The ATM technology was developed for the integrated transmission of various types of traffic. The future networks protocols should be as much as possible compatible and that is one of the main reasons to think about the use of ATM technology for transmission over satellites. Satellite networks present a lot of challenges related to quality of services (QoS) provision and the medium access control access protocols are strongly related to QoS provision.