Anton Donner

MPLS-based satellite constellation networks

Nongeostationary satellite constellations with intersatellite links are a challenge for networking due to their continuously changing topology. In order to make maximal use of the networks capacities, special attention has to be paid to routing and traffic engineering. Multiprotocol label switching (MPLS) as underlying protocol is an interesting candidate for this task since it offers many possibilities to exert influence on traffic flows and supports todays dominating Internet protocol traffic very well. This paper describes a general MPLS-based networking concept for satellite networks and discusses different scenarios considering the particularities and constraints of the dynamic topology. Functional elements of MPLS like ingress, egress, or core routers have to be mapped onto the physical entities of the network and prerequisites for traffic engineering are discussed. Routing and rerouting of paths is of key interest since this affects route computation effort and routing performance. Thus, an analytical estimation of routing effort is deduced and numerical and simulation results are presented.

A delay model for satellite constellation networks with inter-satellite links

Within this paper we examine a non-geostationary satellite constellation network with inter-satellite links (ISLs) for global air traffic control (ATC) and air passenger communication (APC). More specifically, an analysis is done to investigate the impacts of different routing policies on the end-to-end delay, and a general model describing the delays is developed. All considerations are based on a Galileo-like satellite constellation network and real global flight data of all commercial flights during one day

Satellite constellation networks for aeronautical communication: traffic modelling and link load analysis

The authors examine two different non-geostationary satellite constellation networks with inter-satellite links for global air traffic control and air passenger communication. After developing a traffic model for aeronautical communication services, the authors derive bandwidth requirements for such a global system. The influence of different routing policies is discussed and they show that link loads are comparable for both medium earth orbit and low earth orbit constellations. All considerations are based on real global flight data of all commercial flights during 1 day.

Performance of database synchronization algorithms via satellite

In this paper, we examine different database synchronization/replication strategies and compare their suitability for satellite links in terms of latency and exchanged data volume. Earlier works have investigated the performance of these algorithms over terrestrial networks; however, the delay caused by a geostationary satellite has not been taken into account yet. A test-bed emulating a satellite link with database end nodes was used to compare different synchronization algorithms.

SatNEx - the European satellite communications network of excellence

Summary form only given. This paper outlines the primary goal of SatNEx which is to achieve long-lasting integration of the European research in satellite communications and to develop a common base of knowledge. Networks of excellence have been introduced as a new instrument within the 6/sup th/ IST framework program, and SatNEx is one of the first consortia to implement the new ideas and to overcome the fragmentation of European research. Through co-operation of outstanding universities and research organizations with excellent expertise in satellite communications, SatNEx will build a European virtual centre of excellence in satellite communications and contribute to the realization of the European Research Area (ERA) SatNEx will include an advisory board incorporating representatives of the European space industry, satellite service providers, and standardization and regulation organizations. SatNEx will collaborate with these players and put together a critical mass of resources and expertise needed for making Europe a world force in the field of satellite communications.

On mean visibility time of non-repeating satellite orbits

Depending on the parameters of a fixed ground station and on the orbital parameters of a non-geosynchronous satellite, different visibility times are offered to fixed ground stations. In this paper, the focus is on the mean visibility time of a non-geosynchronous satellite with non-repeating ground track as seen by a fixed ground station with a finite sensor range. A mathematical analysis is provided for the calculation of the mean visibility time. There are several possible application areas of these visibility statistics, like optimizing a gateway’s latitude to maximize the mean visibility time of a satellite, thus maximizing the average amount of data that can be uploaded to or downloaded from a satellite during passes. The calculations show a good match with simulation results at all latitudes and the underlying mathematical approach is foreseen to be useful for analyzing and designing complete satellite constellations.

Reliable Multicast for Land Mobile Satellite Channels

While the land mobile satellite channel creates a very demanding environment, broadcast and reliable multicast via satellite have the potential to serve a large audience in the vehicular market. In order to address this segment, normally specialized high power satellites with large link margins are used, e.g., XM-Radio or Sirius. In this article a data link layer protocol for reliable multicast in the land mobile satellite environment for Ku-band is proposed and examined, which can cope with shadowing without additional link margin. The protocol has been designed to be compatible with the DVB-RCS standard and adopts a hybrid FEC/ARQ error correction scheme to recover lost packets.

Satellite Communications for Management of Mass Casualty Incidents: The e-Triage Project

This paper describes the communications infrastructure used in the e-Triage Project. The main objective of e-Triage is the effcient electronic on-site registration of victims in Mass Casualty Incidents (MCIs) to enable a fast distribution of the information to operation control centers and hospitals for a better handling of victims. To achieve this, e-Triage designs the end-device used to register the victims, the distributed database where the information of the victims is saved, and the communications infrastructure necessary to transmit the data. After a disaster event the terrestrial commercial networks are likely to be overloaded, damaged or not operative, if they ever existed. A dynamic network extension is envisaged for dedicated Professional Mobile Radio (PMR) systems, or a complete deployment is foreseen if e-Triage is used abroad where no infrastructure is. This paper focuses on the technologies used to transmit data and voice traffc within the disaster area and to the remote control centers and hospitals. These technologies are GSM/GPRS, TErrestrial Trunked RAdio (TETRA) and WLAN and are backhauled over satellite (BGAN or VSAT) or UMTS links. Some modifications of the protocols underneath have been implemented, which show better performance over slow and limited bandwidth links.

An MPLS networking concept for satellite constellations

MPLS has been designed for IP backbone networks and offers many possibilities to exert influence on traffic flows. Therefore it is an attractive candidate for use in broadband non-geostationary satellite constellations with their continuously changing topologies. The logical structure of an MPLS domain with its ingress, egress and core routers has to be mapped onto the elements of the satellite network, and special attention has to be paid to route computation in order to fulfill user Quality of Service (QoS) requirements. A general MPLS-based networking concept for satellite networks is developed and different possible scenarios considering the particularities and constraints of satellite networks are discussed. As route computation and performance is crucial, an analytical estimation of routing effort is deduced and numerical results are presented.

SatNEx: a network of excellence providing training in satellite communications

Satellite communications represents a specialised area of telecommunications. While the development of satellite technology is relatively slow in comparison to wireless networks evolution, due to the need for high reliability, the services that satellites are able to offer are evolving at much the same pace as their terrestrial counterparts. It is within this context that the satellite communications network of excellence (SatNEx) has evolved its initiative, the aim being to serve the engineering community with the latest technological trends, while also providing a solid grounding in the fundamentals for those new to the subject area.