Ales Svigelj

Routing in ISL networks considering empirical IP traffic

Next-generation satellite networks are expected to provide a variety of applications with diverse performance requirements, which will call for the development of adaptive routing procedures supporting different levels of services. In this paper, we propose traffic class dependent (TCD) routing, which has the potential to differentiate between traffic classes using different optimization criteria in route calculation. The performance of TCD routing is evaluated for different traffic scenarios using an empirical traffic source model derived from the real backbone Internet traffic trace and compared with results obtained with equivalent Poisson traffic as a reference point. In addition, TCD routing is compared with a simple single service routing procedure, which does not make any distinction between traffic classes. Performance analysis, in terms of average packet delay, normalized data throughput, and normalized link load, reveals improved routing resulting from traffic class differentiation, regardless of the traffic scenario considered. The performance measures based of aggregate traffic flow show no significant difference between routing of empirical and equivalent Poisson traffic.

Adaptive routing for packet-oriented intersatellite link networks: performance in various traffic scenarios

Regular mesh topologies typical for satellite communication networks comprised of intersatellite links provide high network flexibility and reliability, but due to dynamic changing of traffic load and interorbit link distance variation, adaptive routing is an absolute requirement for optimizing the network utilization. In this article, we address adaptive routing in the intersatellite link (ISL) segment of nongeostationary packet-switched satellite communication systems, focusing on the relative impacts of traffic load and propagation delay on the link cost. We consider four reference traffic flow scenarios with different levels of traffic concentration. he network performance is evaluated in terms of routing performance measures important from both the end user and the network operator perspectives. Using an ISL network simulator, we reveal some intrinsic effects of the selected constellation and effects introduced with different assumptions regarding the traffic model.

Demographically weighted traffic flow models for adaptive routing in packet-switched non-geostationary satellite meshed networks

In this paper, a performance analysis of adaptive routing is presented for packet-switched inter-satellite link (ISL) networks, based on shortest path routing and two alternate link routing forwarding policies. The selected routing algorithm and link-cost function are evaluated for a low earth orbit satellite system, using a demographically weighted traffic flow model. Two distinct traffic flow patterns are modelled: hot spot and regional. Performance analysis, in terms of quality of service and quantity of service, is derived using specifically developed simulation software to model the ISL network, taking into account topology adaptive routing only, or topology and traffic adaptive routing.

Performance evaluation of adaptive routing algorithms in packet-switched intersatellite link networks

This paper addresses the performance evaluation of adaptive routing algorithms in non-geostationary packet-switched satellite communication systems. The dynamic topology of satellite networks and variable traffic load in satellite coverage areas, due to the motion of satellites in their orbit planes, pose stringent requirements to routing algorithms. We have limited the scope of our interest to routing in the intersatellite link (ISL) segment. In order to analyse the applicability of different routing algorithms used in terrestrial networks, and to evaluate the performance of new algorithms designed for satellite networks, we have built a simulation model of a satellite communication system with intersatellite links. In the paper, we present simulation results considering a network-uniform source/destination distribution model and a uniform source–destination traffic flow, thus showing the inherent routing characteristics of a selected Celestri-like LEO satellite constellation. The updates of the routing tables are centrally calculated according to the Dijkstra shortest path algorithm. Copyright

Alternate link routing for traffic engineering in packet-oriented ISL networks

The implementation of a satellite communication network consisting of intersatellite links provides a highly interconnected backbone in the space segment, increasing the network flexibility and reliability, while, on the other hand, introducing numerous issues related to network dimensioning, efficient resource management, adaptive routing, etc. In this paper we study two forwarding policies based on alternate link routing (ALR) and compare their performance with that of a simple forwarding policy employing shortest path routing (SPR) without options. All forwarding policies compared in this study are operating on routing tables calculated with the Dijkstra shortest path algorithm, capable of adapting to traffic load and propagation delay on the links through the appropriately selected link cost metric. Using an ISL network simulator, we demonstrate that both ALR forwarding policies can efficiently handle traffic load sharing among alternative routes, significantly reducing peak values of link load which is a central goal of ISL network dimensioning.

Adaptive Coding and Modulation for Mobile Wireless Access Via High Altitude Platforms

In this paper we are concerned with broadband wireless access via high altitude platform system, providing the Internet access and broadband multimedia services to passengers equipped with WLAN terminals connecting through a collective terminal mounted on the train. The main challenge in such scenario is the development of efficient and reliable radio interface for the broadband communication link in the mobile wireless access segment. We are focusing on performance analysis of the adaptive coding and modulation scheme in the communication link between a high altitude platform and a collective terminal on-board moving train. In order to increase the reliability of the communication system in a fading environment we also exploit space and platform diversity. The proposed approach significantly increases the throughput of the wireless access system, while bit error rate remains below the target value regardless of the considered propagation environment.

Traffic class dependent routing in ISL networks

This work addresses traffic class dependent (TCD) routing, using different link-cost functions, in the intersatellite link (ISL) network of a nongeostationary packet-switched satellite communication system. Three different traffic classes are introduced, each with its particular optimisation criteria. Performance analysis of TCD routing, in terms of average packet delay and average data throughput of a particular traffic class, is evaluated for homogeneous and nonhomogeneous traffic scenarios using a specifically developed simulation model of the ISL network.

Oscillation suppression for traffic class dependent routing in ISL network

Adaptive per-hop routing in the intersatellite link (ISL) network of a packet-switched, nongeostationary satellite system is addressed. In particular, a traffic class dependent (TCD) routing is proposed with different optimization criteria for different traffic classes. Furthermore, for delay sensitive traffic, performance is enhanced by an exponential smoothing link-cost function, which reduces traffic load oscillations in the network. The performance of the proposed procedures is evaluated in two different traffic scenarios using an appropriate simulation model

The impact of different scheduling policies on traffic class dependent routing in intersatellite link networks

The provision of multimedia applications characterized by the integrated presentation of various data sources requires a network infrastructure providing broadband access, large available bandwidth in the core network, and traffic differentiation which supports efficient utilization of network resources and service level guarantees. In order to distinguish between different traffic classes and to optimize utilization of network resources to their respective requirements, an efficient routing procedure capable of differentiating traffic and adapting to highly dynamic conditions in a non-geostationary ISL network needs to be implemented in combination with advanced fair scheduling policies in the outgoing queues. In this paper we analyze the performance of different scheduling policies in conjunction with adaptive routing procedures in the intersatellite link network of a packet-switched non-geostationary satellite system. In particular, different unfair first come first served and priority and fair weighted round robin, deficit round robin and surplus round robin scheduling policies are considered, in combination with single-service routing and traffic class dependent routing procedures. The performance of different scenarios is assessed, by means of simulation, in terms of average packet delay and average data throughput. The simulation results indicate that differentiated treatment of traffic using traffic class dependent routing and fair scheduling policies provides a significant improvement in overall performance for all traffic classes, regardless of the traffic scenario considered. Copyright

Network traffic modeling for load prediction: a user-centric approach

Nowadays, networks have to be able to cope with ever increasing traffic demands in order to deliver the desired quality to end users. Thus, proper network planning is essential in order to preserve telecom revenues by reduced income per bandwidth unit. This article addresses a user-centric approach to network and user traffic modeling that has been validated and used in the process of introducing, optimizing, and planning new services at the Slovenian national telecom operator and service provider, Telekom Slovenije d.d. The proposed approach is based on the end users and their user group profiles that are founded on real measurements from the observed telecommunication network consisting of more than 1000 MSANs and more than 300,000 subscribers. The proposed approach has been successfully validated, showing that for the observed period the modeled link load deviates less than 5 percent from the measurements. Furthermore, in the presented case study the proposed approach is used successfully in the process of introducing the Fast Channel Change service.