Network emulation focusing on QoS-Oriented satellite communication

This chapter proposes network emulation basics and a complete case study of QoS-oriented Satellite Communication

Low cost network emulator with ethernet and E1 interfaces

Contemporary Next Generation Networks (NGN) are mainly built on the Internet Protocol (IP) and Ethernet. Major challenge for emerging types of wired and wireless IP-based networks is to provide an adequate Quality of Service (QoS) for different services. The quality of evaluation requires a detailed knowledge of the performance requirements for particular services and applications. The paper is primarily oriented to the end-to-end testing for the Ethernet-based terminal equipment. The low cost Ethernet network emulator was developed on the Department of Telecommunication Technology of the Faculty of Electrical Engineering of the Czech Technical University in Prague. The extension for emulation network with the E1 interfaces and TDM over IP transmission can be used with external converters

Modellierung und Evaluierung der “Required Communication Performance” von Luft-Boden Datenverbindungen mit “Erasure Codes”.

In this work, a model to calculate the air-ground data link performance using the “Required Communication Performance” metric used in aviation is proposed. This model is applied to evaluate the performance of data links and to estimate the minimum link performance required to meet the safety requirements. The results show that it is highly unlikely that air-ground data links achieve the minimum performance. “Erasure codes” and a multiple link concept are proposed and evaluated to improve the performance of the links.Diese Arbeit beschreibt ein Modell, mit welcher die Leistung von Luft-Boden Datenverbindungen unter Verwendung der in der Luftfahrt verwendeten Metrik „Required Communication Performance“, berechnet werden. Dieses Modell wird angewendet, um die Leistung von Datenverbindungen zu bewerten und die minimale Verbindungsleistung abzuschätzen, die erforderlich ist, um die Sicherheitsanforderungen zu erfüllen. Die Ergebnisse zeigen, dass es sehr unwahrscheinlich ist, dass Luft-Boden Datenverbindungen die Mindestleistung erreichen. Zur Verbesserung der Leistung der Links werden Konzepte basierend auf “Erasure Codes" und mehreren Links vorgeschlagen und evaluiert

A cross-layer approach to enhance QoS for multimedia applications over satellite

The need for on-demand QoS support for communications over satellite is of primary importance for distributed multimedia applications. This is particularly true for the return link which is often a bottleneck due to the large set of end-users accessing a very limited uplink resource. Facing this need, Demand Assignment Multiple Access (DAMA) is a classical technique that allows satellite operators to offer various types of services, while managing the resources of the satellite system efficiently. Tackling the quality degradation and delay accumulation issues that can result from the use of these techniques, this paper proposes an instantiation of the Application Layer Framing (ALF) approach, using a cross-layer interpreter(xQoS-Interpreter). The information provided by this interpreter is used to manage the resource provided to a terminal by the satellite system in order to improve the quality of multimedia presentations from the end users point of view. Several experiments are carried out for different loads on the return link. Their impact on QoS is measured through different application as well as network level metrics

Contributions to simulation and emulation of Inter-Satellite Links

Recently, there has been a paradigm shift in space missions. They no longer rely on a single satellite to achieve all the objectives of a mission. Responsibility is shared between devices that can communicate and share resources to achieve these objectives. This paradigm shift has increased the need to assess communication performance within FSS. Despite proposals for simulators and emulators to achieve this goal, none of them integrates the dynamics of satellites with their communications. This thesis presents two proposals and the implementation of one of them to extend the capabilities of the communication channel of the simulator developed by the NanoSat Lab of the UPC. Additionally, following the lines of the i2Cat Space Communications research group, a test bench is also presented to demonstrate the feasibility of a satellite contact emulator. As it will be demonstrated, developing such an emulator has not been possible. Finally, it is concluded that both parts of this thesis may converge. Thus, combining the possibilities offered by the current simulator with those available in the emulator under development.En el transcurso de los últimos años se ha observado un cambio en el paradigma en las misiones espaciales. Éstas ya no cuentan sólo con un único satélite que tenga que alcanzar todos los objetivos de una misión. Se reparte la responsabilidad entre diferentes dispositivos que son capaces de comunicarse y compartir recursos para alcanzar tales objetivos. De ese cambio de paradigma nace la necesidad de poder evaluar el comportamiento de las comunicaciones dentro de un FSS. A pesar de la existencia de simuladores y propuestas de emuladores para alcanzar tal objetivo, ninguno de ellos integra las dinámicas de los satélites con sus comunicaciones. En esta tesis, se presentan dos propuestas y la implementación de una de ellas para ampliar las capacidades del canal de comunicaciones del simulador desarrollado por NanoSat Lab de la UPC. Además, siguiendo las líneas del grupo de investigación de Comunicaciones Espaciales de i2Cat también se presenta un test-bed para demostrar la viabilidad de un emulador de contactos de satélites. Pues, como se va a demostrar, el desarrollador de uno como tal no ha sido posible. Por último, se concluirá que ambas partes de esta tesis puedan converger en algún momento combinando así las posibilidades que ofrece el actual simulador con las de un emulador que está en desarrollo.En el transcurs dels últims anys s’ha observat un canvi en el paradigma de les missions espacials. Aquestes ja no compten només d’un únic satèl·lit que hagi d’assolir tots els objectius d’una missió. Es reparteix la responsabilitat entre diferents dispositius els quals són capaços de comunicar-se i compartir recursos per tal d’assolir tals objectius. D’aquest canvi de paradigma neix la necessitat de poder avaluar el comportament de les comunicacions dins d’un FSS. Tot i l’existència de simuladors i propostes d’emuladors per assolir tal objectiu, cap d’ells integra les dinàmiques dels satèl·lits amb les seves comunicacions. En aquesta tesi, es presenten dues propostes i la implementació d’una d’elles per tal d’ampliar les capacitats del canal de comunicacions del simulador desenvolupat pel NanoSat Lab de la UPC. A més a més, seguint les línies del grup de recerca de Comunicacions Espacials d'i2Cat també es presenta un test-bed per tal de poder demostrar la viabilitat d’un emulador de contactes de satèl·lits. Doncs, com es demostrarà, el desenvolupant d’un com a tal no ha estat possible. Finalment, es conclourà que ambdues parts d'aquesta tesi puguin convergir en algun moment combinant així les possibilitat que ofereix l'actual simulador amb les d’un emulador que està en desenvolupamen

Active emulation of a DVB-RCS satellite link in an end-to-end QoS-oriented heterogeneous network

Our contribution aims to propose a platform integrating an emulation processor and potentially complex emulation model into an easy-to-deploy system

The performance of DCCP TCP-like with initial slow-start threshold manipulation

This paper investigates the performance of the implementation of modified initial slow-start threshold size in Datagram Congestion Control Protocol (DCCP) TCP-like (CCID-2) over long delay link network.TCP-like is one of a congestion control mechanism for DCCP which is suitable for the delivery of multimedia data with abrupt changes during the transmission. The scenario is set for long delay link network,where the impact of the modified slow-start threshold value in TCP-like is significant.As a result, we managed to reduce the time required to obtain the maximum throughput in TCP-like during in the slow-start phase.The result shows that with the correct manipulation of initial slow-start threshold size for TCP-like, it will give a significant improvement to TCP-like performance over long delay link where the maximum throughput during the slow-start phase can be achieved faster