Contributions based on cross-layer design for quality-of-service provisioning over DVB-S2/RCS broadband satellite system

Contributions based on cross-layer design for Quality-of-Service provisioning over DVB-S2/RCS Broadband Satellite Systems Nowadays, geostationary (GEO) satellite infrastructure plays a crucial role for the provisioning of IP services. Such infrastructure can provide ubiquity and broadband access, being feasible to reach disperse populations located worldwide within remote areas where terrestrial infrastructure can not be deployed. Nevertheless, due to the expansion of the World Wide Web (WWW), new IP applications such as Voice over IP (VoIP) and multimedia services requires considering different levels of individual packet treatment through the satellite network. This differentiation must include not only the Quality of Service (QoS) parameters to specify packet transmission priorities across the network nodes, but also the required amount of bandwidth assignment to guarantee its transport. In this context, the provisioning of QoS guarantees over GEO satellite systems becomes one of the main research areas of organizations such as the European Space Agency (ESA). Mainly because, their current infrastructures require continuous exploitation, as launching a new communication satellite is associated with excessive costs. Therefore, the support of IP services with QoS guarantees must be developed on the terrestrial segment to enable using the current assets. In this PhD thesis several contributions to improve the QoS provisioning over DVB-S2/RCS Broadband Satellite Systems have been developed. The contributions are based on cross-layer design, following the layered model standardized in the ETSI TR 102 157 and 462. The proposals take into account the drawbacks posed by GEO satellite systems such as delay, losses and bandwidth variations. The first contribution proposes QoSatArt, an architecture defined to improve QoS provisioning among services classes considering the physical layer variations due to the presence of rain events. The design is developed inside the gateway, including the specification of the main functional blocks to provide QoS guarantees and mechanisms to minimize de delay and jitter values experienced at the application layer. Here, a cross-layer design between the physical and the network layer has been proposed, to enforce the QoS specifications based on the available bandwidth. The proposed QoSatArt architecture is evaluated using the NS-2 simulation tool. In addition, the performance analysis of several standard Transmission Control Protocol (TCP) variants is also performed. This is carry out to find the most suitable TCP variant that enhances TCP transmission over a QoS architecture such as the QoSatArt. The second contribution proposes XPLIT, an architecture developed to enhance TCP transmission with QoS for DVB-S2/RCS satellite systems. Complementary to QoSatArt, XPLIT introduces Performance Enhanced Proxies (PEPs), which breaks the end-to-end semantic of TCP connections. However, it considers a cross-layer design between the network layer and the transport layer to enhance TCP transmission while providing them with QoS guarantees. Here, a modified TCP variant called XPLIT-TCP is proposed to send data through the forward and the return channel. XPLIT-TCP uses two control loops (the buffer occupancy and the service rate to provide optimized congestion control functions. The proposed XPLIT architecture is evaluated using the NS-2 simulation tool. Finally, the third contribution of this thesis consists on the development of a unified architecture to provide QoS guarantees based on cross-layer design over broadband satellite systems. It adopts the enhancements proposed by the QoSatArt architecture working at the network layer, in combination with the enhancements proposed by the XPLIT architecture working at the transport layer.Actualmente, los satélites Geoestacionarios (GEO) juegan un papel muy importante en la provisión de servicios IP. Esta infraestructura permite proveer ubicuidad y acceso de banda ancha, haciendo posible alcanzar poblaciones dispersas en zonas remotas donde la infraestructura terrestre es inexistente. Sin embargo, en la provisión de aplicaciones como Voz sobre IP (VoIP) y servicios multimedia, es importante considerar el tratamiento diferenciado de paquetes a través de la red satelital. Esta diferenciación debe considerar no solo los requerimientos de Calidad de Servicio (QoS) que especifican las prioridades de los paquetes a través de los nodos de red, si no también el ancho de banda asignado para garantizar su transporte. En este contexto, la provisión de garantías de QoS sobre satélites GEO es una de las Principales áreas de investigación de organizaciones como la Agencia Espacial Europea (ESA) persiguen. Esto se debe principalmente ya que dichas organizaciones requieren la explotación continua de sus activos, dado que lanzar un nuevo satélite al espacio representa costos excesivos. Como resultado, el soporte de servicios IP con calidad de servicio sobre la infraestructura satelital actual es de vital importancia. En esta tesis doctoral se presentan varias contribuciones para el soporte a la Calidad de Servicio en redes DVB-S2/RCS satelitales de banda ancha. Las contribuciones propuestas se basan principalmente en el diseño ”cross-layer” siguiendo el modelo de capas definido y estandarizado en las especificaciones ETSI TR 102 157 [ETS03] y 462 [10205]. Las contribuciones propuestas consideran las limitaciones presentes de los sistemas satelitales GEO como lo son el retardo de propagación, la perdida de paquetes y las variaciones de ancho de banda causados por eventos atmosféricos. La primera contribución propone QoSatArt, una arquitectura definida para mejorar el soporte a la QoS. Esta arquitectura considera las variaciones en la capa física debido a la presencia de eventos de lluvia para priorizar los niveles de QoS. El diseño se desarrolla en el gateway e incluye las especificaciones de los principales elementos funcionales y mecanismos para garantizar la QoS y minimizar el retardo presente en la capa de aplicación. Aquí, se propone un diseño ”cross-layer” entre la capa física y la capa de red, con el objetivo de reforzar las especificaciones de QoS considerando el ancho de banda disponible. La arquitectura QoSatArt es simulada y evaluada empleando la herramienta de simulación NS-2. Adicionalmente, un análisis de desempeño de diversas variantes de TCP (Transmission Control Protocol) es realizado con el objetivo de encontrar la variante de TCP más adecuada para trabajar en un ambiente con QoS como QoSatArt. La segunda contribución propone XPLIT, una arquitectura desarrollada para mejorar las transmisiones TCP con QoS en un sistema satelital DVB-S2/RCS. Complementario a QoSatArt, XPLIT emplea PEPs (Performance Enhanced Proxies), afectando la semántica end-to-end de las conexiones TCP. Sin embargo, XPLIT considera un diseño ”cross-layer” entre la capa de red y la capa de transporte con el objetivo de mejorar las transmisiones TCP considerando los parámetros de QoS como la ocupación de la cola y la tasa de transmisión (_i, _i). Aquí, se propone el uso de una nueva variante de TCP es propuesta llamada XPLIT-TCP, que usa dos bucles para proveer funciones mejoradas en el control de congestión. La arquitectura XPLIT es simulada y evaluada empleando la herramienta de simulación NS-2. Finalmente, la tercera contribución de esta tesis consiste en el desarrollo de un arquitectura unificada para el soporte a la QoS en redes satelitales de banda ancha basada en técnicas ”cross-layer”. Esta arquitectura adopta las mejoras propuestas por QoSatArt en la capa de red en combinación con las mejoras propuestas por XPLIT en la capa de transporte

QoSatAr: a cross-layer architecture for E2E QoS provisioning over DVB-S2 broadband satellite systems

This article presents QoSatAr, a cross-layer architecture developed to provide end-to-end quality of service (QoS) guarantees for Internet protocol (IP) traffic over the Digital Video Broadcasting-Second generation (DVB-S2) satellite systems. The architecture design is based on a cross-layer optimization between the physical layer and the network layer to provide QoS provisioning based on the bandwidth availability present in the DVB-S2 satellite channel. Our design is developed at the satellite-independent layers, being in compliance with the ETSI-BSM-QoS standards. The architecture is set up inside the gateway, it includes a Re-Queuing Mechanism (RQM) to enhance the goodput of the EF and AF traffic classes and an adaptive IP scheduler to guarantee the high-priority traffic classes taking into account the channel conditions affected by rain events. One of the most important aspect of the architecture design is that QoSatAr is able to guarantee the QoS requirements for specific traffic flows considering a single parameter: the bandwidth availability which is set at the physical layer (considering adaptive code and modulation adaptation) and sent to the network layer by means of a cross-layer optimization. The architecture has been evaluated using the NS-2 simulator. In this article, we present evaluation metrics, extensive simulations results and conclusions about the performance of the proposed QoSatAr when it is evaluated over a DVB-S2 satellite scenario. The key results show that the implementation of this architecture enables to keep control of the satellite system load while guaranteeing the QoS levels for the high-priority traffic classes even when bandwidth variations due to rain events are experienced. Moreover, using the RQM mechanism the user’s quality of experience is improved while keeping lower delay and jitter values for the high-priority traffic classes. In particular, the AF goodput is enhanced around 33% over the drop tail scheme (on average)

Guide to the selection and application of pneumatic tools

SIGLEAvailable from British Library Document Supply Centre-DSC:97/16597 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Adaptive IP scheduler design to support QoS guarantees over satellite systems

This paper presents an adaptive algorithm for man-aging the weight values of the Weighted Round Robin (WRR)scheduler to provide End-to-End (E2E) Quality of Service (QoS)guarantees for Broadband satellite systems. The weight calcu-lation depends on the capacity variations present in the DigitalVideo Broadcasting-Second Generation (DVB-S2) satellite link.The algorithm is defined to optimize the bandwidth utilizationwhile satisfying the QoS requirements for different traffic classes.The operation of the proposed algorithm is demonstrated usingthe NS-2 simulator tool. The results show that the proposedadaptive WRR algorithm optimizes the bandwidth utilizationwhile enforces the priority level of each service class whenan extreme reduction of bandwidth caused by rain events isexperienced in the satellite system.Peer ReviewedPostprint (author's final draft

XPLIT: A cross-layer architecture for TCP services over DVB-S2/ETSI QoS BSM

This article proposes XPLIT, a new architecture based on TCP cross-layering and splitting for optimizing the transport layer performance in a DVB-S2 satellite link that employs the ETSI QoS Broadband Satellite Multimedia Services (BSM) standard. The main novelty of our proposal is a complete architecture that perfectly fits this new DVB-S2/ETSI QoS BSM scenario. Our architecture includes the design of satellite-optimized cross-layer TCP protocol, called XPLIT-TCP that uses two control loops to properly manage the system load. The proposal has been implemented to be tested in the NS-2 simulator and we include the most interesting performance evaluation results, which show the excellent performance of our architecture for the intended scenarioPeer Reviewe

Analysis of TCP variants over a QoS DVB-S2 system

This paper presents a performance analysis of the TCP protocol considering the DiffServ architecture to provide Quality of Service guarantees working over a Digital Video Broadcasting - Second Generation (DVB-S2) satellite system. The analysis is carried out using the NS-2 simulator tool where three TCP variants are considered: Sack TCP, Hybla TCP and Cubic TCP. The objective is to evaluate the TCP performance taking in to account goodput, friendliness and fairness parameters and the most typical problems presented in a DVB-S2 satellite link such as delay, losses and bandwidth variations.Peer ReviewedPostprint (published version

Cross-layer packet scheduler for QoS support over digital video broadcasting-second generation broadband satellite systems

This article presents a cross-layer packet scheduler to provide end-to-end QoS guarantees for Digital Video Broadcasting-Second Generation (DVB-S2) broadband satellite systems. The scheduler design is based on a cross-layer mechanism defined between the physical and the network layer. It includes an algorithm to guarantee the required QoS specifications established in the service level agreement. The algorithm calculation depends basically on two parameters: the available bandwidth present in a DVB-S2 satellite link and the QoS requirements of each traffic class defined by the satellite operator. The cross-layer scheduler's operation is demonstrated using the NS-2 simulator tool. The results show that the proposed mechanism maximizes the bandwidth utilization while enforcing the priority level of each service class when an extreme reduction of bandwidth caused by rain events is experienced. Copyright (C) 2012 John Wiley & Sons, Ltd.Peer Reviewe

XPLIT: A cross-layer architecture for TCP services over DVB-S2/ETSI QoS BSM

This article proposes XPLIT, a new architecture based on TCP cross-layering and splitting for optimizing the transport layer performance in a DVB-S2 satellite link that employs the ETSI QoS Broadband Satellite Multimedia Services (BSM) standard. The main novelty of our proposal is a complete architecture that perfectly fits this new DVB-S2/ETSI QoS BSM scenario. Our architecture includes the design of satellite-optimized cross-layer TCP protocol, called XPLIT-TCP that uses two control loops to properly manage the system load. The proposal has been implemented to be tested in the NS-2 simulator and we include the most interesting performance evaluation results, which show the excellent performance of our architecture for the intended scenarioPeer Reviewe

Performance evaluation of selected transmission control protocol variants over a digital video broadcasting-second generation broadband satellite multimedia system with QoS

This paper presents an analysis of several Transmission Control Protocol (TCP) variants working over a digital video broadcasting-second generation (DVB-S2) satellite link with the support of the Differentiated Services (DiffServ) architecture to provide quality of service (QoS). This analysis is carried out using the NS-2 simulator tool. Three TCP variants are considered: SACK TCP, Hybla TCP, and CUBIC TCP. These TCP variants are taken as a starting point because they have proven to be the most suitable variants to deal with long delays present in satellite links. The DVB-S2 link also introduces the challenge of dealing with variable bandwidth, whereas the DiffServ architecture introduces the challenge of dealing with different priorities. In this paper, we propose a DiffServ model that includes a modified queuing mechanism to enhance the goodput of the assured forwarding traffic class. This modified DiffServ model is simulated and tested, considering the interaction of the selected TCP variants. In addition, we present evaluation metrics, significant simulations results, and conclusions about the performance of these TCP variants evaluated over the proposed scenario. As a general conclusion, we show that CUBIC TCP is the TCP variant that shows the best performance in terms of goodput, latency, and friendliness.Peer Reviewe

Analysis of TCP variants over a QoS DVB-S2 system

This paper presents a performance analysis of the TCP protocol considering the DiffServ architecture to provide Quality of Service guarantees working over a Digital Video Broadcasting - Second Generation (DVB-S2) satellite system. The analysis is carried out using the NS-2 simulator tool where three TCP variants are considered: Sack TCP, Hybla TCP and Cubic TCP. The objective is to evaluate the TCP performance taking in to account goodput, friendliness and fairness parameters and the most typical problems presented in a DVB-S2 satellite link such as delay, losses and bandwidth variations.Peer Reviewe