No / The design of a network architecture that can efficiently integrate WLAN and cellular networks is a challenging task, particularly when the objective is to make the interoperation between the two networks as seamless and as efficient as possible. To provide end-to-end quality of service (QoS) support is one of the key stages towards such a goal. Due to various constraints, such as the unbalanced capacity of the two systems, handoff from user mobility and unreliable transmission media, end-to-end QoS is difficult to guarantee. In this paper, we propose a generic reservation-based QoS model for the integrated cellular and WLAN networks. It uses an adaptation mechanism to address the above issues and to support end-to-end QoS. The validity of the proposed scheme is demonstrated via simulation experiments. The performance results reveal that this new scheme can considerably improve the system resource utilization and reduce the call blocking probability and handoff dropping probability of the integrated networks while maintaining acceptable QoS to the end users.

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La gran cantidad de contenidos puestos a disposición de los usuarios en Internet, ha exigido estudiar la conveniencia de aplicación de diversas técnicas para mejorar la performance de las redes de telecomunicaciones, las cuales son afectadas por retardos, variación del retardo, ancho de banda y pérdida de paquetes. Dado que, estos parámetros están presentes permanentemente, que a veces no pueden mejorarse por cuestiones físicas y que las aplicaciones poseen requerimientos para su correcto funcionamiento, estas propiedades deben ajustarse dentro de ciertos límites para garantizar a los usuarios la entrega de la información, priorizar el tráfico, minimizar y controlar la congestión, entre otras cosas. Estos límites se acuerdan entre cliente y proveedor mediante Acuerdos de Niveles de Servicio. Desde los comienzos del desarrollo de Internet, estuvo presente un servicio de entrega de datos denominado Mejor Esfuerzo, el cual se caracteriza por la no aplicación de técnicas orientadas a brindar calidad de servicio. Las aplicaciones envían paquetes de datos cada vez que deben hacerlo, en la cantidad que necesiten y sin ningún tipo de permiso ni informe a la red de datos sobre los requerimientos de la transmisión. Resulta innegable que un modelo de estas características no posee la mejor performance ni el mejor desempeño. Para dar soporte a este gran volumen de tráfico se han desarrollado arquitecturas de calidad de servicio que plantean modelos para mejorar la performance de las aplicaciones. El primer modelo se denomina Arquitectura de Servicios Integrados y se caracteriza por analizar el tráfico y aplicar reservas de ancho de banda a determinados flujos de datos asociados a sesiones individuales. En función de cuan tolerante al retardo, a su variación y a la pérdida de paquetes sea una aplicación, se utilizan los servicios Garantizados y de Carga Controlada. El primero aplica estrictos límites de retardo y el segundo es utilizado en ambientes donde las aplicaciones pueden aceptar un cierto grado de variación del retardo. El segundo modelo se denomina Arquitectura de Servicios Diferenciados y se caracteriza por proporcionar diferentes niveles de servicio al tráfico mediante su clasificación en grupos denominados clases. La aplicación de cada una de estas, otorgará al flujo de datos un tratamiento predefinido para el reenvío de paquetes. El enfoque de la arquitectura de Servicios Diferenciados se encuentra en algún punto entre el servicio de Mejor Esfuerzo y la arquitectura de Servicios Integrados, pues, trata de dar un paso más allá del modelo de mejor esfuerzo para ofrecer un servicio mejor que el de mejor esfuerzo. En el presente trabajo se estudiarán técnicas para evitar y controlar la congestión, como así también la aplicación de la aplicación de políticas y modelado del tráfico. Este desarrollo inicial, complementa la posterior descripción de las arquitecturas de calidad de servicio mencionadas. / The vast quantity of content at Internet users’ disposal has demanded the consideration of applying diverse techniques to improve web performance in telecommunication seriously affected by delay, delay variation (jitter), bandwidth and packet loss. As these parameters are permanently present, sometimes it is not possible to improve them both due to physical reasons and the fact that applications possess requirement for their correct functioning, those properties must be adjusted within certain limits to guarantee users’ information delivery, prioritize traffic, minimize and control congestion and so on. Such limits are agreed upon between client and provider by Service Level Agreements. From the beginning of Internet development, a delivery service called Best Effort has been present characterised by not applying techniques oriented to provide quality of service. Applications send data packets each time they must, in the quantity needed and with neither permission nor report to the network of transmission requirements data. It goes without saying that such model does not perform or function well. Quality of Service Architectures has been developed to support this vast volume of traffic establishing models to improve applications performance. The first one is called Integrated Services Architecture, it analyses traffic and applies bandwidth reserves to determined data flows associated to individual sessions. Guaranteed and Controlled Load services are used depending on how tolerant is an application to delay, jitter and packet loss. The first one applies strict delay limits and the second one is used when applications can accept certain degree of jitter. The second architecture is called Differentiated Services and it provides different levels of services through sorting traffic in groups called classes. The use of each one of this will provide the data flow with predefined treatment for packet forwarding. The Architecture of Differentiated Services locates itself between the Best Effort service and the Integrated Services Architecture because it tries to go a step forward beyond the Best Effort model to offer a better service. The present work studies the techniques to control and avoid congestion as well as the application of policies and traffic modelling. This initial development complements the subsequent description of the service quality architectures above mentioned.

Voice over DSL (VoDSL) is a technology that enables the transport of data and multiple voice calls over a single copper-pair. VoDSL employs packet voice technology instead of the traditional circuit switched voice. Voice over ATM (VoATM) and Voice over IP (VoIP) are the two main alternatives for carrying voice packets over DSL. ATM is currently the preferred technology, since it offers the advantage of ATM's built-in Quality of Service (QoS) mechanisms. IP, on the other hand, cannot provide QoS guarantees in its traditional form. IP QoS mechanisms have been evolved only in the recent years. VoIP has gained popularity in the core networks. If it could replace VoATM in the access networks, it would open the door for end-to-end IP telephony that would result in major cost savings. In this thesis, we propose a VoIP-based VoDSL architecture that provides QoS guarantees comparable to those offered by ATM in the DSL access network. Our QoS architecture supports Premium and Regular service categories for voice traffic and the Best-Effort service category for data traffic. Voice and data packets are placed in separate output queues at the bottleneck link. The Weighted Fair Queuing algorithm in used to schedule voice and data packets for transmission over the bottleneck link. Fragmentation of large data packets reduces the waiting time for voice packets in the link. We also propose a new admission control mechanism called Admission Control by Implicit Signaling. This mechanism takes advantage of application layer signaling by mapping it to the IP header. The router can infer the resource requirements for the connection by looking at certain field in the IP header of the application layer signaling packets. This eliminates the need for an explicit signaling protocol. We evaluate the performance of our QoS architecture by means of a simulation study. Our primary metrics are the end-to-end delay of voice packets across the access network and the bandwidth consumed by a voice call. Our results show that the end-to-end delays of voice packets in our VoIP architecture are comparable to that in the VoATM architecture. ACIS limits the number of voice calls admitted into the premium service class and provides guaranteed service to those calls under all loads. It also provides acceptable service to regular calls under light loads. We also show that PPP is a better choice than ATM as a Layer 2 protocol for our VoIP architecture. PPP offers the advantages of low bandwidth requirement and interleaving of voice packets in between fragments of large data packets during transmission over the bottleneck link. We conclude that our VoIP architecture would be suitable for future VoDSL deployments. / Master of Science

Video-on-Demand (VoD) is a service that allows people to request and view stored videos or movies of their choice directly online from a VoD service provider. The selected streaming videos are then delivered over the broadband Internet. The bursty nature of Variable-Bit-Rate (VBR) compressed video (such as MPEG) poses some important issues for video delivery over high-speed networks due to its significant bit rate variation over multiple time scales. However, sufficient quality of service (QoS) mechanisms must be in place before it can be widely enabled and deployed over Internet. Conventionally a static bandwidth level close to the peak rate is reserved for a streaming video flow. Any static allocation of network resources for VBR video traffic would be difficult and inefficient considering the peak rate to be significantly higher than the average data rate. Since the traffic pattern over time is already known for pre-recorded videos, this issue is addressed by the Renegotiated Constant Bit Rate (RCBR) service which proposes QoS allocation over multiple time scales. Since this mechanism has been tested via simulations and analysis only we implemented it on a real test bed with a VoD server and clients to study its performance. We observed that under heavy bandwidth constraints the performance of RCBR is much better than traditional CBR in terms of packet loss rate. We also implement a new Adaptive Buffer Window mechanism and the concept of application level smoothing to increase the scalability of a VoD server. / Master of Science

This thesis introduces a novel framework for enabling intelligent machines and robots with the fifth-generation (5G) cellular network technology. Autonomous robots, such as Unmanned Aerial Vehicles (UAVs), Autonomous Guided Vehicles (AGVs), and more, can notably benefit from multi-agent collaboration, human supervision, or operation guidance, as well as from external computational units such as cloud edge servers, in all of which a framework to utilize reliable communication infrastructure is needed. Autonomous robots are often employed to alleviate humans by operating demanding missions such as inspection and data collection in harsh environments or time-critical operations in industrial environments - to name a few. For delivering data to other robots to maximize the effectiveness of the considered mission, for executing complex algorithms by offloading them into the edge cloud, or for including a human operator/supervisor into the loop, the 5G network and its advanced Quality of Service (QoS) features can be employed to facilitate the establishment of such a framework. This work focuses on establishing a baseline for integrating various time-critical robotics platforms and applications with a 5G network. These applications include offloading computationally intensive Model Predictive Control (MPC) algorithms for trajectory tracking of UAVs into the edge cloud, adapting data sharing in multi-robot systems based on network conditions, and enhancing network-aware surrounding autonomy components. We have identified a set of key performance indicators (KPIs) crucially affecting the performance of network-dependent robots and applications. We have proposed novel solutions and mechanisms to meet these requirements, which aim to combine traditional robotics techniques to enhance mission reliability with the exploitation of 5G features such as the QoS framework. Ultimately, our goal was to develop solutions that adhere to the essential paradigm of co-designing robotics with networks. We thoroughly evaluated all presented research using real-life platforms and 5G networks.

With the rising popularity of Voice over IP (VoIP) services, understanding the effects of a global network on Quality of Service is critical for the providers of VoIP applications. This thesis builds on a model that analyzes the round trip time, packet delay jitter, and packet loss between endpoints on an Autonomous System (AS) level, extending it by mapping AS pairs onto an Internet topology. This model is used to produce a mean opinion score estimate. The mapping is introduced to reduce the size of the problem in order to improve computation times and improve accuracy of estimates. The results of testing show that estimating mean opinion score from this model is not desirable. It also shows that the path mapping does not affect accuracy, but does improve computation times as the input data grows in volume.

Localised QoS routing is a relatively new, alternative and viable approach to solve the problems of traditional QoS routing algorithms which use global state information resulting in the imposition of a large communication overhead and route flapping. They make use of a localised view of the network QoS state in source nodes to select paths and route flows to destination nodes. Proportional Sticky Routing (PSR) and Credit Based Routing (CBR) have been proposed as localised QoS routing schemes and these can offer comparable performances. However, since network state information for a specific path is only updated when the path is used, PSR and CBR operate with decision criteria that are often stale for paths that are used infrequently. The aim of this thesis is to focus on localised QoS routing and contribute to enhancing the scalability of QoS routing algorithms. In this thesis we have developed three new localised QoS routing schemes which are called Score Based QoS Routing (SBR), Bandwidth Based QoS Routing (BBR) and Delay Based Routing (DBR). In some of these schemes, the path setup procedure is distributed and uses the current network state to make decisions thus avoiding problems of staleness. The methods also avoid any complicated calculations. Both SBR and BBR use bandwidth as the QoS metric and mean delay is used as the QoS metric in DBR. Extensive simulations are applied to compare the performance of our proposed algorithms with CBR and the global Dijkstra's algorithm for different update intervals of link state, different network topologies and using different flow arrival distributions under a wide range of traffic loads. It is demonstrated by simulation that the three proposed algorithms offer a superior performance under comparable conditions to the other localised and global algorithms.