856 research outputs found

    Network coding-aided MAC protocols for cooperative wireless networks

    Get PDF
    The introduction of third generation (3G) technologies has caused a vast proliferation of wireless devices and networks, generating an increasing demand for high level Quality of Service (QoS). The wide spread of mobile applications has further reinforced the user need for communication, motivating at the same time the concepts of user cooperation and data dissemination. However, this trend towards continuous exchange of information and ubiquitous connectivity is inherently restricted by the energy-greedy functionalities of high-end devices. These limitations, along with the pressure exerted on the Information and Communications Technology (ICT) industry towards energy awareness, have induced the design of novel energy efficient schemes and algorithms. In this context, the Medium Access Control (MAC) layer plays a key role, since it is mainly responsible for the channel access regulation, the transmission scheduling and the resource allocation, thus constituting an appropriate point to effectively address energy efficiency issues that arise due to the users overcrowding. This dissertation provides a contribution to the design, analysis and evaluation of novel MAC protocols for cooperative wireless networks. In our attempt to design energy efficient MAC schemes, we were extensively assisted by the introduction of new techniques, such as Network Coding (NC), that intrinsically bring considerable gains in system performance. The main thesis contributions are divided into two parts. The first part presents NCCARQ, a novel NC-aided Cooperative Automatic Repeat reQuest (ARQ) MAC protocol for wireless networks. NCCARQ introduces a new access paradigm for cooperative ARQ schemes, exploiting NC benefits in bidirectional communication among wireless users. The NCCARQ performance in terms of QoS and energy efficiency is assessed by means of analytical probabilistic models and extensive computer-based simulations, revealing the significant gains we can achieve compared to standardized MAC solutions. In addition, the impact of realistic wireless channel conditions on the MAC protocol operation further motivated us to study the NCCARQ performance in wireless links affected by correlated shadowing, showing that the channel correlation may adversely affect the distributed cooperation benefits. The second part of the thesis is dedicated to the investigation of MAC issues in wireless data dissemination scenarios. In particular, the existence of multiple source nodes in such scenarios generates conflicting situations, considering the selfish behavior of the wireless devices that want to maximize their battery lifetime. Bearing in mind the energy efficiency importance, we propose game theoretic medium access strategies, applying energy-based utility functions which inherently imply energy awareness. In addition, Random Linear NC (RLNC) techniques are adopted to eliminate the need of exchanging excessive control packets, while Analog NC (ANC) is employed to efface the impact of collisions throughout the communication. During the elaboration of this thesis, two general key conclusions have been extracted. First, there is a fundamental requirement for implementation of new MAC protocols in order to effectively deal with state-of-the-art techniques (e.g., NC), recently introduced to enhance both the performance and the energy efficiency of the network. Second, we highlight the importance of designing novel energy efficient MAC protocols, taking into account that traditional approaches - designed mainly to assist the collision avoidance in wireless networks - tend to be obsolete.La presente tesis doctoral contribuye al diseño, análisis y evaluación de nuevos protocolos MAC cooperativos para redes inalámbricas. La introducción de nuevas técnicas, tales como la codificación de red (NC), que intrínsecamente llevan un considerable aumento en el rendimiento del sistema, nos ayudó ampliamente durante el diseño de protocolos MAC energéticamente eficientes. Las principales contribuciones de esta tesis se dividen en dos partes. La primera parte presenta el NCCARQ, un protocolo cooperativo de retransmisión automática (ARQ), asistido por NC para redes inalámbricas. La segunda parte de la tesis se centra en el diseño de protocolos de capa MAC en escenarios inalámbricos de difusión de datos. Teniendo en cuenta la importancia de la eficiencia energética, se proponen técnicas de acceso al medio basadas en teoría de juegos dónde las funciones objetivo están motivadas por el consumo energético. Las soluciones propuestas son evaluadas por medio de modelos analíticos y simulaciones por ordenador

    Radio resource management techniques for QoS provision in 5G networks

    Get PDF
    Premi extraordinari doctorat UPC curs 2017-2018. Àmbit d’Enginyeria de les TICAs numerous mobile applications and over-the-top (OTT) services emerge and mobile Internet connectivity becomes ubiquitous, the provision of high quality of service (QoS) is more challenging for mobile network operators (MNOs). Research efforts focus on the development of innovative resource management techniques and have introduced the long term evolution advanced (LTE-A) communication standard. Novel business models make the growth of network capacity sustainable by enabling MNOs to combine their resources. The fifth generation (5G) mobile networks will involve technologies and business stakeholders with different capabilities and demands that may affect the QoS provision, requiring efficient radio resource sharing. The need for higher network capacity has introduced novel technologies that improve resource allocation efficiency. Direct connectivity among user equipment terminals (UEs) circumventing the LTE-A infrastructure alleviates the network overload. Part of mobile traffic is offloaded to outband device-to-device (D2D) connections (in unlicensed spectrum) enabling data exchange between UEs directly or via UEs-relays. Still, MNOs need additional spectrum resources and infrastructure. The inter-operator network sharing concept has emerged motivating the adoption of virtualization that enables network slicing, i.e., dynamic separation of resources in virtual slices (VSs). VSs are managed in isolation by different tenants using software defined networking and encompass core and radio access network resources allocated periodically to UEs. When UEs access OTT applications, flows with different QoS demands and priorities determined by OTT service providers (OSPs) are generated. OSPs’ policies should be considered in VS allocation. The coexisting technologies, business models and stakeholders require sophisticated radio resource management (RRM) techniques. To that end, RRM is performed in a complex ecosystem. When D2D communication involves data concurrently downloaded by the mobile network, QoS may be affected by LTE-A network parameters (resource scheduling policy, downlink channel conditions). It is also affected by the relay selection, as UEs may not be willing to help unknown UE pairs and UEs’ social ties in mobile applications may influence willingness for D2D cooperation. Thus, effective medium access control (MAC) mechanisms should coordinate D2D transmissions employing advanced techniques, e.g., network coding (NC). When UEs access OTT applications, OSPs’ policies are not considered by MNOs in RRM and OSPs cannot apply flow prioritization. Network neutrality issues also arise when OSPs claim resources from MNOs aiming to minimize grade of service (GoS). OSPs’ intervention may delay flows’ accommodation due to the time required for OSP-MNO interaction and the time the flows spent waiting for resources. This thesis proposes novel solutions to the RRM issues of outband D2D communication and VS allocation for OSPs in 5G networks. We present a cooperative D2D MAC protocol that leverages the opportunities for NC in D2D communication under the influence of LTE-A network parameters and its throughput performance analysis. The protocol improves D2D throughput and energy efficiency, especially for UEs with better downlink channel conditions. We next introduce social awareness in D2D MAC design and present a social-aware cooperative D2D MAC protocol that employs UEs’ social ties to promote the use of friendly relays reducing the total energy consumption. Motivated by the lack of approaches for OSP-oriented RRM, we present a novel flow prioritization algorithm based on matching theory that applies OSPs’ policies respecting the network neutrality and the analysis of its GoS and delay performance. The algorithm maintains low overhead and delay without affecting fairness among OSPs. Our techniques highlight the QoS improvement induced by the joint consideration of different technologies and business stakeholders in RRM design.A medida que varias aplicaciones móviles y servicios over-the-top (OTT) surgen y el Internet móvil se vuelve ubicua, la prestación de alta calidad de servicio (QoS) es desafiante para los operadores de red móvil (MNOs). Los estudios de investigación se enfocan en técnicas innovadoras para la gestión de recursos de red y han resultado en la especificación del estándar de comunicación long term evolution advanced (LTE-A). Modelos comerciales nuevos hacen que el crecimiento de la capacidad de red sea sostenible al permitir que MNOs combinen sus recursos. La quinta generación (5G) de redes móviles implicará tecnologías y partes comerciales interesadas con varias habilidades y demandas que pueden afectar la provisión de QoS y demandan la gestión eficaz de recursos de radio. La necesidad de capacidad de red más alta ha introducido tecnologías que hacen más eficiente la asignación de recursos. La conectividad directa entre terminales de equipos de usuarios (UEs) eludiendo la infraestructura LTE-A alivia la sobrecarga de red. Parte del tráfico es dirigido a conexiones de dispositivo a dispositivo (D2D) outband permitiendo la comunicación de UEs directamente o con relés. Los MNOs necesitan nuevos recursos de espectro e infraestructura. El intercambio de recursos entre MNOs ha surgido motivando la adopción de virtualización que realiza la segmentación de red i.e., la separación dinámica de recursos en trozos virtuales (VSs). Los VSs son administrados de forma aislada por inquilinos diferentes con software defined networking y abarcan recursos de red core y radio access asignadas periódicamente a UEs. Cuando UEs usan aplicaciones OTT, flujos de aplicación con demandas y prioridades definidas por proveedores de servicios OTT (OSPs) se generan. Las políticas de OSPs deben ser integradas en la asignación de VSs. La coexistencia de varias tecnologías y partes comerciales demanda técnicas sofisticadas de gestión de recursos radio (RRM). Con ese fin, la RRM se realiza en un ecosistema complejo. Si la comunicación D2D involucra datos descargados simultáneamente por la red móvil, los parámetros de red LTE-A (política de scheduling de recursos, condiciones de canal downlink) afectan el QoS. La selección de relés afecta el rendimiento porque los UEs no desean siempre ayudar a UEs desconocidos. Las relaciones sociales de los UEs en aplicaciones móviles pueden determinar la voluntad para la comunicación cooperativa D2D. Por lo tanto, mecanismos de control de acceso al medio (MAC) deben coordinar las transmisiones D2D con técnicas avanzadas ej., codificación de red. Si los UEs usan servicios OTT, las políticas de OSPs no son consideradas en RRM y los OSPs no emplean flujos prioritarios. Problemas de neutralidad de red surgen cuando los OSPs reclaman recursos de MNOs para minimizar el grado de servicio (GoS). La intervención de OSPs puede causar retraso en el servicio de flujos debido a la interacción OSP-MNO y el tiempo requerido para que los flujos reciban recursos. Esta tesis presenta soluciones nuevas para los problemas RRM de comunicación D2D outband y asignación de VSs a OSPs en redes 5G. Proponemos un protocolo D2D MAC cooperativo que explota las oportunidades de NC bajo la influencia de parámetros de red LTE-A y su análisis de rendimiento. El protocolo mejora el rendimiento y la eficiencia energética especialmente para UEs con mejores condiciones de canal downlink. Introducimos la conciencia social en el D2D MAC y proponemos un protocolo que utiliza relaciones sociales de UEs para elegir relés-amigos y reduce el consumo de energía. Dada la falta de técnicas que aborden el problema RRM de OSPs presentamos un algoritmo que aplique políticas de OSPs y respete la neutralidad usando la teoría de matching, y su análisis de GoS y retraso. El algoritmo induce bajo coste y retraso sin afectar la imparcialidad entre OSPs. Estas técnicas demuestran la mejora de QoS gracias a la consideración de tecnologas y partes comerciales diferentes en RRM.Award-winningPostprint (published version

    D13.2 Techniques and performance analysis on energy- and bandwidth-efficient communications and networking

    Get PDF
    Deliverable D13.2 del projecte europeu NEWCOM#The report presents the status of the research work of the various Joint Research Activities (JRA) in WP1.3 and the results that were developed up to the second year of the project. For each activity there is a description, an illustration of the adherence to and relevance with the identified fundamental open issues, a short presentation of the main results, and a roadmap for the future joint research. In the Annex, for each JRA, the main technical details on specific scientific activities are described in detail.Peer ReviewedPostprint (published version

    Recent Advances in Cellular D2D Communications

    Get PDF
    Device-to-device (D2D) communications have attracted a great deal of attention from researchers in recent years. It is a promising technique for offloading local traffic from cellular base stations by allowing local devices, in physical proximity, to communicate directly with each other. Furthermore, through relaying, D2D is also a promising approach to enhancing service coverage at cell edges or in black spots. However, there are many challenges to realizing the full benefits of D2D. For one, minimizing the interference between legacy cellular and D2D users operating in underlay mode is still an active research issue. With the 5th generation (5G) communication systems expected to be the main data carrier for the Internet-of-Things (IoT) paradigm, the potential role of D2D and its scalability to support massive IoT devices and their machine-centric (as opposed to human-centric) communications need to be investigated. New challenges have also arisen from new enabling technologies for D2D communications, such as non-orthogonal multiple access (NOMA) and blockchain technologies, which call for new solutions to be proposed. This edited book presents a collection of ten chapters, including one review and nine original research works on addressing many of the aforementioned challenges and beyond

    Game Theory for Multi-Access Edge Computing:Survey, Use Cases, and Future Trends

    Get PDF
    Game theory (GT) has been used with significant success to formulate, and either design or optimize, the operation of many representative communications and networking scenarios. The games in these scenarios involve, as usual, diverse players with conflicting goals. This paper primarily surveys the literature that has applied theoretical games to wireless networks, emphasizing use cases of upcoming multiaccess edge computing (MEC). MEC is relatively new and offers cloud services at the network periphery, aiming to reduce service latency backhaul load, and enhance relevant operational aspects such as quality of experience or security. Our presentation of GT is focused on the major challenges imposed by MEC services over the wireless resources. The survey is divided into classical and evolutionary games. Then, our discussion proceeds to more specific aspects which have a considerable impact on the game's usefulness, namely, rational versus evolving strategies, cooperation among players, available game information, the way the game is played (single turn, repeated), the game's model evaluation, and how the model results can be applied for both optimizing resource-constrained resources and balancing diverse tradeoffs in real edge networking scenarios. Finally, we reflect on lessons learned, highlighting future trends and research directions for applying theoretical model games in upcoming MEC services, considering both network design issues and usage scenarios

    Achieving reliable and enhanced communication in vehicular ad hoc networks (VANETs)

    Get PDF
    A thesis submitted to the University of Bedfordshire in partial fulfilment of the requirement for the degree of Doctor of PhilosophyWith the envisioned age of Internet of Things (IoTs), different aspects of Intelligent Transportation System (ITS) will be linked so as to advance road transportation safety, ease congestion of road traffic, lessen air pollution, improve passenger transportation comfort and significantly reduce road accidents. In vehicular networks, regular exchange of current position, direction, speed, etc., enable mobile vehicle to foresee an imminent vehicle accident and notify the driver early enough in order to take appropriate action(s) or the vehicle on its own may take adequate preventive measures to avert the looming accident. Actualizing this concept requires use of shared media access protocol that is capable of guaranteeing reliable and timely broadcast of safety messages. This dissertation investigates the use of Network Coding (NC) techniques to enrich the content of each transmission and ensure improved high reliability of the broadcasted safety messages with less number of retransmissions. A Code Aided Retransmission-based Error Recovery (CARER) protocol is proposed. In order to avoid broadcast storm problem, a rebroadcasting vehicle selection metric η, is developed, which is used to select a vehicle that will rebroadcast the received encoded message. Although the proposed CARER protocol demonstrates an impressive performance, the level of incurred overhead is fairly high due to the use of complex rebroadcasting vehicle selection metric. To resolve this issue, a Random Network Coding (RNC) and vehicle clustering based vehicular communication scheme with low algorithmic complexity, named Reliable and Enhanced Cooperative Cross-layer MAC (RECMAC) scheme, is proposed. The use of this clustering technique enables RECMAC to subdivide the vehicular network into small manageable, coordinated clusters which further improve transmission reliability and minimise negative impact of network overhead. Similarly, a Cluster Head (CH) selection metric ℱ(\u1d457) is designed, which is used to determine and select the most suitably qualified candidate to become the CH of a particular cluster. Finally, in order to investigate the impact of available radio spectral resource, an in-depth study of the required amount of spectrum sufficient to support high transmission reliability and minimum latency requirements of critical road safety messages in vehicular networks was carried out. The performance of the proposed schemes was clearly shown with detailed theoretical analysis and was further validated with simulation experiments
    corecore