Green Cellular Networks: A Survey, Some Research Issues and Challenges

Energy efficiency in cellular networks is a growing concern for cellular operators to not only maintain profitability, but also to reduce the overall environment effects. This emerging trend of achieving energy efficiency in cellular networks is motivating the standardization authorities and network operators to continuously explore future technologies in order to bring improvements in the entire network infrastructure. In this article, we present a brief survey of methods to improve the power efficiency of cellular networks, explore some research issues and challenges and suggest some techniques to enable an energy efficient or "green" cellular network. Since base stations consume a maximum portion of the total energy used in a cellular system, we will first provide a comprehensive survey on techniques to obtain energy savings in base stations. Next, we discuss how heterogeneous network deployment based on micro, pico and femto-cells can be used to achieve this goal. Since cognitive radio and cooperative relaying are undisputed future technologies in this regard, we propose a research vision to make these technologies more energy efficient. Lastly, we explore some broader perspectives in realizing a "green" cellular network technologyComment: 16 pages, 5 figures, 2 table

MEC vs MCC: performance analysis of real-time applications

Hoje em dia, numerosas são as aplicações que apresentam um uso intensivo de recursos empurrando os requisitos computacionais e a demanda de energia dos dispositivos para além das suas capacidades. Atentando na arquitetura Mobile Cloud, que disponibiliza plataformas funcionais e aplicações emergentes (como Realidade Aumentada (AR), Realidade Virtual (VR), jogos online em tempo real, etc.), são evidentes estes desafios directamente relacionados com a latência, consumo de energia, e requisitos de privacidade. O Mobile Edge Computing (MEC) é uma tecnologia recente que aborda os obstáculos de desempenho enfrentados pela Mobile Cloud Computing (MCC), procurando solucioná-los O MEC aproxima as funcionalidades de computação e de armazenamento da periferia da rede. Neste trabalho descreve-se a arquitetura MEC assim como os principais tipos soluções para a sua implementação. Apresenta-se a arquitetura de referência da tecnologia cloudlet e uma comparação com o modelo de arquitetura ainda em desenvolvimento e padronização pelo ETSI. Um dos propósitos do MEC é permitir remover dos dispositivos tarefas intensivas das aplicações para melhorar a computação, a capacidade de resposta e a duração da bateria dos dispositivos móveis. O objetivo deste trabalho é estudar, comparar e avaliar o desempenho das arquiteturas MEC e MCC para o provisionamento de tarefas intensivas de aplicações com uso intenso de computação. Os cenários de teste foram configurados utilizando esse tipo de aplicações em ambas as implementações de MEC e MCC. Os resultados do teste deste estudo permitem constatar que o MEC apresenta melhor desempenho do que o MCC relativamente à latência e à qualidade de experiência do utilizador. Além disso, os resultados dos testes permitem quantificar o benefício efetivo tecnologia MEC.Numerous applications, such as Augmented Reality (AR), Virtual Reality (VR), real-time online gaming are resource-intensive applications and consequently, are pushing the computational requirements and energy demands of the mobile devices beyond their capabilities. Despite the fact that mobile cloud architecture has practical and functional platforms, these new emerging applications present several challenges regarding latency, energy consumption, context awareness, and privacy enhancement. Mobile Edge Computing (MEC) is a new resourceful and intermediary technology, that addresses the performance hurdles faced by Mobile Cloud Computing (MCC), and brings computing and storage closer to the network edge. This work introduces the MEC architecture and some of edge computing implementations. It presents the reference architecture of the cloudlet technology and provides a comparison with the architecture model that is under standardization by ETSI. MEC can offload intensive tasks from applications to enhance computation, responsiveness and battery life of the mobile devices. The objective of this work is to study and evaluate the performance of MEC and MCC architectures for provisioning offload intensive tasks from compute-intensive applications. Test scenarios were set up with use cases with this kind of applications for both MEC and MCC implementations. The test results of this study enable to support evidence that the MEC presents better performance than cloud computing regarding latency and user quality of experience. Moreover, the results of the tests enable to quantify the effective benefit of the MEC approach

Nomadic fog storage

Mobile services incrementally demand for further processing and storage. However, mobile devices are known for their constrains in terms of processing, storage, and energy. Early proposals have addressed these aspects; by having mobile devices access remote clouds. But these proposals suffer from long latencies and backhaul bandwidth limitations in retrieving data. To mitigate these issues, edge clouds have been proposed. Using this paradigm, intermediate nodes are placed between the mobile devices and the remote cloud. These intermediate nodes should fulfill the end users’ resource requests, namely data and processing capability, and reduce the energy consumption on the mobile devices’ batteries. But then again, mobile traffic demand is increasing exponentially and there is a greater than ever evolution of mobile device’s available resources. This urges the use of mobile nodes’ extra capabilities for fulfilling the requisites imposed by new mobile applications. In this new scenario, the mobile devices should become both consumers and providers of the emerging services. The current work researches on this possibility by designing, implementing and testing a novel nomadic fog storage system that uses fog and mobile nodes to support the upcoming applications. In addition, a novel resource allocation algorithm has been developed that considers the available energy on mobile devices and the network topology. It also includes a replica management module based on data popularity. The comprehensive evaluation of the fog proposal has evidenced that it is responsive, offloads traffic from the backhaul links, and enables a fair energy depletion among mobiles nodes by storing content in neighbor nodes with higher battery autonomy.Os serviços móveis requerem cada vez mais poder de processamento e armazenamento. Contudo, os dispositivos móveis são conhecidos por serem limitados em termos de armazenamento, processamento e energia. Como solução, os dispositivos móveis começaram a aceder a estes recursos através de nuvens distantes. No entanto, estas sofrem de longas latências e limitações na largura de banda da rede, ao aceder aos recursos. Para resolver estas questões, foram propostas soluções de edge computing. Estas, colocam nós intermediários entre os dispositivos móveis e a nuvem remota, que são responsáveis por responder aos pedidos de recursos por parte dos utilizadores finais. Dados os avanços na tecnologia dos dispositivos móveis e o aumento da sua utilização, torna-se cada mais pertinente a utilização destes próprios dispositivos para fornecer os serviços da nuvem. Desta forma, o dispositivo móvel torna-se consumidor e fornecedor do serviço nuvem. O trabalho atual investiga esta vertente, implementado e testando um sistema que utiliza dispositivos móveis e nós no “fog”, para suportar os serviços móveis emergentes. Foi ainda implementado um algoritmo de alocação de recursos que considera os níveis de energia e a topologia da rede, bem como um módulo que gere a replicação de dados no sistema de acordo com a sua popularidade. Os resultados obtidos provam que o sistema é responsivo, alivia o tráfego nas ligações no core, e demonstra uma distribuição justa do consumo de energia no sistema através de uma disseminação eficaz de conteúdo nos nós da periferia da rede mais próximos dos nós consumidores

User-centric power-friendly quality-based network selection strategy for heterogeneous wireless environments

The ‘Always Best Connected’ vision is built around the scenario of a mobile user seamlessly roaming within a multi-operator multi-technology multi-terminal multi-application multi-user environment supported by the next generation of wireless networks. In this heterogeneous environment, users equipped with multi-mode wireless mobile devices will access rich media services via one or more access networks. All these access networks may differ in terms of technology, coverage range, available bandwidth, operator, monetary cost, energy usage etc. In this context, there is a need for a smart network selection decision to be made, to choose the best available network option to cater for the user’s current application and requirements. The decision is a difficult one, especially given the number and dynamics of the possible input parameters. What parameters are used and how those parameters model the application requirements and user needs is important. Also, game theory approaches can be used to model and analyze the cooperative or competitive interaction between the rational decision makers involved, which are users, seeking to get good service quality at good value prices, and/or the network operators, trying to increase their revenue. This thesis presents the roadmap towards an ‘Always Best Connected’ environment. The proposed solution includes an Adapt-or-Handover solution which makes use of a Signal Strength-based Adaptive Multimedia Delivery mechanism (SAMMy) and a Power-Friendly Access Network Selection Strategy (PoFANS) in order to help the user in taking decisions, and to improve the energy efficiency at the end-user mobile device. A Reputation-based System is proposed, which models the user-network interaction as a repeated cooperative game following the repeated Prisoner’s Dilemma game from Game Theory. It combines reputation-based systems, game theory and a network selection mechanism in order to create a reputation-based heterogeneous environment. In this environment, the users keep track of their individual history with the visited networks. Every time, a user connects to a network the user-network interaction game is played. The outcome of the game is a network reputation factor which reflects the network’s previous behavior in assuring service guarantees to the user. The network reputation factor will impact the decision taken by the user next time, when he/she will have to decide whether to connect or not to that specific network. The performance of the proposed solutions was evaluated through in-depth analysis and both simulation-based and experimental-oriented testing. The results clearly show improved performance of the proposed solutions in comparison with other similar state-of-the-art solutions. An energy consumption study for a Google Nexus One streaming adaptive multimedia was performed, and a comprehensive survey on related Game Theory research are provided as part of the work

Quality of service differentiation for multimedia delivery in wireless LANs

Delivering multimedia content to heterogeneous devices over a variable networking environment while maintaining high quality levels involves many technical challenges. The research reported in this thesis presents a solution for Quality of Service (QoS)-based service differentiation when delivering multimedia content over the wireless LANs. This thesis has three major contributions outlined below: 1. A Model-based Bandwidth Estimation algorithm (MBE), which estimates the available bandwidth based on novel TCP and UDP throughput models over IEEE 802.11 WLANs. MBE has been modelled, implemented, and tested through simulations and real life testing. In comparison with other bandwidth estimation techniques, MBE shows better performance in terms of error rate, overhead, and loss. 2. An intelligent Prioritized Adaptive Scheme (iPAS), which provides QoS service differentiation for multimedia delivery in wireless networks. iPAS assigns dynamic priorities to various streams and determines their bandwidth share by employing a probabilistic approach-which makes use of stereotypes. The total bandwidth to be allocated is estimated using MBE. The priority level of individual stream is variable and dependent on stream-related characteristics and delivery QoS parameters. iPAS can be deployed seamlessly over the original IEEE 802.11 protocols and can be included in the IEEE 802.21 framework in order to optimize the control signal communication. iPAS has been modelled, implemented, and evaluated via simulations. The results demonstrate that iPAS achieves better performance than the equal channel access mechanism over IEEE 802.11 DCF and a service differentiation scheme on top of IEEE 802.11e EDCA, in terms of fairness, throughput, delay, loss, and estimated PSNR. Additionally, both objective and subjective video quality assessment have been performed using a prototype system. 3. A QoS-based Downlink/Uplink Fairness Scheme, which uses the stereotypes-based structure to balance the QoS parameters (i.e. throughput, delay, and loss) between downlink and uplink VoIP traffic. The proposed scheme has been modelled and tested through simulations. The results show that, in comparison with other downlink/uplink fairness-oriented solutions, the proposed scheme performs better in terms of VoIP capacity and fairness level between downlink and uplink traffic

Analysis, simulation and testing of ITS applications based on wireless communication technologies

Intelligent Transportation Systems (ITS) aim to improve road transport safety and efficiency, to manage road networks in the interest of the society and to provide real time responses to events. In order to reach these goals, real time feedback to the drivers is expected through the integration of telecommunications, sensing and information technologies with transport engineering. Wireless communication technologies, that have been used in industrial applications for more than 30 years, play a crucial role in ITS, as based on the concept of multiple devices (on both vehicle and infrastructure side) interconnected in different ways. Connectivity, in tandem with sensing technologies, is fuelling the innovations that will inevitably lead to the next big opportunity for road transport: autonomous vehicles. Therefore, this study has investigated - through analysis, simulation and field testing – on applications based on wireless communication technologies meant to support both Data acquisition and Data diffusion as fundamental aspects/ phases in ITS, where data is widely individuated as being the key element

Integration of Heterogeneous Networks: Protocols, Technologies, and Applications

Today, the possibility of being connected to the Internet at every time and without interruption is almost a reality. The great capabilities of new generation cellular networks and their wide coverage enable people to use the innumerable resources of the Internet, almost everywhere and in any mobility scenario. All modern mobile devices have multiple interfaces to get connected to the Internet, and (almost) all smartphone users think to know which interface is the best one to use in a specific situation. In particular, despite the great improvement of cellular networks, in certain situations, the use of an alternative network (for instance, WiFi, is to be preferred). Therefore, the selection of the best network is not straightforward. If we change perspective and we do not talk about people and their smartphones, rather about mobile machines (say vehicles) that have to stay connected in order to provide or to receive a certain service, then the matter of finding, at every time, the best network to connect to, appears a little more urgent. Furthermore, since in some situations it could be very important to have a performing connection, for example with very low delay, then it is evident that the selection of the best network is not trivial. The characteristics of the networks to use, in order to choose the best network, are different according to the application at hand. A world where machines move automatically and use the Internet just like humans seems at the moment far away, but it is rapidly approaching. Besides the problem of network selection, one could wonder why one should just use the best network, instead of using all networks available in order to get the best "sides" of all? The development of efficient methods for the integration of multiple networks is an interesting but still open research area. This thesis focuses on the interaction and integration of heterogeneous networks. Several innovative protocols, technologies, and applications developed, in order to make network integration easier for humans and automatic for machines, will be presented

Development and evaluation of smartphone-based ITS applications for vehicular networks

[ES] Una de las áreas de investigación que está recibiendo más atención recientemente es la de vehículos autónomos. Los investigadores están en este momento centrados en el tercer de los cinco niveles de autonomía, los cuales son: asistencia en la conducción, automatización parcial, automatización condicional, alta automatización y automatización completa. A pesar de los rápidos progresos que están habiendo en este campo, la adopción de estas soluciones llevará tiempo no sólo debido a cuestiones legales, sino también por el hecho de que los avances tecnológicos se enfrentan a un lento respaldo por parte de los fabricantes. Además, la baja tasa de renovación de vehículos de carretera, dificulta el despliegue de tecnologías innovadoras, como es el caso de la red vehicular. Ocho años después de la introducción de la norma 802.11p para la comunicación vehicular del Instituto de Ingenieros Eléctricos y Electrónicos (IIEE), los vehículos que se usan a diario todavía carecen de la capacidad de comunicarse entre sí. Este hecho impide el uso de las muchas aplicaciones de seguridad del Sistema de Inteligencia de Transporte (SIT) que aprovecha la red vehicular para el intercambio de datos. La forma obvia de manejar este problema es poner las tecnologías disponibles a la disposición de los usuarios comunes para desarrollar soluciones que se puedan implementar fácilmente y, además, económicas. Por esta razón, trasladamos nuestra atención a los dispositivos inteligentes, especialmente a los teléfonos inteligentes, los cuales han recorrido un largo camino desde la primera introducción de teléfonos móviles a finales del siglo XX. Hoy en día casi todos llevan uno en su bolsillo a donde sea que vayan, permitiéndoles no sólo hacer llamadas, sino también medir y controlar diferentes parámetros con la ayuda de los muchos sensores integrados que están disponibles para estos dispositivos compactos pero potentes. Nuestro objetivo es estudiar los efectos de la integración de los teléfonos inteligentes a la red vehicular para desarrollar aplicaciones de seguridad del SIT. La elección de los teléfonos inteligentes aquí no solo está justificada por su amplia disponibilidad y uso, sino también porque están evolucionando hacia terminales de alto rendimiento con microprocesadores de múltiples núcleos cargados dotados de un grupo suficientemente diverso de sensores. En esta tesis proponemos tres diferentes aplicaciones de seguridad SIT para teléfonos inteligentes, diseñados para aprovechar el entorno de red vehicular: una aplicación de generación de advertencia llamada Messiah que alerta a los conductores de la presencia de vehículos de emergencia en las cercanías; una aplicación de Advertencia de Colisión Frontal (ACF) que advierte a los conductores si no se mantiene la distancia de seguridad mínima entre el vehículo que va delante y el que lo sigue; y, por último, una aplicación que tiene como objetivo ayudar a los conductores con asistencia visual durante el adelantamiento, llamada EYES. Todas estas aplicaciones han sido desarrolladas para la plataforma Android, y dependen de la transmisión de datos entre vehículos. Dado que los vehículos que utilizamos día a día no admiten la posibilidad de comunicarse entre sí, también diseñamos GRCBox, que es una unidad integrada de bajo coste que permite la comunicación del Vehículo a Todo (V2X). A partir de nuestro estudio de aplicaciones para dispositivos móviles diseñados para redes vehiculares, descubrimos que el uso de teléfonos inteligentes proporciona una nueva dirección para la investigación relacionada con SIT y redes vehiculares al permitir la adopción rápida de las soluciones existentes, donde los usuarios pueden descargar y usar las aplicaciones con sólo un clic a un botón. Al mismo tiempo, la portabilidad y compacidad de los dispositivos los hace limitados en términos de velocidad, potencia de procesamiento y precisi[CA] Una de les àrees d'investigació que està rebent més atenció recentment és la de vehicles autònoms. Els investigadores estan en este moment centrats en el tercer dels cinc nivells d'autonomia, els quals són: assistència en la conducció, automatització parcial, automatització condicional, alta automatització i automatització completa. Malgrat els ràpids progressos que s'estan donant en este camp, l'adopció d'estes solucions portarà temps no sols degut a qüestions legals, sinó també pel fet que els avanços tecnològics s'enfronten a un lent recolzament per part dels fabricants. A més a més, la baixa taxa de renovació de vehicles de carretera, dificulta el desplegament de tecnologies innovadores com és el cas de la xarxa vehicular. Huit anys després de la introducció de la norma 802.11p per a la comunicació vehicular de l'Institut d'Enginyers Elèctrics i Electrònics (IEEE), els vehicles que s'utilitzen a diari encara manquen de la capacitat de comunicar-se entre sí. Este fet impedeix l'ús de les moltes aplicacions de seguretat del Sistema d'Intel·ligència de Transport (SIT) que aprofita la xarxa vehicular per a l'intercanvi de dades. La forma òbvia de tractar aquest problema és posar les tecnologies disponibles a la disposició dels usuaris comuns per a desenvolupar solucions que es puguen implementar fàcilment, còmodes d'adoptar i, a més a més, econòmiques. Per aquesta raó, traslladem la nostra atenció als dispositius intel·ligents, especialment als telèfons intel·ligents, els quals han recorregut un llarg camí des de la primera introducció de telèfons mòbils a finals del segle XX. Hui en dia quasi tots porten un en la butxaca on siga que vagen, permetent-los no sols fer cridades, sinó també mesurar i controlar diferents paràmetres amb l'ajuda dels molts sensors integrats que estan disponibles per a estos dispositius compactes però potents. El nostre objectiu és estudiar els efectes de la integració dels telèfons intel·ligents a la xarxa vehicular per a desenvolupar aplicacions de seguretat del SIT. L'elecció dels telèfons intel·ligents ací no està sols justificada per la seua àmplia disponibilitat i ús, sinó també perquè estan evolucionant cap a terminals d'alt rendiment amb microprocessadors de múltiples nuclis dotats amb un grup suficientment divers de sensors. En esta tesi proposem tres diferents aplicacions de seguretat SIT per a telèfons intel·ligents, dissenyats per a aprofitar l'entorn de xarxa vehicular: una aplicació de generació d'advertència anomenada Messiah que alerta els conductors de la presència de vehicles d'emergència en les proximitats; una aplicació Advertència de Col·lisió Frontal (ACF) que adverteix els conductors si no mantenen la distància de seguretat mínima entre el vehicle que va davant i el que el segueix; i, per últim, una aplicació que té com objectiu ajudar els conductors amb assistència visual durant l'avançament, anomenat EYES. Totes aquestes aplicacions han sigut desenvolupades per a la plataforma Android, i depenen de la transmissió de dades entre vehicles. Donat que els vehicles que utilitzem a diari no admeten la possibilitat de comunicar-se entre sí, també dissenyem GRCBox, que és una unitat integrada de baix cost que permet la comunicació de Vechicle a Tot (V2X). A partir del nostre estudi d'aplicacions per a dispositius mòbils dissenyats per a xarxes vehiculars, descobrim que l'ús de telèfons intel·ligents proporciona una nova direcció per a la investigació relacionada amb SIT i xarxes vehiculars al permetre l'adopció ràpida de les solucions existents, on els usuaris poden descarregar i utilitzar les aplicacions amb un sol clic a un botó. Però al mateix temps, la portabilitat i la compacitat dels dispositius els fa limitats en termes de velocitat, potència de processament i precisió del sensor integrat, cosa que afecta al rendiment de les aplicacions.[EN] One of the research areas that is receiving a lot of attention recently is autonomous vehicles. Researchers are currently focused on the third level of autonomy out of the five levels, which are: drive assistance, partial automation, conditional automation, high automation, and full automation. Even though rapid progress is being made in this field, the adoption of these solutions will take time not only due to legal issues, but also due to the fact that technological improvements face slow endorsement by manufacturers. Also, the slow renewal rate of vehicles on road hinders the deployment of novel technologies, as is the case of Vehicular Networks (VNs). Eight years after the introduction of the IEEE 802.11p standard for vehicular communication, vehicles used on a daily basis still lack the capability of communicating with one other. This fact impedes the use of the many ITS safety applications that take advantage of VNs for data exchange. The obvious way to handle this problem is to use the available technologies at the disposal of common users to develop solutions that are easily deployable, effortless to adopt, and moreover, cost effective. For this reason we shift our attention to smart devices, specially smartphones, which have come a long way since the first introduction of mobile phones in the late 20th century. Nowadays, nearly everyone carries one in their pocket anywhere they go, allowing them to not only make calls, but also to measure and monitor different parameters with the help of the many on-board sensors that are available to these compact yet powerful devices. Our objective is to study the effects of integrating smartphones to vehicular networks, to develop ITS safety applications. The choice of smartphones here is not only justified by their wide availability and use, but also because they are evolving towards high performance terminals with multi-core microprocessors packed with a sufficiently diverse group of sensors. In this thesis we propose three different ITS safety applications for smartphones, designed to take advantage of the vehicular network environment: a warning generation application called Messiah that alerts drivers of the presence of emergency vehicles in close proximity; a FCW application which warns drivers if a minimum safe distance is not maintained between the vehicle ahead and the one following it; and lastly an application that aims to aid drivers with visual assistance while overtaking, named EYES. All these applications have been developed for the Android platform, and are dependent on the data transmission among vehicles. Since vehicles we use on a day to day basis still do not accommodate the possibility to communicate with one another, we also designed the GRCBox, which is a low cost on-board unit that supports V2X communication. From our study of applications for mobile devices designed for VNs, we found that the use of smartphones provides a new direction to research related to ITS and VNs by allowing a quick adoption of the existing solutions, where users are able to download and use applications just by one click of a button. But at the same time, the portability and compactness of the devices makes them limited in terms of speed, processing power, and accuracy of the on-board sensor, thus affecting the performance of the applications. In our case, the simpler Messiah application performed very well, while the EYES application that is dependent on GPS data, and the FCW application which required heavy processing and use of the camera due to its dependence on plate recognition, were affected by the hardware limitations of the smartphones.Patra, S. (2019). Development and evaluation of smartphone-based ITS applications for vehicular networks [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/124058TESI

Internet of Vehicles: Motivation, Layered Architecture, Network Model, Challenges, and Future Aspects

© 2013 IEEE. Internet of Things is smartly changing various existing research areas into new themes, including smart health, smart home, smart industry, and smart transport. Relying on the basis of 'smart transport,' Internet of Vehicles (IoV) is evolving as a new theme of research and development from vehicular ad hoc networks (VANETs). This paper presents a comprehensive framework of IoV with emphasis on layered architecture, protocol stack, network model, challenges, and future aspects. Specifically, following the background on the evolution of VANETs and motivation on IoV an overview of IoV is presented as the heterogeneous vehicular networks. The IoV includes five types of vehicular communications, namely, vehicle-to-vehicle, vehicle-to-roadside, vehicle-to-infrastructure of cellular networks, vehicle-to-personal devices, and vehicle-to-sensors. A five layered architecture of IoV is proposed considering functionalities and representations of each layer. A protocol stack for the layered architecture is structured considering management, operational, and security planes. A network model of IoV is proposed based on the three network elements, including cloud, connection, and client. The benefits of the design and development of IoV are highlighted by performing a qualitative comparison between IoV and VANETs. Finally, the challenges ahead for realizing IoV are discussed and future aspects of IoV are envisioned