An overview of link-level measurement techniques for wide-area wireless networks

By building wireless link-level measurement tools we hope to improvement the design, deployment and management of wide-area wireless community networks. This paper identifies existing link-level measurement techniques and discusses the advantages and disadvantages of each in the context of measuring and monitoring such networks. Finally, we make a case for the need for more sophisticated techniques and tools which will assist both day-to-day network operations as well as wireless network research

State-of-the-art in Power Line Communications: from the Applications to the Medium

In recent decades, power line communication has attracted considerable attention from the research community and industry, as well as from regulatory and standardization bodies. In this article we provide an overview of both narrowband and broadband systems, covering potential applications, regulatory and standardization efforts and recent research advancements in channel characterization, physical layer performance, medium access and higher layer specifications and evaluations. We also identify areas of current and further study that will enable the continued success of power line communication technology.Comment: 19 pages, 12 figures. Accepted for publication, IEEE Journal on Selected Areas in Communications. Special Issue on Power Line Communications and its Integration with the Networking Ecosystem. 201

Towards a network management solution for vehicular delay-tolerant networks

Vehicular networks appeared as a new communication solution where vehicles act as a communication infrastructure, providing data communications through vehicle-to-vehicle (V2V) or vehicle-to-infrastructure (V2I) communications. Vehicular Delay-Tolerant Networks (VDTNs) are a new disruptive network architecture assuming delay tolerant networking paradigm where there are no end-to-end connectivity. In this case the incial node transmits the data to a closed node, the data will be carried by vehicles, hop to hop until the destination. This dissertation focuses on a proposal of a network management solution, based standard protocol Simple Network Management Protocol (SNMP) to VDTN networks. The developed solution allows control a VDTN netowork through a Network Management System (NMS) with the objective to detect and, if it’s possible, anticipate, possible errors on network. The research methodology used was the prototyping. So, it was built a network management module to the laboratorial prototype, called VDTN@Lab. The system built include a MIB (Management Information Base) placed in all vehicular network nodes. The solution was built, demonstrated, validated and evaluated their performance, being ready for use.As redes veiculares foram desenhadas para permitir que os veículos possam transportar dados criando assim um novo tipo de redes, caracterizando-se por dois tipos de comunicação: comunicações veículo-para-veículo (V2V) ou comunicações veículo-parainfra-estrutura (V2I). Redes veiculares intermitentes (do Inglês Vehicular Delay-Tolerant Networks - VDTNs) surgiram como uma nova arquitectura de rede de dados onde os veículos são utilizados como infra-estruturas de comunicação. As VDTNs caracterizam-se por serem redes veiculares baseadas no paradigma de comunicações intermitentes. Nas redes VDTN não existe uma ligação permanente extremo a extremo entre o emissor e o receptor. Neste caso, o nó inicial transmite os dados para um nó que esteja junto dele e assim sucessivamente, os dados vão sendo transportados pelos veículos, salto a salto até ao destinatário final. Esta dissertação centra-se na proposta de uma solução de gestão de rede, baseada no protocolo estandardizado Simple Network Management Protocol (SNMP) para redes VDTN. A solução construída permite controlar uma rede VDTN através de um sistema de gestão de rede (do Inglês Network Management System - NMS) com o objectivo de detectar e, se possível antecipar, possíveis erros na rede. A metodologia de investigação utilizada foi a prototipagem. Assim, foi construído um módulo de gestão de redes para o protótipo laboratorial, chamado VDTN@Lab. O sistema construído inclui uma MIB (Management Information Base) que é colocada em todos os nós de uma rede veicular, tanto fixos como móveis. A solução foi construída, demonstrada, validade e avaliado o seu desempenho, estando assim pronta para ser utilizada

Frequency management in a campus-wide Wi-Fi deployment

Over the past years, Internet is spreading more and more. And not only in home devices, but also in other personal devices thus producing a collective mobile lifestyle. At the beginning of its rise, cable solution was the most applied technology. However, in a world becoming a “mobile world”, wired networks can’t fulfil all new challenges. Thus, Wireless networks are increasingly encroaching on the niche of traditional access technologies. In fact, mobile broadband is exponentially being integrated into every aspect of life; and that seems to be only the beginning of what is to come, as the several millions of people using the latest trend gadgets ratify. One of the key technologies that enable mobile Internet access is IEEE 802.11, commonly known by its trademark, Wi-Fi, which assures interoperability and backward compatibility between products. Part of the popularity achieved by Wi-Fi is due to the use of unlicensed (i.e. free) spectrum. Traditionally, only three of the fourteen frequency channels established in the 2.4GHz are used. This is so in order to avoid interference, as these channels (1, 6 and 11) belong to non-overlapping frequencies. However, the recent explosive growth in the number of wireless devices together with the multitude of wireless protocols operating in the unlicensed radio spectrum bands and sharing the same spectrum, lead to a saturation of the limited available spectrum, thus causing the frequency channels assigned to be repeated in close cells. Definitely, it results in interference and performance degradation, and broadly, a non-optimal performance of the network. Within this context, in which the number of users is very large but the radio resources are scarce, efficient channel allocation becomes crucial for the successful deployment and operation of IEEE802.11-based WLANs. And this is indeed the main purpose of this Master Thesis, in which a system able to establish communication with a controller and set a new channel distribution according to a renowned mathematical algorithm is exposed. The presented system has been tested in CBL – UPC Barcelona Tech campus, giving satisfactory outcomes and conclusions as a result. But before going deep into the process details, this work also reviews WLAN 802.11 standards and radio resource management techniques used nowadays, so the reader will easily understand the context which encompasses this work and how the system presented is able to improve an already settled technology.Castellà: Desde hace unos años, Internet se está extendiendo cada vez más. Y no sólo en los hogares, sino también en aparatos de uso personal que están convirtiendo nuestro estilo de vida en un estilo “móvil”. Al principio de su aparición, la tecnología cableada era la más recurrida. Sin embargo, en este mundo cada vez más móvil, nos encontramos con que las redes cableadas no pueden satisfacer los nuevos retos. Es por esto que las redes inalámbricas están invadiendo el espacio de las tecnologías de acceso tradicionales. De hecho, la banda ancha móvil se está acoplando a un ritmo vertiginoso en muchos aspectos de nuestra vida; y esto parece ser sólo el comienzo, como demuestran los varios millones de personas que utilizan los aparatos tecnológicos más modernos. Una de las tecnologías clave que permiten acceso móvil a Internet es IEEE 802.11, más conocida como Wi-Fi, término comercial que asegura interoperabilidad y compatibilidad entre productos. Parte de su popularidad se debe al uso del rango de frecuencias libres de licencia. Tradicionalmente, sólo tres de los catorce canales que establece la banda de 2,4GHz son asignados. Esto ha sido siempre así para evitar interferencias, ya que estos canales (1, 6 y 11) pertenecen a frecuencias que no se solapan. Sin embargo, la reciente explosión en el número de dispositivos inalámbricos así como la cantidad de protocolos que trabajan en el mismo rango frecuencial, provocan una saturación de este espectro limitado, haciendo así que se asignen los mismos canales en celdas cercanas. Sin duda, esto se traduce en interferencias, y en general, hace que el comportamiento de la red no sea el óptimo. En este contexto, en el que el número de usuarios es elevado pero los recursos radio escasos, la asignación eficiente de canales se vuelve crucial para tener buen despliegue y funcionamiento de las redes WLAN basadas en IEEE802.11. Y éste es de hecho el propósito principal de esta Master Thesis, que presenta un sistema capaz de establecer comunicación con una controladora y decidir una nueva distribución de canales según un conocido algoritmo matemático. El sistema que se presenta ha sido probado en el campus CBL–UPC Barcelona Tech, obteniendo resultados y conclusiones satisfactorios. Pero antes de entrar en los detalles del proceso, este trabajo también analiza los estándares IEEE 802.11 así como las técnicas actuales utilizadas en la gestión de recursos, de manera que el lector entenderá fácilmente el contexto en el que este trabajo se realiza y cómo el sistema presentado es capaz de mejorar una tecnología ya asentada

Interoperability of wireless communication technologies in hybrid networks: Evaluation of end-to-end interoperability issues and quality of service requirements

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Hybrid Networks employing wireless communication technologies have nowadays brought closer the vision of communication “anywhere, any time with anyone”. Such communication technologies consist of various standards, protocols, architectures, characteristics, models, devices, modulation and coding techniques. All these different technologies naturally may share some common characteristics, but there are also many important differences. New advances in these technologies are emerging very rapidly, with the advent of new models, characteristics, protocols and architectures. This rapid evolution imposes many challenges and issues to be addressed, and of particular importance are the interoperability issues of the following wireless technologies: Wireless Fidelity (Wi-Fi) IEEE802.11, Worldwide Interoperability for Microwave Access (WiMAX) IEEE 802.16, Single Channel per Carrier (SCPC), Digital Video Broadcasting of Satellite (DVB-S/DVB-S2), and Digital Video Broadcasting Return Channel through Satellite (DVB-RCS). Due to the differences amongst wireless technologies, these technologies do not generally interoperate easily with each other because of various interoperability and Quality of Service (QoS) issues. The aim of this study is to assess and investigate end-to-end interoperability issues and QoS requirements, such as bandwidth, delays, jitter, latency, packet loss, throughput, TCP performance, UDP performance, unicast and multicast services and availability, on hybrid wireless communication networks (employing both satellite broadband and terrestrial wireless technologies). The thesis provides an introduction to wireless communication technologies followed by a review of previous research studies on Hybrid Networks (both satellite and terrestrial wireless technologies, particularly Wi-Fi, WiMAX, DVB-RCS, and SCPC). Previous studies have discussed Wi-Fi, WiMAX, DVB-RCS, SCPC and 3G technologies and their standards as well as their properties and characteristics, such as operating frequency, bandwidth, data rate, basic configuration, coverage, power, interference, social issues, security problems, physical and MAC layer design and development issues. Although some previous studies provide valuable contributions to this area of research, they are limited to link layer characteristics, TCP performance, delay, bandwidth, capacity, data rate, and throughput. None of the studies cover all aspects of end-to-end interoperability issues and QoS requirements; such as bandwidth, delay, jitter, latency, packet loss, link performance, TCP and UDP performance, unicast and multicast performance, at end-to-end level, on Hybrid wireless networks. Interoperability issues are discussed in detail and a comparison of the different technologies and protocols was done using appropriate testing tools, assessing various performance measures including: bandwidth, delay, jitter, latency, packet loss, throughput and availability testing. The standards, protocol suite/ models and architectures for Wi-Fi, WiMAX, DVB-RCS, SCPC, alongside with different platforms and applications, are discussed and compared. Using a robust approach, which includes a new testing methodology and a generic test plan, the testing was conducted using various realistic test scenarios on real networks, comprising variable numbers and types of nodes. The data, traces, packets, and files were captured from various live scenarios and sites. The test results were analysed in order to measure and compare the characteristics of wireless technologies, devices, protocols and applications. The motivation of this research is to study all the end-to-end interoperability issues and Quality of Service requirements for rapidly growing Hybrid Networks in a comprehensive and systematic way. The significance of this research is that it is based on a comprehensive and systematic investigation of issues and facts, instead of hypothetical ideas/scenarios or simulations, which informed the design of a test methodology for empirical data gathering by real network testing, suitable for the measurement of hybrid network single-link or end-to-end issues using proven test tools. This systematic investigation of the issues encompasses an extensive series of tests measuring delay, jitter, packet loss, bandwidth, throughput, availability, performance of audio and video session, multicast and unicast performance, and stress testing. This testing covers most common test scenarios in hybrid networks and gives recommendations in achieving good end-to-end interoperability and QoS in hybrid networks. Contributions of study include the identification of gaps in the research, a description of interoperability issues, a comparison of most common test tools, the development of a generic test plan, a new testing process and methodology, analysis and network design recommendations for end-to-end interoperability issues and QoS requirements. This covers the complete cycle of this research. It is found that UDP is more suitable for hybrid wireless network as compared to TCP, particularly for the demanding applications considered, since TCP presents significant problems for multimedia and live traffic which requires strict QoS requirements on delay, jitter, packet loss and bandwidth. The main bottleneck for satellite communication is the delay of approximately 600 to 680 ms due to the long distance factor (and the finite speed of light) when communicating over geostationary satellites. The delay and packet loss can be controlled using various methods, such as traffic classification, traffic prioritization, congestion control, buffer management, using delay compensator, protocol compensator, developing automatic request technique, flow scheduling, and bandwidth allocation

A Dynamically Refocusable Sampling Infrastructure for 802.11 Networks

The edge of the Internet is increasingly wireless. Enterprises large and small, homeowners, and even whole cities have deployed Wi-Fi networks for their users, and many users never need to--- or never bother to--- use the wired network. With the advent of high-throughput wireless networks (such as 802.11n) some new construction, even of large enterprise build- ings, may no longer be wired for Ethernet. To understand Internet traffic, then, we need to understand the wireless edge. Measuring Wi-Fi traffic, however, is challenging. It is insufficient to capture traffic in the access points, or upstream of the access points, because the activity of neighboring networks, ad hoc networks, and physical interference cannot be seen at that level. To truly understand the MAC-layer behavior, we need to capture frames from the air using Air Monitors (AMs) placed in the vicinity of the network. Such a capture is always a sample of the network activity, since it is physically impossible to capture a full trace: all frames from all channels at all times in all places. We have built a monitoring infrastructure that captures frames from the 802.11 network. This infrastructure includes several channel sampling strategies that will capture repre- sentative traffic from the network. Further, the monitoring infrastructure needs to modify its behavior according to feedback received from the downstream consumers of the captured traffic in case the analysis needs traffic of a certain type. We call this technique refocusing . The coordinated sampling technique improves the efficiency of the monitoring by utilizing the AMs intelligently. Finally, we deployed this measurement infrastructure within our Computer Science building to study the performance of the system with real network traffic

Mesh-Mon: a Monitoring and Management System for Wireless Mesh Networks

A mesh network is a network of wireless routers that employ multi-hop routing and can be used to provide network access for mobile clients. Mobile mesh networks can be deployed rapidly to provide an alternate communication infrastructure for emergency response operations in areas with limited or damaged infrastructure. In this dissertation, we present Dart-Mesh: a Linux-based layer-3 dual-radio two-tiered mesh network that provides complete 802.11b coverage in the Sudikoff Lab for Computer Science at Dartmouth College. We faced several challenges in building, testing, monitoring and managing this network. These challenges motivated us to design and implement Mesh-Mon, a network monitoring system to aid system administrators in the management of a mobile mesh network. Mesh-Mon is a scalable, distributed and decentralized management system in which mesh nodes cooperate in a proactive manner to help detect, diagnose and resolve network problems automatically. Mesh-Mon is independent of the routing protocol used by the mesh routing layer and can function even if the routing protocol fails. We demonstrate this feature by running Mesh-Mon on two versions of Dart-Mesh, one running on AODV (a reactive mesh routing protocol) and the second running on OLSR (a proactive mesh routing protocol) in separate experiments. Mobility can cause links to break, leading to disconnected partitions. We identify critical nodes in the network, whose failure may cause a partition. We introduce two new metrics based on social-network analysis: the Localized Bridging Centrality (LBC) metric and the Localized Load-aware Bridging Centrality (LLBC) metric, that can identify critical nodes efficiently and in a fully distributed manner. We run a monitoring component on client nodes, called Mesh-Mon-Ami, which also assists Mesh-Mon nodes in the dissemination of management information between physically disconnected partitions, by acting as carriers for management data. We conclude, from our experimental evaluation on our 16-node Dart-Mesh testbed, that our system solves several management challenges in a scalable manner, and is a useful and effective tool for monitoring and managing real-world mesh networks

Validation platform implementation description – D5.2

Deliverable D5.2 del projecte OneFITPostprint (published version