Supporting Internet Access and Quality of Service in Distributed Wireless Ad Hoc Networks

In this era of wireless hysteria, with continuous technological advances in wireless communication and new wireless technologies becoming standardized at a fast rate, we can expect an increased interest for wireless networks, such as ad hoc and mesh networks. These networks operate in a distributed manner, independent of any centralized device. In order to realize the practical benefits of ad hoc networks, two challenges (among others) need to be considered: distributed QoS guarantees and multi-hop Internet access. In this thesis we present conceivable solutions to both of these problems. An autonomous, stand-alone ad hoc network is useful in many cases, such as search and rescue operations and meetings where participants wish to quickly share information. However, an ad hoc network connected to the Internet is even more desirable. This is because Internet plays an important role in the daily life of many people by offering a broad range of services. In this thesis we present AODV+, which is our solution to achieve this network interconnection between a wireless ad hoc network and the wired Internet. Providing QoS in distributed wireless networks is another challenging, but yet important, task mainly because there is no central device controlling the medium access. In this thesis we propose EDCA with Resource Reservation (EDCA/RR), which is a fully distributed MAC scheme that provides QoS guarantees by allowing applications with strict QoS requirements to reserve transmission time for contention-free medium access. Our scheme is compatible with existing standards and provides both parameterized and prioritized QoS. In addition, we present the Distributed Deterministic Channel Access (DDCA) scheme, which is a multi-hop extension of EDCA/RR and can be used in wireless mesh networks. Finally, we have complemented our simulation studies with real-world ad hoc and mesh network experiments. With the experience from these experiments, we obtained a clear insight into the limitations of wireless channels. We could conclude that a wise design of the network architecture that limits the number of consecutive wireless hops may result in a wireless mesh network that is able to satisfy users’ needs. Moreover, by using QoS mechanisms like EDCA/RR or DDCA we are able to provide different priorities to traffic flows and reserve resources for the most time-critical applications

WING/WORLD: An Open Experimental Toolkit for the Design and Deployment of IEEE 802.11-Based Wireless Mesh Networks Testbeds

Wireless Mesh Networks represent an interesting instance of light-infrastructure wireless networks. Due to their flexibility and resiliency to network failures, wireless mesh networks are particularly suitable for incremental and rapid deployments of wireless access networks in both metropolitan and rural areas. This paper illustrates the design and development of an open toolkit aimed at supporting the design of different solutions for wireless mesh networking by enabling real evaluation, validation, and demonstration. The resulting testbed is based on off-the-shelf hardware components and open-source software and is focused on IEEE 802.11 commodity devices. The software toolkit is based on an "open" philosophy and aims at providing the scientific community with a tool for effective and reproducible performance analysis of WMNs. The paper describes the architecture of the toolkit, and its core functionalities, as well as its potential evolutions

Mecanismos de descubrimiento de gateways adaptativos para redes ad hoc conectadas a redes fijas

Los principales objetivos de este TFC son el análisis de un nuevo mecanismo de descubrimiento de gateways para las redes ad hoc conectadas a redes fijas y la propuesta de un nuevo mecanismo, variante del mecanismo anterior. Una vez analizados los dos mecanismos los compararemos con los mecanismos que se implementan en la actualidad y sacaremos conclusiones sobre que mecanismo es más eficiente para las aplicaciones en tiempo real que funcionan sobre redes ad hoc conectadas a redes fijas. Hemos fragmentado el proyecto en varios puntos, para entender el funcionamiento de este tipo de redes, sus protocolos, sus características, y finalmente llevar a cabo nuestros objetivos. Los puntos son los siguientes: • Estudio de las redes ad hoc • Estudio de los diferentes mecanismos de descubrimiento de gateways de redes ad hoc que existen en la actualidad. • Estudio de un nuevo protocolo de descubrimiento de gateways con provisión de QoS. • Propuesta y estudio de una nueva variante basada en protocolo anterior. • Simulación de los protocolos de descubrimiento de gateways híbrido, adaptativo y nuestra variante. • Comparación de los resultados de las simulaciones y conclusiones. • Realización de la patente de los protocolos propuestos.La gran evolución que han sufrido las comunicaciones en los últimos años y la necesidad surgida de estar conectado en cualquier momento y en cualquier lugar, ha permitido que las redes inalámbricas tomen un papel relevante en las comunicaciones actuales, permitiendo movilidad y conectividad permanentes. En este TFC nos centraremos en el estudio, análisis y simulación de las redes ad hoc conectadas a una red fija a través de gateways. Analizaremos los tres mecanismos de descubrimiento de gateways que se utilizan actualmente para las comunicaciones en las redes ad hoc. Presentaremos un nuevo protocolo de descubrimiento de gateways que mejora el rendimiento y la eficiencia de la red y añadiremos una nueva variante, derivada de este nuevo protocolo, ideada por nosotros. Con estas nuevas propuestas se consigue añadir QoS (Quality of service, calidad de servicio), inexistente en los protocolos actuales, priorizando el tráfico de las aplicaciones de tiempo real (VoIP) frente al resto de flujos de la red. Para obtener los datos necesarios sobre el comportamiento de estos nuevos protocolos, se ha optado por utilizar el programa de simulación de redes NS (Network Simulator). En estas simulaciones se ha comparado el comportamiento del protocolo de descubrimiento de gateways híbrido, con el protocolo propuesto y con nuestra variante. Analizando los resultados de las simulaciones vemos que el comportamiento del protocolo propuesto y de nuestra variante mejoran la eficiencia de la red ad hoc conectada a la red fija. Por último, se han seguido los pasos necesarios para presentar una solicitud de patente en la Oficina Española de Patentes y Marcas, del protocolo de descubrimiento de gateways presentado y nuestra variante

IP-Enabled WAN EMS System

The focus of this project was to determine the feasibility of a ubiquitous, reliable, IP-enabled Next Generation 911 (NG911) infrastructure. A detailed investigation was conducted in order to determine the limitations of both the existing emergency architecture. Germane legislation was then analyzed to determine the constraints of any new proposed architecture. Additionally, past proposals to expand the functionality and reliability of the E911 networks were evaluated. Lastly, the feasibility of an NG911 architecture leveraging existing technology was determined

Designing multihop wireless backhaul networks with delay guarantees

Abstract — As wireless access technologies improve in data rates, the problem focus is shifting towards providing adequate backhaul from the wireless access points to the Internet. Existing wired backhaul technologies such as copper wires running at DSL, T1, or T3 speeds can be expensive to install or lease, and are becoming a performance bottleneck as wireless access speeds increase. Longhaul, non-line-of-sight wireless technologies such as WiMAX (802.16d) hold the promise of enabling a high speed wireless backhaul as a cost-effective alternative. However, the biggest challenge in building a wireless backhaul is achieving guaranteed performance (throughput and delay) that is typically provided by a wired backhaul. This paper explores the problem of efficiently designing a multihop wireless backhaul to connect multiple wireless access points to a wired gateway. In particular, we provide a generalized link activation framework for scheduling packets over this wireless backhaul, such that any existing wireline scheduling policy can be implemented locally at each node of the wireless backhaul. We also present techniques for determining good interference-free routes within our scheduling framework, given the link rates and cross-link interference information. When a multihop wireline scheduler with worst case delay bounds (such as WFQ or Coordinated EDF) is implemented over the wireless backhaul, we show that our scheduling and routing framework guarantees approximately twice the delay of the corresponding wireline topology. Finally, we present simulation results to demonstrate the low delays achieved using our framework. I

FastM: Design and Evaluation of a Fast Mobility Mechanism for Wireless Mesh Networks

Although there is a large volume of work in the literature in terms of mobility approaches for Wireless Mesh Networks, usually these approaches introduce high latency in the handover process and do not support realtime services and applications. Moreover, mobility is decoupled from routing, which leads to inefficiency to both mobility and routing approaches with respect to mobility. In this paper we present a new extension to proactive routing protocols using a fast mobility extension, FastM, with the purpose of increasing handover performance in Wireless Mesh Networks. With this new extension, a new concept is created to integrate information between neighbor wireless mesh routers, managing locations of clients associated to wireless mesh routers in a certain neighborhood, and avoiding packet loss during handover. The proposed mobility approach is able to optimize the handover process without imposing any modifications to the current IEE 802.11 MAC protocol and use unmodified clients. Results show the improved efficiency of the proposed scheme: metrics such as disconnection time, throughput, packet loss and control overhead are largely improved when compared to previous approaches. Moreover, these conclusions apply to mobility scenarios, although mobility decreases the performance of the handover approach, as expected

Self-Configuration and Self-Optimization Process in Heterogeneous Wireless Networks

Self-organization in Wireless Mesh Networks (WMN) is an emergent research area, which is becoming important due to the increasing number of nodes in a network. Consequently, the manual configuration of nodes is either impossible or highly costly. So it is desirable for the nodes to be able to configure themselves. In this paper, we propose an alternative architecture for self-organization of WMN based on Optimized Link State Routing Protocol (OLSR) and the ad hoc on demand distance vector (AODV) routing protocols as well as using the technology of software agents. We argue that the proposed self-optimization and self-configuration modules increase the throughput of network, reduces delay transmission and network load, decreases the traffic of HELLO messages according to network’s scalability. By simulation analysis, we conclude that the self-optimization and self-configuration mechanisms can significantly improve the performance of OLSR and AODV protocols in comparison to the baseline protocols analyzed