Wednesday, 13 June 2007
Session 1: Protocols and Algorithms for Services |
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An Association Discovery Protocol for Hybrid Wireless Mesh Networks |
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Abstract: Recently, various working groups of standardization bodies, have finalized or have been finalizing standards for wireless mesh networks (WMNs), which will provide some ad-hoc network capabilities to wireless networks. An example is the task group “S”, 802.11s, focusing on mesh extensions for Wi-Fi networks. Such networks accommodate two kinds of nodes: mesh routers which form networks automatically in a similar fashion to ad-hoc networks ; and mesh clients which can simply associate with these mesh routers to access to the rest of the network. Because of the discrepancy of behaviour between mesh routers and mesh clients, WMNs have a hybrid structure, where the mesh routers form a backbone, and where clients have no routing capability. Routing in WMNs may be achieved with an extension of routing with two levels of information: traditional routing tables between mesh routers, complemented with association tables for linking mesh clients to mesh routers. For the first level, routing between mesh routers, can be used, for instance modified versions of MANET protocols. For the second level, we propose an Association Discovery Protocol (ADP): it allows each mesh router to determine where are located the other stations. Our proposal had actually been integrated in the early 802.11s proposals [6], and in this article, our focus will be on such 802.11 mesh networks. Because the ADP has parameters which can be tuned, a performance analysis of the protocol is essential. In this article, we describe this protocol, and provide a analytic model of its performance. The performance evaluation is confirmed by simulation results. Pages: 1-8 |
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Optimized Service Selection for MANETs using an AODV-based Service Discovery Protocol |
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Abstract: Mobile Ad hoc Networks (MANETs) are networks, which operate without the need of an infrastructure. In such networks, mobile nodes must rely on their own capabilities and on other peers’ capabilities to perform their tasks. In this context, many service discovery protocols have been proposed in order for mobile peers to be able to discover and take advantage of each other’s services. A basic building block for service discovery protocols is their service selection strategy. Especially in service-rich environments with many (possibly resource poor) mobile nodes, the service selection strategy employed is of major importance. In this paper we investigate the impact of two basic and easy to implement service selection strategies on the lifetime of mobile servers. The first strategy takes into account hop-based server proximity and promotes the selection of the nearest mobile server, while the second strategy takes into account the remaining energy of service providers and promotes the selection of the mobile server with the maximum remaining energy. Through extensive simulations, we show that the provider’s remaining energy yields the best performance when used as a service selection criterion under most situations, and that the shortest path selection criterion presents very competitive performance. The performance metrics used for evaluating both service selection strategies are service and network lifetimes, service success and service discoverability ratios. Pages: 9-16 |
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Human-Network Interface for QoS Management in Ad hoc Networks |
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Abstract: Though the network quality-of-service (QoS) metrics are defined in terms of technical parameters (e.g., delay, jitter, bandwidth), they are rather subjective when it comes to the end user. Oftentimes, the end user finds it difficult to express his desired QoS in such technical parameters though he has a fair idea of what QoS he desires. In this paper, we propose a simple interface that is primarily meant for tactical network implementation within a military setting of network-centric warfare. The interface translates the user inputs to networking parameters that are used by various layers of the protocol stack. In particular, we show how the media access control (MAC) and routing strategies change in an ad hoc network when the user changes his priority i.e., trades delay performance to maximize the lifetime of the network. We show also how the user supplied parameters translate to network parameters at the MAC and routing layer and the strategies are changed to incorporate the use inputs and yield the desired QoS. We conduct simulation experiments based on ns-2. Results demonstrate how delay, throughput, and network lifetime are affected when the different levels of QoS are required. Pages: 17-24 |
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Performance of a Simple Positioning Algorithm (SimPA) in wireless heterogeneous mobile mesh networks |
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Abstract: Localization information is now a valuable data for every type of services and networks. But determining the physical location of a node in a wireless mobile environment is a challenging task for nodes with no self-locating capability such as a GPS. Simple Positioning Algorithm (SimPA) is a realistic, light and simple solution to estimate a position for such heterogeneous wireless networks and is based on a connectivity approach. SimPA performs well in static environment as shown in [1]-[12]. This paper addresses the performance of SimPA in a mobile context such as a wireless heterogeneous mobile mesh networks. We present an evaluation of SimPA’s accuracy for several mobility models. Pages: 25-31 |
