An integrated architecture for multi-hop infrastructure wireless networks

Rapid growth in wireless networks has resulted in a growing need for fast and ubiquitous connectivity. Most networks deployed currently are single hop access point (AP) networks, where the end user is connected to an AP if it is within communication range of the AP. While such networks are popular and have been deployed extensively, the inherent low range of Wi-Fi networks limits their coverage. Again, high deployment costs of high speed wired networks do not allow single hop networks to provide ubiquitous and cheap connectivity. Recently, a highly viable solution to the above problem has appeared in the form of multihop infrastructure networks (MINs). A MIN is a network of wireless routers connected to an AP and provides multihop coverage in an area. These networks may present a highly viable and cheap alternative to the problem of universal coverage. While the concept of MINs is exciting, deployment of such networks cannot commence without a thorough inspection of the performance, handoffs mechanisms and security considerations involved. The aim of this thesis is to provide a complete architecture for MINs and explore the various aspects that affect the performance and security of such networks. We solve the problem in a number of phases. First, we provide an analytical framework using which the end-to-end delay and throughput characteristics of the network can be predicted. This framework can then be used to predict the scalability of such networks. The model can also be used for bottleneck determination in such networks and to provide effective routing techniques. The behavior of the delay characteristics of MINs have been effectively addressed by taking both bulk traffic and single arrival traffic into consideration. The queue modeling for forwarder nodes in MINs is complicated by the fact that traditional queuing mechanisms are no longer valid as the arrival and departure processes can never be simultaneous. We propose two different approaches to queuing analysis in MINs. Secondly, we propose to provide an architecture for handoffs in MINs. This involves defining a handoff for MINs, and outlining a method to perform handoffs depending on the parameters that need to be optimized. The suggested protocols should also aim towards minimizing the delays and message overheads involved in the handoff process. Protocols have also been proposed to reduce the delay and message overheads involved in handoffs by the use of pre-authentication mechanisms. Finally, we propose a security architecture for MINs. The first part of this security architecture addresses the problem of key distribution for group communication. The second part of the security architecture allows communication between the members of a MIN by the establishment of robust key agreement protocols for node-to-node pair wise communication. These protocols can be used for ad-hoc network communication as well.