Provisioning Robustness and Security in Ubiquitous Wireless Access Networks

Abstract

The growth of the Internet use and wireless network has accelerated the rapid implementation of ubiquitous services. Internet connectivity to wireless access networks based IEEE 802.11 Wireless local area network (WLAN) have gained popularity due to fact that they minimize the need for expensive wired infrastructure and are relatively easy to deploy and maintain. Furthermore, Mobile Ad Hoc Networks (MANETs), which are systems of mobile nodes that dynamically self-organize in arbitrary network topologies allowing nodes to communicate each other without any pre-existing communication infrastructure, have tremendous potential to be the technology of choice for providing ubiquitous Internet connectivity. Even though multihop wireless networks enable truly pervasive, mobile access, they significantly exacerbate several wireless networking challenges that must be addressed before these networks can become practical and useful. Future applications of wireless networks such as MANETs are expected to be based on all-IP architecture and be capable of carrying multitude real-time multimedia applications such as voice and video as well as data. It is necessary for MANETs to have an efficient reliable and secure routing to support diverse applications. In this dissertation, we focus on some challenges that are particularly aggravated in multihop scenarios, and that we believe are among the most significant hurdles obstructing the widespread use of these networks. We have depicted authentication scheme based on hash chain for wireless mobile network. In this thesis, we deal with isolated as well as hybrid multihop wireless network. In this regard, we have proposed a multipath ad hoc routing scheme called "Ad hoc On-demand Distance Vector Routing - Multiple Alternative Paths (AODV-MAP)", which is robust and efficient scheme for the ad hoc network where frequent communication failure occurs. Multipath routing allows the establishment of multiple paths between a source and destination node. It is beneficial not only to frequent link breaks in communication because of mobility of nodes but also to avoid traffic congestion. The features of AODV-MAP scheme are path accumulation technique, selective route request forwarding scheme, path selection strategy, and path label setting strategy. We have devised traffic allocation strategy in AODV-MAP scheme using scalable audio coding and hence evaluated the effectiveness of such a technique for multimedia delivery over multipath MANET. Although AODV-MAP provides robust and efficient multipath routing in MANETs, it is vulnerable to various attacks. To provide security, we have developed Secure AODV-MAP, which is robust not only to topological changes but also malicious activities. Moreover, we have illustrated an approach for global connectivity in hybrid multipath ad hoc network. This approach is suitable for the integrated Internet with MANET with multiple gateways. In this approach, we have put forward a robust gateway selection scheme to select optimum gateway as well as extended version of AODV-MAP to adopt well in hybrid environment. We have also provided security extension to this approach considering vulnerability of Internet connectivity as well as ad hoc routing. Finally, we have analyzed a reliable distributed multimedia delivery network over hybrid multipath MANET using unequal error protection (UEP).