Abstract
One feature that distinguishes a mobile ad hoc network (MANET) from traditional wired networks is that all hosts are allowed to move freely without the need for static access points. This distinct feature, however, presents a great challenge to the design of the routing scheme and the support of multimedia services, since the link quality and the network topology may be fast changing as hosts roam around. This dissertation investigates three major areas in mobile ad hoc networks: (a) Dynamic IP routing in highly mobile environments; (b) Quality-of-Service (QoS) Routing support; and (c) Integration of ad hoc networks with wide area mobile networks. Dynamic routing in MANETs is a multi-objective task that presents stringent requirements. These requirements include: high accuracy, low overhead, robust path maintenance, scalability, in terms of network control overhead, as the network population grows, etc. A new routing approach for routing in ad hoc wireless networks, called Relative Distance Micro-Discovery Ad Hoc Routing (RDMAR) is proposed. RDMAR is an on-demand protocol that reactively discovers and repairs routes within a local region of the network. As demonstrated through simulations, the localisation of routing control messaging serves to minimise communication overhead and overall network congestion. The protocol has been an IETF (Internet Engineering Task Force) candidate since September 1999. To support bandwidth (QoS) sensitive multimedia applications, a new set of slot reservation and distributed channel assignment protocols for mobile ad hoc networks, called MBCA (Minimum Blocking Channel Assignment) and BRCA (Bandwidth Reallocation Channel Assignment), is presented. A fundamental feature of the proposed channel assignment algorithms is that they make use of the congestion states (i.e., available and used bandwidth) of the network. The performance results assert that a basic dynamic channel assignment (DCA) scheme can be significantly improved using the proposed MBCA and BRCA heuristics. Finally, a generic platform for accommodating relaying in the GSM (Global System for Mobile Communications) cellular network is presented. A prototype network layer system model tailored for operation within a GSM-MANET integrated system has been developed for the adaptive routing of calls in the presence of shadowing. The proposed system model is intended to support seamless communication by handing over (rerouting) a suffering call to another mobile terminal, which lies in a more advantageous position and can help as intermediate node of communication between the mobile terminal and base station.