Efficient and robust multicast routing in mobile ad hoc networks

This dissertation examines multicast routing in mobile ad hoc networks. Previous work done in the field can be classified into either mesh based or tree based multicasting. Mesh based protocols offer path redundancy for packets to move from sender to receiver. As a result they offer greater resilience to link breakages than tree based protocols which offer only a single path from sender to receiver. Though mesh based protocols have a higher packet delivery ratio, they also have a higher overhead due to path redundancy. In addition to examining the tradeoff between tree based and mesh based protocols in detail, we also consider methods for improvement of multicasting protocols not considered before. These include use of directional antennas and multiple channels. We propose a series of protocols for this purpose, and compare them against ODMRP and MAODV which are the state of the art in mesh based and tree based multicasting respectively. Our main objective in designing these protocols was to minimize overhead and maximize packet delivery ratio.; The first protocol we present is Robust Multicasting in Ad hoc Networks using Trees (ROMANT). ROMANT evolved from an investigation into the reasons for the drastic degradation in the performance of MAODV once certain thresholds in terms of mobility, multicast group size and traffic load were crossed. Like MAODV, ROMANT is a receiver-initiated tree based protocol. ROMANT mainly differs from MAODV in the way it constructs and maintains the multicast tree. The next protocol we present is the protocol for unified multicasting through announcements (PUMA), which has an entirely different approach to mesh construction compared to ROMANT. As a result, PUMA is able to cut down the control overhead in ROMANT to almost half. Additionally we also present the following protocols: Adaptive Mesh-Based Multicast, Multicasting Over Directional Antennas (MODA) and Cross Layer Ad hoc Multiple channel Multicasting Protocol (CLAMMP). Adaptive Mesh-Based Multicast is the first protocol which provides a mechanism to control the redundancy of the mesh depending on network conditions, unlike earlier protocols which were either mesh based or tree based. MODA examines how directional antennas can be used to improve multicasting performance, and CLAMMP examines how multicasting performance can be improved through simultaneous transmissions in non-overlapping channels. (Abstract shortened by UMI.)...