MUNet: Multicasting protocol in unidirectional ad-hoc networks .

摘要

The dissertation proposes a multicast routing protocol for unidirectional ad-hoc networks, called MUNet, based on the concept of spatial locality. Utilization of unidirectional links in ad-hoc networks is not generally considered by the mainstream research community because of the complexity and failure proneness. These weaknesses, which may be presented by a significant portion of unidirectional links can be overcome by the collaboration of neighbor nodes. The use of neighbor nodes significantly increases network resilience through path self-healing and path shortening. Potential link breakage can be detected and prevented by using neighbor nodes, prior to any costly, time-consuming link recovery.;The advantageous impact of utilizing unidirectional links is studied using Random Graph and Euclidean Graph models. The Random Graph model, where node connection and link direction are the only concerns, serves as a theoretical benchmark for the study. The Euclidean Graph model, where more physical characteristics of the wireless network are captured, examines the ability of the network to provide network connectivity through unidirectional links.;Similar to most routing protocols, MUNet consists of three main functions: path establishment, path maintenance, and link recovery. With the concept of spatial locality, it constructs a multicast meshed tree, enhanced by the inclusion of neighbor nodes.;Because of the absence of essential feedback at the MAC layer, broadcast is the only applicable link layer protocol. The use of neighbor nodes without proper selection strategies can adversely affect the overall routing performance. In order to improve the routing efficiency and resource utilization, we proposed an enhanced version of MUNet which heuristically selects which neighbor nodes should participate. Instantaneously determined by local control traffic density, a node probabilistically sets a level of its responsiveness to participate in the routing protocol maintenance.;Simulations using GlomoSim show that the packet delivery performance of MUNET is comparable to that of On-Demand Multicast Routing Protocol (ODMRP) but with significantly less routing overhead, in both unidirectional and bi-directional ad-hoc networks. The enhanced protocol shows further improvement in routing effectiveness along with a reduction in protocol overhead.