Disjoint Multipath Routing for Mobile Ad Hoc Networks

Abstract

A mobile ad hoc network (MANET) is a collection of mobile nodes without any fixed infrastructure or any form of centralized administration such as access points and base stations. In such a network, each node plays a router for multi-hop routing as well. MANETs can be effectively applied to military battlefields, emergency disaster relief, and many commercial applications supporting collaborative group dynamics. The network topology in MANETs may keep changing dynamically due to node mobility, and thus routing protocols to find a path from a source to a destination are more complicated than those of wired and cellular wireless networks. The ad hoc on-demand distance vector routing (AODV) protocol (AODV) protocol is one of the Internet-Drafts submitted to the Internet engineering task force (IETF) MANET working group. Like other routing protocols, AODV also has inherently unstable routing paths which are dynamically changed and frequently broken. To resolve this problem, approaches to provide multiple paths for backup routing have been exploited. This thesis proposes a new multipath routing protocol called maximally disjoint multipath AODV (MDAODV), which exploits maximally node- and link-disjoint paths simultaneously and outperforms the conventional multipath protocols based on AODV as well as the basic AODV protocol. The key idea to provide maximally node- and link-disjoint paths simultaneously is to extend only route request (RREQ) message by adding source routing information and to make the destination node select two paths from multiple RREQs received for a predetermined time period. Compared to the other multipath routing protocols, the proposed MDAODV provides more reliable and robust routing paths and higher performance because both the alternative routing path may be used if the current routing path is broken and it is maximally node- and link- disjoint from the main path. Unlike the other multipath routing protocol, the proposed MDAODV makes the destination node determine the maximally node- and link-disjoint paths, reducing the overhead incurred at intermediate nodes. Our extensive simulation study shows that the proposed MDAODV outperforms the conventional multipath routing protocols based on AODV in terms of packet delivery ratio and average end-to-end delay, but reduces route discovery frequency and routing overhead. It is also shown from the simulation results that the proposed MDAODV provides more robust routing paths than the conventional approaches in worse operational environments such as higher node mobility, larger number of sessions and higher node density. Our approach to maximally node- and link-disjoint multipath routing can be easily extended and applied to other routing protocols for MANETs in order to provide more robust and scalable routing paths.