Integration of On-Demand Service and Route Discovery in Mobile Ad Hoc Networks

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Title: Integration of On-Demand Service and Route Discovery in Mobile Ad Hoc Networks
Author: Rao, Ranjana
Advisors: Douglas S Reeves, Committee Chair
Abstract: This thesis studies the idea of adding on-demand service discovery to on-demand routing protocols for mobile ad hoc wireless networks. When on-demand service discovery is used, the service discovery process is initiated only when a node requires access to a service. The address of the service provider is returned to the initiator of the service discovery process. However, the initiator still has to discover a route to the service provider. By integrating service and route discovery, both the identity of the node providing the service and the route to the service are discovered together. This approach differs from related work on service discovery in ad hoc networks which perform service discovery at the application layer and do not discover a route to the service. A combined process for service provider identification and discovery of a route to this provider saves additional message transmissions and reduces the delay incurred if the two processes were done separately at the application and network layers respectively. The idea of adding on-demand service discovery to on-demand routing protocols for mobile ad hoc networks was earlier proposed in an Internet-Draft and simulated using Ad Hoc On-Demand Distance Vector Protocol (AODV) as the routing protocol. In this thesis, we propose modifications and extensions to the Internet-Draft. We discuss solutions to the problem of notifying the nodes in the network when a service provider terminates its service. We also present a modified simulation of the integration of service discovery with AODV (we discovered a number of bugs in the original simulation). We then present a simulation of the integration of service discovery with the Dynamic Source Routing Protocol (DSR). Lastly, we compare the performance of service discovery with AODV and DSR. We find that integrating service discovery with AODV gives better results in terms of service route acquisition latency. In terms of path length and the ratio of the path length to the shortest path, DSR gives better results for a smaller network size, while AODV gives better results for a larger network size. Further, the number of service discovery failures is higher when DSR is used, especially in larger networks. However, due to the aggressive caching in DSR, a node which requires a service is more likely to have a route to the service provider and hence may not need to initiate a service discovery. Since the DSR implementation in ns-2 that we consider does not actively purge stale routes from its cache, such a cached route is likely to be valid only in conditions of low mobility. Overall, we conclude that integration of service discovery with AODV gives better results than integration with DSR.
Date: 2004-01-08
Degree: MS
Discipline: Computer Science
URI: http://www.lib.ncsu.edu/resolver/1840.16/440


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