Routing over a Multihop Wireless Network of Mobile Computers

An ad hoc network is the cooperative engagement of a collection of mobile nodes without the required intervention of any centralized access point. In this chapter we present a design for the operation of such ad hoc networks. The basic idea of the design is to operate each mobile node as a specialized router, which periodically advertises its view of the interconnection topology with other mobile nodes within the network. This amounts to a new sort of routing protocol. We have investigated modifications to the basic Bellman-Ford [Bertsekas+ 1987] routing mechanisms, as specified by the Routing Information Protocol (RIP) [Malkin 1993], making it suitable for a dynamic and self-starting network mechanism as is required by users wishing to utilize ad hoc networks. Our modifications address some of the previous objections to the use of Bellman-Ford, related to the poor looping properties of such algorithms in the face of broken links and the resulting time-dependent nature of the interconnection topology describing the links between the mobile nodes. Finally, we describe the ways in which the basic network-layer routing can be modified to provide MAC-layer support for ad hoc networks. Note: From Mobile Computing, Imielinski, T., and Korth, H. F. (eds.), pp. 183–206— Chapter 6 by C. E. Perkins and P. Bhagwat. Norwood, Mass.: Kluwer, 1996. Copyright c © Kluwer Publishing. Used with permission.