This paper compares the performance of various routing protocols over "ad hoc" multi-hop wireless networks that do not require network infrastructure or centralized administration, such as the rooftop network discussed in a previous paper. Specifically, the DSDV, TORA, DSR and AODV protocols are evaluated over a ns-2 network simulator. The authors provide a very useful introduction to the potential applications of ad hoc networks and briefly discuss the ns-2 physical and link layer simulator. Destination-sequenced Distance Vector (DSDV) ensures loop-freedom and updates routing tables based on temporal locality of path information as well as optimal path metrics. Temporally-reordered Routing Algorithm (TORA) takes a very different approach, discovering routes on-demand and placing less emphasis on shortest-path routing. Dynamic Source Routing (DSR) completely abandons hop-by-hop routing and stores the complete, optimal node path at the source. This protocol does not require periodic route advertisement but one wonders how effective this can be over larger networks. Finally, Ad Hoc On-demand Distance Vector (AODV) combines several features of the DSDV and DSR protocols.
The simulation results indicate that while all protocols perform well in the absence of node mobility (large pause time), DSR and AODV come out on top in the presence of mobility. In terms of overhead, only the periodic DSDV routing protocol maintains a nearly constant overhead with respect to mobility rate. I really enjoyed this paper because it provided an overview of various approaches to multi-hop routing and built upon the previous few papers. The discussion was fairly straightforward as well.
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