Performance Evaluation of Multi-Hop Packet Radio Networks using Simulation

Design of a multi-hop store-and-forward packet radio network with mobile stations is quite complex due to the changing connectivity environment. In view of this, a number of heuristic procedures for retransmission control, congestion control, updating of routing tables, etc. become necessary as can be found in the existing literature on packet radio networks (mostly related to the packet radio program of the Defense Advanced Research Project Agency). Since such procedures are not easily amenable to analysis, simulations and hardware/software testbeds are required to obtain a meaningful assessment of performance of the networks. In this paper, we describe a preliminary simulation model for packet radio networks, developed using the discrete event simulation language, SIMSCRIPT, on a VAX 11/780. In the present model, a number of functions such as routing, passive and active acknowledgments, determination of good neighbor nodes, carrier sense multiple access, and pacing are incorporated. Some numerical results are obtained using a topology with five stations. In future work, the model will be enhanced and used as a vehicle to analyze performance with different medium access and routing schemes and with higher level protocols such as the transport layer.