Experimental Validation of the ns-2 Wireless Model using Simulation, Emulation, and Real Network

Wireless network research in the last years is often based on simulation. Ns-2 is a widely used wireless network simulation tool for this purpose. However, there are no published results about the accuracy of the ns-2 wireless model in the literature so far. In this paper we present the validation of one wireless network model built with ns-2 done by comparing the network characteristics of a simulated, an emulated, and a real wireless network. In order to show only the relevant differences, we have calibrated the radio propagation model of ns-2 to the real network and have used the same routing protocol implementation and the same application data traffic in all the compared networks. The results show that the packet delivery ratios, the connectivity graphs, and the packet latencies are represented in the model with an average error of 0.3%, 10%, and 57% respectively. Based on these results we conclude that the packet delivery ratios, and network topologies are accurately represented in ns-2, once the simulation parameters are properly adjusted. The accuracy of the packet latencies is lower and therefore statements about latencies in the real network based on the simulation results have a lower validity. Based on these results we provide recommendations for future development of the ns-2.