Many methods for end-to-end bandwidth estimation on wired networks assume that link capacities are constant and that all cross-traffic interaction occurs through queuing delays at node buffers. Wireless ad hoc networks do not conform to these assumptions due to the shared and unreliable nature of the transmission medium. In this paper we show that the end-to-end bandwidth is a random variable distributed within some range, which depends on the packet length, among other factors. After developing a simple theoretical framework to compare with, we devise a simple and effective dispersion-based method to estimate the mean of the end-to-end bandwidth as a function of packet length. The method is shown to converge quickly to an accurate estimate for any packet length, to be robust against cross-traffic, and to timely track bandwidth variations. All this is accomplished with high efficiency.
Marco A. Alzate, Maria P. Salamanca, Néstor