On the implementation of a capacity estimator for wireless ad hoc networks

End-to-end capacity is a useful metric for network applications such as traffic engineering, QoS verification, peer-to-peer file distribution, video/audio streaming, admission control, etc. Although several tools have been developed to estimate end-to-end capacity and available bandwidth in wired networks, estimators for wireless ad-hoc networks are still to be developed. The paper briefly describes the model of a new capacity estimation tool for wireless ad-hoc networks. Then, it discusses two critical aspects in the implementation of any estimation tool: time stamping packets and clock synchronization. The paper details how to time stamp packets under the Linux and Windows operating systems, and a describes a regression-based mechanism that eliminates measurement errors due to clock drifts. The time stamping methods and the regression algorithm are implemented in the capacity estimator, which shows accurate capacity estimations.

I. Introduction

Bandwidth estimation can be useful and benefit different areas of networking such as traffic engineering, QoS verification, peer-to-peer file distribution, video/audio streaming, and admission control, among others. The estimation of the end-to-end path capacity or maximum bandwidth has been studied extensively in wired networks. As a result, several tools are already available, such as Pathrate [1], Sprobe [2], and CapProbe [3].