Knowledge of end-to-end path capacity is useful for video/audio stream adaptation, network management and overlay design. Capacity estimation in wired and last-hop wireless networks has been extensively investigated, but a thorough and systematic study in ad hoc, multihop wireless networks is still lacking. Yet the rate of a wireless link can change dynamically (and rapidly) due to changes in interference, distance or energy optimization policy. Timely knowledge of path capacity is key to efficient routing, traffic management and application deployment. In this paper, we present AdHoc Probe, a packet-pair based technique, to estimate end-to-end path capacity in ad hoc wireless networks. We apply AdHoc Probe to path capacity estimation in auto rate wireless networks with variable displacement and interference; and, in remote wireless networks across the Internet. Using analysis, simulation and testbed experiments, we show AdHoc Probe can withstand mobility and is able to trace the rate adaptation of wireless networks timely and correctly. AdHoc Probe is simpler, faster and much less intrusive than current schemes.
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