Field trials of two 802.11 residual bandwidth estimation methods

Ad hoc networks have attracted much attention due to their decentralized architecture and potential mobility. The latter promise has sparked research aimed towards routing and quality of service (QoS) admission schemes. The volatile links that are inherent to these networks have however spawned a need for a cross-layering service below IP for local route and QoS decision making, or information dissemination to participating hosts. We have conducted field trials of an active and a passive estimation method implemented in a real wireless driver to estimate the residual bandwidth. Through these tests we show how residual bandwidth estimates can be obtained in an 802.11 wireless network and identify the strengths and weaknesses of their underlying methods. The implemented wireless driver collects per link bandwidth data, local retransmission count and expected transmission time