J Supercomput (2008) 45: 15–28 DOI 10.1007/s11227-008-0176-2 Dynamic and context-aware streaming adaptation to smooth quality degradation due to IEEE 802.11 performance anomaly Paolo Bellavista · Antonio Corradi · Luca Foschini Published online: 20 February 2008 © Springer Science+Business Media, LLC 2008 Abstract The need for application-level context visibility to properly perform streaming service management in wired-wireless integrated networks is widely recognized. In particular, the paper claims the need for full application-level aware- ness of context data about the IEEE 802.11 performance anomaly, i.e., when even a single node located at the borders of the coverage area of a Wi-Fi access point pro- duces a relevant degradation in the connectivity quality of all other nodes in the area. We propose a middleware that on the one hand portably predicts and detects anomaly situations via decentralized and lightweight client-side mechanisms and, on the other hand, exploits anomaly awareness to promptly react with application-level manage- ment operations (streaming quality downscaling and traffic shaping). In particular, the paper focuses on how our middleware performs anomaly-driven quality down- scaling both to preserve the goodput at nodes in well-covered areas and to minimize quality degradations at the clients generating the anomaly. The reported experimental results point out how anomaly prediction/detection can relevantly improve the ef- fectiveness of streaming downscaling, thus allowing to maintain acceptable service quality notwithstanding Wi-Fi anomaly occurrences. Keywords Service management · Wireless networks · Streaming adaptation · IEEE 802.11 anomaly · Middleware 1 Introduction The popularity of wireless devices and the increasing availability of IEEE 802.11 Access Points (APs) force to consider novel and challenging service provisioning environments. In particular, the widespread Wi-Fi connectivity is pointing out some P. Bellavista ( ) · A. Corradi · L. Foschini DEIS, University of Bologna, Viale Risorgimento 2, Bologna 40136, Italy e-mail: pbellavista@deis.unibo.it