Adaptive quality of service techniques can e ectively respond to time-varying channel conditions found in wireless networks. In this paper we assess the state-of-the-art in quality of service adaptive wireless systems and argue for new adaptation techniques that are better suited to respond to application speci c adaptation needs. A quality of service adaptive data link control model is presented that accounts for application speci c adaptation dynamics that include adaptation time-scales and

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... aptation policies. A centralized adaptation controller employs a novel utility-fair allocation scheme that supports the dynamic bandwidth needs of adaptive o ws over a range of operating conditions. Three wireless service classes play a n i n tegral role in accommodating a wide variety of adaptation strategies. In this paper, we discuss the design of the utility-fair bandwidth allocation scheme and the interaction between the centralized adaptation controller and a set of distributed adaptation handlers, which play a k ey role in intelligently responding to time-varying channel capacity experienced over the air-interface.