A programmable MAC framework for utility-based adaptive quality of service support

We describe the design and evaluation of a programmable medium access control framework which is based on a hybrid centralized/distributed data link controller. The programmable framework and its associated algorithms are capable of supporting adaptive real-time applications over time-varying and bandwidth limited networks (e.g,, wireless networks) in a fair and efficient manner taking into account application-specific adaptation needs. The Framework is flexible, extensible and supports the dynamic introduction of new adaptive ser,ices on-demand. As part of the service creation process, applications interact with a set of distributed adaptation handlers to program services without the need to upgrade the centralized adaptation controller. This approach is in contrast to existing techniques that offer a fixed set of "hard-wired'' services at the data link from which applications select. We present a framework where a centralized adaptation controller responsible for the fair allocation of available bandwidth among adaptive applications is driven by application specific bandwidth utility curves, A set of distributed adaptation handlers execute at edge devices interacting with a central controller allowing applications to program their adaptation needs in terms of utility curves, adaptation time scales and adaptation policy. The central controller offers a set of simple meta-services called "profiles" that distributed handlers use to build sophisticated adaptive real-time services.