Reservation and admission control for QoS support in wireless networks

Supporting multimedia streams (e.g. voice/video over IP), in a wireless LAN requires guaranteed access to channel capacity, which is best provided using capacity reservations. Existing medium access control (MAC) protocols for wireless LANs either do not provide guaranteed access or do so in a synchronous (e.g. polling, TDMA) context. We present a novel mechanism for reserved access within the asynchronous or contention-based paradigm (for example CSMA/CA, or 802.11 DCF). Our protocol, called asynchronous reservation oriented multiple access (AROMA), allows a client to specify a capacity request using a moving window or leaky bucket descriptor. The server performs admission control, reserves the capacity and provides access to the capacity in a simple, efficient manner. The fully distributed version of AROMA provides a scalable control scheme that dynamically adapts backoff parameters for best-effort users based on measured traffic estimates, thus protecting otherwise vulnerable QoS reservations. AROMA is backward compatible with IEEE 802.11 DCF. The performance of AROMA using experimental analysis is analyzed. Experimentally, our comprehensive simulations using an enhancement of OPNET´s 802.11 model, shows that AROMA can support more VoIP call with a better QoS than IEEE 802.11e EDCF.