A 802.11 multiservices cross-layer approach for QoS management

The original 802.11 media access control protocol was designed with two simple access functions: DCF (distributed coordination function) which does not support any type of priority access and PCF (point coordination function) which supports time sensitive traffic flows but does not differentiate between traffic types. Enhancements that IEEE proposes in the 802.11e standard introduce the concept of traffic but no guarantees of service are provided. Today, 802.11 is widely used and its ability to support and manage real time and multimedia services is required. These are services that involve stringent QoS guarantees. In our study, we propose to take advantage of the knowledge of the 802.11 physical layer´s (PHY) state to manage the MAC layer´s access and to manage higher layer tasks too. It is an approach based on a cross-layer concept that takes advantage of information about the PHY layer state contained in the SNR. We also propose a decision policy which is user decision oriented depending on the PHY layer characteristics compared to users needs. Performance evaluations show that it is a solution that can manage efficiently 802.11 networks.