A new per-class flow fixed proportional differentiated service for multi-service wireless LAN

In this paper, we propose a new per-CLAss Row fixed proportional differentiated service model (CLAF) and a companion medium access control scheme for multi-service wireless LANs (WLANs). The scheme is based on the IEEE 802.11 framework. Different from conventional relative differentiated service, in CLAF, a fixed bandwidth quality ratio is guaranteed on per-class per-flow basis regardless of the traffic load of each service class. Specifically, each service class is assigned a number of separate coordination periods, proportional to the policy-based bandwidth quality ratio for class isolation. Each class is associated with its own contention window size which is dynamically adjusted in accordance with the number of flows in the class in such a way to minimize collision probability between flows of the same class. Simulations results of the CLAF performance as well as a comparison with IEEE 802.11e EDCF including the support of QoS-sensitive VoIP applications are presented. The results show that the proposed scheme outperforms EDCF and achieves better resource utilization efficiency. It can provide users a more predictive, affirmative service guarantees than conventional relative differentiated service like IEEE 802.1 le EDCF.