A new QoS point coordination function for multimedia wireless LANs

In this paper, we propose a new MAC protocol, named Q-PCF (quality-of-service PCF), which provides QoS guarantees to real-time multimedia applications for WLANs. Specifically, Q-PCF has the following attractive features. First, it supports multiple priority levels and guarantees that high-priority stations always join the polling list earlier than low-priority stations. Second, it provides fast reservation scheme such that real-time stations can get on the polling list in bounded time. Third, it employs dynamic bandwidth allocation scheme to support CBR/VBR transportation and provide per-flow probabilistic performance assurances. Forth, it adopts the novel mobile-assisted admission control technique such that the access point can admit as many newly flows as possible, while not violating admitted flows' guarantees. Simulation results do confirm that Q-PCF achieves high goodput and low frame delay dropped rate. Last but not least, we believe that the Q-PCF protocol can be easily applied to the current IEEE 802.11 products without major modifications.