Admission and Traffic Control Schemes Suitable for QoS Applications in WLAN Systems

This paper proposes the use of admission and traffic control schemes for real-time applications. The admission control scheme determines the admission of high-priority real-time applications such as voice and video streams in terms of their bandwidth utilization time (medium time), whereas the traffic control scheme maintains the communication quality of applications permitted admission by restricting other traffic. Owing to the use of contention-based access, a conventional scheme without admission control will degrade the communication quality when the number of terminals using high-priority applications increases. Moreover, only the capabilities (i.e., frame and sequence procedures) of admission control are defined in the IEEE 802.11e standard; the detailed usage in terms of the application characteristics is not specified, and it may be difficult to achieve a sufficient level of quality of service (QoS). The proposed schemes achieve the optimum QoS for actual services. The software used in the proposed schemes was implemented into hardware at the access point, and was evaluated experimentally. Based on the evaluation results, excellent performances with high QoS applications were obtained.