On the Service Differentiation Capabilities of EY-NPMA and 802.11 DCF

Most existing WLAN access mechanisms cannot provide QoS assurances. Even those that are QoS aware can only provide relative service differentiation. Based on EY-NPMA, the HIPERLAN Medium Access Control algorithm, the authors propose a dynamic priority medium access scheme to provide time-bounded services. By approximating an ideal Earliest Deadline First (EDF) scheduler, the proposed scheme can offer delay and delay jitter assurances while achieving high medium utilization. Furthermore, they compare their scheme with a mechanism that enhances the IEEE 802.11 MAC protocol with QoS support. Simulation studies document and confirm the positive characteristics of the proposed mechanism.