IEEE 802.11 PCF mode is defined to support time bounded applications in wireless LANs. The poll scheduling plays an important role in PCF mode operation. It differs from the packet scheduling of routers in that incomplete queueing information in each pollable station is known to the scheduler. This paper proposes an adaptive polling algorithm to improve the wireless medium utilization. In our scheme, each mobile station is assigned a priority by the point coordinator. Based on recent poll feedbacks, the priority for each mobile station will be dynamically updated using the Additive Increase/Multiplicative Decrease algorithm. The proposed polling algorithm is compatible with the IEEE 802.11 standard and requires a simple extension. our simulation studies show that the performance of wireless LANs are improved in terms of the successful poll rate and the aggregate throughput.
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