WTTP: A Scheduling Algorithm for Supporting QoS in IEEE 802.11e

This paper proposes a scheduling algo-rithm, the Wireless Timed Token Protocol (WTTP) for the Access Point of an IEEE 802.11e wireless network, to serve traffic streams with QoS guaran-tees. WTTP provides the established streams with rate-based guarantees. Furthermore, it makes the capacity not used by those streams available to con-tention-based access. The performance of WTTP is compared to that of a reference scheduler defined in the 802.11e draft standard using the ns2 simulator. The results show that WTTP outperforms the refer-ence scheduler with VBR traffic, both in terms of resource utilization and maximum number of ad-mitted flows.