Enhancing QoS Support in IEEE 802.11e HCCA

IEEE 802.11e standard develops a reference design to support the contention-free access. In the reference design, the packet transmission opportunity (TXOP) duration is calculated based on the mean data rate and the mean packet size, whereas the scheduled service interval (SI) is calculated based on the most stringent delay requirement. Such design can not effectively utilize the bandwidth and support the guaranteed packet loss requirement. This paper proposes a packet-loss-based and bandwidth-utilization-based (PB-based) design to address the two problems. In the PB-based design, the TXOP is calculated based on the data rate and packet size fluctuation, whereas the SI is calculated based on different delay requirements. In addition, when packet loss requirement is not taken into account, we propose an equal-spacing-based (ES-based) design to improve the bandwidth utilization. The proposed designs are helpful to provide more comprehensive QoS support.