How to simultaneously achieve fairness and quality-of-service (QoS) guarantee in QoS-oriented wireless local area networks (LANs) is an important and challenging issue. Targeting at this goal and jointly taking priority setting, fairness, and cross-layer design into account, four scheduling schemes designed for the QoS-oriented wireless LAN mainly based on concepts of deficit count and allowance are proposed in this paper to provide better QoS and fairness. Using multiple deficit count to interframe space (IFS) and allowance to IFS mappings for different priorities, enhanced distributed deficit round robin (EDDRR) and enhanced distributed elastic round robin (EDERR) schemes are designed to reduce (or even eliminate) possible collisions, while EDDRR with backoff interval and EDERR with backoff interval schemes still keep the backoff procedure but dynamically adjust backoff intervals for nonfailure events (the events excluding collisions and failed transmissions) depending on the priority setting and deficit count or allowance with a cross-layer design. Through extensive numerical examples, we show that the proposed schemes outperform the closest scheduling schemes in the literature and exhibit much better QoS as well as station-level and flow-level fairness.

Two scheduling mechanisms called enhanced distributed deficit round robin with backoff interval (EDDRR-BI) and enhanced distributed elastic round robin with backoff interval (EDERR-BI) are proposed in this paper for the IEEE 802.11e wireless LAN. EDDRR-BI and EDERR-BI take both priority which is a mean to guarantee quality of service (QoS) and fairness simultaneously into account so that QoS and fairness can be well taken care. The idea behind the proposed mechanisms mainly relies on dynamic adjustment of the backoff interval according to priority, collision rate, and deficit count or allowance. Through numerical experiments, we demonstrate that the proposed mechanisms can reach station-level fairness as well as flow-level fairness within the same (among different) access category (categories). Of course, these mechanisms outperform the related schemes in the literature.