A Novel Call Admission Control Scheme for the IEEE 802.11e EDCA

The IEEE 802.11e standard aims at supporting quality of service (QoS) for real-time transmissions over WLANs and proposes the hybrid coordination function (HCF) that consists of two channel access methods: a contention-based channel access mechanism called enhanced distributed channel access (Edicts) and a controlled channel access mechanism called HCF-controlled channel access (HCCA) [1]. Although the HCF succeeds in supporting service differentiation, it does not guarantee strict QoS, hence the call admission control (CAC) is required. In the IEEE 802.1 le standard, the contention-based CAC and the controlled access CAC are proposed for EDCA and HCCA, respectively. In this paper, we propose a novel CAC scheme that manipulates the CWmin parameter to enhance the CAC performance in IEEE 802.11e EDCA where the packet size is small. This scheme (1) guarantees average delay and throughput, and (2) accepts as many calls (or requests) as possible at the same time.