IEEE 802.11e: The Problem of the Virtual Collision Management Within EDCA

IEEE 802.11e is the draft of amendments introducing QoS (quality of service) to the IEEE 802.11 standard. 802.11e supports HCF (hybrid control access) combining two access modes: EDCA (enhanced distributed channel access) and HCCA (HCF controlled channel access). EDCA is a distributed channel access function enabling prioritization. In this paper we discuss problems inherent to collision management within EDCA. The paper organizes as follows : the first part present the enhanced distributed channel access. Then we expose the issue of collision management. In the third part we detail our proposal for a modification of the EDCA´s collision management.