A novel delay analysis model for EDCA with virtual collision handler

The IEEE 802.11e standard is specified to support quality-of-service (QoS) for medium access control (MAC) layer in wireless local area network. Existing work on the enhanced distributed channel access (EDCA), which is the primary medium access mechanism in 802.11e, had forced on the saturation throughput and delay, and the virtual collision handler (VCH) was seldom considered. However, real-time applications always work under unsaturated conditions because of their delay restrictions. The main contribution of this paper is to present a novel delay analysis model with a virtual collision handler; then, the total delay under unsaturated conditions, which includes the queuing delay and the channel access delay, is analyzed by using the combination of M/G/1 model and the proposed model. The analytical and simulation results show the accuracy of our model under unsaturated conditions.