A practical model for transmission delay of IEEE 802.11e enhanced distributed channel access

The soon to be ratified IEEE 802.11e MAC layer QoS enhancements to the 802.11 protocol are making their way into production wireless networking equipment. As greater numbers of local area networks utilize the QoS features of 802.11e, we can expect to see aggregation of these networks into larger systems capable of addressing the needs for high bandwidth, real time services. We present a practical and accurate analytical model for the saturation transmission delay of EDCA. Our model is distinguished by its ability to provide a cumulative distribution function for transmission delay and by its treatment of the post-collision period, heretofore ignored by all other 802.11 models. We prove that our model accurately predicts the cumulative distribution of transmission delay with results from the ns-2 simulator.