The contemporary research articles [6-13] on EDCA are all based on simulations. The analytical models [14-17] of EDCA have implemented only one active AC or flow per station. Here a real-time higher priority class interactive voice or multimedia application cannot be simultaneously run with a non-real-time, lower priority class data application like
file transfer, on the same work-station. This does not make full use of the computational power of today’s computers with parallel architecture and multitasking, multi-threaded operating systems environment. Keeping this in mind, the IEEE 802.11e EDCA standard suggests four active ACs per station. The aforesaid papers have also not considered the virtual collision handling feature. The models have not implemented the back-off counter freezing during back-off
process.