Hello All, I recently played around with the IEEE 802.11e EDCA Model from TKN Berlin. I used ns 2.28. I enabled MAC tracing in their example script 'multi_udpflows.tcl' and set all UDP agents to priority 0. Surprisingly there were no collisions in the trace file. So, I disabled edca support [set opt(mac) Mac/802_11] and rerun the simulation. Now, there are collisions as expected in the trace.
With edca support enabled, I expect collisions when QoS stations of prio 0 and 1 are trying to access the channel in the same slot, or when more than one station of a specific prio is active. Access category voice and video have the same AIFS of 2. Therefore collisions should occur. In my test I set all udp flows to prio 0. Why there are no collisions? Are collision not traced, or is there a problem in the implementation? I would like to exchange experiences with you. Best regards Sven
