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

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