Therefore, we conclude that the extra slot after the end of an EIFS will not be used by any
station (either involved in a collision as well as other stations monitoring the channel). Of course, in the
assumption that a DIFS is employed after a collision, then the fact that an Ack Timeout is greater than a DIFS is
even more evident.
Performance Study of IEEE 802.11 DCF and IEEE 802.11e EDCA 83
] P [ E / S
N D = (43)
In fact, under the assumption that no frames are lost because of the retry limit (i.e.,
R=infinity), each of the N stations is contending with a HOL frame. Moreover, S/E[P]
represents the throughput S measured in frames per seconds, and thus represents the frame
departure rate from the system.
The delay computation is more elaborate when a frame is discarded after reaching a
predetermined maximum number of retries R. In fact, in such a case, a correct delay
computation should take into account only the frames successfully delivered at the
destination, while should exclude the contribution of frames dropped because of the frame
retry limit (indeed, the delay experienced by dropped frames would have no practical
significance).
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