Kommunikatsioonimudel
is sensed idle for an amount of time equal to or greater than the Distributed Inter Frame Space (DIFS),
a station is then allowed to transmit. As with any random access protocol, this frame will be
successfully received at the destination station if no other station's transmission has interfered with the
frame's transmission.
When a receiving station has correctly received a frame for which it was the addressed recipient, it
waits a short period of time (the Short Inter Frame Spacing - SIFS) and sends an acknowledgment
frame back to the sender. We will see shortly that this explicit acknowledgment is needed because,
unlike the case of wired Ethernet, a wireless sender can not itself determine whether or not its frame
transmission was successfully received at the destination.
This is the case when the sender senses the channel to be idle. If the sender senses the channel
busy, the station performs a backoff procedure. The sender will defer its access until the channel is
annaabi.ee 
