Why wait DIFS time before sending in CSMA/CA
1 Answer
In CSMA/CA different inter-frame spacing periods after the end of the previous frame are employed, in order to be able give different priorities to different kinds of frames.
There is for example the short interframe space (SIFS), which is shorter than the DCF interframe space (DIFS) and thus gives higher priority to frames, which only have to wait for one SIFS period after the end of the previous frame.
For example SIFS is employed for a clear to send (CTS) frame following a request to send (RTS) frame, or for a data frame following the CTS frame.