SIFS

Short Inter Frame Space

Used to separate transmissions belonging to a single dialog (e.g. Fragment-Ack), and is the minimum Inter Frame Space, and there is always at most one single station to transmit at this given time, hence having priority over all other stations. This value is a fixed value per PHY and is calculated in such a way that the transmitting station will be able to switch back to recieve mode and be capable of decoding the incomming packet, on the 802.11 FH PHY this value is set to 28 microseconds.