PCF Interframe Space
PCF Interframe Space (PIFS) is one of the interframe space used in IEEE 802.11 based Wireless LANs. PCF enabled access point wait for PIFS duration rather than DIFS to occupy the wireless medium. PIFS duration is less than DIFS and greater than SIFS (DIFS > PIFS > SIFS). Hence AP always has more priority to access the medium.
PIFS duration can be calculated as follows:
PIFS = SIFS + Slot time [1]
| Standard | Slot time (µs) | PIFS (µs) |
|---|---|---|
| IEEE 802.11-1997 (FHSS) | 50 | 78 |
| IEEE 802.11-1997 (DSSS) | 20 | 30 |
| IEEE 802.11b | 20 | 30 |
| IEEE 802.11a | 9 | 25 |
| IEEE 802.11g | 9 or 20 | 19 or 30 |
| IEEE 802.11n (2.4 GHz) | 9 or 20 | 19 or 30 |
| IEEE 802.11n (5 GHz) | 9 | 25 |
| IEEE 802.11ac | 9 | 25 |
See also
References
- ↑ "IEEE 802.11-2007 Standard" (PDF).
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