Editing Carrier-sense multiple access (section)

===P-persistent===
This approach lies between the 1-persistent and non-persistent CSMA access modes.<ref>F. Calí, M. Conti, and E. Gregori, "Dynamic IEEE 802.11: design, modeling
and performance evaluation," IEEE J. Selected Areas Commun., vol. 18, pp. 1774–1786, Sept. 2000</ref> When the transmitting node is ready to transmit data, it senses the transmission medium for idle or busy. If idle, then it transmits immediately. If busy, then it senses the transmission medium continuously until it becomes idle, then transmits with probability ''p''. If the node does not transmit (the probability of this event is ''1-p''), it waits for a [[Randomness|random]] period of time before re-attempting the same procedure, using the same probability ''p''.<ref>{{Cite journal |last1=Kleinrock |first1=L. |last2=Tobagi |first2=F. |date=December 1975 |title=Packet Switching in Radio Channels: Part I--Carrier Sense Multiple-Access Modes and Their Throughput-Delay Characteristics |url=https://ieeexplore.ieee.org/document/1092768 |journal=IEEE Transactions on Communications |language=en |volume=23 |issue=12 |pages=1400–1416 |doi=10.1109/TCOM.1975.1092768 |s2cid=5879608 |issn=0096-2244}}</ref> If the transmission medium is not busy, it transmits again with the same probability ''p''. This probabilistic hold-off repeats until the frame is finally transmitted or when the medium is found to become busy again (i.e. some other node has already started transmitting). In the latter case the node repeats the whole logic cycle (which started with sensing the transmission medium for idle or busy) again. p-persistent CSMA is used in CSMA/CA systems including [[Wi-Fi]] and other [[packet radio]] systems. Note that ''p = 0''-persistent CSMA is different from non-persistent CSMA. Both can only transmit at the start of the procedure (if the channel is idle), but their behaviour on a busy channel differs: non-persistent CSMA doesn't attempt to sense the channel and restarts its logical cycle, whilst ''p = 0'' necessarily gets stuck in an infinite loop of waiting (since it has zero probability of transmission even if the channel goes back to being idle).