Carrier Sense Multiple Access(CSMA) In certain situations nodes can hear each other by listening to the channel “ Carrier Sensing CSMA: Polite version of aloha Nodes listen to the channel before they start transmission Channel idle = Transmit Channel busy = Wait goin backlog) When do backlogged nodes transmit? When channel becomes idle backlogged nodes attempt transmission with probability q=1 Persistent protocol, =1 Non-persistent protocol, g 1Carrier Sense Multiple Access (CSMA) • In certain situations nodes can hear each other by listening to the channel - “Carrier Sensing” • CSMA: Polite version of Aloha – Nodes listen to the channel before they start transmission Channel idle => Transmit Channel b usy => Wait (join backlog) – W h e n do backlogged nodes t r a nsmit? When channel becomes idle bac klogged nodes att empt tran s mission with probability qr= 1 Persistent protocol, qr= 1 Non-persistent protocol, qr< 1 Eytan Modiano Slide 2