CSTDMA
Carrier Sense TDMA: The channel access scheme used by AIS Class B systems
Requires that the Class B AIS listens to the AIS network to determine if the network is free of activity and, only if the network is free, can it transmit its information.
This Class B AIS is also required to listen for reservations from base stations and comply with these reservations. This style of operation ensures that Class B AIS minimises the probability of interference with Class A, Base Station or AtoN AIS operations.