carrier sense TDMA (CSTDMA)

Carrier Sense TDMA (CSTDMA) is an access method for radio channels used in Automatic Ship and Identification Surveillance System( AIS) Class B.

In the Class B version, the AIS networkchecks the radio traffic to determine when there is no more activity on the network. Only when the radio network is completely free of radio traffic can it access a channel and transmit the information.

With Class B, the network must be listened to and used by the base station for reservation. The advantage of CSTDMA operation is that the probability of interference between Class A and Class B is extremely low.