listen before talking (Ethernet) (LBT)

The Listen Before Talking(LBT) technique can be used where several subscribers share a transmission channel, for example in mobile communications and in the access method for Ethernet.

In both techniques, mobile communications and Ethernet, the aim is to check whether the transmission channel is free or is being used by another subscriber. The LBZ technique can be used equally for checking radio frequencies or wired media.

In the Ethernet access method Carrier Sense Multiple Access( CSMA), Listen Before Talking is a fundamental rule. In a CSMA network, when a station wants to send a data packet, the station willing to send first listens to the transmission medium. If the medium remains free for a certain time, the station can start the transmission. As long as the medium is occupied, a special signal indicates this.

Corresponding operating modes are used not only in Ethernet, but also in radio technologies such as Medical Implant Communications Service( MICS) and in Short Range Device( SRD) technology.