This is called a collision . Assigned a fixed time slot to each station. Each station has to wait for assigned slot to be ready then transmit one unit of data Data unit can be one character, one packet, or one bit. Good for all stations have consistent traffic patterns. It is wasteful of resources.
Control station sends a polling massage to the station.
The station transmit data after received polling massage. Adding a go-ahead massage to indicate the complete transmission. If the polling station has no data transmit, it immediately sends a go-ahead massage back. Roll call Polling Operation by each station. After transmission, the token state is switched back to free.