Test messages sent from the AP out to the network that are looped back manually from any segment between the AP and the base station or CDM are checked for corruption and timing when they are received back at the AP.

• AP 和基站或 CDM 之间的任意段会手工地回送这些从 AP 向网络发出的消息，而 AP 则会在收到回送消息时进行冲突检查和计时。