Optionally, the remote terminal device may receive or monitor a paging message sent by the network device.

Optionally, the state information is used to indicate whether the remote terminal device has a subscription relationship and/or a connection relationship with a relay terminal device, and/or indicate whether the remote terminal device is within coverage of a network.

In some implementation, the operation that the remote terminal device sends the state information to the network device includes an operation as follows. The remote terminal device sends the state information to the network device through an air interface message.

Optionally, the remote terminal device sends the state information to a first access network device through the air interface message; or the remote terminal device sends the state information to a first core network device through the air interface message; or the remote terminal device sends the state information to at least one second access network device through the air interface message.

In some implementation, the operation that the remote terminal device sends the state information to the network device includes an operation as follows. The remote terminal device sends the state information to the network device through the relay terminal device.

Optionally, the remote terminal device sends the state information to the first access network device through the relay terminal device; or the remote terminal device sends the state information to the first core network device through the relay terminal device; or the remote terminal device sends the state information to the at least one second access network device through the relay terminal device.