Apparatus and method for proximity-based service communication

A radio terminal apparatus comprising:

• at least one radio transceiver;
• and
• at least one processor coupled to the at least one radio transceiver and configured to:
• receive, when the radio terminal apparatus cannot connect to a network, a radio configuration transmitted from a first radio terminal which is in a state of being able to connect to the network, the radio configuration comprising a radio parameter for the radio terminal apparatus to perform sidelink communication with the first radio terminal, the sidelink communication comprising at least one of direct discovery and direct communication;
• perform the sidelink communication in accordance with the radio configuration, with the first radio terminal via the at least one radio transceiver;
• attempt to receive, when detecting that the radio terminal apparatus is about to be in the state of being unable to connect to the network, a first signal transmitted by a neighboring radio terminal;
• and
• send, to the network, when the first signal has been successfully received, an identifier of the first signal or an identifier indicating a radio terminal which has transmitted the first signal.