Patent ID: 8649732

Claim:
A radio terminal in a tree-structured network, wherein the radio terminal directly communicates with a radio base station such that the radio terminal is a root of the tree-structured network, the radio terminal comprising: a communication unit configured to directly communicate with the radio base station; a communication relay unit configured to relay communications between the radio base station and a lower-level radio terminal in the tree-structure network; an inquiry message transmitter configured to transmit, to the lower-level radio terminal, an inquiry message for inquiring whether or not the lower-level radio terminal can directly communicate with the radio base station, in accordance with a transmissible data amount in a communication bandwidth assigned to the communications between the communication unit and the radio base station, even when the radio terminal does not receive a request for transmitting the inquiry message from the radio base station: a response message receiver configured to receive from the lower-level radio terminal a response message indicating that direct communications with the radio base station are possible, when the lower-level radio determines that direct communications with the radio base station are possible; and an instruction message transmitter configured to transmit to the lower-level radio terminal an instruction message instructing to start direct communications with the radio base station, thereby causing the lower-level radio to perform direct communications with the radio base station.