RADIO RELAY DEVICE

PROBLEM TO BE SOLVED: To provide a technique capable of informing a mobile station of installation of a radio relay device at a point where a radio wave is very weak.SOLUTION: A transmission/reception unit on a base station side 14 receives a radio signal from a radio communication device on a base station 300 side, and outputs it to an electric field level detection unit 13. The electric field level detection unit 13 detects a signal level of the radio signal, and outputs it to a determination unit 12. The determination unit 12 determines whether the signal level is equal to or lower than a predetermined threshold value or not, and when the level is equal to or lower than the predetermined threshold value, notifies a mobile station IF unit 10 that the radio signal is very weak . The mobile station IF unit 10 transmits an installation request notice requesting to install a radio relay device to the mobile station 200, and notifies a user of the mobile station 200 that the radio relay device should be installed.