Patent ID: 8396505

Claim:
A radio communication system in which a plurality of small cell base stations are installed within a large cell formed by a large cell base station and each are configured to form a small cell smaller than the large cell, and the small cell base stations are configured to control transmission powers of radio terminals connected to the small cell base stations, wherein a network side device that is formed of at least one of the large cell base station and an upper-level device of the large cell base station comprises: an upper-limit value determination unit configured to determine an upper-limit value of an amount of interference which is received by the large cell base station from each of the radio terminals based on a permissible value of a total amount of interference which is received by the large cell base station from the radio terminals and the number of the small cell base stations within the large cell; and a transmitter configured to transmit upper-limit value information indicating the upper-limit value determined by the upper-limit value determination unit to the small cell base stations, and the small cell base stations each comprises: a receiver configured to receive the upper-limit value information from the network side device; a maximum value determination unit configured to determine a maximum value of transmission power of a corresponding one of the radio terminals based on the upper-limit value information received by the receiver and a propagation loss value indicating a propagation loss from the corresponding one of the radio terminals to the large cell base station; and a transmission power controller configured to control transmission power of the corresponding one of the radio terminals so the transmission power does not exceed the maximum value determined by the maximum value determination unit.