Mobile station device and transmission power control method

A mobile station device for performing a handover from a first base station device to a second base station device, the mobile station device comprising:

• a first transmission loss calculator that calculates a transmission loss of a downlink signal sent from the first base station device, wherein the first transmission loss calculator obtains a transmission power of the downlink signal, based on a known base station maximum transmission power defined for the first base station device and transmission power control information of the downlink signal notified by the first base station device;
• a second transmission loss calculator that calculates a transmission loss of a broadcast signal sent from the second base station device, wherein the second transmission loss calculator obtains a transmission power of the broadcast signal, based on a known base station maximum transmission power defined for the second base station device and transmission power control information of the broadcast signal notified by the second base station device;
• and
• a transmission power controller that controls a transmission power of an uplink signal to the second base station device, based on a transmission power of an uplink signal to the first base station device and a difference between the transmission loss calculated by the first transmission loss calculator and the transmission loss measured by the second transmission loss calculator.