Mobile communication system, base station, and handover execution method

A handover execution method for use in a mobile communication system comprising a plurality of base stations, an upper node connected to the plurality of base stations, and a mobile station capable of connecting via radio to any one of the plurality of base stations, wherein

• while a first base station of the plurality of base stations that is currently connected via radio to the mobile station is receiving a first downlink signal from a second base station of the plurality of base stations that was previously connected via radio to the mobile station and that received the first downlink signal from the upper node for transmission to the mobile station, when the mobile station is connected via radio to a third base station of the plurality of base stations as a result of a handover, the first base station sends a redirection request signal requesting the second base station to redirect the first downlink signal to the third base station,
• the second base station, in response to the redirection request signal, redirects the first downlink signal to the third base station, and
• the third base station transmits the first downlink signal to the mobile station.