A first base station (1) is configured to establish a first signaling bearer with a mobility management apparatus (5), establish a second signaling bearer with a second base station (2), and to establish a signaling radio bearer with a mobile station (3) in a first cell (10). The second base station (2) is configured to establish the second signaling bearer with the first base station (1), establish a data bearer with a data transfer apparatus (6), and to establish a data radio bearer with the mobile station (3) in a second cell (20). Furthermore, the first base station (1) is configured to transmit, to the second base station (2) through the second signaling bearer configuration information, necessary to establish the data bearer and the data radio bearer in the second base station (2). Thus, for example, bearer architecture suitable for a C/U plane split scenario is provided.