FIG. 27 is a schematic structural diagram 6 of a device embodiment for adding a secondary serving cell according to the present invention. As shown in FIG. 27, the secondary base station device includes a seventh sending unit 231B, a tenth receiving unit 232B, and an eighth sending unit 233B. The seventh sending unit 231B is configured to send a secondary serving cell addition response message to a primary base station, where the secondary serving cell addition response message includes a serial number of a random access preamble code and a serial number of a physical random access channel mask code. The tenth receiving unit 232B is configured to receive a random access request message that is sent by a terminal and carries the random access preamble code obtained according to the serial number of the random access preamble code. The eighth sending unit 233B is configured to obtain a time advance command TAC according to the random access request message, and send, to the terminal, a random access response message that carries the TAC, so that the terminal adjusts, according to the TAC, time advance TA of the terminal on a secondary serving cell corresponding to the secondary base station.
According to the foregoing secondary base station device, the secondary serving cell addition response message further includes a random access response window size, of the secondary serving cell, that is used by the terminal to receive the random access response message.
