1. A method for operating a controller for wireless communications, the method comprising: broadcasting, by the controller, information of a first preamble for a random access procedure; broadcasting, by the controller, information of a second preamble for the random access procedure; transmitting, by the controller, control information in response to receiving a random access message transmitted by a user equipment (UE) in the random access procedure, the control information being carried in resources of a common search space in a wireless subframe, wherein the common search space is located in a control region of the wireless subframe when the random access message comprises a preamble corresponding to the first preamble, and the common search space is located in a data region of the wireless subframe when the random access message comprises a preamble corresponding to the second preamble, the wireless subframe comprising the control region and the data region, and the data region being non-overlapping with the control region; and transmitting, by the controller to the UE, configuration information of a user specific search space for the UE when the random access message comprises a preamble corresponding to the second preamble, the user specific search space being a control channel search space for the UE and located in a data region of a wireless subframe, and the configuration information for the user specific search space signaled in the common search space.