A data transmission method includes receiving information about a plurality of shared control channels, selecting at least one of the plurality of shared control channels using a User Equipment (UE) identity, receiving a message indicating the use of a shared data channel through the selected shared control channel, and receiving data through the shared data channel according to the message. When receiving a RRC message, such as a RRC connection setup message, transmitted through a shared data channel, a user equipment can decide a shared control channel to be monitored.