A method for enhancing data transmission efficiency for a radio resource control, hereinafter called RRC, procedure for a user equipment, also called UE, of a wireless communications system includes initiating an RRC update procedure; sending an update message corresponding to the RRC update procedure to a network terminal; reselecting a serving cell after the update message is sent to the network terminal; and using a common HS-DSCH radio network transaction identifier, abbreviated to common H-RNTI, for a high speed downlink operation corresponding to a CELL_FACH state if the selected serving cell supports the high speed downlink operation.