Abstract: A retransmission method and apparatus performed in a transmitter of a mobile communication system supporting a Hybrid Automatic Retransmission reQuest (HARQ) operation and an Automatic Retransmission request (ARQ) operation for retransmission of a packet are provided. At least one ARQ entity generates at least one ARQ packet, and an HARQ entity transmits an HARQ packet including the at least one ARQ packet to a receiver, and transmits a local NACK signal indicating transmission fail of the ARQ packet to a corresponding ARQ entity, if the HARQ packet fails in transmission.

Abstract: Disclosed is a method for efficiently transmitting and receiving control information messages necessary for a Multimedia Broadcast/Multicast Service (MBMS) provided in a mobile communication system. The method includes setting information elements for the control information messages to reduce unnecessary signaling overhead during the transmission of the control information. The method prevents a user equipment (UE) from performing duplicate reception on the control information, thereby reducing power consumption of a battery.

Abstract: A method and apparatus for reordering data sent from a user equipment (UE). The UE assigns transmission sequence numbers (TSNs) to medium access control (MAC)-e protocol data units (PDUs) through an enhanced uplink dedicated channel (E-DCH). A Node B assigns, to received PDUs, time stamps (TSs) indicating time points when the PDUs are received. Using the TSNs and the TSs, a radio network controller (RNC) solves a problem of PDU disorder due to hybrid automatic retransmission request (HARQ) operations and transfer delay between the Node B and the RNC, and reorders the PDUs.