Patent ID: 8249103

Claim:
A method for transmitting control data of a PDCP (Packet Data Convergence Protocol) layer in a mobile communication system, the method comprising: generating a control PDU (Packet/Protocol Data Unit) including one or more first control information and one or more second control information generated at a PDCP layer; and transmitting the generated control PDU, wherein the generated control PDU includes an E (Extension) field indicating whether next control information exists, wherein the E field indicates the presence of fields in the order of a ‘Control PDU Type’ filed, a ‘Length’ field, and an ‘E’ field, as header information corresponding to the next control information, or the E field indicates, if there is a ‘Reserved’ field for a header byte alignment, the presence of the ‘Reserved’ field and that control information starts at the next byte, or the E field indicates that control information starts at the next byte, if there is no ‘Reserved’ field.