Device for each other transmit different types of data in a wireless packet data communication system

A method and apparatus for encapsulating a PDU in a wireless packet data communication system. In a system providing voice and high-rate packet data services, an LAC layer and an RLP layer generate SDUs of MuxPDU Type 1, 2 , or 4 with signaling information and RLP_control information. A MAC layer determines whether to transmit the SDUs on a PDCH supporting MuxPDU Type 5 . If the PDCH is connected, the MAC layer encapsulates the SDUs with a MuxPDU Type 5 header and an extension header having encapsulation information, thereby generating MuxPDUs of MuxPDU Type 5 . A physical layer transmits the MuxPDUs on the PDCH.