Method and apparatus for data processing in mobile communication system

A data processing method of a mobile communication system and a device thereof are provided to perform a header process and a payload data process in parallel, while two memory devices can carry out parallel processing without sharing a bus. Two dual port memories are separated into a downlink memory(710) and an uplink memory(720) by using internal memories. Each one port of the respective memories is connected to a bus matrix(730) while the other ports are connected to IP(Internet Protocol) devices such as a modem(760), an external interface device(750), and an encryption/decryption unit(740) through a direct bus. Further, the IP(Internet Protocol) devices contain a DMA(Direct Memory Access).