Disclosed is an uplink random access procedure in an NB-TDD (Narrow Band
Time Division Duplexing) system. To achieve an acknowledgement for data
transmission from a UTRAN (UMTS Terrestrial Radio Access Network), a UE
selects one of a plurality of sync codes by which the UTRAN identifies
UEs that request data transmission and transmits the selected sync code
in a time slot of a sub-frame to the UTRAN. Then, the UE receives the
sync code information, information about the arrival time of the sync
code, time update information indicating a variation in the transmission
time of data, and power information indicating an adjustment to a power
gain in the UE from the UTRAN on an FPACH (Fast Physical Access Channel).
The UE transmits the data on a P-RACH (Physical Random Access Channel)
mapped from the FPACH according to the time update information and the
power information.