Method of combining TAB of DCH for USTS

PURPOSE: A method for combining a TAB(Timing Alignment Bit) of a dedicated channel for a USTS(Uplink Synchronous Transmission System) is provided to simply combine TAB information transmitted during 20 frames for maintaining a timing obtained in an initial synchronization. CONSTITUTION: Node B compares a receiving signal timing from a UE(User Equipment) with a desired timing per every 200ms. If the receiving signal timing is quicker than the desired timing, the node B sets a TAB as "0". If the receiving signal timing is slower than the desired timing, the node B sets a TAB as "1". When 10 bits is transmitted to the UE, the 10 bits are simply combined for enhancing the reliability of timing control by the TAB for USTS. Every frame is skipped in a soft handover region, and a TPC(Transmit Power Command) of the 14th slot is replaced with the TAB and the TAB is transmitted. The TAB is simply combined during 20 frames and a decision is performed. The number of a hard decision value about each TAB is calculated for performing the last decision. Soft decision values about each TAB are combined for performing the last decision.