Channel assignment apparatus and method for common packet channel in wcdma communication system

PURPOSE: A method for assigning channels of a common packet channel(CPCH) in a code division multiple access(CDMA) communication system is provided to actively assign the CPCH required in a user equipment(UE) of a base station, to reduce time for setting up the CPCH, and to decrease a collision probability caused when many UEs request a CPCH using, to prevent a waste of wireless resources, then to assign a stable CPCH through a power control preamble(PC_P) between the UEs and a UMTS(Universal Mobile Telecommunications System) terrestrial radio access network(UTRAN) and to supply a stability relating to the CPCH using. CONSTITUTION: A terminal assigns reverse channels as follows, in a code division multiple access(CDMA) communication system. The terminal transmits an access preamble signal having channel information for being used to access a base station. The terminal receives an access preamble acquisition indication signal responding to the receiving of the access preamble signal of the base station, from the base station. The terminal responds to the received access preamble acquisition indication signal, and transmits a collision detection preamble capable of reconfirming accuracy of a reverse channel using. The terminal receives a first indication signal of a collision detection preamble acquisition and a second indication signal indicating a channel assignment. The base station responds to the collision detection preamble signal in the collision detection preamble acquisition. When the first and the second indication signal are received, the terminal transmits reverse channel data through a reverse channel assigned by the second indication signal.