SYSTEM OF CONTROLLING INITIAL POWER RAMP-UP IN CDMA SYSTEM BY USING SHORT CODE

摘要

PROBLEM TO BE SOLVED: To improve a control method of transmission power ramp-up during the establishment of a communication channel between a subscriber unit and a base station in a radio CDMA communication system. SOLUTION: The system and method of controlling transmission power during the establishment of a channel in a CDMA communication system utilize the transmission of a short code from a subscriber unit to a base station during initial power ramp-up. The short code is a sequence for detection by the base station which has a much shorter period than a conventional spreading code. The ramp-up starts from a power level that is guaranteed to be lower than the required power level for detection by the base station. The subscriber unit quickly increases transmission power while repeatedly transmitting the short code until the signal is detected by the base station. Once the base station detects the short code, it sends an indication to the subscriber unit to cease increasing transmission power. The use of short codes limits power overshoot and interference to other subscriber stations and permits the base station to quickly synchronize to the spreading code used by the subscriber unit.