Friday, March 12, 2010

WCDMA system


The power control technology is one of the most important technologies in WCDMA system. The capacity and quality of the system is deeply dependent on reverse-link power control, so it is very important. Inner loop power control technology is a quick close-loop power control technology. It works in the physical layer between the base station and the mobile handsets. The mobile control its own transmited power based on the commands send from the base station. The base station generates command by comparing its own transmited power and SIR with the target transmited power and SIR.Combining hardware and software studies, this paper introduces three methods to improve the mobile inner loop power control performance, which are good RF circuit match, accurate mobile RF power calibration and precise RF temperature frequency temperature power compensation. From hardware studies, mobile RF performance is based on good matching. If not, the transmited power range from -56dBm to 24dBm can’t meet requirement, then no inner loop power control can be done.From software studies, accurate RF power calibration can improve inner loop power control performance in segment E, F, G, H obviously. RF power amplifier temperature will vary quickly according to the output power and call time, while mobile need to work in different temperatures. Precise RF temp frequency compensation and temp power compensation can help to make up it, then to improve inner loop control in segments E, F efficiently. Test results show, inner loop power control performance meets all the requ-irements by appling these three methods.