Study Of Power Control Algoriyhm In TD-SCDMA System

Power control technology can control the transmitter's transmission power, reduce the interference between base station and mobile station. Therefore, in CDMA system, power control is particularly important. In the third generation mobile communication systems, power control technology has been optimized and improved and power control algorithm has also been greatly improved.In this paper, it studies power control technology of TD-SCDMA system. Against the problem of lag compensation of existing fixed step power control algorithm when arising fast fading, the original variable step power control algorithm is improved, based on the research of Markov state variable step power control algorithm.Improved algorithm is based on measuring the signal to noise ratio of received signal. Firstly, it applies the Markov process theory to the power control algorithm, uses memory cells to record the power control adjustment command. It divides the whole process into four Markov state, using the relationship of the TPC command between current time slot and the before two time slots. Different state selects different step values, so that the system can choose a larger step size to compensate channel fading when it is in harsh environment. Secondly, it uses the Kalman filter to estimate fading channel real-timely. It uses the fading of the current moment and several before moments to estimate the next time fading accurately. It applies the estimated results to the power control process in order to determine the next power adjust step, so that the received signal power can achieve the best value.