Performance analysis of automatic frequency control loop for cellular devices

The paper proposes a novel method to analyze the correctness of frequency correction loop in a 2G system, so that the mobile station accurately synchronizes to the base station. The setup contains an automatic frequency control (AFC) module to track and control the frequency/timing offset of the crystal. The main functionality of the AFC module is to estimate the optimum frequency correction value and minimize the frequency error of the system. It also contains a long term learning (LTL) module whose functionality is to derive an estimate for the crystal behavior due to temperature and aging and maintain a learning database containing the frequency correction values for the crystal in the operating temperature range. A separate module is used to correct advance/forward time drift on slave SIM, when oscillator is locked to the Master SIM. Various COST 207 GSM/EDGE channel models for mobile radio communication are implemented to test the frequency correction loop.