ADAPTIVE COHERENT DEMODULATION SYSTEM FOR MOBILE COMMUNICATION SYSTEM

摘要

PURPOSE: An adaptive coherent demodulation system for a mobile communication system is provided to maximize channel estimation efficiency regardless of moving speed of a mobile terminal by adjusting coefficient of a low band pass filter adaptively, thereby increasing channel volume. CONSTITUTION: A reference signal despreader(100) correlates I and Q channel data samples with a PN code generated from a PN generator of a receiver, and accumulates the result values for a predetermined period. A speed discriminator(110) receives each output signal of the reference signal despreader(100) for estimating moving speed of a mobile terminal or the maximum doppler frequency deviation and setting a low and pass filter coefficient. A reference signal filter(120) performs low band pass filtering for removing noise components of the I and Q channel data samples by using the low band pass filter coefficient. A traffic signal despreader(130) receives the I and Q channel data samples and accumulates each I and Q channel data sample during a traffic symbol section for obtaining each traffic symbol signal. A delay compensating buffer(140) delays each traffic symbol signal as long as low band pass filtering. A coherent demodulator(150) receives each output signal of the delay compensating buffer(140) and the output value of the reference signal filter(120) for compensating phase and demodulating the desired traffic signal.