A study of adaptive modulation method for private mobile radio

摘要

We propose a new adaptive modulation method with both the instantaneous channel characteristics estimator and the maximum Doppler frequency estimator for Private Mobile Radio. The maximum Doppler frequency estimator is based on taking the time average of the normalized moving distance of pilot symbols on IQ-plane. Our proposal is to classify the estimated Doppler frequency fd by some thresholds, and carry out the various modulation control (the switch of adaptive modulation mode/fixed modulation mode, the change of selection table for modulation level), according to the resulting fd class. Therefore, this method can be applied to the fast fading channel. This paper also reports the computer simulation results for our proposal.