Interference rejection for AMPS using time dependent adaptive filtering and model-based demodulation

In this paper, we explore the combination of the time dependent adaptive filter (TDAF) and the model-based frequency modulation (FM) demodulator for Advanced Mobile Phone System (AMPS) interference rejection. The time dependent adaptive filter, which is blindly adapted using the constant modulus algorithm (CMA), can reject interference by exploiting the cyclostationary and constant envelope properties of the AMPS signal. The model-based FM demodulator uses a parametric method based on forward-backward linear prediction to provide high resolution frequency estimates for distinguishing interference from the desired signal. Examples are provided showing the performance of the combination of the CMA-constrained TDAF and the model-based demodulator in various signal environments. The computer simulation results show that this combination provides better performance for co-channel interference rejection than using only the TDAF or the model-based demodulator.