Adaptive receiver for high-order modulated signals over fading channels

A system for providing a final smoothed phase estimate of a phase of a carrier from high-order MQAM and MPSK data modulated signals comprising,

• an adaptive phase tracking loop for receiving a high-order modulated input signal and generating a predicted phase for adjusting a reference phase to reduce an error between the phase of the carrier and the reference;
• an adaptive signal processor for estimating a nominal channel gain and an adaptive fade envelope estimation for generating normalized sampled baseband signals and non fading normalized sampled baseband signals;
• an adaptive fade envelope estimator for generating a preliminary sample estimate correlated to the adaptive fade envelope, and for generating a substantially noise free estimate of the fade envelope;
• a phase detector for generating the inphase and quadrature detected signals, and for generating a prediction error,
• a Kalman filter/fixed lag smoother for receiving the prediction error, for generating filtered and predicted state estimates, for generating the predicted phase from the predicted state estimate, for generating smoothed state estimates from the filter states and the prediction error, and for generating the smoothed phase estimate from the final smoothed state estimate, the smoothed phase estimate delayed from the input by a fixed delay;
• and
• a smoothed symbol detector for receiving the delayed predicated phase, the smoothed phase estimate, and the delayed non fading normalized sampled baseband signals, for generating the smoothed detected real component and the smoothed detected imaginary component and the smoothed detected symbol.