A high-efficiency loop delay estimator in digital predistortion subsystem

A high-efficiency time delay estimation method is presented to obtain the accurate loop delay (including integer and fractional loop delay) between the input signal and the time delayed feedback signal in digital predistortion subsystem within the same process. Compared with the conventional, a sampling position adjusting scheme for complex signals using the piecewise-parabolic filter assisted by a steady decision criterion for limited data length achieves a significant reduction in time complexity and an improvement in loop delay estimation stability and precision. Results from simulations and experiments show that the proposed method is high-efficiency and valid.