An algorithm for precisely estimating loop-delay in digital predistortion system

In digital predistortion (DPD) design, loop-delay estimation for synchronization is an important work. In this paper, an algorithm for precisely estimating loop-delay in DPD system is proposed. The whole algorithm consists of integer loop-delay estimation and fractional loop-delay estimation. Amplitude-difference correlation function is used to estimate the integer loop-delay estimation. The fractional loop-delay estimation gets the estimate through recursive least squares (RLS) algorithm based on interpolation filter structure. Finally, a series of simulations prove the validity of the algorithm and the effect on the DPD system.