Gradient-Adaptive Spline-Interpolated LUT Methods for Low-Complexity Digital Predistortion

In this paper, new digital predistortion (DPD) solutions for power amplifier (PA) linearization are proposed, with particular emphasis on reduced processing complexity in future 5G and beyond wideband radio systems. The first proposed method, referred to as the spline-based Hammerstein (SPH) approach, builds complex spline-interpolated lookup table (LUT) followed by a linear finite impulse response (FIR) filter. second memory polynomial (SMP) contains multiple parallel LUTs together an input delay line such that more versatile modeling can be achieved. For both structures, gradient-based learning algorithms derived efficiently estimate LUT control points other related DPD parameters. Large set of experimental results provided, specific focus New Radio (NR) systems, showing successful PA samples well 28 GHz active antenna array, incorporating channel bandwidths up 200 MHz. Explicit performance-complexity comparisons also reported between SPH SMP systems widely-applied ordinary memory-polynomial (MP) solution. show capabilities methods very close MP DPD, particularly while having substantially lower complexity.