Incremental DPD Linearization for Mobile Terminals with Non-Flat Frequency Response in Dynamic Bandwidth Re-Allocation Scenarios
This paper presents a low-complexity open-loop digital linearization system for handset applications with non-flat frequency response when considering a 5G new radio dynamic bandwidth re-allocation scenario. The proposed digital predistorter (DPD) is scalable with the signal bandwidth by simply activating or deactivating basis kernels, without re-training nor re-assigning the model coefficients. To support this feature, an incremental bandwidth (IBW) generalized memory polynomial behavioral model is proposed, and the coefficients adaptation procedure is described. In order to find the most relevant basis supporting the IBW feature, a constrained version of the doubly orthogonal matching pursuit (DOMP) algorithm is proposed. Experimental results considering a handset power amplifier (PA) SoC under a mismatched load condition (i.e., non-flat frequency response) will validate the proposed approach.