Cellular Digital Post-Distortion : Signal Processing Methods and RF Measurements

Abstract

In this paper, we study the feasibility of digital post-distortion (DPoD) based mitigation of transmitter nonlinear distortion in cellular networks. With specific emphasis on downlink, we describe a computationally efficient one-shot method to estimate and mitigate the cascaded multipath channel and transmitter nonlinear distortion effects at terminal receiver, building on demodulation reference symbols (DMRSs). We also describe a DMRS boosting approach to match the envelope characteristics of the DMRS and the actual data-bearing multicarrier symbols such that accurate mitigation is feasible. We provide RF measurement results with a state-of-the-art 28 GHz active antenna array and 256-QAM data modulation, demonstrating larger performance enhancements in received signal error vector magnitude (EVM) compared to existing computationally expensive iterative methods.