A Low-complexity Crest Factor Reduction Design for 5G NR sub-6 GHz Digital Front-end with Restricted Peak Regrowth

In recent years, orthogonal frequency division multiplexing (OFDM) has gained widespread adoption in communication technologies, exemplified by long-term evolution (LTE), 5th generation new radio (5G NR sub-6GHz), and others. These technologies are instrumental in meeting the increasing demands for high data rates, throughput, and reliable downlink network access. However, a notable challenge associated with OFDM is the high peak-to-average power ratio (PAPR), imposing limitations on the efficiency of power amplifiers that often operate with significant back-offs. To mitigate this issue, the widely employed crest factor reduction (CFR) technique aims to enhance efficiency. This paper introduces a novel CFR methodology utilizing mixed and multi-iterative signal distortion-based techniques. Our approach is versatile, demonstrating effectiveness for low-bandwidth signals like LTE, as well as large-bandwidth signals reaching up to 100 MHz, as seen in 5G NR FR1. Also, digital up-sampling used to achieve the required high sample rate causes the issue of peak regrowth even after the required PAPR reduction achieved by CFR processing, which defeats the purpose of CFR. Our proposed design offers a solution to this challenge, enabling operation at a low data rate before digital up-sampling while effectively mitigating peak regrowth. Importantly, the implementation significantly reduces FPGA resource utilization, alleviating the complexity associated with multiple-input multiple-output (MIMO) radio systems. Demonstrating compliance with 3rd generation partnership project (3GPP) specifications for 5G NR on a real-time testbed, our approach stands as a practical and efficient solution for contemporary communication systems.