基于星座变换的5G超大调制带宽功率放大器的带内数字线性化研究

The fifth generation wireless communication system (5G) is the main tendency for the evolution of global information technology. To effectively increase the data rate, the transmitted signal with large modulated bandwidth will be employed in 5G systems, e.g. 540 MHz at Q band, which will bring in revolutionary development for the whole communication system architecture. This project proposed a novel in-band digital linearization technique based on constellation transformation, which targets at the power amplifier’s nonlinearity issue incurred by large modulated bandwidth, especially focusing on the scenario of millimeter waves as a main candidate of 5G. By employing the proposed single-constellation and multi-constellation modeling technique, the behavior of PA excited by the signal with large modulated bandwidth can be accurately described. With the assist of the proposed technique, the baseband processing bandwidth can be largely reduced from the five times modulated bandwidth in the conventional system to only the original modulated bandwidth, which will break through the limitation of baseband processing bandwidth, leading to the effective utilization of the bandwidth resource in the whole transceiver chain.

第五代移动通信系统(5G)是全球信息技术领域的重点发展方向。为了有效提高信息传输速率，5G将采用超大调制带宽传输信号（例如Q波段的540 MHz调制带宽），这将对整个通信系统架构带来巨大的挑战。本课题针对5G超大调制带宽功率放大器的非线性失真问题，重点研究毫米波候选频段，提出基于星座变换的带内数字线性化技术。通过提出的单星座及多星座变换的数学建模方法，可以精确描述功率放大器在超大调制带宽信号激励下的行为特性，进而建立带内线性化方案。此技术可以有效地将线性化基带处理带宽从传统通信系统中的五倍信号调制带宽需求降低至等同于信号调制带宽本身，突破宽带线性化技术中基带处理带宽这一瓶颈问题，最终实现整个通信链路带宽资源的有效利用。

在第五代移动通信系统（5G）中，射频功率放大器和发射机的非线性特性将变得愈加复杂和重要。相应地，数字线性化技术也面临着诸多挑战, 例如超大带宽、共发多频段、大规模MIMO的波束扫描等等。本项目主要围绕以下三个方面展开深入研究：(1)基于单星座变换的输入输出关系的精确建模；(2)基于多星座变换的输入输出关系的精确建模；(3) 基于多星座变换的线性化架构。同时，特别针对5G大规模多输入多输出发射机以及包络跟踪功率放大器等新颖架构的建模及其线性化技术进行调研，并将神经网络算法创新地应用于数字预失真技术。本项目提出了多种全新的解决方案，例如包络预生成模型、通用模型、带内模型、带内外联合补偿模型、全角度线性化、多波束线性化等，可以弥补已有方案的复杂度高、稳定性低、处理速率要求高等不足。本项目的成果丰富，扩充了5G功放和发射机的建模和数字预失真方法，有力促进了未来移动通信发射机乃至整个系统的发展。