基于特征提取预失真的高功效线性功放技术研究

In present, large energy consumption of communication network has been a huge problem in the development of communication industry. Considering the major reason is low efficiency of power amplifier (PA), which is caused by serious distortion of PA, in this project we focus on the high efficiency linear power amplifier based on distortion elimination. Firstly, the PA distortion model will be analyzed detailly in order to form its inverse structure, i.e., predistorter. After we get its inverse structure, the linear PA can be structured by the combination of PA and predistorter. Secondly, in this project we propose an appropriate test sequence. Using test sequence as input signal, the distortion characteristic of PA can be estimated clearly by analyzing the PA output signal, which is amplifier by the PA. Since the distortion characteristic of PA can be obtained, the optimal status of predistorter can be calculated directly. Finally, because the distortion characteristic of PA will slowly change, the status of predistorter update algorithm must be involved in our research. The purpose of update algorithm is tracing the drift of PA, which is important for keeping the great linear performance of PA. The high efficiency linear PA proposed by this project has the advantages of high linearity performance, high iteration speed and high power efficiency. Meanwhile, the implementation is also considered in the project, therefore it has the advantages of universality and realizability. The achievement can promote the significant development strategy of Low-Carbon economic, and meet the requirement of energy conservation and emissions reduction. .

通信网络能耗过大问题已经成为影响通信产业发展的重大问题。考虑到能耗问题很大程度上由基站功率放大器的低功效问题引起，而功放失真又是引起低功效的主要原因，因此本项目重点研究高功效线性功放技术。首先通过分析功放模型，设计满足其逆特征的预失真器，并将二者串联构建高功效线性功放结构；随后，设计合理的测试序列，分析测试序列经过功放后的畸变特征，进行特征提取，并依据特征提取结果直接分析预失真器最佳初始状态；最后，考虑到功放失真特性会发生漂移，对应的预失真器状态也会发生改变，因此须设计预失真器状态的自适应更新策略，以跟踪功放的失真漂移、维持良好的线性化性能。本项目研究成果具有线性化精度高，工作至线性状态速度快，功率效率高等特点，同时由于在设计初期就考虑了工程实现，因此具有普适性和可实现性。本项目的研究成果能够直接支撑国家“低碳经济”重大发展战略，满足节能减排的要求，对促进通信产业的升级有较好的推动作用。

为了消除功放固有的记忆性失真和非线性失真，本项目针对功放线性化数字预失真技术展开研究，解决了传统的预失真技术无法解决记忆性干扰的难题，可以同时消除记忆性和非线性失真，从而扩大功放的线性区间，提升功放的功率效率。考虑到带反馈的预失真器存在原始信号/反馈信号偏移问题，本项目通过采用特征提取的方法，基于训练序列直接得到预失真器的模型和参数，从而能够在初始完成预失真器的模型参数配置，降低迭代时间，消除同步失真的影响。本项目面向实现的要求，研究基于训练序列的特征提取方法的非迭代预失真技术，首先通过分析功放模型，设计满足其逆特征的预失真器，并将二者串联构建高功效线性功放结构；随后，设计合理的测试序列，分析测试序列经过功放后的畸变特征，进行特征提取，并依据特征提取结果直接分析预失真器最佳初始状态；最后，考虑到功放失真特性会发生漂移，对应的预失真器状态也会发生改变，因此须设计预失真器状态的自适应更新策略，以跟踪功放的失真漂移、维持良好的线性化性能。经过本项目执行期间的研究，实现了基于特征提取的高线性化功放预失真技术的整体构架和核心算法，项目执行期产生论文5篇，其中参加国际会议2次，申请专利5项，为该技术的进一步应用奠定了基础。该成果可以用于未来B4G/5G场景下的功率放大器的线性化设计技术中，能够有效的提升功放的放大效率，降低功放的能耗。