基于数字预处理的同时同频全双工射频自干扰抑制关键技术

Comparing with TDD and FDD, the spectrum efficiency can be doubled in co-time co-frequency full duplex (CCFD) wireless communication, where the key technique is how to cancel the influence on the receiver from the strong self-interference effectively. However, at most 62 dB self-interference cancellation can be provided in RF at present, which cannot meet the requirement of the practical engineering projects. That is just the target of this project, exploring new RF cancellation method providing at least 80 dB self-interference cancellation. This project focuses on digital-preprocessing RF self-interference cancellaiton framework, with which the RF self-interference cancellation can be improved significantly. The signal preprocess method is studied so as to cancel the self-interference in RF effectively. The limitation of the self-interference cancellation is analyzed theoretically in the receiver with digital-preprocessing RF self-interference. The test platform will be established to confirm the theoretical analysis on the key techniques. The project reveals the relationship between CCFD communication mechanism and spectrum-efficient transmission, which provides effect guidance for the design of wireless communication devices and systems, such as mobile communication network, broadband wireless access network, military data link, EMC and the Internet of things.

同时同频全双工无线通信，与时分双工、频分双工相比能提高频谱效率1倍，核心关键 技术是如何有效抑制自身发射的强信号对接收通道的干扰。目前已有技术，射频域最多抑制干扰62dB，不能满足现实工程需要。这就是本项目的目标，探寻干扰抑制能力达到80dB的射频域干扰抑制新方法。 本项目重点研究能显著提高射频自干扰抑制能力的数字预处理射频自干扰抵消架构；探索该架构下有效抑制射频自干扰的信号预处理方法；分析数字预处理射频自干扰抵消接收机的自干扰抑制理论极限；搭建实验平台，完成关键技术的理论验证。 该项目将会揭示同时同频全双工通信体制与频谱高效率传输相互作用的深层机理，对移动通信网、宽带无线接入网、军用数据链与物联网等无线通信设备和系统的设计具有现实指导意义。

同时同频全双工下，自干扰信号与远端有用信号间的差异远超接收通道动态范围，故项目目标是探寻射频域自干扰抑制新方法，将自干扰压制在动态范围内。项目围绕数字预处理同时同频全双工射频自干扰抑制技术，发表了SCI论文23篇，EI论文12篇，授权和申请专利15个，培养了9位博士生、15位硕士生、5位青年教师。开展射频自干扰抵消新架构研究，提出数模混合联合信号处理方法，完成实验验证：.(1)针对数字重建射频自干扰无法抑制非线性成分问题，设计了数字辅助射频自干扰抵消结构及处理算法。在抑制非线性同时，兼顾数字重建快速特点。较之传统结构将射频自干扰抑制提高22dB。.(2)为扩大(1)干扰抑制量(受限DAC动态)，提出数字预处理两段式模拟域自干扰抑制结构及处理算法。采用射频直接耦合和数字重建，在LNA前后进行两次抑制，使干扰抑制量突破DAC限制，兼顾非线性抑制。.(3)理论分析相噪、非线性和量化噪声对抵消性能影响，在(1)、(2)技术基础上，提出对三者均能抑制的模拟辅助自干扰抑制及处理算法。分析表明，理想信道估计时，三者可完全被抑制。.(4)针对多天线全双工，为解决发射通道间串扰及非线性，在(3)基础上，复用反馈通道进行串扰补偿及非线性处理，使发射通道线性化且相互独立，降低抑制复杂度和成本。.(5)考虑低成本下采用低动态ADC全双工场景，在兼容(1)~(4)技术基础上，提出将数字自干扰抑制提到ADC前的前置抑制技术。分析显示，ADC仅3bit下也能保证对自干扰抑制。.(6)针对高发射功率射频重建引入非线性问题，提出射频重建通道非线性校正技术，采用差分测量通道，提取非线性特征，在数字域去除该非线性。实验表明抑制能力提高10dB。.(7)理论分析了欠抽头多径自干扰抑制极限性能，建立射频欠抽头干扰抑制、信道时变性、线性度、信噪比预算关系，定量揭示射频残余自干扰对灵敏度的恶化。为全双工链路预算提供理论支撑。.(8)搭建LTE-A标准全双工体制实验平台，射频自干扰抑制能力达到了80dB以上。