面向5G移动通信的高效多维光载无线扩容机理研究

With the full commercial launching of 4G services, the research on 5G wireless technology is highly desired. However, the stringent requirements of large capacity, high efficiency and low cost will bring great challenges to the design of 5G system. In this project proposal, a novel method which could expand the capacity of 5G system based on high efficient and multi-dimensional radio over fiber (RoF) technology is proposed. Three scientific problems which include how to realize broadband optical-wireless transceiver at low costs, how to efficiently and multi-dimensionally increase the capacity of RoF system, and how to precisely equalize the fiber-wireless hybrid channels are comprehensively investigated from three layers which are modules, links and systems. In this project, a low-cost and broadband optical-wireless transceiver which could reduce the requirement of expensive external optical modulator and high linear optoelectronic devices will be studied and designed by using push-pull directly-modulated structure and DSP pre-compensation techniques. A high-efficient and multi-dimensional capacity expansion method which could realize high capacity 5G system by using sub-6GHz spectrum will be presented based on the orthogonal frequency division multiplex/offset QAM (OFDM/OQAM) multicarrier modulation technique and multi-core fiber (MCF) space division multiplexing technique. A high performance fiber-wireless hybrid channel estimation and compensation algorithm which could effectively enhance the inter-core crosstalk tolerance and support much more core number MCF and more remote radio nodes will be investigated. At last, a novel low-cost, high-capacity (10Gbps wireless access rate and 20km 19-core fiber), and bidirectional 8×8 MIMO 5G radio over fiber system will be proposed and experimentally demonstrated. Research results of this project can lay the foundation for sustainable development of 5G and Ultra-5G mobile communications.

随着4G商用的全面启动，5G移动通信技术研究已势在必行，而超大容量、高能效和低成本的严苛要求将会给5G系统设计带来极大挑战。本项目创新地提出一种面向5G移动通信的高效多维光载无线扩容机制，从模块、链路和系统三个层次出发解决低成本宽带光无线信号收发、高效多维光纤无线信道扩容和高精度光纤无线混合信道均衡三个科学问题。研究基于推挽直调和DSP后补偿的低成本宽带光无线收发技术以有效规避系统对昂贵外调制器或高线性光电器件的依赖。研究基于OFDM/OQAM技术和多芯光纤的高效多维光纤无线信道扩容方法以实现低载频（6GHz以下）上的大容量传输。设计高精度光纤无线混合信道均衡算法以有效提升芯间串扰容忍度以支持更大纤芯数和更多远端射频节点。最终构建面向5G的10Gbps无线接入速率、19芯光纤、单纤双向8×8 MIMO光载无线接入系统，完成实验验证与测试，为我国5G和超5G移动通信产业的可持续发展奠定基础。

本项目以实现面向5G移动通信的低成本高效多维光载无线扩容为目标，从模块、链路和系统三个层次出发，从四个方面开展了研究工作，包括：基于推挽直调和DSP后补偿的低成本宽带光无线收发模块设计、FBMC（OFDM/OQAM）多载波技术和多芯光纤的高效多维光纤无线信道扩容技术、多维RoF扩容的高精度光纤无线混合链路均衡与补偿技术和面向5G的单纤双向光载无线接入系统的评测与验证。成功研制一款高性能直接调制模拟光收发一体化模块，每个通道的3dB带宽都达到了19.1GHz以上，所有通道SFDR3均达到了90.5dB·Hz2/3以上；研制的两级预失真电路模块可提升商用收发模块SFDR至120dB·Hz2/3；提出并实验验证了一种基于SCMA与OFDM/OQAM的RoF系统，可以将频谱效率提升1.89倍，而且可以支持更多的用户；完成了MIMO-OFDM/OQAM信号对多芯光纤芯间串扰容忍度的研究，实验验证所提出算法可支撑64芯光纤的串扰；提出并实验验证了一种基于联合推挽结构与自适应后补偿算法提高直调ROF系统的线性度技术；基于实验室自研的7芯光纤搭建了基于对称上下行4x4MIMO光载无线传输系统，实现了11.04Gb/s 4x4 MIMO SCMA-OFDM/OQAM信号传输20km 7芯光纤和0.4m无线的双向光载无线传输，实验验证基于所提出的技术，系统频谱效率可提升65.2%。基于上述研究内容，项目执行期内发表SCI期刊论文20篇，国际光学会议论文8篇（包括OFC、ECOC会议论文4篇），申请国家技术发明专利4项（其中授权2项）。培养博士生5名，硕士研究生7名。本项目研究成果将会在未来B5G移动通信中有广阔的应用前景。项目成果已受到了包括华为在内的行业多家公司关注，也于2019年与华为公司正式开展了横向课题合作（项目经费142万），2020年12月该项目以优秀结题。第二阶段横向课题也已经进入了华为公司内部评审，即将于2021年初开展。