基于非正交多址的认知无线网接入技术研究

The modulation techniques used in mobile communications including cognitive radio networks generally allocate resources based on orthogonal multiple access. These techniques, i.e. time division multiple access(TDMA), code division multiple access (CDMA) and orthogonal frequency division multiple (OFDM) allocate different resources to different users by exploiting orthogonality. Recent studies imply that both wideband services, i.e. high-definition Television, and narrow band services, i.e. applications of Internet of Things co-exist in the future 5G communication networks. The traditional orthogonal modulation techniques are not applicable to the future 5G communication networks as the backwards including low utilization ratio of spectrum and dissatisfaction of the fairness of uses. I n this proposal, the scheme combining the new non-orthogonal multiple access modulation technique and cognitive radio network is proposed. The focus of the study is that the design of non-orthogonal multiple access scheme based on power domain superposition and space time code, and the design of adaptation code of multi-dimension pattern with different service qualities of users and space and time domain combination in the multiple antennas transmission systems. In this scheme, the signal is transmitted in a non-orthogonal way in the time-frequency domain and power domain without the backwards of low spectrum efficiency and the low service quality of cell edge users. Meanwhile, the dynamic access of frequency-time domain of channel and the adaptation code of multi-dimension pattern are studied in cognitive radio network combing with the non-orthogonal transmission scheme. The cooperative communication is studied in the non-orthogonal multiple access cognitive radio networks in order to further improve the utilization ratio of spectrum and the quality of experience (QoE) of cognitive users.

现有移动通信包括认知网络中调制技术都是基于正交思想进行资源分配，如TDMA,CDMA以及OFDMA，不同用户分配不同通信资源。但大量已有研究表明，5G时代将是宽带和窄带业务共存，面对这种新的通信环境，传统正交调制存在频谱利用率难以进一步提高，使用不灵活，用户公平性不能满足等不足。为此，本项目首次提出将NOMA调制与认知无线网络两种提高频谱利用率技术相结合的新方案。项目拟研究基于功率域叠加和空时编码的非正交多址方案；研究多天线传输中设计具有不同用户质量、联合空时域功率域的自适应多域联合编码；使信号在时频-功率域上实现非正交传输，克服传统正交方式中频谱效率不足和小区边缘用户服务质量差的缺点，同时研究5G无线通信环境下认知网络中基于动态频谱接入的编码方式。项目拟进一步从对用户服务需求差异性出发，研究如何基于非正交技术在认知无线网络中实现协作通信，进一步提高频谱利用率和改善认知用户服务体验QoE。

迄今，无线通信的频谱资源共享技术通常是基于正交思想进行资源分配，如TDMA、FDMA和OFDMA等。但5G时代将是宽带和窄带业务共存，各种新业务层出不穷，频率资源日益稀缺。面对这种新的通信环境，传统正交多址接入方式存在频谱利用率较低、使用不灵活和用户公平性不能满足等不足。面向5G时代，如何提高频谱效率和降低能耗将是无线通信领域十分紧迫和重要的课题。.为此，本项目首次提出将非正交多址接入（NOMA）技术与认知无线网络两种提高频谱利用率的技术相结合的新方案。项目从六个方面展开深入研究：.（1）面向认知场景的NOMA技术.（2）面向NOMA的天线分集和空时编码技术.（3）面向NOMA的协作通信技术.（4）面向NOMA的能量效率优化.（5）基于NOMA的安全通信技术.（6）面向绿色物联网的通信技术.本项目的研究目标如下：一是使信号在时频-功率域上实现非正交传输和随机接入，显著提高频谱效率；二是克服小区边缘用户服务质量差的缺点，提高用户服务公平性；三是针对海量终端接入面临巨大的安全问题，基于新的物理层安全的NOMA接入技术来提高安全性；四是针对频谱效率和能量效率同时提升问题，通过基于无线供电通信的非正交多址技术，实现海量物联网终端的通信。本项目对于全双工NOMA和协作中继NOMA系统提高吞吐量、MIMO-NOMA系统物理层的编码确保安全性，正交和非正交复用混合系统中用户配对提高吞吐量和改善用户公平性、实际场景难以获得准确信道信息的MIMO-NOMA系统性能分析、多中继NOMA系统和最佳发送天线选择提高吞吐量、无线供电终端与NOMA结合同时改善频谱和能量效率系统等的设计和分析，都取得重要研究成果。