无线网络中的功率域非正交多址接入技术

功率域非正交多址接入(Dower Domain Non-orthogonal Multiple Access,PD-NOMA)技术,作为未来无线通信系统中重要的多址接入技术之一,可满足系统高频谱效率、高连接密度及低时延等需求。相比正交多址接入技术(Orthogonal Multiple,OMA),PD-NOMA利用用户间信道差异、功率域复用及串行干扰消除算法,实现多用户同时共享时、频、码资源。为推动功率域非正交多址接入技术的学术研究与实际应用,梳理了其基本原理,并从信息论角度验证了其相比正交多址接入技术可获得更高的频谱效率。基于PD-NOMA的现存研究工作,分别归纳讨论了单天线PD-NOMA、多天线PD-NOMA、协作PD-NOMA、能效PD-NOMA、可见光通信中的PD-NOMA、认知PD-NOMA及PD-NOMA的性能优化等关键技术研究方向。针对上述方向,进一步剖析了其未来研究趋势,并分别从接收机设计、信令开销、物联网应用及标准化4个方面深入探讨PD-NOMA在实际应用中所面临的难题。最后指出PD-NOMA的基本理论研究已接近成熟,但多技术融合仍需深入研究以加快该技术成果转化,从而充分发挥其在未来无线网络中的高频谱效率优势。

Power Domain Non-orthogonal Multiple Access Technology for Wireless Communication Networks

The power domain non-orthogonal multiple access(PD-NOMA) technology,one of the key enabling technologies for the future wireless networks,has become a research hotspot due to its capability to provide superior spectral efficiency,massive connections,lower handover latency and so on.In contrast to the conventional orthogonal multiple access(OMA),PD-NOMA enables multiple users to share the same time/frequency/code resources simultaneously by exploiting channel condition difference among users,power domain multiplexing and serial interference cancellation algorithm.In order to promote the academic research and actual application of PD-NOMA technology,its basic principle is analyzed,and it is concluded from information theory that it can obtain higher spectral efficiency compared with orthogonal multiple access technology.Based on the current research work of PD-NOMA,the key research directions are respectively summarized and discussed,including single-antenna PD-NOMA,multi-antenna PD-NOMA,cooperative PD-NOMA,energy-efficient PD-NOMA,PD-NOMA in visible light communication,cognitive PD-NOMA and performance optimization.According to the above research directions,several future research trends of PD-NOMA are pointed out.In addition,the problems of PD-NOMA in actual application are analyzed from such four aspects as receiver design,signaling overhead,Internet of Things(IoT) applications and standardization.Finally,it is pointed out that the basic theoretical research of PD-NOMA is more and more mature,but the multi-technology integration still needs to be studied in depth to accelerate the transformation of the technology and maintain its higher spectral efficiency in future wireless networks.