Advanced Signal Processing Enabled Massive MIMO With NOMA

当前无线网络的容量正成为主要瓶颈，因为大部分射频带宽已经被分配用于特定服务。相比之下，在30- 300 GHz频带内操作的毫米波（mmWave）通信是用于第五代（5G）和更高代（B5 G）无线网络的有前途的技术。由于其丰富的带宽和短波长，毫米波能够实现比传统微波通信（例如，Sub-6 GHz）。此外，其短波长允许在基站中部署大量天线，并将多个天线集成在小型手持设备中，使大规模多输入多输出（MIMO）系统与毫米波网络齐头并进。另一方面，非正交多址接入（NOMA）作为一种潜在的提高系统频谱和能量效率的技术，近年来受到了极大的关注。NOMA允许多个用户在同一时间和频率资源块上接入网络，并通过根据信道状态信息（CSI）分配不同的功率电平来分离不同用户的信号。 然而，尽管使用大规模MIMO和NOMA的毫米波通信具有许多优点，但是在实现这种复杂系统时存在技术挑战。这些包括需要广泛的CSI，这在大规模MIMO下难以获取，以及用于天线元件的许多射频（RF）链。此外，与微波信号相比，毫米波信号经历严重的路径损耗、高穿透损耗和恶劣的大气吸收，因此需要具有尖锐波束的定向传输来克服毫米波信号的严重路径损耗。此外，NOMA不可避免地在同时和频率共享非正交资源的多个用户之间引入干扰。在这个项目中，我们研究和开发新的信号处理方法，以解决未来B5 G网络在毫米波频率下运行的大规模MIMO-NOMA系统的基本挑战。该提案的长期目标是为大规模MIMO-NOMA系统设计支持B5 G无线通信的信号处理技术。短期目标包括（1）毫米波大规模MIMO系统的新型信道估计技术的设计;（2）收发器波束成形和波束跟踪的优化;（3）NOMA用户聚类和功率分配;以及（4）毫米波MIMO-NOMA系统的性能评估。拟议的项目还涉及将在康考迪亚大学为本科生和研究生以及博士后研究员开展的重要培训活动。

The capacity of current wireless networks is becoming a major bottleneck as most of the radio frequency bandwidth has already been allocated for specific services. In contrast, millimeter-wave (mmWave) communication operating within the 30-300GHz frequency band is a promising technology for the 5th generation (5G) and beyond (B5G) wireless networks. Due to its abundant bandwidth and short wavelength, mmWave enables much higher capacities and transmission rates than conventional microwave communications (e.g., Sub-6 GHz). Moreover, its short wavelength allows a large number of antennas to be deployed in the base station and multiple antennas to be integrated in a small hand-held device, making massive multiple-input multiple-output (MIMO) systems go hand-in-hand with mmWave networks. On the other hand, non-orthogonal multiple access (NOMA), as a potential technology to boost system spectral and energy efficiencies, has recently received a great deal of attention. NOMA allows multiple users to access networks at the same time and frequency resource block, and separates the signals of different users by allocating different power levels according to channel state information (CSI). Despite many advantages of mmWave communication using massive MIMO and NOMA, however, there are technical challenges in implementing such a complex system. These include requiring extensive CSI, which is difficult to acquire under massive MIMO, and many radio-frequency (RF) chains for the antenna elements. Moreover, mmWave signals experience severe path loss, high penetration loss and harsh atmospheric absorption as compared to micro-wave signals, and therefore directional transmission with sharp beam is required to overcome the severe path loss of mmWave signals. In addition, NOMA inevitably introduces interferences between multiple users that share nonorthogonal resources at the same time and frequency. In this project, we investigate and develop novel signal processing approaches to tackle the fundamental challenges in massive MIMO-NOMA systems operating at mmWave frequencies for future B5G networks. The long-term objective of this proposal is to design enabling signal processing technologies for massive MIMO-NOMA systems in support of B5G wireless communications. The short-term objectives include (1) design of novel channel estimation techniques for mmWave massive MIMO systems; (2) optimization of transceiver beamforming and beam-tracking; (3) NOMA user clustering and power allocation; and (4) performance evaluation of mmWave MIMO-NOMA systems. The proposed project also involves significant training activities for both undergraduate and graduate students as well as post-doctoral research fellows that will take place at Concordia University.