Robust 3D Beamforming using Electronically Steerable Metamaterial Antennas for Millmeter wave Communications

毫米波通信中使用电子可控超材料天线的稳健3D波束形成由于对更高容量的需求以及在高毫米波频率下克服强大气吸收的需要，3D波束形成是毫米波（mmWave）通信中一种很有前途的技术。通过在方位角和仰角方向上形成窄波束，3D波束成形允许有效的空间划分，并导致更高的用户容量、更好的覆盖、更少的干扰和更好的能量效率。然而，由于硬件和算法方面的巨大挑战，这项技术的真正前景尚未实现。现有的波束成形方法依赖于相控阵天线，其具有庞大的、高功耗的移相器和相关的放大器，并且尺寸不适合于实际的手机。真正的毫米波波束成形需要轻薄的天线，能够产生清晰的波束，这些波束可以在三维的大范围角度内进行电子转向。对于有效的波束成形，由于毫米波传播的强方向性、其高路径损耗以及对遮蔽和阻塞的脆弱性，在接收器和发射器两者处准确地估计信道存在额外的困难。这样的信道条件要求强大的3D波束形成算法，紧密耦合到新的天线设计，以将它们集成到高效的communicationsystems.This建议提出了跨越信号处理，天线设计和集成系统的水平几个关键的创新。 （一） 信号处理创新在于用于平面天线阵列的鲁棒3D波束成形算法，考虑到信道估计中的误差，特别是在特定于毫米波传播的出发角和到达角中的误差，以及由硬件中的固有非理想性和特定于所提出的超材料天线的工艺失配引起的天线波束形成的变化。这两种误差来源以前都没有考虑过。 (2)硬件创新在于使用基于超材料的谐振腔发射/接收天线，其超薄用于电子波束转向，通过在软件中智能偏置的超材料中嵌入有源组件（例如变容二极管）来实现。所提出的天线是从具有笨重的机械移动部件或移相器和相关放大器的现有相控阵天线的根本转变，从而也节省了显著的功率，同时提供宽转向角的灵活的窄波束宽度。 (3)这两个创新的方面，然后集成在一个多层次的评估计划，包括详细的测试和评估，在组件（天线），系统（收发器对），和网络（蜂窝）的水平。特征化的天线波束轮廓被集成在网络仿真中，该网络仿真利用详细的毫米波信道模型来实现所提出的鲁棒3D波束成形。项目成果预计将对毫米波通信产生直接影响，以满足蜂窝、车辆和物联网系统对高数据速率连接的需求。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Robust 3D Beamforming using Electronically Steerable Metamaterial Antennas for Millmeter wave Communications3D beamforming is a promising technology for millimeter wave (mmWave) communications, due to the demand for higher capacity and the need to overcome strong atmospheric absorption at high mmWave frequencies. By forming narrow beams in both the azimuth and elevation directions, 3D beamforming allows efficient spatial division and leads to higher user capacity, better coverage, less interference, and better energy efficiency. The true promise of this technology, however, has not yet been realized due to immense challenges in both hardware and algorithms. Existing beamforming approaches rely on phased array antennas with bulky, power-hungry phase shifters and related amplifiers and size not suitable for practical handsets. True mmWave beamforming requires thin, lightweight antennas with the ability to produce sharp beams that are electronically steerable over a wide range of angles in three dimensions. For effective beamforming, there is an added difficulty in estimating the channel accurately at both the receiver and transmitter because of strong directionality of mmWave propagation, its high path loss and vulnerability to shadowing and blockage. Such channel conditions call for robust 3D beamforming algorithms that are tightly coupled to novel antenna designs in order to integrate them into efficient communication systems.This proposal puts forth several key innovations spanning across signal processing, antenna design and integrated system levels. (1) The signal processing innovation lies in robust 3D beamforming algorithms for a planar antenna array, taking into account errors in channel estimation, particularly in angles of departure and arrival specific to mmWave propagation, and also variation in antenna beam formation caused by inherent non-idealities in hardware and process mismatch specific for the proposed metamaterial antenna. Both of these sources of error have not previously been considered. (2) The hardware innovation lies in the use of metamaterial-based resonant cavity transmit/receive antennas that are ultra-thin for electronic beam steering, achieved by embedding active components such as varactors in the metamaterial that are biased intelligently in software. The proposed antenna is a fundamental shift from the existing phase-array antennas with bulky mechanical moving parts or phase shifters and related amplifiers, thereby also saving significant power, while providing flexible narrow beam-width of wide steering angles. (3) These two innovative aspects are then integrated in a multi-level evaluation plan, including detailed testing and evaluation at component (antenna), system (transceiver pair), and network (cellular) levels. Characterized antenna beam profile is integrated in a network simulation that implements the proposed robust 3D beamforming with detailed mmWave channel model. Project results are expected to have direct impact on mmWave communications in meeting the demand for high data rate connectivity in cellular, vehicular, and IoT systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.