MEMS Reconfigurable Antennas Integrated with Adaptive Space-Time Processing Algorithms for Use in Wireless MIMO Systems

智力价值：拟议的研究活动集中在电磁理论、通信理论和射频微电子机械系统(RFMEMS)等跨学科领域的创新概念和技术。该项目将使多功能可重构天线的设计、分析、制造和测试能够与用于新型无线通信系统的自适应空时处理算法相结合。特别是，用于快速变化的多径条件的环境中的便携式或车载集成自适应多输入多输出(MIMO)微系统是目标。其目标是有效地利用多个可重构天线在容量和分集方面的理论收益，以最小化理论与实践之间的差距。为了实现这一目标，天线阵列特性(即辐射方向图、极化、工作频率和输入阻抗)和自适应传输信令方案被联合优化以适应变化的信道条件。这种联合优化过程需要能够改变其特性的可重构天线单元以及利用天线特性、传输信令方案和传播环境之间的相互关系的自适应算法。天线特性的动态适应是UCI最近的一项发展，代表了天线设计的一项重大进步。并行地，结合波束形成和空时编码的算法在发射端利用部分信道信息也是最近发展起来的。这项用于构建可重构天线阵列的创新技术是我们课题组通过DARPA计划开发的一种新型RFMEMS制造技术。该技术与微波叠层基板兼容，允许MEMS与印刷电路板上的天线元件进行单片集成。由于其单片集成能力，MEMS成为天线几何结构的物理组成部分，是实现高度多功能和结构可重构性的关键。该项目按照以下主要步骤组织：1.设计、分析、制造和测试一种新型天线，该天线具有多功能和在极化、辐射方向图、工作频率和阵列配置方面的可重构性。开发自适应编码和信号处理方案，以利用不断变化的信道环境。确定天线阵列特性、传输信令方案(空时编码、空间复用、波束形成)和传播环境(散射密度、散射体布置)之间的联系。对基于步骤1、2和3.5建立的MIMO系统进行了实验研究。在步骤1、2、3和4的基础上提出了一种自适应算法，通过将步骤1、2和3整合在一起，以使MIMO信道中的可用资源始终最大化。广泛影响：所提出的多功能可重构天线的概念超过了智能天线或自适应天线的能力，并与智能天线或自适应天线有明显的区别。在文献中，智能或自适应天线是指没有智能与信号处理能力相结合的天线阵列，通过该天线阵列，来自或去往各个天线单元的信号被加权和组合，以优化辐射方向图以响应信号环境。另一方面，可重构天线阵由多个天线单元组成，每个单元都具有一定的智能性。这种智能源于重新配置单个单元的物理结构的能力，通过该物理结构改变阵列的极化、辐射和频率属性。因此，可重新配置的天线阵列中的单元具有在频谱和角域中智能处理信号的能力，这是对系统现有的时域处理的补充。由于智能天线阵列即相控阵与可重构阵列的本质区别，本项目将发展描述可重构天线阵行为的理论。这将在电磁学教科书中的天线与传播一章中引入一个新的章节。还需要开发能够受益于这种新型天线的信号处理和通信理论。此外，在整个项目中采用的综合跨学科研究理念将允许PI开发和提供电磁学、通信和MEMS领域的跨学科教育计划，以满足UCI对能够处理新兴多功能微通信系统并为其提供解决方案的新一代工程师(特别是少数族裔学生)的需求。

Intellectual Merit:The proposed research activity focuses on innovative concepts and technologies in the interdisciplinary areas ofelectromagnetic theory, communication theory, and radio frequency microelectromechanical systems (RF MEMS).This project will enable the design, the analysis, the fabrication, and the testing of multifunctional reconfigurableantennas operated in conjunction with adaptive space-time processing algorithms for use in novel wirelesscommunication systems. In particular, man-portable or vehicle mounted integrated adaptive multi-input multi-output (MIMO) microsystems used in environments with rapidly changing multipath conditions are targeted. Thegoal is to effectively exploit the theoretical gains in capacity and diversity offered by multiple reconfigurableantennas in order to minimize the gap between theory and practice. To accomplish this goal, the antenna arrayproperties (i.e. radiation pattern, the polarization, the operation frequency, and the input impedance) and adaptivetransmission signaling schemes are jointly optimized to adapt to the changing channel conditions. This jointoptimization procedure requires reconfigurable antenna elements capable of changing their properties and anadaptive algorithm that uses the interrelationships among antenna properties, transmission signaling schemes, andpropagation environment. Dynamic adaptation of the antenna properties is a recent UCI development representing amajor advancement in antenna design. In parallel, algorithms that combine beamforming and space-time coding touse partial channel information at the transmitter have also recently been developed. The innovative technology,which will be used to construct the reconfigurable antenna arrays, is a novel RF MEMS fabrication technologydeveloped in our group by a DARPA program. This technology is compatible with microwave laminate substratesallowing monolithic integration of MEMS with antenna elements on a printed circuit board. Due to its monolithicintegration capability, MEMS becomes a physical part of the antenna geometry, which is the key in achieving highdegree of multifunctionality and structural reconfigurability. The project is organized under the following mainsteps:1. Design, analyze, fabricate, and test a new class of antennas providing multifunctionality andreconfigurability in polarization, radiation pattern, operating frequency, and array configuration.2. Develop adaptive coding and signal processing schemes to take advantage of changing channelenvironments.3. Determine the links among antenna array properties, transmission signaling schemes (space-time coding,spatial multiplexing, and beamforming), and propagation environment (scattering density, disposition ofthe scatterers).4. Experimental investigation of the MIMO system established based on Steps 1, 2, and 3.5. Based on Steps 1, 2, 3, and 4 develop an adaptation algorithm through which Steps 1, 2, and 3 areintegrated together in order to maximize the resources available in MIMO channel at all times.Broader Impact:The multifunctional reconfigurable antenna concept in the proposed work surpasses the capabilities of and has adistinct difference with smart or adaptive antennas. In the literature, a smart or adaptive antenna refers to an antennaarray of elements with no intelligence combined with signal-processing capability through which the time domainsignals from or to the individual antenna elements are weighted and combined to optimize the radiation pattern inresponse to the signal environment. On the other hand, a reconfigurable antenna array consists of antenna elementseach of which has some intelligence. This intelligence stems from the ability of reconfiguring the physical structureof individual elements through which polarization, radiation and frequency properties of the array are changed.Thus, the elements in the reconfigurable antenna array have the ability to intelligently process the signals in spectraland angular domains adding to the already present time domain processing of the system. Due to the fundamentaldifference between smart antenna array, i.e. phased array, and a reconfigurable array, the theory describing thebehavior of the reconfigurable antenna arrays will be developed under this project. This will introduce a new sectionin the chapter of antennas and propagation in electromagnetics textbooks. There is also a need to develop the signalprocessing and communication theory that can benefit from this new class of antennas. Furthermore the integratedinterdisciplinary research philosophy adopted throughout this project will allow the PIs to develop and offerinterdisciplinary educational programs in the fields of electromagnetics, communications, and MEMS that willanswer the need for the new generation of engineers (in particular among minority students) at UCI who can dealwith and provide solutions to the emerging multifunctional micro-communication-systems.