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

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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.