Holographic MIMO Communications: Theoretical Foundations, Enabling Technologies, and Future Directions

Future wireless systems are envisioned to create an endogenously holography-capable, intelligent, and programmable radio propagation environment, that will offer unprecedented capabilities for high spectral and energy efficiency, low latency, and massive connectivity. A potential and promising technology for supporting the expected extreme requirements of the sixth-generation (6G) communication systems is the concept of the holographic multiple-input multiple-output (HMIMO), which will actualize holographic radios with reasonable power consumption and fabrication cost. The HMIMO is facilitated by ultra-thin, extremely large, and nearly continuous surfaces that incorporate reconfigurable and sub-wavelength-spaced antennas and/or metamaterials. Such surfaces comprising dense electromagnetic (EM) excited elements are capable of recording and manipulating impinging fields with utmost flexibility and precision, as well as with reduced cost and power consumption, thereby shaping arbitrary-intended EM waves with high energy efficiency. The powerful EM processing capability of HMIMO opens up the possibility of wireless communications of holographic imaging level, paving the way for signal processing techniques realized in the EM-domain, possibly in conjunction with their digital-domain counterparts. However, in spite of the significant potential, the studies on HMIMO communications are still at an initial stage, its fundamental limits remain to be unveiled, and a certain number of critical technical challenges need to be addressed. In this survey, we present a comprehensive overview of the latest advances in the HMIMO communications paradigm, with a special focus on their physical aspects, their theoretical foundations, as well as the enabling technologies for HMIMO systems. We also compare the HMIMO with existing multi-antenna technologies, especially the massive MIMO, present various...Comment: double column, 58 page

Intellectual Agent Ensemble with Professional Competencies, Pattern Recognition and Decision Making

Each competence is exercised by an intellectual agent with a competent functional professional image. Intellectual agents form an ensemble with clever ethical artificial intelligence. The use of an ensemble with intelligent ethical artificial intelligence in various environments is carried out by synergistically adjusting the interaction of intelligent agents based on data from a specific environment obtained by an analytical competent intellectual agent. Modeling holographic processes of the human psyche based on artificial intelligence of machine learning with Fourier transformation using full parametric sequences of necessary and sufficient data of holograms of target objects solves the problem of their unambiguous detection in different environments and in different conditions. An ensemble of intelligent decision-making agents is a cognitive information system that makes a decision based on an objective analysis of available data in difficult situations, in an interactive mode, taking into account performance criteria and resource-time constraints. Decision-making criteria are functionalities that express preferences and allow ranking the quality of decisions. Decisions are made on the basis of rules. Decision rules are a set of logical constructs used to produce a decision based on criteria, data, and knowledge. An ensemble of intellectual agents with professional competencies, pattern recognition and decision-making fully model the abilities of the human psyche

Advanced Wavefront Control with Linear and Nonlinear Metasurfaces

Metasurfaces offer unique opportunities for functional flat optics and allow controlling the transmission, reflection, and polarization of light. In particular, all-dielectric resonant metasurfaces have reached remarkable efficiencies and performances. The meta-atoms based on generalized Huygens' principle give flexible full-range phase modulation with nearly no loss. Holographic calculations can carefully map out the spatial arrangement of the meta-atoms and exploit the potential of the metasurface platform for wavefront control. Such advanced and complex wavefront engineering is fully studied and extended to the nonlinear regime, where the nonlinear optical response of metasurfaces opens up new degrees of freedom. This offers a paradigm shift in nonlinear optics. The nonlinear metaholograms are expected to revolutionize subwavelength photonics by enhancing substantially the nonlinear response of natural materials combined with an efficient control of the phase of their nonlinear waves. It is believed that the joint effects of advanced wavefront control in linear and nonlinear optics could eventually lead to integrated photonic computing and nanophotonics quantum circuits. In this thesis, the development of the nonlinear holographic metasurfaces is presented in a progressive order. In Chapter 1, we provide a comprehensive introduction to the development of metasurfaces, followed by the motivation of creating practical nanophotonic devices. Chapter 2 explains the principles of designing holographic Metasurfaces and phase modulating meta-atoms. We demonstrate a complex wavefront control using the highly efficient polarization-insensitive holographic Huygens' metasurface based on resonant silicon meta-atoms. Moving forward, we demonstrate the transparent meta-holograms based on silicon metasurfaces that allow high-resolution grayscale images to be encoded. The holograms feature the highest diffraction and transmission efficiencies, and operate over a broad spectral range. Chapter 3 explores various types of nonlinear nano-antennas. The multipolar nature of nonlinear resonance is firstly proved by experiment using a nonlinear setup. Our method of optical diagnostics provides a fast and convenient way to acquire the information on materials' nonlinear responses, and it links the nonlinear behaviors of materials to their intrinsic properties. Both numerically and experimentally, the third-harmonic generation (THG) from silicon dimers composed of pairs of two identical silicon nanoparticles demonstrates the multipolar harmonic modes near the Mie resonances that allow shaping of directionality of nonlinear radiation. Efficient control of both electric and magnetic components of light leads to the enhancement of nonlinear effects near electric and magnetic Mie resonances with an engineered radiation directionality. Second harmonic generation (SHG) from III-V based nano-structures reveal that AlGaAs nanodisk antennas can emit second harmonic in preferential direction with a backward-to-forward ratio of up to five, and they can also generate complex vector polarization beams, including beams with radial polarization. We distinguish experimentally the contribution of electric and magnetic nonlinear response by analyzing the structure of polarization states of SHG vector beams. The transition between electric and magnetic nonlinearities is controlled continuously by tuning polarization of an optical pump. Finally, Chapter 4 presents a general theoretical approach and experimental platform for nonlinear wavefront control with highly-efficient nonlinear dielectric metasurfaces. This approach is based on the generalized Huygens' principle extended to nonlinear optics and it allows creating arbitrary phase gradients and wavefronts via excitation of electric and magnetic Mie-resonance multipoles. Based on our concept, we design and demonstrate experimentally the first nonlinear all-dielectric metasurface that generates a third harmonic signal with a high precision in its wavefront control. Multipolar analysis and numerical calculations are performed over a broad pump spectral range with comparisons to the experimental results. Chapter 5 summarizes the key achievements of this work and discusses the future applications based on these results

Equipment concept design and development plans for microgravity science and applications research on space station: Combustion tunnel, laser diagnostic system, advanced modular furnace, integrated electronics laboratory

Taking advantage of the microgravity environment of space NASA has initiated the preliminary design of a permanently manned space station that will support technological advances in process science and stimulate the development of new and improved materials having applications across the commercial spectrum. Previous studies have been performed to define from the researcher's perspective, the requirements for laboratory equipment to accommodate microgravity experiments on the space station. Functional requirements for the identified experimental apparatus and support equipment were determined. From these hardware requirements, several items were selected for concept designs and subsequent formulation of development plans. This report documents the concept designs and development plans for two items of experiment apparatus - the Combustion Tunnel and the Advanced Modular Furnace, and two items of support equipment the Laser Diagnostic System and the Integrated Electronics Laboratory. For each concept design, key technology developments were identified that are required to enable or enhance the development of the respective hardware

Vision technology/algorithms for space robotics applications

The thrust of automation and robotics for space applications has been proposed for increased productivity, improved reliability, increased flexibility, higher safety, and for the performance of automating time-consuming tasks, increasing productivity/performance of crew-accomplished tasks, and performing tasks beyond the capability of the crew. This paper provides a review of efforts currently in progress in the area of robotic vision. Both systems and algorithms are discussed. The evolution of future vision/sensing is projected to include the fusion of multisensors ranging from microwave to optical with multimode capability to include position, attitude, recognition, and motion parameters. The key feature of the overall system design will be small size and weight, fast signal processing, robust algorithms, and accurate parameter determination. These aspects of vision/sensing are also discussed

Reconfigurable Intelligent Surfaces for Wireless Communications: Principles, Challenges, and Opportunities

Recently there has been a flurry of research on the use of reconfigurable intelligent surfaces (RIS) in wireless networks to create smart radio environments. In a smart radio environment, surfaces are capable of manipulating the propagation of incident electromagnetic waves in a programmable manner to actively alter the channel realization, which turns the wireless channel into a controllable system block that can be optimized to improve overall system performance. In this article, we provide a tutorial overview of reconfigurable intelligent surfaces (RIS) for wireless communications. We describe the working principles of reconfigurable intelligent surfaces (RIS) and elaborate on different candidate implementations using metasurfaces and reflectarrays. We discuss the channel models suitable for both implementations and examine the feasibility of obtaining accurate channel estimates. Furthermore, we discuss the aspects that differentiate RIS optimization from precoding for traditional MIMO arrays highlighting both the arising challenges and the potential opportunities associated with this emerging technology. Finally, we present numerical results to illustrate the power of an RIS in shaping the key properties of a MIMO channel.Comment: to appear in the IEEE Transactions on Cognitive Communications and Networking (TCCN

Drone robotic construction: A methodology for simulating the construction performed by drones using virtual and augmented reality

The economic and social impacts of robotic construction in Architecture, Engineering, and construction (AEC) are hard to assess and quantify without physical in situ testing, which is expensive and time-consuming This paper presents a methodology for the simulation of robotic construction technologies, namely drones, in a human-machine cooperation (HMC) using virtual (VR) and augmented (AR) reality environments. The developed methodology for robotic construction has the potential to be applied before the start of construction and to use real, virtual and augmented environments for robotic construction simulations. The application of such simulation methodology allows to test HMC scenarios and has the potential to increase construction precision while predicting both construction duration and cost. We present a review of the literature on drone and hybrid automatic construction solutions, as well as VR and AR construction simulations. Then a HMC simulation methodology is proposed and detailed. Three cases of application of the methodology are presented testing different approaches and cooperation scenarios in robotic construction. These cases are: (i) a drone construction in a real environment, (ii) a VR robotic construction simulation and (iii) an AR HMC. The application cases assess how the developed methodology is applicable to a set of different types of simulations that include different criteria.info:eu-repo/semantics/publishedVersio