Prof. Dominique Schreurs, KU Leuven, Belgium
Title: Analysis of Channel Hardening for SWIPT using Measured Massive MIMO Channels
Abstract: The performance of simultaneous wireless information and power transfer (SWIPT) is often inhibited by high pathloss and multi-path fading. The massive multiple-input-multipleoutput (MIMO) system is seen as an effective technique to overcome the wireless channel distortion. This work analyzes how massive MIMO enables channel hardening and thus influences the optimal SWIPT transmission strategy. This study focuses on the MISO case (i.e., 64-antenna transmitter and a single receiver node) and is done based on a non-linear energy harvesting model and measured channel state nformation (CSI). The results confirm that massive MIMO hardens the channel which makes frequency domain pre-equalization unnecessary for both nonline- of-sight (NLoS) and line-of-sight (LoS) channels. The impact is, as expected, more noticeable in NLoS scenario. We show that the array gain introduced by the 64-antenna transmitter using a 15-tone multi-sine signal, can improve the normalized power conversion efficiency (PCE) by more than 80%, and the channel capacity by more than 2 times, for both NLoS and LoS channels.
Prof. Changzhi Li, Texas Tech University, USA
Title: Portable Microwave Radar Systems for
Life Activity Sensing and Human Localization
Abstract:Portable biomedical radar systems with embedded control and signal processing have the potential to improve the quality of service in many healthcare, human-computer interface, and internet of things (IoT) applications. This paper provides an overview of our recent research activities in developing smart microwave radar sensors aided with advanced technologies such as digital/RF beamforming, synthetic aperture radar (SAR), inverse synthetic aperture radar (ISAR), and machine learning. Several radar systems operating in interferometry, Doppler, frequency-modulated continuous-wave (FMCW), and frequency shift keying (FSK) modes at 5.8 GHz, 24 GHz, and 120 GHz will be discussed. Case studies will be presented on bioengineering applications including sleep study, fall detection, human-aware indoor localization, and anomaly detection.
Prof. Dr. Felip Riera-Palou,
Universitat de les Illes Balears, Spain
Title: Trade-offs in Cell-free Massive MIMO Networks
Abstract: Cell-free Massive MIMO (CF-M-MIMO) networks have recently emerged as one of the most promising architectural solutions to satisfy the requirements of future networks (i.e., beyond 5G, 6G). The CFM- MIMO paradigm advocates for the irregular deployment of a large number of access points (AP) throughout the network coverage area, all connected to a central processing unit (CPU), with the aim of bringing the radio access frontend closer to the users. Indeed, the cell-free topology can be interpreted as a fully distributed implementation of the Massive MIMO (M-MIMO) technology that is currently permeating the rollout of 5G. Interestingly, the large body of theoretical results derived for M-MIMO over the last decade can be recast in the CF-M-MIMO framework yet the distributed nature of the system needs to be carefully factored in. This paper aims at highlighting the different trade-offs affecting various performance metrics in CF-M-MIMO networks, in particular, the influence and consequences of different precoding strategies, power allocation techniques, AP-CPU functional splits and fronthaul designs will be discussed and assessed.
Prof. Giovanni Crupi, University of Messina, Italy
Title: A Comprehensive and Critical Overview of the Kink Effect in S22 for HEMT Technology
Abstract: Nowadays, we are witnessing an explosive expansion of the wireless communication market. To the consumers, this market expansion manifests itself via the widespread adoption of smartphones, smartwatches, tablets, handheld gaming consoles, and soon, the Internet of Things. To sustain and fulfill this massive market growth, transistor technologies are constantly pushed to perform better, since the transistor is the key component for microwave circuits, which are in turn at the heart of wireless systems. With the aim of enabling microwave engineers to exploit advanced microwave transistor technologies at their best, a growing attention is being paid to the investigation of the non-idealities of the I\V characteristics and small-signal parameters, that, representing the actual bottleneck to achieve the desired performance, guide the technology process evolution. The kink effect in the output reflection coefficient, due to its direct link with circuit performance, has largely interested both industrial and academic researchers. To gain a comprehensive and critical understanding of the kink effect, this invited talk presents a measurement-based analysis, focusing on the HEMT technology as a case study. The kink effect is analyzed over a wide range of operating conditions, such as bias point, ambient temperature, device size, and semiconductor technology. The achieved findings represents a powerful know-how to entitle microwave engineers to take the kink effect into account properly in the fabrication, modeling, and design phases.
Prof. Nicola Donato, University of Messina, Italy
Title: Resonant devices and gas sensing:
from low frequencies to microwave range.
Abstract: The research of new typologies of sensors with high performance and low power consumption features is today one of the areas of greatest interest in the market. In particular, low power sensors are mandatory in wireless sensors networks to achieve the right balance between sensing performance and battery lifetime. In such a frame relatively new category of sensors can be represented by resonant devices. Resonant sensors are one of the key issue in many industrial applications, operating in a wide frequency range roughly spanning from kHz to GHz. By considering resonance frequency values from few to hundreds MHz, (Bulk and Surface) acoustic wave sensors are extremely versatile devices that are just beginning to achieve their commercial potential. Acoustic wave sensors are so called because of their detection mechanism, involving mechanical, or acoustic, waves. As the acoustic wave propagates through/on the surface of the material, any changes to the characteristics of the propagation path affect the velocity and/or amplitude of the wave. Changes in velocity can be monitored by measuring either the frequency or phase characteristics of the sensor and they can then be correlated to the corresponding chemical and/or physical quantity being measured. By increasing the frequency value, microwave resonant sensors are showing interesting properties in terms of fast response, low power consumption, fully compatibility with wireless technologies and room temperature operating value. The two main output parameters of such devices are the resonance frequency value and the quality factor, then their variations when exposed to several gas target concentrations. These devices can be included in conductometric transducers category, with a slightly different mechanism of transduction than traditional ones, because, in this case, change of permittivity of sensitive layer is involved in the transduction process. Therefore, the adsorption of molecules on the surface of the sensing layer and correspondent variation of the permittivity is a phenomenon which operates only in the second order as a conductometric transducer. In particular, the possibility to balance between the sensing material properties and the resonator configuration for design of the sensor make them very versatile for different applications. Microstrip technology, widely employed in the design of microwave resonators and filters, can be successfully used in the development of such sensors. This work exploits the design and characterization of BAW, SAW and microwave resonant gas sensors developed at the University of Messina laboratories by describing several case studies and related application examples.
Prof. Zoran Bojković, University of Belgrade, Serbia
Title: Influences of Weighting Techniques
on TOPSIS-based Network Slcce
Abstract: Cell-free Massive MIMO (CF-M-MIMO) networks have recentlyemerged as one of the most promising architectural solutions to satisfy the requirements of future networks (i.e., beyond 5G, 6G). The CFM- MIMO paradigm advocates for the irregular deployment of a large number of access points (AP) throughout the network coverage area, all connected to a central processing unit (CPU), with the aim of bringing the radio access frontend closer to the users. Indeed, the cell-free topology can be interpreted as a fully distributed implementation of the Massive MIMO (M-MIMO) technology that is currently permeating the rollout of 5G. Interestingly, the large body of theoretical results derived for M-MIMO over the last decade can be recast in the CF-M-MIMO framework yet the distributed nature of the system needs to be carefully factored in. This paper aims at highlighting the different trade-offs affecting various performance metrics in CF-M-MIMO networks, in particular, the influence and consequences of different precoding strategies, power allocation techniques, AP-CPU functional splits and fronthaul designs will be discussed and assessed.
Prof. Dejan Drajić, University of Belgrade, Serbia
Title: User Engagement for Large Scale Pilots in the Internet of Things
Abstract: With an expected 50 billion connected devices by 2020, the Internet of Things (IoT) will reshape our environment with great economic opportunities. However, the IoT market evolution will depend directly on the end-user adoption, so it necessary to support the Large Scale Pilots (LSPs) in order to actively engage end-users in the large scale pilot design, deployment and assessment. In this paper we are presenting end-user engagement methodologies, including co-creative workshops, crowdsourcing, Living Labs, and developed online tools and resources for end-user engagement, crowdsourcing and personal data protection.
Prof. Igor Belyaev, Slovak Academy of Sciences, Slovakia
Title: Main regularities and health risks from exposure to non-thermal microwaves of mobile communication
Abstract: Various responses to non-thermal microwaves (MW) from mobile communication including adverse health effects related to electrohypersensitivity, cancer risks, neurological effects, and reproductive impacts have been reported while some studies reported no such effects. This presentation provides an overview of the complex dependence of the MW effects on various physical and biological variables, which account for, at least partially, an apparent inconsistence in the published data. Among other variables, dependencies on carrier frequency, polarization, modulation, intermittence, electromagnetic stray fields, genotype, physiological traits, and cell density during exposure were reported. Nowadays, biological and health effects of 5G communication, which will use microwaves of extremely high frequencies (millimeter waves MMW, wavelength 1- 10 mm), is of significant public concern. It follows from available studies that MMW, under specific conditions of exposure at very low intensities below the ICNIRP guidelines, can affect biological systems and human health. Both positive and negative effects were observed in dependence on exposure parameters. In particular, MMW inhibited repair of DNA damage induced by ionizing radiation at specific frequencies and polarizations. To what extend the 5G technology and the Internet of Things will affect the biota and human health is definitely not known. However, based on possible fundamental role of MMW in regulation of homeostasis and almost complete absence of MMW in atmosphere due to effective absorption, which suggests the lack of adaptation to this type of radiation, the health effects of chronic MMW exposures may be more significant than for any other frequency range. The data showing dependence of MW effects on extremely low frequency and static magnetic fields at the location of exposure suggested a strategy for reducing health effects from MW of mobile communication. .
Prof. Bartomeu Alorda Ladaria, Universitat de les Illes Balears (UIB), Spain
Title: Energy Consumption Analysis in Adaptive Wireless Sensor Networks
Abstract: WSNs are characterized by multi-hop lossy wireless links and severely resource constrained nodes. Among the resource constraints, energy is probably the most crucial one since sensor nodes are typically battery powered and the lifetime of the battery imposes a limitation on the operation hours of the sensor network. Energy efficiency is a critical concern in wireless sensor network protocol design. Researchers are investigating energy conservation at every layer in the traditional protocol stack, from the physical layer up to the network layer and application layer. It has been recently shown that introduces mechanisms for online adaptation, are useful for solving the problem of dynamically allocating bandwidth in a WSN, while still satisfying both quality and energy constraints. We will discuss the relevance of considering the transmission power of the nodes to comply with energy constraints without impact the quality of the service. Based on experimental data, it will be shown that this parameter has a strong impact on both the energy consumed by the nodes and the quality/reliability of the communication.