SPECIAL SESSION 1

PROF. DR. TETSURO IMAI

Tokyo Denki University, JAPAN

Title: A Cooperative Multi-UAV RIS-Based Relay System for Mobile Communications

Abstract: Recently, reconfigurable intelligent surfaces (RISs), which can dynamically control the direction of radio-wave reflection, have been actively studied to eliminate coverage holes and extend coverage in mobile communication systems. When an RIS is deployed within a service area, sufficient performance can be achieved only if it is placed at a location with line-of-sight (LoS) links to both the base station and the target coverage area. This requirement imposes significant constraints on RIS deployment. To address this issue, mounting RISs on unmanned aerial vehicles (UAVs) has been proposed. By using drones as UAV platforms, RISs can be deployed more flexibly, even in urban environments. However, the size and weight of RISs that can be mounted on UAVs are limited, and a small RIS may not provide sufficient performance. In this paper, we propose a relay system in which RISs mounted on multiple UAVs cooperate with each other and theoretically evaluate its performance in terms of channel capacity.

Biography: Tetsuro Imai was born in Tochigi, Japan, in 1967. He received the B.E. and Ph.D. degrees from Tohoku University, Japan, in 1991 and 2002, respectively. In 1991, he joined the Radio Communication Systems Laboratories of Nippon Telegraph and Telephone Corporation (NTT), Kanagawa, Japan. Since then, he has been engaged in research and development of radio propagation, antenna systems, and wireless system design for mobile communications. He is currently a Professor at Tokyo Denki University, Tokyo, Japan. Dr. Imai received the IEICE Young Researcher’s Award in 1998, the IEICE Best Paper Awards in 2006 and 2013, the IEICE Communications Society Best Paper Awards in 2014 and 2020, and the IEICE Achievement Award in 2019. He is a member of the Institute of Electronics, Information and Communication Engineers (IEICE) and the Institute of Electrical and Electronics Engineers (IEEE).

SPECIAL SESSION 2

PROF. HIROYUKI ARAI

Defense Innovation Science & Technology Institute, ATLA, JMOD, JAPAN

Title: Switchable Reflector for Windfarm Effect Mitigation on Radar Systems

Abstract: Wind power are expected as clean and renewable energy, cutting carbon emission for the future sustainable society. Wind turbines gathered in massive areas, such as windfarms, have a significant impact on radar systems, causing clutter or interference to desensitize the radar, and make real targets vanish. Small-scale windfarms are one of the promising energy supply in remote islands, which also brings about serious troubles in radar systems not to follow the guidelines by WMO (World Mythological Organization) giving instructions to build wind turbines. These problems may affect the windfarm deployment and cancel renewable future projects and plans. To overcome the above, many solutions have been proposed to mitigate the impact of the windfarm on radar systems. Several solutions are windfarm compliant radars to prevent radars from hindering the development of wind energy, classified into (i) radar antenna beam tilt, switching or sidelobe cancelling, (ii) the post or preliminary signal processing, and (iii) the system replacement by MIMO radar or using gap-filler radar. The windfarm options are telemetry from windfarm to radar, stealthy wind turbines and radar optimized windfarm layout. We propose a novel approach as an option in radar site to introduce the switchable reflector to provide detour for radar illumination path. This reflector, a kind of passive repeater, can change the direction of radar path and be transparency in a non-operating state. The background and the design strategy will be also presented in this talk.

Biography: Hiroyuki Arai received the B.E. degree in Electrical and Electronic Engineering, M.E. and D.E. in Physical Electronics from Tokyo Institute of Technology in 1982, 1984 and 1987, respectively. He is Professor Emeritus, Yokohama National University and Program Manager, Defense Innovation Science & Technology Institute, ATLA, JMOD. He was editor-in-chief of IEICE Trans. on Communications, 2005 -2007, and was chair of IEEE AP-S Japan Chapter, 2009 – 2010. He was associate editor of IEEE Transactions on Antennas and Propagation, 2011-2013, and the chair of Technical Group on Antennas and Propagation of IEICE, 2013-2014, and the general chair of ISAP 2020, Osaka. He is Fellow of IEEE and IEICE.