Poster Presentations

Session Information

Time: 11:40-13:00

Room: 1st Floor, Lounge, Main Building, Research Institute of Electrical Communication (RIEC)

P1: Direction of Arrival Estimation of Radio Waves using Compressed Sensing in Adaptive Beam Space

Authors: Ryu Shimamura1, Nobuyoshi Kikuma1, Kunio Sakibara1

Affiliation: 1Nagoya Institute of Technology, Japan

Abstract: A Study on How the Estimation Accuracy of Direction of Arrival (DOA) of Radio Waves Improves by Introducing Adaptive Beam Space into Compressed Sensing.

P2: Design of SIW Rotman Lens Multibeam Antenna with Broadband Termination Connecting to Back SIW in 300-GHz Band

Authors: Koki Shikano1, Kenta Nishimura1, Azuki Iwamoto1, Kunio Sakibara1, Yoshiki Sugimoto1, Nobuyoshi Kikuma1

Affiliation: 1Nagoya Institute of Technology, Japan

Abstract: A Rotman lens multibeam antenna combining with a substrate‐integrated waveguide (SIW) traveling‐wave slot array with broadband termination connecting to back SIW operating in the 300‐GHz band was designed. Electromagnetic simulations confirmed that the proposed antenna achieves high gain and beam‐scanning capability while effectively suppressing reflected waves over a wide bandwidth.

P3: OTFS and OFDM Performance in Q/V-Band LEO Satellites Under High Doppler Shifts

Authors: Ryo Arimura1, Masataka Miyake1, Suguru Kameda1

Affiliation: 1Hiroshima University, Japan

Abstract: This study investigates the effectiveness of orthogonal time frequency space (OTFS) modulation for reliable low Earth orbit (LEO) satellite communications in the Q/V bands. The bit error rate (BER) performance is evaluated with respect to satellite elevation angles, and a comparison with orthogonal frequency division multiplexing (OFDM) under high Doppler shift conditions demonstrates that OTFS offers superior reliability for high‐mobility and high‐frequency satellite communication systems.

P4: Joint Optimization of Transmission Parameters in Single-Carrier Systems with Band-Limited Analog Front-End Constraints

Authors: Shun Ishihara1, Minoru Fujishima2, Suguru Kameda2, Kosuke Katayama3, Janne Lehtomaki4, Nuutti Tervo4, Kenta Umebayashi1

Affiliations:
1Tokyo University of Agriculture and Technology, Japan
2Hiroshima University, Japan
3Tokuyama National College of Technology, Japan
4University of Oulu, Finland

Abstract: This paper examines a single‐carrier system that employs pre‐equalization to mitigate inter‐symbol interference caused by a band‐limited analog front end. The approach adaptively chooses design parameters to improve performance based on computer simulations.

P5: Implementation and Evaluation of Synchronized SS-CDMA Using Space-Time Synchronization on USRP X310

Authors: Toshiki Ouchi1, Serena Akasaka1, Masataka Miyake1, Suguru Kameda1

Affiliation: 1Hiroshima University, Japan

Abstract: Synchronized spread spectrum code division multiple access (SS-CDMA), utilizing wireless two-way interferometry (Wi-Wi) for space-time synchronization, enables high-capacity Internet of Things (IoT) connectivity. The use of USRP X310 and root raised cosine (RRC) filters before transmission and after reception allowed for a comparative evaluation of BER performance between conventional and improved systems.

P6: Wideband Waveguide-to-differential-line Transition with Slots and Back-short in Multilayer Substrate

Authors: Azuki Iwamoto1, Makoto Yamazaki1, Yoshiki Sugimoto1, Kunio Sakibara1, Shumpei Kishi1, Nobuyoshi Kikuma1

Affiliation: 1Nagoya Institute of Technology, Japan

Abstract: This paper proposes a wideband waveguide-to-differential-line transition with slots and a back-short structure for use in the 300-GHz band. Double resonance is achieved in a multilayer substrate, enabling a low-loss connection with a wide bandwidth.

P7: A study on threshold optimization for SIMO Systems with 1-Bit ADCs

Authors: Rina Takagi1, Kenta Umebayashi1, Antti Tölli2, Bikshapathi Gouda2, Janne Lehtomäki2

Affiliations:
1Tokyo University of Agriculture and Technology, Japan
2University of Oulu, Finland

Abstract: This research investigates the quantization threshold setting in 1-bit ADCs for SIMO communication systems. By employing an optimal detector that considers the distribution of the received signals, numerical simulations indicate that the proposed threshold significantly improves the symbol error rate (SER) performance.

P8: Design of Parallel Differential-line Fed Planar Aperture Antenna Excited by X-shaped Patch Using Slot Coupling

Authors: Taisuke Uemura1, Yoshiki Sugimoto1, Kunio Sakibara1, Nobuyoshi Kikuma1

Affiliation: 1Nagoya Institute of Technology, Japan

Abstract: A planar aperture antenna with a parallel-differential line excited by an X-shaped patch using slot coupling is developed for the 300-GHz band. This design reduces the occupied area on the bottom layer by coupling the differential transmission lines and the X-shaped patch via a slot.

P9: Evaluation of Time Synchronization Offset of Wireless Two-Way Interferometry (Wi-Wi) by Using Automatic Measurement System

Authors: Hiroto Kita1, Masataka Miyake1, Suguru Kameda1, Satoshi Yasuda2, Nobuyasu Shiga2

Affiliations:
1Hiroshima University, Japan
2National Institute of Information and Communications Technology (NICT), Japan

Abstract: Wireless two-way interferometry (Wi-Wi) enables high-precision time synchronization in wireless systems. This study automates the measurement of the time-synchronization offset, increasing the number of measurements and facilitating evaluations under stable radio conditions.

P10: Measurement Characteristic of Endfire Antenna with Step Horn Structure in Multilayer Substrate

Authors: Daisuke Sakai1, Yoshiki Sugimoto1, Kunio Sakibara1, Ken Takahashi2, Nobuyoshi Kikuma1

Affiliations:
1Nagoya Institute of Technology, Japan
2Panasonic System Networks R&D Lab. Co., Ltd., Japan

Abstract: An eight-layer substrate-integrated waveguide (SIW) end-fire antenna with E-plane horn structure is designed at 275 GHz. The length of matching with a free space and SIW is different from the length of matching within SIWs with each other. So, these lengths need to be different. Simulated results show that the smaller the size of the matching between the free space and the waveguide, the larger the resonance frequency and the wider the bandwidth. The fabricated antenna is evaluated and its measured characteristics are presented.

P11: Multibeam Microstrip Array Antenna Fed by Low-Loss and Compact Rotman-Lens in 300-GHz Band

Authors: Kenta Nishimura1, Yoshiki Sugimoto1, Kunio Sakibara1, Motoko Sakamoto1, Nobuyoshi Kikuma1

Affiliation: 1Nagoya Institute of Technology, Japan

Abstract: A multibeam antenna fed by a microstrip Rotman lens was designed for the 300-GHz band. By minimizing the Rotman lens for the required number of beams and array elements, transmission losses are reduced while achieving a gain of over 20 dBi across a 60° range at 274 GHz.

P12: Design of a 300-GHz-Band Up-Conversion Mixer for Self-Heterodyne Transceiver in 0.13-μm SiGe BiCMOS

Authors: Taiga Noguchi1, Kyoya Takano1

Affiliation: 1Tokyo University of Science, Japan

Abstract: An up-conversion mixer in 0.13-μm SiGe BiCMOS technology for 300-GHz wireless communication using a self-heterodyne system is presented. Simulation results indicate a maximum conversion gain of -8.8 dB, a 3 dB bandwidth of 46 GHz, an input 1 dB compression point (IP1dB) of 2.5 dBm, and an output 1 dB compression point (OP1dB) of -1.96 dBm.

P13: Low Scan-Loss Multi-Beam Lens Antenna Fed by Horns with Separated Phase Centers in E/H-Planes

Authors: Shota Takada1, Yoshiki Sugimoto1, Kunio Sakibara1, Nobuyoshi Kikuma1

Affiliation: 1Nagoya Institute of Technology, Japan

Abstract: This study proposes a wide-angle beam-scanning multi-beam lens antenna fed by horns with separated phase centers in the E/H-planes, achieved by different wall heights. The phase centers are aligned at the lens focus position (separated by astigmatism), thereby improving directivity in wide-angle directions.

P14: Performance evaluation of ADGG-HEMT THz plasmonic detectors for beyond-5G wireless communication networks

Authors (collective affiliations): M. Nagatsu1, K. Narita1, Y. Takida2, H. Minamide2, T.-T. Lin1, T. Suemitsu3, T. Otsuji4, A. Satou1

Affiliations: 1Research Institute of Electrical Communication, Tohoku University, Sendai, Japan; 2RIKEN Center for Advanced Photonics, RIKEN, Sendai, Japan; 3New Industry Creation Hatchery Center, Tohoku University, Sendai, Japan; 4Research Institute of Electrical Communication, Tohoku University, Sendai, Japan, International Research Institute of Disaster Science, Tohoku University, Sendai, Japan, Center of Excellence ENSEMBLE3 Ltd., Warsaw, Poland;

Abstract: The so-called Asymmetric Dual-Grating-Gate (ADGG) terahertz (THz) plasmonic detectors based on InGaAs-channel HEMTs have been developed and experimentally evaluated. Performance metrics such as detection responsivity, linearity, and frequency bandwidth (around 1 THz) were measured, demonstrating high performance for beyond-5G wireless communication networks.

P15: Evaluation of Input Signals for Deep Learning-Based Antenna Spacing Control in Adaptive Arrays

Authors: Junya Miura1, Kenta Umebayashi1

Affiliation: 1Tokyo University of Agriculture and Technology, Japan

Abstract: This research employs deep learning to optimize antenna spacing in adaptive array antennas. Experimental evaluations demonstrate that while optimized spacing can effectively suppress multiple interfering signals using only two antennas, the performance of the system varies significantly with the input to the deep learning model.

P16: 300-GHz Band Capacitor Modeling with Passivity-Constrained Rational Polynomial Approximation

Authors: Yuto Hirayama1, Shun Beppu1, Shinsuke Hara2, Akifumi Kasamatsu2, Yoshio Mita3, Kyoya Takano1

Affiliations:
1Tokyo University of Science, Japan
2National Institute of Information and Communications Technology (NICT), Japan
3The University of Tokyo, Japan

Abstract: A modeling method based on rational polynomial approximation (RPA) is proposed for metal-oxide-metal (MOM) capacitors used in 300-GHz band applications. Constrained re-fitting is applied to ensure passivity and causality, enabling the development of highly accurate equivalent circuits for high-frequency simulations.

P17: Ultra-wide Band Coplanar Waveguide Crossover with Coupling Suppression and Low Loss for Millimeter-Wave Applications

Authors: Leshan Xu1, Satoshi Tanaka1, Takeshi Yoshida1, Minoru Fujishima1

Affiliation: 1Hiroshima University, Japan

Abstract: To minimize the influence of crossover in D-band phased arrays, a crossover design with metallic ground shields is proposed. The design achieves an improvement in isolation by 18 dB compared with conventional designs while maintaining an insertion loss of less than 0.2 dB.

P18: Decoupling Technique for Power Line that Balances Noise Suppression and Chip Area Reduction

Authors: Yudai Miyoshi1, Takeshi Yoshida1, Satoshi Tanaka1, Minoru Fujishima1

Affiliation: 1Hiroshima University, Japan

Abstract: A novel power panel structure extending 0 Ω transmission lines into a two-dimensional layout is proposed, enabling compact and low-DC-resistance decoupling. This approach significantly reduces chip area—from 1.985 mm² to 0.45 mm²—while maintaining sufficient decoupling capacitance for high-frequency integrated circuits.

P19: A study of DOA estimation by time sample thinning utilizing received signal levels

Authors: Ryo Watabe1, Kenta Umebayashi1, Antti Tölli2

Affiliations:
1Tokyo University of Agriculture and Technology, Japan
2University of Oulu, Finland

Abstract: A novel direction-of-arrival (DOA) estimation method is proposed whereby time sample thinning is performed based on received signal levels. By selecting only those samples that exceed a predefined signal strength threshold, the method achieves improved DOA estimation accuracy, especially when the number of available samples is limited.

P20: A Compact D-Band 360° Active Differential Phase Shifter for Sub-Terahertz Phased-Array Antennas in 40nm CMOS

Authors: Zhen Yan1, Satoshi Tanaka1, Takeshi Yoshida1, Minoru Fujishima1

Affiliation: 1Hiroshima University, Japan

Abstract: This study presents the design of a D-band 156-GHz active differential phase shifter intended for phased-array transceiver circuits to receive terahertz signals. The phase shifter employs a tunable active circuit composed of series-connected NMOS transistors with bias voltage control to adjust the drain-source resistance, enabling both continuous and fixed phase shifts. The full 360° phase shift is achieved through the interconnection of multiple adjustable units, a 0°/60° phase shift switch, and a Gilbert cell functioning as a 0°/180° phase switch. Fabricated using TSMC’s 40nm CMOS process, the circuit features a compact layout and has demonstrated effective operation in measurements, indicating strong potential for further research and practical applications.

P21: Spectrum Usage Prediction in Wireless Systems Using Human Activity Patterns

Authors: Leow Yau Hong1, Kenta Umebayashi1, Sergio Infante2, Julia Robles2, Manuel Díaz2, Cristian Martín2

Affiliations:
1Tokyo University of Agriculture and Technology, Japan
2University of Málaga, Málaga, Spain

Abstract: This research introduces human presence as a novel feature for predicting spectrum usage in wireless systems. Traditional approaches relying solely on historical usage data often fail to anticipate sudden increases caused by random human activity. Experimental results demonstrate that incorporating human activity provides a strong prior for predicting these sudden usage increases.