Details of a Researcher - Adachi, Koichi

Papers - Adachi, Koichi

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Channel Phase Nonreciprocity Compensation for Space-Frequency Line Coded OFDM Systems

Han-Gyeol Lee, Jihoon Choi, Juyeop Kim, Koichi Adachi, Yue Xiao, Jingon Joung

IEEE Access 2025.06

Research paper (scientific journal), Joint Work, Accepted

Access to Document (DOI)

Transmit Antenna Selection Using Gated Recurrent Units for UAV-to-LEO Satellite Communications

Jaehong Kim, Seok-Jin Hong, Koichi Adachi, Jian Zhao, Eui-Rim Jeong, Jingon Joung

IEEE Transactions on Vehicular Technology (IEEE) 1 - 6 2025.05

Research paper (scientific journal), Joint Work, Accepted

Access to Document (DOI)

Transmission Timing and Synchronization Control for Energy-Efficient Multi-Hop LoRaWAN

Hiroto Shida, Aoto Kaburaki, Koichi Adachi

IEEE Access 12 183195 - 183204 2024.11

Research paper (scientific journal), Accepted

Access to Document (DOI)

Tackling Hidden Node Problem Utilizing Traffic Periodicity and Downlink Carrier Sense in LPWAN

Aoto Kaburaki, Koichi Adachi, Osamu Takyu

IEEE Internet of Things Journal 12 ( 6 ) 6536 - 6547 2024.11

Research paper (scientific journal), Accepted

Access to Document (DOI)

Differential Space-Time Line Codes

Jingon Joung, Koichi Adachi, Chau Yuen

IEEE Transactions on Vehicular Technology (Institute of Electrical and Electronics Engineers (IEEE)) 73 ( 10 ) 15837 - 15842 2024.10

Research paper (scientific journal), Accepted, ISSN 0018-9545

Access to Document (DOI)

Novel Environmental Recognition Scheme with Mobile Data Gathering Station in Physical Wireless Parameter Conversion Sensor Networks

Toshi Ito, Osamu Takyu, Mai Ohta, Takeo Fujii, Koichi Adachi

The 2024 IEEE 100th Vehicular Technology Conference (VTC2024-Fall) 1 - 5 2024.10

Research paper (international conference proceedings), Accepted

FSF-LoRa: Fractional-Spreading-Factor-LoRa for Flexible Resource Allocation

Ryoya Saito, Koichi Adachi

The 2024 IEEE 100th Vehicular Technology Conference (VTC2024-Fall) 1 - 5 2024.10

Research paper (international conference proceedings), Corresponding author, Accepted

Indoor Radio Environment Map Construction Using Node Position Estimation for Smart Factories

Hayato Mukasa, Kohei Yuzawa, Takeo Fujii, Koichi Adachi

IEEE Int. Symp. on Personal, Indoor and Mobile Radio Commun. 3rd Workshop on Integrated, Intelligent and Ubiquitous Connectivity for 6G 1 - 5 2024.09

Research paper (international conference proceedings), Accepted

Radio Resource Allocation Scheme Considering Future Channel Conditions Based on Radio Environment Map

Kotaro Yoshikawa, Takumi Tanagi, Koichi Adachi

The 20th IEEE Asia Pacific Wireless Commun. Symp. (APWCS 2024) 1 - 5 2024.08

Research paper (international conference proceedings), Corresponding author, Accepted

Chirp Index Space Partitioning Based Multiple Access Technique

Hinata Sakamoto, Koichi Adachi

The 15th Int. Conf. on Ubiquitous and Future Networks (ICUFN 2024), 1 - 5 2024.07

Research paper (international conference proceedings), Corresponding author, Accepted

Resource Management for Wireless Power Transfer and Wireless Information Transfer in Industrial IoT

Daichi Watabe, Kotaro Yoshikawa, Koichi Adachi

The 5th Int. Workshop on Smart Radio for IoT Era (SRIoT 2024), The 15th Int. Conf. Ubiquitous and Future Netw. (ICUFN 2024) 1 - 5 2024.07

Research paper (international conference proceedings), Corresponding author, Accepted

Received Signal Aided Implicit Node Clustering in LPWAN

Takahiro Saraya, Aoto Kaburaki, Koichi Adachi, Osamu Takyu, Takeo Fujii, Mai Ohta

IEEE Veh. Technol. Conf. (VTC’24)-spring 1 - 5 2024.06

Research paper (international conference proceedings), Corresponding author, Accepted

An Environment-Aware Adaptive Data-Gathering Method for Packet-Level Index Modulation in LPWA

Osamu Takyu, Keita Takeda, Ryuji Miyamoto, Koichi Adachi, Mai Ohta, Takeo Fujii

Sensors (MDPI AG) 24 ( 8 ) 2514 - 2514 2024.04

Research paper (scientific journal), Accepted

Low-power wide-area (LPWA) is a communication technology for the IoT that allows low power consumption and long-range communication. Additionally, packet-level index modulation (PLIM) can transmit additional information using multiple frequency channels and time slots. However, in a competitive radio access environment, where multiple sensors autonomously determine packet transmission, packet collisions occur when transmitting the same information. The packet collisions cause a reduction in the throughput. A method has been proposed to design a mapping table that shows the correspondence between indexes and information using a packet collision minimization criterion. However, the effectiveness of this method depends on how the probability of the occurrence of the information to be transmitted is modeled. We propose an environment-aware adaptive data-gathering method that identifies the location of factors affecting sensor information and constructs a model for the probability of the occurrence of sensor information. The packet collision rate of the environment-aware adaptive data-gathering method was clarified through computer simulations and actual experiments on a 429 MHz LPWA. We confirm that the proposed scheme improves the packet collision rate by 15% in the computer simulation and 30% in the experimental evaluation, respectively.