Koya Sato
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View article: Adaptively Weighted Averaging Over-the-Air Computation and Its Application to Distributed Gaussian Process Regression
Adaptively Weighted Averaging Over-the-Air Computation and Its Application to Distributed Gaussian Process Regression Open
This paper introduces a noise-tolerant computing method for over-the-air computation (AirComp) aimed at weighted averaging, which is critical in various Internet of Things (IoT) applications such as environmental monitoring. Traditional Ai…
View article: Fast Reflective Beamforming With Situational Awareness in IRS Assisted Communication Systems
Fast Reflective Beamforming With Situational Awareness in IRS Assisted Communication Systems Open
In this paper, we investigate reflective beamforming methods for intelligent reflecting surface (IRS)-assisted communication systems. In our envisioned system, the IRS is equipped with computer vision to acquire situational awareness. Leve…
View article: Bayesian Optimization Framework for Channel Simulation-Based Base Station Placement and Transmission Power Design
Bayesian Optimization Framework for Channel Simulation-Based Base Station Placement and Transmission Power Design Open
This study proposes an adaptive experimental design framework for a channel-simulation-based base station (BS) design that supports the joint optimization of transmission power and placement. We consider a system in which multiple transmit…
View article: Indoor Radio Map Construction via Ray Tracing With RGB-D Sensor-Based 3D Reconstruction: Concept and Experiments in WLAN Systems
Indoor Radio Map Construction via Ray Tracing With RGB-D Sensor-Based 3D Reconstruction: Concept and Experiments in WLAN Systems Open
This paper proposes an RGB-D sensor-aided ray-tracing simulation framework for indoor radio map construction that models indoor information, such as walls and obstacles, as a set of cuboids. Radio maps can accelerate indoor wireless system…
View article: Over-the-Air Gaussian Process Regression Based on Product of Experts
Over-the-Air Gaussian Process Regression Based on Product of Experts Open
This paper proposes a distributed Gaussian process regression (GPR) with over-the-air computation, termed AirComp GPR, for communication- and computation-efficient data analysis over wireless networks. GPR is a non-parametric regression me…
View article: A Communication-Efficient Secure Routing Protocol for IoT Networks
A Communication-Efficient Secure Routing Protocol for IoT Networks Open
This paper proposes a secure routing protocol based on an ad hoc on-demand distance vector to simultaneously achieve communication efficiency and security. Many studies have discussed secure protocols. However, conventional protocols tend …
View article: Radio Map Extrapolation Using Compensated Empirical CDF Under Interference-Limited Observations
Radio Map Extrapolation Using Compensated Empirical CDF Under Interference-Limited Observations Open
The radio map has attracted attention as a promising tool for accurately estimating radio propagation and determining communication parameters. Conventional radio maps are mainly used in wireless systems with a single target transmitter. H…
View article: Performance Evaluation of Reinforcement Learning Based Distributed Channel Selection Algorithm in Massive IoT Networks
Performance Evaluation of Reinforcement Learning Based Distributed Channel Selection Algorithm in Massive IoT Networks Open
In recent years, the demand for new applications using various Internet of Things (IoT) devices has led to an increase in the number of devices connected to wireless networks. However, owing to the limitation of available frequency resourc…
View article: A High-Speed Channel Assignment Algorithm for Dense IEEE 802.11 Systems via Coherent Ising Machine
A High-Speed Channel Assignment Algorithm for Dense IEEE 802.11 Systems via Coherent Ising Machine Open
This letter reports on an ultra-fast and accurate channel assignment approach using a coherent Ising machine (CIM) for dense wireless LAN (WLAN) systems. CIM is a laser-based high-speed hardware approach for solving Ising problems using op…
View article: Predicting partially observed processes on temporal networks by Dynamics-Aware Node Embeddings (DyANE)
Predicting partially observed processes on temporal networks by Dynamics-Aware Node Embeddings (DyANE) Open
Low-dimensional vector representations of network nodes have proven successful to feed graph data to machine learning algorithms and to improve performance across diverse tasks. Most of the embedding techniques, however, have been develope…
View article: Rate-Adapted Decentralized Learning Over Wireless Networks
Rate-Adapted Decentralized Learning Over Wireless Networks Open
This paper proposes a communication strategy for decentralized learning in wireless systems that employs adaptive modulation and coding capability. The main objective of this work is to address a critical issue in decentralized learning ba…
View article: Image-Driven Spatial Interpolation With Deep Learning for Radio Map Construction
Image-Driven Spatial Interpolation With Deep Learning for Radio Map Construction Open
Radio maps are a promising technology that can boost the capability of wireless networks by enhancing spectrum efficiency. Since spatial interpolation is a critical challenge to construct a precise radio map, the latest works have proposed…
View article: Space-Frequency-Interpolated Radio Map
Space-Frequency-Interpolated Radio Map Open
This paper presents a novel method for radio map construction that simultaneously interpolates the received signal power values over space and frequency domains. Radio maps can be used to improve spectrum management and for localization sy…
View article: Dynamic Radio Map Using Statistical Hypothesis Testing
Dynamic Radio Map Using Statistical Hypothesis Testing Open
Private fifth-generation mobile communication networks (5G) have garnered considerable attention for providing various communication services. In private 5G systems, such as those employed in smart factories, it is necessary to appropriate…
View article: Network-Density-Controlled Decentralized Parallel Stochastic Gradient Descent in Wireless Systems
Network-Density-Controlled Decentralized Parallel Stochastic Gradient Descent in Wireless Systems Open
This paper proposes a communication strategy for decentralized learning on wireless systems. Our discussion is based on the decentralized parallel stochastic gradient descent (D-PSGD), which is one of the state-of-the-art algorithms for de…
View article: DyANE: Dynamics-aware node embedding for temporal networks
DyANE: Dynamics-aware node embedding for temporal networks Open
Low-dimensional vector representations of network nodes have proven\nsuccessful to feed graph data to machine learning algorithms and to improve\nperformance across diverse tasks. Most of the embedding techniques, however,\nhave been devel…
View article: DyANE: Dynamics-aware node embedding for temporal networks
DyANE: Dynamics-aware node embedding for temporal networks Open
Low-dimensional vector representations of network nodes have proven successful to feed graph data to machine learning algorithms and to improve performance across diverse tasks. Most of the embedding techniques, however, have been develope…
View article: Directivity control of a finite cylindrical loudspeaker array based on circular harmonics and longitudinal multipole expression
Directivity control of a finite cylindrical loudspeaker array based on circular harmonics and longitudinal multipole expression Open
The directivity control of a finite cylindrical loudspeaker array can be applied to various systems such as personal audio and smart speaker systems. As a conventional directivity control method, the filter coefficients of a cylindrical ar…
View article: On the Performance of Neural Network Residual Kriging in Radio Environment Mapping
On the Performance of Neural Network Residual Kriging in Radio Environment Mapping Open
This paper addresses the research question: can feedforward neural network (FFNN)-based path loss modeling improve the accuracy of Kriging? Radio propagation factors, which consist of path loss and shadowing, can accurately be obtained via…
View article: Visuo-Haptic Interface to Augment Player's Perception in Multiplayer Ball Game
Visuo-Haptic Interface to Augment Player's Perception in Multiplayer Ball Game Open
We developed a system that augments the player's perception and support situation awareness for motivating them to participate in multiplayer sports in the context of a soccer game. The positional relationship of the opponents was provided…
View article: Modeling the Kriging-Aided Spatial Spectrum Sharing Over Log-Normal Channels
Modeling the Kriging-Aided Spatial Spectrum Sharing Over Log-Normal Channels Open
In this letter, we first show that the error in the received signal power estimation with an optimally interpolated radio environment map (REM) over a shadowing environment can be modeled using a correlation coefficient, similar to that of…
View article: Sidelobe suppression by desired directivity pattern optimization for a small circular loudspeaker array
Sidelobe suppression by desired directivity pattern optimization for a small circular loudspeaker array Open
Directivity control using a loudspeaker array is widely studied for various applications. Suppressing sidelobe levels is important for applications such as personal audio systems. In this paper, we propose a filter design method using a wi…
View article: Crowdsourcing-Assisted Radio Environment Database for V2V Communication
Crowdsourcing-Assisted Radio Environment Database for V2V Communication Open
In order to realize reliable Vehicle-to-Vehicle (V2V) communication systems for autonomous driving, the recognition of radio propagation becomes an important technology. However, in the current wireless distributed network systems, it is d…
View article: New City Block Design Approaches Incorporating Environmental Assessment for Downtown Districts in Cities with Severe Winter Climates
New City Block Design Approaches Incorporating Environmental Assessment for Downtown Districts in Cities with Severe Winter Climates Open
Urban design approaches in many Japanese cities are based on principles that are similar throughout the country without considering the variety in regional climates. Especially in cities with severe winter weather, providing desirable envi…
View article: Replication data for: How the nature of web services drives vocabulary creation in social tagging
Replication data for: How the nature of web services drives vocabulary creation in social tagging Open
Tagging data of the social network service named RoomClip. This data corresponds to the article "How the nature of web services drives vocabulary creation in social tagging"
View article: How the nature of web services drives vocabulary creation in social tagging
How the nature of web services drives vocabulary creation in social tagging Open
A social tagging system allows users to add arbitrary strings, called "tags", on a shared resource to organize and manage information. The Yule--Simon process, which has shown the ability to capture the population dynamics of social taggin…
View article: Modeling and Analysis of Tag Co-occurrence Dynamics Using Yule-Simon process
Modeling and Analysis of Tag Co-occurrence Dynamics Using Yule-Simon process Open
Social Tagging System (STS) which is one of the content management techniques is widely adopted in the online content sharing service. Using STS, users can give any strings (tags) to contents as annotations. It is important to know the usa…