Corporate organizations face increasingly complex tasks that demand effective team management. A key concept is the Shared Mental Model (SMM), which enables members to maintain performance despite limited communication. Traditional measurements rely on interviews or questionnaires, which are labor-intensive, context-specific, and unsuitable for continuous monitoring. Consequently, leaders lack practical tools to track shared cognition in real time. This paper’s empirical analysis shows that only specific categories (e.g., informative exchanges) correlate strongly with SMM, clarifying which forms of communication can influence shared cognition. This insight leads to our proposed approach, which estimates SMM from instant messaging systems like Slack. Our approach categorizes messages into communicative acts using large language models, constructs category-wise communication graphs, and applies a graph neural network for estimation. The model outperforms baselines, demonstrating the feasibility of continuous, scalable monitoring without intrusive surveys. While validated in corporate contexts, the approach extends to education, healthcare, and disaster response domains.

Air-to-ground (A2G) wireless networks comprising unnamed aerial vehicles (UAVs) can provide flexible communications services to ground users. However, battery capacity limitations of UAVs affect the stability of the A2G networks. To improve network stability, we propose an A2G Network using Circularly ORbiting UAVs (ANCOR), where UAV base stations (UAV-BSs) always move in circular orbits. ANCOR is based on the fact that hovering UAVs consume more power than moving UAVs. We also propose an arrangement method for the orbits of the UAV-BSs to improve the average energy efficiency, which is defined as the ratio of the average capacity to the average power consumption. The arrangement method comprises two steps. In the first step, the orbits of the UAV base stations are optimized to minimize coverage holes and maximize the minimum capacity in the area. In the second step, the moving speeds of the UAV BSs in orbit are optimized to maximize the average energy efficiency with the user density distribution of the area. Moreover, we evaluate the performance of ANCOR via simulation experiments.

In the field of robotics, tag systems play an important role in various applications, such as object identification and robot control in real-world environments. While typical visual markers use two-dimensional (2D) patterns and RGB cameras for recognizing object IDs and poses, achieving long-distance recognition necessitates increasing marker size and camera magnification to ensure the required resolution. Furthermore, the growing adoption of event cameras in robotics captures rapid changes in pixel brightness but faces limitations in recognizing stationary 2D markers. Although compact blinker markers using blinking light-emitting diodes (LEDs) achieve long-distance recognition, they are constrained by the number of IDs or recognition speed when used with standard RGB cameras. In addition, recognizing object pose using only a single blinking LED presents challenges. To address these challenges, we introduce ‘Bicode,’ an indoor visual marker designed for event cameras. Bicode seamlessly integrates 2D and blinker markers within a single marker unit. We have developed prototypes of 2.5, 5, and 10 cm square acrylic 2D markers, each equipped with a single LED blinking at 1 kHz, enabling recognition with an event camera. Our experiments revealed the effects of marker size, LED light quantity, recognition distance, and angle, external lighting conditions, and camera or marker movement on accuracy. Notably, using the 5 cm marker, we confirmed its compatibility to recognize IDs at distances exceeding 20 m, and pose recognition at 2.5 m was confirmed.

One of the useful methods of ensuring stable communication for autonomous vehicles is to predict communication quality using radio environment maps. We propose a Kriging method for constructing radio environment maps to improve interpolation accuracy by using anisotropy of the shadowing correlation on the distance and azimuth-angle plane based on the base-station position. Using $2.2-\mathrm{GHz}$ band path-loss data measured in an urban area, we evaluated the accuracy when interpolating the total measurement data of approximately 14,000 points from sample data of 10 and 100 points. We compared the proposed method with four conventional methods: nearest neighbor interpolation, K-nearest neighbors, inverse distance weighting, and conventional ordinary kriging. The median and minimum root means square errors when sample data were extracted 30 times were approximately 8.2 and 6.4 dB when the number of samples was 10, and approximately 4.7 and 4.2 dB when the number of samples was 100. These results indicate that the proposed method can interpolate with higher accuracy than the conventional methods.

One of the requirements for 6G in the 2030s is ultrahigh-speed communications exceeding 100 Gbps and large-capacity communications 10 times that of 5G. In order to realize these requirements, the use of sub-THz bands above 100 GHz is being considered for 6G. In this paper, we report on the measurement and evaluation results of propagation channel characteristics in an office environment in the 160 GHz band, which is one of the frequency bands under consideration for the sub-THz band in 6G. The measurements were made in our office environment, which is approximately 50 m x 16 m in size and 2.7 m in height from ceiling to floor. In this environment, OFDM signals with a bandwidth of 2 GHz were used at 7 LoS (Line-of-Sight) points and 12 NLoS (Non-Line-of-Sight) points, for a total of 19 points. An omni-antenna was used for the transmitter (Tx) at a height of 2 m and a horn antenna was used for the reciever (Rx) at a height of 1 m. The receiving antenna was rotated and measurements were made by SISO channel soundings. The propagation channel characteristics of the delay and angle profiles were obtained at distances from 8.5 m to 35.5 m between the Tx and Rx. The measurement results showed that at the LoS point, the direct wave and the reflected wave at the ceiling and the floor were confirmed, and that at the NLoS point, the reflected wave from the glass window was received more strongly than the reflected wave from the Tx direction. Furthermore, the delay spread in this environment was compared with the CDF at the LoS and NLoS points, and the results were almost the same.

To establish a simulation technology for estimating and predicting radio propagation characteristics with short calculation time and high accuracy, we proposed a novel method named color images method (CIM) and showed its high performances at low frequency band of 1 GHz. However, the performances of the CIM in high frequency bands have not been clarified. In this paper, we compare estimated path loss results of an outdoor urban environment using the CIM with the measured results in high frequency bands of sub-6 GHz band and millimeter-wave to clarify the estimation performance of the CIM. The root mean squared errors (RMSEs) of the difference between the estimated results and the measured results are small about 8 dB for all frequencies. The calculation time is extremely short.

Many managers and human resource departments transfer a person in an attempt to increase the performance of an organization or team. When we define performance as team efficiency, the performance is influenced by the density of team communications. However, whether or not the candidate transferee will actually increase the density of team communications is an unknown. In this paper, we propose a new approach that estimates whether or not a person who joins a team will improve the density of team communications based on an instant messaging system (IMS). In the proposed approach, we embed people in feature space using graph neural networks. In this embedding process, we do not use the content of text communications but utilize only communication graph architectural information that expresses who is talking to whom and how often. Additionally, the proposed approach does not require a questionnaire to indicate the density of team communication as in some previous studies. In the proposed approach, we develop a machine learning model classifying whether or not a transferee will improve the density of team communications. The model classifies transferees at an accuracy of 0.57 and precision of 0.58. Since this model does not use text contents from the IMS, it is valuable in actual business situations.

In this paper, we present a novel screen system employing polarizers that allow switching of the projection surface to the front, rear, or both sides using only two projectors on one side. In this system, we propose a method that employs two projectors equipped with polarizers and a multi-layered screen comprising an anti-reflective plate, transparent screen, and wire grid polarizer. The multi-layered screen changes whether the projected image is shown on the front or rear side of the screen depending on the polarization direction of the incident light. Hence, the proposed method can project images on the front, rear, or both sides of the screen by projecting images from either or both projectors using polarizers. In addition, the proposed method can be easily deployed by simply attaching multiple optical films. We implement a prototype and confirm that the proposed method can selectively switch the projection surface.

In 6G design, radio propagation analysis with high accuracy is required. Radio wave propagation analysis with ray-tracing (RT) is based on searching for ray-paths between Tx and Rx. Here, in order to improve the analysis accuracy, it is necessary to search for multiple ray-paths that contribute to the propagation characteristics, but the amount of calculation increases exponentially as the number of structures to be considered and the number of interactions with structures increase. On the other hand, at present, attention is focused on quantum annealing (QA) computer that enable ultra-high-speed operations for combinatorial optimization problems. Here, it can be said that the searching for ray-paths is one of the combinatorial optimization problems. Therefore, this paper proposes novel ray-path search method applicable to QA. And the validation results are shown.

Storm and flood disasters such as typhoons and torrential rains are becoming more intense and frequent. The national government and municipalities must respond to such natural disasters as soon as possible. When the scale of damage is large; however, it takes much time to investigate the severity of damage, and the initial response can be delayed. If we could precisely and rapidly estimate the severity of damage for each city at an early stage, the national government would be able to better support the municipalities, and consequently respond quickly to help citizens. In this paper, we propose a novel approach to estimate the severity of disaster damage within a short time period after a disaster occurs by exploiting real-time population data generated from cellular networks. First, we investigate the relationship between real-time population data and the severity of damage. Then, we design a Graph Convolutional Networks for Disaster Damage Estimation, called D2E-GCN, which fully exploits the directed and weighted characteristics of human mobility graph. We conduct an offline evaluation on real-world datasets including two typhoons that hit Japan. The evaluation results show that the proposed method outperforms baseline methods which do not consider the graph structure of cities, and the proposed method can estimate the severity of damage approximately 48 hours after typhoons passed. Moreover, we find the experimental insight that the estimation performance can be significantly affected by the graph construction method for GCN models.

We present ZeRONE, a new indoor drone that does not use rotating blades for propulsion. The proposed device is a helium blimp type drone that uses the wind generated by the ultrasonic vibration of piezo elements for propulsion. Compared to normal drones with rotating propellers, the drone is much safer because its only moving parts are the piezo elements whose surfaces vibrate at the order of micrometers. The drone can float for a few weeks and the ultrasonic propulsion system is quiet. We implement a prototype of the drone and evaluate its performance and unique characteristics in experiments. Moreover, application scenarios in which ZeRONE coexists with people are also discussed.

We present CamTrackPoint, a new input interface that can be controlled by finger gestures captured by front or rear cameras of a mobile device. CamTrackPoint mounts a 3D-printed ring on the camera's bezel, and it senses the movements of the user's finger by tracking the light passed through the finger. The proposed method provides mobile devices with a new input interface that offers physical force feedback like a pointing stick. The cost of our method is low as it needs only a simple ring-shaped part on the camera bezel. Moreover, the ring doesn't disturb the functions of the camera, unless a user uses the interface. We implement a prototype for a smartphone; two CamTrackPoint rings are made for the front and rear cameras. We evaluate its performance and characteristics in an experiment. The proposed technique provides smooth scrolling and would give better game experience on the available smartphone.

This paper presents path loss frequency dependence on the basis of measurement campaign results in two urban macro (UMa) cell environments using four frequencies between 2 and 66 GHz. For a 3rd Generation Partnership Project (3GPP) UMa model above 6 GHz band, the dependence is shown by 20log(f). However, some studies for the environments show the frequency dependence more than 20log(f) and its propagation phenomena as its cause. The 3GPP model is based on measurements whose dynamic range and distance are limited. So, we measured the path loss characteristics using wide dynamic range equipment capable, for example, of measuring the path loss more than 170 dB at 26 GHz. The measurement results show that the dependence is similar to 3GPP model in Line-of-Sight areas, but that in Non-Line-of-Sight (NLoS) areas it increases more than the dependence of 20log(f). The measured path loss also show that the high frequency dependence can be seen in far distance area and the high path loss area. Taking into account the geographical and urban environment, the high frequency dependence in the far distance NLoS area may be explained by the dominance of diffraction over reflective propagation along the buildings. These results can contribute to clarify the site-specific path loss characteristics and design the cell area for the high frequency bands.

Touch sensing with multiple electrodes allows expressive touch interactions. The adaptability and flexibility of the sensor are important in efficiently prototyping touch based systems. The proposed technique uses capacitive touch sensing and simplifies the connections as the electrodes are connected in series via capacitors and the interface circuit is connected to the electrode array by just two wires. The touched electrode is recognized by measuring the capacitance changes while switching the polarity of the signal. We show that the technique is capable of detecting different touches through simulations and actual measurements. User tests show that ten electrodes are successfully recognized after user calibration. They also show the proposal's other novel capabilities of multi-touch (2-touch) and `capacitor-free' design. Various forms of electrodes and applications are examined to elucidate the application range.

We present iSphere, a flying spherical display that can display high resolution and bright images in all directions from anywhere in 3D space. Our goal is to build a new platform which can physically and directly emerge arbitrary bodies in the real world. iSphere flies by itself using a built-in drone and creates a spherical display by rotating arcuate multi light-emitting diode (LED) tapes around the drone. As a result of the persistence of human vision, we see it as a spherical display flying in the sky. The proposed method yields large display surfaces, high resolution, drone mobility, high visibility and 360° field of view. Previous approaches fail to match these characteristics, because of problems with aerodynamics and payload. We construct a prototype and validate the proposed method. The unique characteristics and benefits of flying spherical display surfaces are discussed and we describe application scenarios based on iSphere such as guidance, signage and telepresence.

Fifth generation (5G) mobile communication systems are being actively investigated to increase the system capacity. For 5G, utilizing frequency bands above 6 GHz is being investigated because it is considered that ensuring a wide frequency band above 6 GHz is relatively easier than that under 6 GHz, which is used for IMT-Advanced systems. In this report, a site general type path loss prediction model for 5G system radio link design is investigated for the above mentioned frequency band in a non-line-of-sight (NLOS) microcell environment. More specifically, based on measurement data, extending the applicable frequency range of the path loss prediction model for a hexagonal layout in a NLOS microcell environment for under 6 GHz, which is defined in Report ITU-R M.2135, is investigated. The root mean square of the prediction error (RMSE) of the original M.2135 prediction model increases with an increase in frequency; however, the model modifies the frequency term of M.2135 which improves the RMSE at higher frequencies.

A tag system is proposed that offers a practical approach to ubiquitous computing. It provides small and low-power tags that are easy to distribute; does not need a special device to read the tags (in the future), thus enabling their use anytime, anywhere; and has a wide reading range in angle and distance that extends the design space of tag-based applications. The tag consists of a kind of liquid crystal (LC) and a retroreflector, and it sends its ID by switching the LC. A depth sensing camera that emits infrared (IR) is used as the tag reader; we assume that it will be part of the user's everyday devices, such as a smartphone. Experiments were conducted to confirm its potential, and a regular IR camera was also tested for comparison. The results show that the tag system has a wide readable range in terms of both distance (up to 8m) and viewing angle offset. Several applications were also developed to explore the design space. Finally, limitations of the current setup and possible improvements are discussed.

The objective of this research is to realize a method that detects a user's entrance to predefined geographic area so that appropriate services are provided without explicit user action. Though such geofencing technology is gathering attention due to its wide range of applications, it is a challenge to overcome trade-off between power consumption and detection accuracy. Conventional variable interval positioning methods fall short on battery saving due to difficulties such as sparse and erroneous position measurement data, and the unpredictable speed and trajectory of the terminal. In this paper, we propose a method for position detection whose activation frequency is determined by speed toward the target spot. The method is robust against positioning error and fluctuation of the terminal's movement by leveraging the access angle to the target spot. Simulation results show that the proposed access speed correction method reduces power consumption from 42% to 52% against conventional method, while holding the false negative ratio to detect the target spot to less than 5%.

This paper proposes a method for applying interlink correlation to evaluate a multiuser-multiple input multiple output (MU-MIMO) system and describes measurement of a multi-link MIMO propagation channel. The proposed method is validated through comparison of measurement results to those of the conventional MIMO propagation channel model. The results show that the proposed method employing the Weichselberger model can handle the interlink correlation property, and accurately reconstructs a MIMO propagation channel.

In this paper, to evaluate the basic performance of MIMO cooperative transmission systems, a simple prediction method which calculation complexity is decreased for evaluating indoor MIMO cooperative transmission is proposed. 5.2 GHz indoor MIMO propagation measurements are carried out in line of sight condition. And the frequency utilization efficiency and eigenvalues are evaluated by measurement data. Simple prediction method of MIMO channel matrix, which takes into account the phase difference of direct waves based on the antenna position, is used to simulate the MIMO channel. The simulation results are then compared to the measurement results. Based on this comparison the proposed prediction method can accurately estimate the characteristics of indoor MIMO cooperative transmission systems.

This paper proposes a 2.4/5-GHz dual-band horizontally-polarized planar antenna for use in a 3-MIMO antenna configuration OFDM wireless LAN (WLAN) system. The proposed antenna provides a voltage standing wave ratio of 2 in the 2.4-2.5 and 4.9-6 GHz bands when printed on a printed circuit board for commercial PCMCIA or WLAN cards and inserted into a notebook PC. The capacities and correlation coefficients of 3times3 MIMO channels in an indoor multipath LOS/NLOS environment were measured. The results show that the proposed planar antenna is superior to the conventional monopole antenna with respect to channel capacity when polarization matching between the base station and personal station antennas is obtained.