Yuichi Kawamoto

Recently, the concept of Internet of Things, referred to as IoT, has drawn a great deal of research attention for realizing an intelligent society. The IoT is expected to comprise millions of heterogeneous smart “things” having sensor terminals, which may collect various types of information. By sending these collected information via IoT, it is possible to construct many smart systems, e.g., automatic prevention of traffic jam and so on. However, the coverage of IoT and the capacity of its grou

Multi-Layered Satellite Networks (MLSNs) have enormous potential to provide a ubiquitous wireless environment due to their advantages, such as extensive coverage, high network capacity, and lower delay performance. Since MLSNs are flexible and can be expanded easily to construct useful communication networks, researchers have paid a great deal of attention to find out how to use them efficiently. However, traffic congestion may occur in such networks since the distribution of MLSN users is heavi

The development of technologies related to the Internet of Things (IoT) provides a new perspective on applications pertaining to smart cities. Smart city applications focus on resolving issues facing people in everyday life, and have attracted a considerable amount of research interest. The typical issue encountered in such places of daily use, such as stations, shopping malls, and stadiums is crowd dynamics management. Therefore, we focus on crowd dynamics management to resolve the problem of c

Unmanned aircraft systems have recently been considered as effective solutions to establish communication network infrastructures in isolated regions, and perform environment-related tasks such as crop monitoring and topographic surveying. In a UAV network, the data from onboard video cameras, sensors, and communication devices are retrieved by a ground station. The performance of this type of network depends on efficient resource allocation to achieve a high throughput under the usually limited

The recent development of communication devices and wireless network technologies continues to advance the new era of the Internet and telecommunications. The various “things”, which include not only communication devices but also every other physical object on the planet, are also going to be connected to the Internet, and controlled through wireless networks. This concept, which is referred to as the “Internet of Things (IoT)”, has attracted much attention from many researchers in recent years

Satellite communication systems have attracted considerable attention recently because they can communicate in various conditions, including terrestrial, airspace, and marine terrain. In addition, high-throughput satellites (HTSs) that allow high-speed and large-capacity communication are currently being launched. However, the allocation of communication resources to each beam is fixed in conventional HTSs, which exhibit low flexibility under state changes. This includes requests to the satellit

We found this population to be panmictic, with a low degree of genetic variability. On the basis of an mtDNA phylogeny, we inferred that these macaques' ancestors originated from Java in Asia. Weak gametic disequilibrium was observed, suggesting decay of non-random associations between genomic genes at the time of founding. The results suggest that macaques bred in Mauritius are valuable as model animals for biomedical research because of their genetic homogeneity.

In recent years, unmanned aircraft systems (UASs) have garnered significant attention, and the demand for communication utilizing unmanned aircrafts (UAs) has increased. However, the limited available frequency for UA communication, despite the increasing utilization, poses a problem. Moreover, for the practical application of UA communication, the changes and differences in the propagation environment and communication demand of each UA communication must be considered because of the variety of

Cooperative satellite cells and terrestrial wireless communication networks (comprising macrocells, picocells, and the Internet) are much anticipated access technologies to enable users to seamlessly access rich multimedia content (e.g., TV broadcasting, VoD streaming, and other services) on their devices. Furthermore, context awareness has become popular to accompany these services not only to enhance the users' perceived service quality but also to improve the overall utilization of such coope

The concept of Internet of things (IoT) has attracted attention as a key technology for realizing future industrial society. In the future society, numerous “things” with sensors are deployed and connected to networks, and data collected from these devices are used for a wide variety of industrial applications. In this paper, we focus on data collection for location-based authentication system as an application of industrial IoT. The authentication system uses ambient information, which is colle

To support safe driving and automatic operation, collecting and providing information are important in intelligent transport systems (ITSs). Information and communication technology utilization is needed even when disasters occur because it is possible to collect and analyze vehicle position information via roadside units and thus locate accidents and traffic jams. However, if the roadside units are damaged by disasters or power outages, these functions cannot be provided. Therefore, we consider

Satellite communication is increasingly essential and widely used, especially with the rapid development of the Internet of Things (IoT) and networks beyond fifth-generation (B5G), providing ubiquitous coverage. However, the current reactive approaches to optimize resources have become inadequate due to the massive rise in IoT traffic with varying patterns and limited resources of satellite networks. These approaches fail to predict dynamic traffic and its requirements. To efficiently allocate s