Aerosol observation at Okayama with Skyradiometer and LIDAR

　Aerosol is one of the controlling parameter for the global climate and also effects on local health hazards. The measurement of the aerosol was originally carried out as in-situ sampling and mass weight measurement including chemical analysis. Recently, remote sensing method is applied as satellite remote sensing and surface based remote sensing. Skyradiometer and LIDAR are surface based remote sensing system. Skyradiometer measures solar radiation as direct and scattered solar radiation affected by aerosols. LIDAR emit laser beam upward and it is backscattered by overlying aerosols. The backscattered light is received by a telescope and vertical distributions of the aerosols are obtained. These measurements require atmospheric radiation physics. 　A Skyradiometer and a LIDAR were operated continuously at Okayama University campus and aerosol parameters were obtained from both of the system. Seasonal variations of the AOT (Aerosol Optical Thickness) and Angstrom parameter (α) are evaluated. During some dust events (e.g. yellow sand and PM2.5), time variations of these parameters were identified from both of the measurement system

Autonomous Data Transmission Control Based on Node Density for Multiple Spatio-temporal Data Retention

Although countless services can now be accessed via the Internet, some specific services such as local traffic conditions and limited-time sale advertisements are strongly dependent on geographical locations and times. Information of this type, which is commonly referred to as spatio-temporal data (STD), is not readily available online. Since the paradigm of local production and consumption of STDs can be effective for location-dependent applications, we previously proposed an STD data retention system that uses vehicular networks to create a mobile cloud. Unfortunately, effective data retention is difficult when multiple STDs exist in the same area because channel interference will result from the increased number of data transmissions. To resolve this issue, we herein propose an autonomous data transmission control method based on node density for multiple STD retention that facilitates a highly reliable coverage rate while limiting the individual data transmissions for each STD. Then, through simulations, we show that our proposed method is effective for simultaneously retaining multiple STDs.7th IEEE International Conference on Cloud Networking (CloudNet 2018), 22-24 October, 2018, Tokyo, Japa

Development of Vehicle Management System using Location Data Collected by 920MHz LoRa

The MaaS (Mobility as a Service), which collects, analyzes, and utilizes various data obtained various types of vehicles, is expected to solve various problems about traffic jams, autonomous driving, social community, etc. In this paper, we propose the vehicle management system at a low cost and effecivery using LoRa and Wi-Fi communication. Furthermore, we propose the application to estimate the arrival time assuming the use by a rental car company. The effectiveness of the proposed method is evaluated through demonstration experiments.2020 International Conference on Computational Science and Computational Intelligence (CSCI 2020), 16-18 December, 2020, Las Vegas, Nevada, US

Spatio-Temporal Data Retention System with MEC for Local Production and Consumption

To facilitate local production and consumption (LPAC) of spatio-temporal data (STD) generated by Internet of Things (IoT) devices, we propose a STD retention system that works in collaboration with Mobile Edge Computing (MEC) infrastructure. In this paper, we will introduce the architecture of our proposed system and discuss its contributions and challenges.COMPSAC 2018: The 42nd IEEE International Conference on Computers, Software & Applications, July 23-27, 2018, Tokyo, Japa

Development of Data Collection Platform for Running Cars by using 920MHz LoRa Communication in Urban Area

The MaaS (Mobility as a Service), which collects, analyzes, and utilizes various data obtained various types of vehicles, is expected to solve various problems about traffic jams, autonomous driving, social community, etc. In today’s IoT (Internet of Things) and the MaaS infrastructures, however, data ownership is owned by the vendor created onboard sensor, such as car-navigation systems and driving recorders, and not everyone can easily leverage the data. Therefore, it is necessary to collect various information from sensors mounted on a vehicle at a low cost and effective. This paper proposes the data collection platform using the LoRa andWi-Fi from running cars. Through the demonstration experiment in the urban area, we clarified the acquisition performance of GPS data of cars by LoRa communication and the importance of data collection using Wi-Fi.2020 International Conference on Emerging Technologies for Communications (ICETC2020), December 2-4, 2020, Online, Virtual Conferenc

Experimental Investigation of Static Channel Bonding Performance in Competitive Environment －Impact of Different MAC Procedures in 802.11ac－

Channel bonding technology, which bundles multiple adjacent channels for frame transmission, is one of the promising way for improving throughput performance in IEEE802.11ac wireless LANs. However, channel bonding technology leads to co-channel interference with other access points (APs) within the bonded channels. In our previous study, we investigated transmission performance of several commercially-available 802.11ac APs. As a result, we clarified three communication procedures from difference in method of implementation of Request To Send (RTS) / Clear To Send (CTS) or not. Furthermore, we investigated the impact of RTS/CTS on transmission performance by conducting experiments where two APs using RTS/CTS are competing in a bonded channels. However, we have not investigated transmission performance in the case that APs with different transmission procedures compete with each other in a bonded channels. Therefore, in this study, we conducted experiments using real WLAN products. Then, we compared and evaluated the communication performance in the case that two APs with different transmission procedures compete in the same channel. As a result, we showed that the AP employing CTS-to-self doesn’t set duration time in CTS frames, thereby the communication performance of the AP using RTS/CTS in channel bonding degrades due to frequent collisions in conflict channel. On the other hand, since AP not using RTS/CTS dynamically adjusts the number of data frames for each transmission opportunity to avoid frame collisions, we confirmed that the communication performance can be relatively maintained even under the competitive environment. / IEEE802.11ac規格の通信高速化技術の一つに、隣接する複数のチャネルをまとめて利用するチャネルボンディング機能がある。しかし、通信帯域が拡大するため他の無線LAN機器と競合しやすくなってしまう。先行研究では、競合しない環境の単一のAPの通信性能を調査し、オプション機能のRequest To Send (RTS) / Clear To Send (CTS)の実装方法の違いから3パターンの通信手順があることを明らかにしたうえで、RTS/CTS利用の有無が競合時に性能に与える影響を調査した。しかし、CTS-to-Selfによる競合時の影響は未だ明らかになっていない。そこで本研究では、実機を用いた実験を行い、CTS-to-Selfによる競合時の通信性能を調査するとともに、3パターンの通信手順の競合時における各通信性能の比較および評価を行った。その結果、CTS-to-selfによる通信手順ではNAV期間が確保できていないためフレーム衝突が起こりやすく、RTS/CTSを利用しチャネルボンディングさせていたAPに悪影響を与えていた。それに対して、RTS/CTSを利用しないAPは、送信機会毎のデータフレーム数を調節しながら通信していたためフレーム衝突が起こりにくく、お互いの通信性能への影響が低減されていることがわかった。電子情報通信学会 スマート無線研究会（SR）, 2018年10月30日-31日, Bangkok, Thailan

A Dynamic Channel Switching for ROD-SAN

Wireless sensor and actuator networks (WSANs) are expected to become key technologies supporting machine-to-machine (M2M) communication in the Internet of things (IoT) era. However, sensors must be able to provide high demand response (DR) levels despite severely limited battery power. Therefore, as part of efforts to achieve a high DR, we are working on research and development related to radio-on-demand sensor and actuator networks (ROD-SANs). ROD-SAN nodes are equipped with wake-up receivers that allow all nodes to stay in sleep mode for a long period of time, and transmit only after the receiver receives a wake-up signal. In addition, sender nodes can direct the receiver nodes to switch communication channels because the wake-up signal also includes information on the channel to use for communication between each other. However, as the number of nodes utilizing the same channel increases, frequent packet collisions occur, thereby degrading response performance. To reduce packet collisions, we propose an own-channel-utilization based channel switching (OCS) scheme, which is a modification of the average-channel-utilization based switching (ACS) as our previous works. The OCS scheme decides whether or not to switch channels based on a probability value that considers not only average-channel utilization of nearby nodes but also own-channel utilization. This approach permits node switching to other channels by considering the overall utilization states of all channels. In this paper, based on simulations, we show that our scheme can improve the delivery ratio by approximately 15% rather than ACS scheme

International Collaborative Experiment for RL-based Multi-Resource Management on COSMIC Testbed

To brace next-generation latency and capacity sensitive and diverse mobile applications for 6G and IoT across network domains, there is a need to co-develop high-speed communications and efficient computing infrastructure. Edge Cloud (EC) is poised to address these constraints by providing compute resources at the edge of the network. Yet, the EC being regionally domestic with a smaller scale, faces the challenges radio access bandwidth and computational throughput, calling for a new SDN EC system architecture integrated with the core cloud for resource allocation and task scheduling. Such architecture will promote resource sharing among multiple and heterogeneous network domains. The NSF IRNC supported COSMIC (COSMOS Interconnecting Continents) testbed proposes to build a fully programmable network (from the optical and radio physical layers and above) and computational infrastructure (edge clouds). In the proposed COSMIC architecture, data center near to the mobile users can serve as an edge cloud and be used to offload service requests of real-time and latency-sensitive applications. The data center in a remote LAB or other continents will be emulated as a core cloud, and the delaytolerant services can be offloaded to the data center to achieve efficient resource sharing in a multi-domain network environment. The testbed is well suited to such category of experiments which involve emulated mobility between multiple edge network domains, potentially in different continents. The COSMIC’s global sites will ensure a worst-case evaluation environment for stress-testing of real-time applications. Diverse quality of service requirements germane to IoT traffics will be managed by the proposed SDN architecture. To cope with real-time constraint and scalability issues, Reinforcement Learning based approach is proposed to optimally manage wireless access bandwidth, flow route resource, and VM resources of edge and core clouds. Moreover, Collaborative Learning based approach (such as Federated Learning) is also proposed to flexibly address critical issues such as data privacy, data access to heterogeneous data among multiple edge networks with diverse characteristics. A use-case scenario like edge cloud client environment for business travelers across multiple continents will be developed over the globally connected COSMIC testbed.US-Japan binational research community Workshop on Programmable Networking, November 16-18, 2020 (US dates), onlin

Transmission Control Method for Data Retention Taking into Account the Low Vehicle Density Environments

With the development and spread of Internet of Things (IoT) technology, various kinds of data are now being generated from IoT devices. Some data generated from IoT devices depend on geographical location and time, and we refer to them as spatio-temporal data (STD). Since the “locally produced and consumed” paradigm of STD use is effective for location-dependent applications, the authors have previously proposed a vehicle-based STD retention system. However, in low vehicle density environments, the data retention becomes difficult due to the decrease in the number of data transmissions in this method. In this paper, we propose a new data transmission control method for data retention in the low vehicle density environments

Transmission Control Method to Realize Efficient Data Retention in Low Vehicle Density Environments

With the development and spread of Internet of Things (IoT) technology, various kinds of data are now being generated from IoT devices, and the number of such data is expected to increase significantly in the future. Data that depends on geographical location and time is commonly referred to as spatio-temporal data (STD). Since the “locally produced and consumed” paradigm of STD use is effective for location-dependent applications, the authors have previously proposed using a STD retention system for high mobility vehicles equipped with high-capacity storage modules, high-performance computing resources, and short-range wireless communication equipment. In this system, each vehicle controls its data transmission probability based on the neighboring vehicle density in order to achieve not only high coverage but also reduction of the number of data transmissions. In this paper, we propose a data transmission control method for STD retention in low vehicle density environments. The results of simulations conducted in this study show that our proposed scheme can improve data retention performance while limiting the number of data transmissions to the lowest level possible.11th International Conference on Intelligent Networking and Collaborative Systems(INCoS 2019), September 5-7, 2019, Oita, Japa