Nobuyoshi Komuro

Bio: Nobuyoshi Komuro is an academic researcher from Chiba University. The author has contributed to research in topics: Throughput (business) & Wireless sensor network. The author has an hindex of 11, co-authored 86 publications receiving 377 citations. Previous affiliations of Nobuyoshi Komuro include Tokyo University of Technology & Ibaraki University.

Indoor Location Estimation Technique using UHF band RFID

Abstract: This paper investigates an indoor location estimation system based on UHF band RFID. Tags, separated by 50 cm, are attached to the ceiling and an RFID reader is attached to the person of interest. The location of the person is estimated using the tags' coordinate which are read by the RFID reader. Three simple location estimation algorithms are proposed, and their estimation accuracy is evaluated by an experiment. This paper also presents a ray trace simulation; tag allocation, RFID reader parameters, and location estimation algorithms are evaluated by simulation to minimize the estimation error.

Maximum throughput analysis for RTS/CTS-used IEEE 802.11 DCF in wireless multi-hop networks

Abstract: The purpose of this paper is to analyze the maximum throughput when using RTS/CTS (Request To Send/Clear To Send) in IEEE 802.11 Distributed Coordination Function (DCF) multi-hop networks with a novel approach. Wireless multi-hop networks, in which nodes communicate with each other and convey packets via intermediate nodes without centralized control, have gained increasing attention because of the extension of the wireless communication range associated with such networks. In wireless multi-hop networks, the IEEE 802.11 DCF based on the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) has been commonly used as a Medium Access Control (MAC) protocol. IEEE 802.11 DCF is specifically designed for single-hop wireless LANs, which makes quantitative analyses of the contention behaviors occurring at nodes in typical network topologies important. Although several quantitative throughput analyses for wireless multi-hop networks have been reported, few analyses have examined the use of RTS/CTS in IEEE 802.11 DCF multi-hop networks. While RTS/CTS is effective for avoiding packet collisions caused by hidden terminals, an overhead problem occurs due to the increase in the number of RTS/CTS control packets. As the number of RTS/CTS control packets increases, the collisions between RTS/CTS control packets occur more frequently. The analysis of networks that use RTS/CTS has been considered difficult because of the complex behaviors of RTS/CTS. The present paper introduces a novel approach to the analysis of throughput for networks that use RTS/CTS by considering one-way flow in string multi-hop networks. The end-to-end network maximum throughput is obtained by analyzing the maximum throughput of bottleneck nodes. This analysis provides the transmission failure probability considering not only RTS-RTS collisions but also the influence of the Network Allocation Vector (NAV). A simulation is carried out, and a comparison of the analytical and simulated results validates the proposed analytical expressions.

A Reasonable Throughput Analysis of the CSK/SSMA Unslotted ALOHA System with Nonorthogonal Sequences *

Abstract: In this paper, the throughput performance of the CSK/SSMA ALOHA system with nonorthogonal sequences which combines the ALOHA system with Code Shift Keying using nonorthogonal sequences is analyzed. In this system, the nonorthogonal sequences are constructed by concatenating Mcon orthogonal sequences. The throughput performance of the CSK/SSMA ALOHA system with nonorthogonal sequences is analyzed in consideration that the number of packets changes at intervals of one orthogonal sequence. Moreover, the throughput performance of our system with Channel Load Sensing Protocol (CLSP) is also analyzed. We also examine the influence of unreachable control signal of CLSP. Consequently, it is found that the throughput performance of our system decreases significantly by this analysis. It is also found that the throughput performance of our system improves greatly by using CLSP. However, the unreachable control signal affects the throughput performance of this system, seriously.

End-to-End Delay Analysis for IEEE 802.11 String-Topology Multi-Hop Networks

Abstract: String-topology multi-hop network is often selected as an analysis object because it is one of the fundamental network topologies. The purpose of this paper is to establish expression for end-to-end delay for IEEE 802.11 string-topology multi-hop networks. For obtaining the analytical expression, the effects of frame collisions and carrier-sensing effect from other nodes under the non-saturated condition are obtained for each node in the network. For expressing the properties in non-saturated condition, a new parameter, which is frame-existence probability, is defined. The end-to-end delay of a string-topology multi-hop network can be derived as the sum of the transmission delays in the network flow. The analytical predictions agree with simulation results well, which show validity of the obtained analytical expressions. key words: IEEE 802.11, string topology, VANETs, multi-hop networks, end-to-end delay analysis, MAC layer

Survey on Collaborative Smart Drones and Internet of Things for Improving Smartness of Smart Cities

Abstract: Smart cities contain intelligent things which can intelligently automatically and collaboratively enhance life quality, save people's lives, and act a sustainable resource ecosystem. To achieve these advanced collaborative technologies such as drones, robotics, artificial intelligence, and Internet of Things (IoT) are required to increase the smartness of smart cities by improving the connectivity, energy efficiency, and quality of services (QoS). Therefore, collaborative drones and IoT play a vital role in supporting a lot of smart-city applications such as those involved in communication, transportation, agriculture,safety and security, disaster mitigation, environmental protection, service delivery, energy saving, e-waste reduction, weather monitoring, healthcare, etc. This paper presents a survey of the potential techniques and applications of collaborative drones and IoT which have recently been proposed in order to increase the smartness of smart cities. It provides a comprehensive overview highlighting the recent and ongoing research on collaborative drone and IoT in improving the real-time application of smart cities. This survey is different from previous ones in term of breadth, scope, and focus. In particular, we focus on the new concept of collaborative drones and IoT for improving smart-city applications. This survey attempts to show how collaborative drones and IoT improve the smartness of smart cities based on data collection, privacy and security, public safety, disaster management, energy consumption and quality of life in smart cities. It mainly focuses on the measurement of the smartness of smart cities, i.e., environmental aspects, life quality, public safety, and disaster management.

A Passive UHF-RFID System for the Localization of an Indoor Autonomous Vehicle

Abstract: A global localization system combining odometry data with radio frequency identification (RFID) readings is proposed. RFID tags are placed at the ceiling of the environment and can be detected by a mobile robot unit traveling below them. The detection of the tags is the only information used in the proposed approach (no distance or bearing to the tag is considered available), but differently from similar localization setups reported in the literature, only a small number (about one each square meter or less) of tags are used. This is possible using a suitable tag's antenna in ultrahigh frequency band, expressly designed to obtain regular and stable RFID detection regions, which allows us to consider an efficient Kalman filtering approach to fuse RFID readings with the vehicle odometry data. A satisfactory performance is achieved, with an average position error of about 0.1 m. The hardware/software localization setup described in this paper is cheap and easy to use and may provide a satisfactory approach in several industrial and domestic scenarios.

Coexistence of Wireless Technologies in the 5 GHz Bands: A Survey of Existing Solutions and a Roadmap for Future Research

Abstract: As the 2.4 GHz spectrum band has become significantly congested, there is growing interest from the Wi-Fi proponents, cellular operators, and other stakeholders to use the spectrum in the 5 GHz bands. The 5 GHz bands have emerged as the most coveted bands for launching new wireless applications and services, because of their relatively favorable propagation characteristics and the relative abundance of spectrum therein. To meet the exploding demand for more unlicensed spectrum, regulators across the world such as the United States Federal Communications Commission and the European Electronic Communications Committee have recently started considerations for opening up additional spectrum in the 5 GHz bands for use by unlicensed devices. Moreover, to boost cellular network capacity, wireless service providers are considering the deployment of unlicensed long term evaluation (LTE) in the 5 GHz bands. This and other emerging wireless technologies and applications have resulted in likely deployment scenarios where multiple licensed and unlicensed networks operate in overlapping spectrum. This paper provides a comprehensive overview of the various coexistence scenarios in the 5 GHz bands. In this paper, we discuss coexistence issues between a number of important wireless technologies—viz., LTE and Wi-Fi, radar and Wi-Fi, dedicated short range communication (DSRC) and Wi-Fi, and coexistence among various 802.11 protocols operating in the 5 GHz bands. Additionally, we identify and provide brief discussions on an impending coexistence issue—one between Cellular V2X and DSRC/Wi-Fi. We summarize relevant standardization initiatives, explain existing coexistence solutions, and discuss open research problems.

Reliability in Internet of Things: Current Status and Future Perspectives

Abstract: The Internet of Things (IoT) aims to transform the human society toward becoming intelligent, convenient, and efficient with potentially enormous economic and environmental benefits. Reliability is one of the main challenges that must be addressed to enable this revolutionized transformation. Based on the layered IoT architecture, this article first identifies reliability challenges posed by specific enabling technologies of each layer. This article then presents a systematic synthesis and review of IoT reliability-related literature. Reliability models and solutions at four layers (perception, communication, support, and application) are reflected and classified. Despite the rich body of works performed, the IoT reliability research is still in its early stage. Challenging research problems and opportunities are then discussed in relation to current underexplored behaviors and future new aspects of evolving IoT system complexity and dynamics.

Indoor Intelligent Fingerprint-Based Localization: Principles, Approaches and Challenges

Abstract: With the rapid development of Internet of Things (IoT) technology, location-based services have been widely applied in the construction of smart cities. Satellite-based location services have been utilized in outdoor environments, but they are not suitable for indoor technology due to the absence of global positioning system (GPS) signal. Therefore, many indoor localization technologies and systems have emerged by utilizing many other signals. In particular, fingerprinting localization has recently garnered attention because its promising performance. In this work, we aim to study recent indoor localization technologies and systems based on various fingerprints, which use machine learning and intelligent algorithms. We also present the architecture of intelligent localization. The development of indoor localization technology should have the ability of self-adaptation and self-learning in the future. And the architecture shows how to make localization become more “smart” by advanced techniques. The state-of-the-art localization systems’ working principles are summarized and compared in terms of their localization accuracy, latency, energy consumption, complexity, and robustness. We also discuss the challenges of existing indoor localization technologies, potential solutions to these challenges, and possible improvement measures.