This paper presents development of passive channel sounder using software defined radio based receivers and commercial transmitter operating in cellular network. Accuracy of developed channel sounder is verified by over-the-air path gain measurement in outdoor open space. For evaluation, line-of-sight path gain is estimated using correlation method and is compared with theoretical path gain.

IoT control applications can be placed in the cloud to reduce the cost of IoT devices. However, the ability to migrate the IoT control application to another server due to system maintenance etc. must be assured. This paper proposes a migration method for real-time IoT control applications that does not affect IoT control of periodically controlled IoT devices with short cycle. We implement and evaluate our FPGA container migration system assuming an IoT control application running on FPGA containers. Experiments show our system is able to migrate the IoT control application with a control cycle of 60ms.

Recently, physical layer security has attracted increased attention. In this context, researchers have proposed secret key-sharing methods using time-varying channel state information (CSI). However, CSI is time-correlated; thus, the randomness of the key deteriorates when the key generation time is shortened. Accordingly, we propose a 256-bit secret key-sharing method that does not degrade the key randomness even when the generation time is shortened. The method is based on exploiting chaos signals exhibiting complex and unpredictable behaviors. Through numerical simulations, we demonstrate that the proposed method passes the randomness evaluation test provided by the National Institute of Standards and Technology in a short time.

The security policy changed from the traditional “castle and moat” approach to the zero-trust security model due to the recent change in work styles. The authors have been developing the overlay network protocol, called CYber PHysical Overlay Network over Internet Communication (CYPHONIC), to support the zero-trust security model easily. Additionally, we have designed an essential function of a gateway device called a CYPHONIC adapter because the proposed protocol requires devices to install a special client program. The initial implementation suffers from performance degradation of Transmission Control Protocol (TCP) due to order changes of packets during packet handling functions. This paper redesigns the adapter functions focused on the packet processing scheme of the CYPHONIC adapter and confirms the throughput improvement in standard protocols.

Antennas mounted on Internet of things (IoT) devices must be small and thin. Additionally, because these devices contain metals, they must be sufficiently robust not to be influenced by surrounding objects. Therefore, a metasurface-inspired antenna chip developed by the KIT EOE Laboratory (MACKEY) is proposed as an antenna that meets these requirements. Furthermore, the MACKEY II unbalanced type, a thinner version of MACKEY that enables an unbalanced power supply, is proposed. This review compares and discusses the analysis and measurement results of the MACKEY Q-type antenna, a miniaturized version of this antenna.

We propose a method for reducing electromagnetic coupling between two monopole antennas for MIMO communications that do not use any lumped element components. In the past, the decoupling method for connecting antennas required two steps, decoupling and matching, in order, and used lumped element components for each step. The previous design method using even-odd mode analysis also uses one lumped element component between antennas. The proposed method of this paper also uses even-odd mode analysis, but the decoupling condition can be set independently for each mode, and both decoupling and matching can be designed simultaneously, without using lumped element components. The decoupling effect was confirmed by simulation and measurement.

This letter proposes a high-density array antenna loaded with unevenly arranged parasitic elements to realize compact and high-power DC rectenna arrays. By adjusting the positions of the parasitic elements loaded above a high-density array antenna, the beam of each antenna element is directed to the front of the array antenna. Hence, the reception performance of the whole array antenna is improved. The aperture ratio, which is defined as a ratio of an effective aperture area and physical area, is examined by simulation and experiment for a 9-element array antenna. The aperture ratio of 1.88 is achieved.

Information-centric networking (ICN) is attracting interest as a next-generation network architecture that sends contents using a content ID instead of an IP address. While the ICN architecture is expected to reduce the overhead related to Internet usage and enable highly efficient content delivery, it is difficult to achieve highly efficient content discovery using only a content ID because of suboptimal cache allocation. We propose an ICN control method that uses content attribute vectors for similarity instead of content IDs and executes cache allocation and search using a self-organizing map.

A system using Hyperledger Fabric (Hyperledger Fabric-based system) provides the value of executing transactions across multiple organizations in a decentralized manner. To maximize this value, it is essential to maintain decentralization not only in the execution system but also in the entire system, including system configuration and management. On the other hand, Hyperledger Fabric is still in the process of maturing and full-decentralization is still difficult to achieve. In this paper, we analyze comprehensive basic requirements for realizing fully-decentralized Hyperledger Fabric-based systems and design a reference architecture to satisfy the basic requirements.

We propose a high-resolution and stable optical power measurement technique employing a temperature controlled amplified-spontaneous-emission feedback circuit (ASEFC). We evaluate the optical power resolution (OPR) and repeatability characteristics of the temperature controlled ASEFC. The results show that small time variations in the optical power of the lights emitted from two types of light sources used in the technique are accurately measured for one hour with improvement factors larger than 97 and OPRs better than 0.10 mdB when we assume a temporal power fluctuation uncertainty of an optical power meter set after the temperature controlled ASEFC equal to 10 mdB.

The development of a system for pollinating tomato flowers using small drones, instead of bees, is currently underway. This system necessitates the collection of visual data from multiple drones, which are subsequently transmitted to a receiving station. This study used epidemic communication as a communication method that is suitable for pollination systems. However, conventional epidemic communication has a long delay time. To address this problem, we proposed two modifications to the conventional epidemic communication: using directional beams of antennas, and controlling the movement of the drones by weighing the movement at a constant rate. The proposed method was able to reduce the delay time.

Remote control has been the focus for next-generation technology. However, the precise delay requirement for remote control cannot be clarified. We measured the accuracy of miniature crane control with a movement of 15cm/s and evaluated the delay requirement. We found that the delay requirement is less than around 110-190ms for an arm movement of 15cm/s, which is half the movement speed of an adult hand.

The impact of soft errors on communication devices are increasing as semiconductor chips become more integrated and miniaturized. Furthermore, since optical network units (ONUs) are installed for each subscriber, frequent failures due to soft errors in the entire network are expected. As a result, there are concerns about Internet outage or frequent recover action. Therefore, focusing on the fact that soft errors can be recovered by rebooting, we developed a mechanism to detect soft errors and perform an autonomous reset, and implemented it in a 10G-EPON ONU. In experiments using neutron irradiation, the failure rate of the implemented 10G-EPON ONU was reduced to 1/860 compared with unimplemented 10G-EPON ONU. As a result, the implemented 10G-EPON ONU showed a significant improvement in reliability against soft errors.