著者

Hideya So Takana Kaho Yasuyoshi Yamamoto Yuta Takahashi Mizuki Suga Yushi Shirato Naoki Kita

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.12, no.4, pp.114-119, 2023-04-01 (Released:2023-04-01)

参考文献数

5

---

Massive MIMO is expected to realize a large capacity for wireless communication technology. To reduce the number of devices of the massive MIMO, utilizing a two-dimensional Butler matrix for the feed circuit has been investigated, but complexing its design. We have proposed a Massive MIMO configuration using a stacked Butler matrix and a staircase array antenna to reduce the circuit design cost. This letter proposes a V-shape staircase array antenna with a stacked Butler matrix to reduce antenna profile. Computer simulation clarifies the beam steering range for the proposed antenna.

著者

Akira Uemura Takumi Katoh Takuji Arima Wakana Kubo

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.12, no.3, pp.84-89, 2023-03-01 (Released:2023-03-01)

参考文献数

15

---

We report a single-layer frequency selective dual band reflectarray operated at 28 and 39GHz simultaneously. The reflectarray consists of cross dipole and spiral elements aligned on the surface of a substrate and dual band frequency selective surfaces aligned on the rear side. We aligned the cross dipole and spiral elements that can control the reflection direction at 28 and 39GHz aligned on the same plane of the substrate, resulting in a simultaneous dual-band control of the reflection direction up to ±30° independently. Furthermore, the dual band reflectarray showed higher transmittance at frequencies except for the target frequencies, indicating the reflectarray function only at 28 and 39GHz and does not interfere with the other communication bands.

著者

Maki Arai Takana Kaho

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.12, no.2, pp.48-53, 2023-02-01 (Released:2023-02-01)

参考文献数

14

---

In this paper, we describe a novel 3-D Luneburg lens using radial holes. A Luneburg lens can suppress the side lobe of the antenna and increase the gain. The prototype Luneburg lens was fabricated using a 30mm radius dielectric sphere with uniform permittivity by 2.1 and many holes by 1mm radius, called radial holes drilled vertically on the sphere surface. The relative permittivity distribution of the Luneburg lens is realized by changing the number and depth of five types of holes. To confirm the effectiveness of the fabricated Luneburg lens, the far-field radiation pattern at 25GHz was measured using a flanged rectangular waveguide as a wave source. It achieved a high gain of 22.4dBi. The measured radiation pattern generally agreed well with the theoretical radiation pattern of the Luneburg lens, and the validity of the Luneburg lens with radial holes at the quasi-millimeter wave was confirmed. It can be used for beam steering in 5G/6G base stations.

著者

Baud Haryo Prananto Iskandar Adit Kurniawan

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.12, no.1, pp.19-23, 2023-01-01 (Released:2023-01-01)

参考文献数

4

---

Handover is very crucial in cellular communication since it may interrupt data transmission. The traditional handover algorithm works well in ideal conditions, but it may fail in certain conditions such as coverage holes. In this letter, we present our simulation to improve handover performance using machine learning. We implement and perform novel modifications on Near-RT RIC, a new network element by O-RAN, to solve the target cell decision problem using a machine learning algorithm in a network with a coverage hole. We show that this solution is proven superior to the traditional handover algorithm.

著者

Tateki Kato Hiroyoshi Yamada Hiroki Mori

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.11, no.12, pp.760-765, 2022-12-01 (Released:2022-12-01)

参考文献数

6

---

Achieving high-resolution 2-dimentional (2D) or 3-dimentional (3D) imaging with millimeter-wave radar requires a large number of antenna elements. Synthetic aperture radar (SAR) is commonly used to achieve high-resolution imaging. However, SAR usually requires long observation time due to mechanical scanning. In this study, we have developed a prototype high-resolution millimeter-wave MIMO (Multiple-Input Multiple-Output) radar with non-uniform planar arrays for both transmitter and receiver. We achieved high-resolution 3D imaging by applying virtual array processing to the received data. In this report, we provide the spatial resolution evaluation of the prototype millimeter-wave non-uniform 2D-MIMO radar by experiments.

著者

Shun Igarashi Daisuke Miyawaki Suguru Yamagishi Ichiro Kuwayama Kengo Iokibe Yoshitaka Toyota

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.11, no.11, pp.691-696, 2022-11-01 (Released:2022-11-01)

参考文献数

4

---

This paper examines the possibility of an electromagnetic interference (EMI) caused by unintentional radiated emissions from an unshielded twisted pair (UTP) cable in the sub-6GHz band of 5G. First, it is experimentally and numerically confirmed that a UTP cable with a twist pitch of 20mm and a sheath with relative permittivity of 2.9 radiates above 5.7GHz. It is also clarified that the radiated emissions are attributable to the twist structure. In addition, the usefulness of two equations, derived in developing radiating pair cables, to easily calculate the radiation band and the radiation angle to solve the EMI problem is validated.

著者

Takanobu Watanabe Kentaro Nishimori Riku Okada

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.11, no.10, pp.619-624, 2022-10-01 (Released:2022-10-01)

参考文献数

6

---

Recently, microwave and millimeter-wave bands have been considered for outdoor applications to cope with the emerging increase in communication traffic. However, a higher the frequency causes larger propagation losses. Consequently, a system that uses UAVs as relay stations to communicate in a line-of-sight (LoS) environment has been studied. In such a system, the numbers of transmitting and receiving antenna elements are different. In this study, we evaluate the performance of an asymmetric LoS-MIMO system with different number of antenna elements for transmission and reception. The effectiveness of the asymmetric LoS-MIMO system is demonstrated by comparing the channel capacity pertaining to the distance between the transmitter and receiver based on a conventional symmetric LoS-MIMO system with an equal number of antenna elements.

著者

Keiji Wada Yukihisa Suzuki Akira Ushiyama Shin Ohtani Kenji Hattori Atsushi Saito Satoshi Nakasono Satoshi Miyawaki Takashi Yanagisawa Yoshiya Ohnuma

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.11, no.10, pp.661-666, 2022-10-01 (Released:2022-10-01)

参考文献数

7

---

This letter presents development of a magnetic field generator to evaluation of biological effects. The magnetic field generator has a frequency bandwidth of 85 kHz because it is intended for wireless power supply for electric vehicles. Furthermore, the generator is designed to operate for only one second, and can produce the induced magnetic field of 10 times compared to basic restrictions of the ICNIRP. By applying the magnetic field generator, it is possible to conduct a evaluation and verification of biological effect depending on electromagnetic fields for WPT systems of electric vehicles.

著者

Ryoga Kawabata Syota Nakamaru Kunihisa Jitsuno Keizo Inagaki Tetsuya Kawanishi

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.11, no.9, pp.555-559, 2022-09-01 (Released:2022-09-01)

参考文献数

5

---

In this study, we evaluated the relationship between the time variability of the transmission characteristics of multimode fiber (MMF) and laser linewidth. By varying the laser linewidth from 0.1kHz to 1.89THz, it is possible to grasp the tendency over a wide range, from narrow to ultra-wide linewidth. We were able to confirm that the time-varying characteristics of the frequency characteristics, which affect the MMF transmission characteristics, depend on the laser linewidth and time variability decreases with an increasing laser linewidth.

著者

Katsumi Fujii

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

pp.2022XBL0127, (Released:2022-09-05)

---

Before performing electromagnetic interference (EMI) measurement tests in the frequency range below 30 MHz, the test site must be evaluated by normalized site insertion loss (NSIL) using a pair of loop antennas. The site insertion loss measurements are performed with three arrangements of loop antennas to measure three-axis components of magnetic fields in the near-field regions. In this paper, it is shown that the locations of the feed gaps on the loop antenna elements change the values of the SIL. The preferable locations of the feed gaps are proposed to perform the NSIL measurements with the measurement results in a semi-anechoic chamber.

著者

Takumi Wada Haruhisa Ichikawa Shinji Yokogawa Yoshito Tobe Yuusuke Kawakita

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.11, no.8, pp.468-473, 2022-08-01 (Released:2022-08-01)

参考文献数

6

---

The study presents a “virtual grid system” currently being developed by the authors. The system consists of a power supply, load, and virtual grid hub (VG-Hub) network connecting them. The VG-Hub network must have a large power distribution capability. Therefore, the challenge is to obtain a graph to evaluate the maximum feasible flow when multiple VG-Hubs are connected to a power source or load. In this paper, we propose a method for generating a graph to derive the maximum feasible flow. A quantitative evaluation of the proposed method is presented.

著者

The Hop Hoang Tzyh-Ghuang Ma Huy Nam Chu

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.11, no.6, pp.290-295, 2022-06-01 (Released:2022-06-01)

参考文献数

6

---

In this paper, a broadband tunable power divider (TPD), whose power division ratio (PDR) can be theoretically tuned from -∞ to +∞, is proposed. The new design is based on a Wilkinson power divider, a branch line coupler, and a new combination of phase reconfigurable synthesized transmission lines (PRSTLs) that comprises varactor diodes as the phase shifters (PSs). The operating principles and design equations will be provided with thorough discussion. For proof-of-concept demonstration, a prototype was designed at 2.4GHz. The performance in the measurement is summarized as follows: the operating bandwidth = 25% (2.1GHz-2.7GHz), very wide PDR tuning range of ±29dB, maximum insertion loss = 1.6dB, and switchable output phase of 0° or 180°.

著者

Minoru ASANO Shinji YOKOGAWA Haruhisa Ichikawa

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

pp.2022XBL0066, (Released:2022-05-10)

---

Autonomous distributed power grids have attracted attention as a way to utilize renewable energy to achieve a carbon-neutral society. In order to properly operate these grids, it is necessary to obtain sufficient information on the supply and demand power capabilities and battery health of connected devices in a short time. In addition, methods based on direct current are essential to maximizing the use of renewable energy. This study proposes a method for acquiring information about the energy storage of devices connected to the grid via USB power delivery using deep learning techniques. Furthermore, we propose a method to diagnose the embedded battery health of the device based on short-time monitoring.

著者

Yasushi Yuminaka Keigo Taya Yosuke Iijima

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.9, no.10, pp.464-469, 2020-10-01 (Released:2020-10-01)

参考文献数

7

被引用文献数

2

---

Four-level pulse amplitude modulation (PAM-4) data formats are adopted to achieve next-generation high-speed data transmission standards. In this letter, a novel eye-opening monitoring technique based on machine learning is proposed to evaluate the received signal quality for the adaptive coefficients setting of a transmitter feed-forward equalizer for PAM-4 signaling. The monitoring technique employs a Gaussian mixture model (GMM) to classify the received PAM-4 symbols. Simulation and measured results of the coefficient adjustment using the GMM method are presented.

著者

Takaharu Yamanaka Takanori Iwai Ryogo Kubo

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.10, no.6, pp.301-306, 2021-06-01 (Released:2021-06-01)

参考文献数

8

---

In networked control systems, the quality of performance (QoP), such as in terms of consistent tracking errors, must be maintained at a constant level. A QoP-aware sleep mechanism in network interfaces can reduce the amount of traffic or the communication rate while maintaining the QoP. However, in a QoP-aware sleep mechanism with a fixed sleep period, the sleep period cannot be entered effectively when the length of the steady-state period is changed; e.g., when the command frequency is changed. This study proposes a variable sleep period control method to reduce the communication rate while adapting to the tracking error. The simulations confirm that, when compared to methods with a fixed sleep period, the proposed method reduces the communication rate regardless of the command frequency.

著者

Song-Ju Kim Hiroyuki Yasuda Ryoma Kitagawa Mikio Hasegawa

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

pp.2021XBL0165, (Released:2021-10-01)

---

We propose a simple channel-allocation method based on tug-of-war (TOW) dynamics, combined with the time scheduling based on nonlinear oscillator synchronization to efficiently use of the space (channel) and time resources in wireless communications. This study demonstrates that synchronization groups, where each node selects a different channel, are non-uniformly distributed in phase space such that every distance between groups is larger than the area of influence. New type of self-organized spatiotemporal patterns can be formed for resource allocation according to channel rewards.

著者

Nobutaka Funaki Kazuki Maruta Chang-Jun Ahn

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.10, no.6, pp.324-330, 2021-06-01 (Released:2021-06-01)

参考文献数

6

被引用文献数

1

---

This letter proposes adaptive null-space expansion (NSE) for multiuser massive MIMO according to users’ mobility. NSE can improve the robustness of multi-user spatial multiplexing in a time-varying channel by expanding null-steering to multiple past channels. Its superiority was verified under the unified moving speed among users. In a realistic environment, users with different speeds coexist. Null-space dimension, which is the number of nullified channels per user terminal, should be optimized in accordance with users’ mobility so as to maximize the beamforming gain and nullification capability. In our proposal, we first show that user mobility can be classified by observing the singular value of time-varying channels. Computer simulation then clarifies that output SINR can be improved by assigning null space dimensions respective to user moving speeds.

著者

Kamiyama Noriaki Hosokawa Yutaro

出版者

一般社団法人 電子情報通信学会

雑誌

IEICE Communications Express

巻号頁・発行日

vol.8, no.8, pp.318-322, 2019

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<p>Using virtualized CDN such as Amazon CloudFront in which cache servers are provided on virtual machines, content providers can flexibly select the regions of using cache servers according to the geographical demand pattern of their users, so they can expect to reduce the cost of using CDN. However, to maximize the profit of content providers, they need to carefully select the locations of cache servers which affect the quality perceived by users as well as the total cost. We propose a method of optimally selecting the geographical regions to use cache servers maximizing the profit of content providers.</p>

著者

Keita Onose Hiroto Kuriki Ryota Kimura Ryo Sawai

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

pp.2021ETL0037, (Released:2021-03-29)

---

In this letter, we propose an advanced incumbent protection method that considers three-dimensional aspects of 5G New Radio (NR) beamforming for dynamic spectrum access (DSA). The proposed method further introduces a concept of area-based protection to satisfy protection criteria for a primary system (PS) with inaccurate location information. We show some computer simulation results for deploying a 5G based secondary system (SS) in a millimeter-wave band which is primarily assigned to a fixed wireless access (FWA) based PS. The results demonstrate that the proposed method increases allowable transmission powers of the SS by up to 15 dB, compared to a conventional method.

著者

Yasumasa Naka Masaya Tamura

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.9, no.10, pp.457-463, 2020-10-01 (Released:2020-10-01)

参考文献数

8

被引用文献数

1

---

Capacitive wireless power transfer is performed using large electrodes or using a medium having high relative permittivity such as water. The transfer efficiency demonstrates a pronounced change with frequency. A lumped-constant equivalent circuit with parasitic elements represents the change. However, a relationship between conditions for generating minimum/maximum values of the transfer efficiency and structural parameters of the electrodes in the coupler has not clarified. In this study, an equivalent circuit is proposed using a distributed-constant circuit. We converted the lumped-constant circuit into two open-ended directional couplers. From the result, we derived the conditions for generating the minimum and maximum values of the voltage input/output ratio. The efficiencies calculated by the distributed-constant circuit and electromagnetic simulation were in good agreement.