-
Yasumasa Naka, Masaya Tamura
Article type: LETTER
Subject area: Energy in Electronics Communications
2020 Volume 9 Issue 10 Pages
457-463
Published: October 01, 2020
Released on J-STAGE: October 01, 2020
Advance online publication: July 10, 2020
JOURNAL
FREE ACCESS
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.
View full abstract
-
Yasushi Yuminaka, Keigo Taya, Yosuke Iijima
Article type: LETTER
Subject area: Transmission Systems and Transmission Equipment for Communications
2020 Volume 9 Issue 10 Pages
464-469
Published: October 01, 2020
Released on J-STAGE: October 01, 2020
Advance online publication: July 14, 2020
JOURNAL
FREE ACCESS
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.
View full abstract
-
Kazuyuki Ishida, Satoshi Yoshima, Ayano Sakamoto, Takashi Suehiro, Mas ...
Article type: LETTER
Subject area: Sensing
2020 Volume 9 Issue 10 Pages
470-475
Published: October 01, 2020
Released on J-STAGE: October 01, 2020
Advance online publication: July 27, 2020
JOURNAL
FREE ACCESS
Optical remote sensing has been greatly expanded by the construction of satellite constellations and improving the performance of the optical sensors. As the data throughput of earth observation satellites increases, photonic technology is expected to be used for the interconnections within the payload in order to reduce its overall size, mass, and power consumption, and to improve its immunity to EMI. Here, we propose an optical time division multiplexing technology for N+1 redundancy in the payload, which is able to improve reliability by reducing the number of active components in the satellites, and present a feasibility study on its transmission efficiency.
View full abstract
-
Takuma Watanabe, Hiroyoshi Yamada, Yasuyuki Oishi
Article type: LETTER
Subject area: Sensing
2020 Volume 9 Issue 10 Pages
476-481
Published: October 01, 2020
Released on J-STAGE: October 01, 2020
Advance online publication: July 27, 2020
JOURNAL
FREE ACCESS
In this letter, we present the first demonstration of the spectral domain polarimetric decomposition concept with an airborne circular synthetic aperture radar (CSAR) dataset. In CSAR systems, radar-carrying aircraft moves along a circular path that encloses the desired target area. The CSAR image contains the scattering characteristics of the target with respect to the azimuth angle, and we can retrieve it by transforming the spatial domain image into its spectral domain representation. Furthermore, the application of polarimetric decomposition to the spectral domain CSAR image provides additional information about the polarimetric scattering mechanisms. We used a publicly released airborne polarimetric CSAR dataset for the demonstration.
View full abstract
-
Takashi Ohira
Article type: LETTER
Subject area: Transmission Systems and Transmission Equipment for Communications
2020 Volume 9 Issue 10 Pages
482-488
Published: October 01, 2020
Released on J-STAGE: October 01, 2020
Advance online publication: July 31, 2020
JOURNAL
FREE ACCESS
This paper considers how a class-E amplifier behaves when the load deviates from its nominal impedance. The Kirchhoff’s law and Fourier series formulate the circuit into three simultaneous equations. These equations are decomposed into zeroth- and first-order terms to apply the perturbation technique. The zeroth-order solutions meet the zero-voltage and zero-current switching conditions. The first-order formulas express the DC current consumption, RF output amplitude and phase, equivalent output impedance, and periodic turn-on power dissipation in terms of the load resistance and reactance deviations.
View full abstract
-
Mampei Kasai, Hidekazu Murata, Toshiro Nakahira, Koichi Ishihara, Taka ...
Article type: LETTER
Subject area: Wireless Communication Technologies
2020 Volume 9 Issue 10 Pages
489-494
Published: October 01, 2020
Released on J-STAGE: October 01, 2020
Advance online publication: July 31, 2020
JOURNAL
FREE ACCESS
Terminal-collaborated multiple-input multiple-output (MIMO) reception with adaptive terminal selection schemes has been studied experimentally. In the experimental system, frequency-domain iterative MIMO equalization was employed, and its performance was evaluated by making use of recorded signal waveforms in a measurement campaign. In iterative signal processing, it is known that early stopping can control unnecessary iterations. In this letter, it is revealed that early stopping can not only reduce computational complexity, but also improve the bit error ratio performance of iterative processing. This is because early stopping prevents the iteration process from causing errors.
View full abstract
-
Kazuyuki Ishida, Satoshi Yoshima, Ayano Sakamoto, Takashi Suehiro, Mas ...
Article type: LETTER
Subject area: Satellite Communications
2020 Volume 9 Issue 10 Pages
495-500
Published: October 01, 2020
Released on J-STAGE: October 01, 2020
Advance online publication: July 31, 2020
JOURNAL
FREE ACCESS
The digital payload for next generation high throughput communication satellites is expected to reduce the operators’ CAPEX and OPEX. Photonic technologies, which have a great affinity with digital signals, have been studied in order to increase the data throughput and reduce the mass of the satellites. Here, we propose an optical time division multiplexing system for routing the signals in the digital channelizer and have conducted a feasibility study on the transmission efficiency. This system has the potential to reduce the cost, mass, and power consumption, and to improve reliability by cleaning up the switches used for routing the signals within the satellites.
View full abstract
-
Kyo Minoguchi, Toshiaki Shitaba, Tomoaki Yoshida, Jun Terada
Article type: LETTER
Subject area: Transmission Systems and Transmission Equipment for Communications
2020 Volume 9 Issue 10 Pages
501-505
Published: October 01, 2020
Released on J-STAGE: October 01, 2020
Advance online publication: August 04, 2020
JOURNAL
FREE ACCESS
We develop the first OLT-pluggable extended-loss-budget transceiver necessary for 10G/1G compatible PON with N: 1 redundant OLT protection. This paper newly define the requirement of the OLT transceiver supporting protection by assuming an additional loss of redundant function. The average output power of 6.95/8.35dBm and minimum receiver sensitivity of -32.02/-34.53dBm for 10G/1G are attained, respectively. Experiments also confirm 40-km-SMF transmission with no dispersion penalties. It achieves the 36.02/35.53-dB loss budget as 10G/1G OLT transceiver, where ONU transceiver’s specification is based on 10GBASE-PR40/1000BASE-PX40, successfully meeting required loss budget for N:1 redundant OLT protection.
View full abstract
-
Kazuya Inoue, Koichi Ichige, Tatsuya Nagao, Takahiro Hayashi
Article type: LETTER
Subject area: Antennas and Propagation
2020 Volume 9 Issue 10 Pages
506-511
Published: October 01, 2020
Released on J-STAGE: October 01, 2020
Advance online publication: August 13, 2020
JOURNAL
FREE ACCESS
In this paper, we propose a radio propagation prediction method using machine learning and building occupancy estimation. There have been learning-based researches using aerial photographs and building occupancy images as spatial information. However, the availability of building occupancy images are often limited to urban areas. We assume the situation that only the aerial photographs are available, and aim to improve radio propagation prediction accuracy by estimating building occupancy images from the given aerial photographs.
View full abstract
-
Akio Ikami, Takahiro Hayashi, Yoshiaki Amano
Article type: LETTER
Subject area: Wireless Communication Technologies
2020 Volume 9 Issue 10 Pages
512-518
Published: October 01, 2020
Released on J-STAGE: October 01, 2020
Advance online publication: August 14, 2020
JOURNAL
FREE ACCESS
For the efficient use of frequency resources, dynamic spectrum allocation (DSA) between different radio systems is promising. In DSA, our approach is to allow different mobile network operators to use the same shared channel without the inter base station (BS) interference. However, this approach is computationally very expensive. Therefore, we formulate this reuse channel allocation as a 0-1 mixed-integer linier programming problem and propose an algorithm to improve the satisfaction of each BS and the time and frequency continuities, which can be used to solve the problem in practical time. Our evaluation demonstrates that our proposed algorithm can improve the satisfaction with the time and frequency continuities simultaneously.
View full abstract