著者

Yuki Arikawa Hiroyuki Uzawa Takeshi Sakamoto Satoshi Shigematsu Shunji Kimura

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.6, no.5, pp.236-241, 2017 (Released:2017-05-01)

参考文献数

6

被引用文献数

1 4

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This paper presents a high-speed radio-resource scheduler that accelerates the scheduling process of fifth-generation mobile communications systems (5G). A scheduler for 5G systems will have to decide the optimal combination of an antenna and user equipment for efficient communications from a huge number of possible combinations. The reported scheduler with a hardware accelerator performs several high-speed searches to find the optimal combination. Experimental results show that it executes several search methods 40 times faster than a scheduler without acceleration. It improves the system throughput and will enable a practical 5G system to be developed.

著者

Zhengqiang Tang Shintaro Arai Tomohiro Yendo Di He Takaya Yamazato

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.2020XBL0058, (Released:2020-05-18)

被引用文献数

6

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In this study, the sequential maximum likelihood decoding (S-MLD) for image sensor based visible light communication, referred to as image sensor communication, is proposed. The conventional system cannot correctly decode degraded captured images. To overcome this problem, S-MLD partitions the LED area on the image into two segments and sequentially creates pseudo-captured images, which imitate all possible LED blinking patterns. This approach is based on MLD for each segment. Moreover, reliability determination is incorporated to improve communication quality. We performed computer simulations and confirmed that S-MLD exhibits superior decoding performance and approximately 90% computational cost reduction compared to the previous MLD.

著者

Jun Kurihara Toru Nakamura

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.2020XBL0055, (Released:2020-05-11)

被引用文献数

1

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In private information retrieval (PIR) from coded storage servers, consider the case where some of servers are Byzantine adversaries and unresponsive. There have been proposed several specialized schemes guaranteeing that the user can correctly obtain the desired message even in the adversarial situation. However, to the best of our knowledge, such resistance to the adversaries in PIR schemes based on arbitrary codes have been not precisely characterized. In this paper, we reveal that the exact resistance to Byzantine and unresponsive servers is expressed in terms of the coset distance of linear codes in linear PIR schemes based on arbitrary storage code.

著者

Naozumi Ando Kazuma Tomimoto Ryo Yamaguchi Mitoshi Fujimoto

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.2, pp.31-35, 2020 (Released:2020-02-01)

参考文献数

5

被引用文献数

2

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Generally, maximum Doppler frequency can be derived from velocity of moving vehicle. However, frequency shifts beyond the maximum Doppler frequency are observed in actual measurement. In this paper, Doppler shift is calculated in consideration with the shift caused by other moving vehicles. Numerical results show that the actual measured Doppler shift can be reproduced with high accuracy by considering the frequency shift at the other moving vehicles.

著者

Katsuya Senoo Kazuki Maruta Takatoshi Sugiyama 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.9, no.1, pp.13-18, 2020 (Released:2020-01-01)

参考文献数

6

被引用文献数

2

---

In order to achieve high-speed and large-capacity communication, efficient use of frequency resources even over different wireless communication systems is an important issue. We previously proposed the spectrum superposing scheme using subcarrier transmission power assignment (STPA) and blind adaptive array (BAA). Even when multiple systems use the same frequency band, the secondary system enables the both receivers to mitigate inter-system interference by STPA-BAA. However, STPA-BAA has a problem that the operational region of the secondary system is limited due to low-level subcarriers. This paper attempts to resolve this issue by introducing subcarrier modulation adaptation. It can effectively expand the operational region of our proposed approach even in the low signal-to-noise-power-ratio (SNR) situation.

著者

Shohei Yamamoto Ken Mishina Akihiro Maruta

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.8, no.12, pp.507-512, 2019 (Released:2019-12-01)

参考文献数

14

被引用文献数

9

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Eigenvalue communication is a promising technology that can overcome capacity limitations caused by the Kerr nonlinearity in optical fibers. In this letter, we propose an artificial neural network-based demodulation method for optical eigenvalue-modulated signals using on-off encoding. The proposed method has a power margin improvement of 9.2 dB at the bit error rate of 3.8 × 10−3 compared with the conventional inverse scattering transform-based demodulation method in numerical simulations.

著者

Yuta Katori Shinji Isogami Tsunehiro Hato Akira Tsukamoto Keiichi Tanabe Nobuhito Ohnishi Chikara Furukawa Kan Okubo

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.7, no.3, pp.71-76, 2018 (Released:2018-03-01)

参考文献数

9

被引用文献数

1

---

Our research group reported successful observation of “co-faulting” Earth’s magnetic field changes because of piezomagnetic effects caused by earthquake tremors during the 2008 Iwate-Miyagi Nairiku earthquake of M7.2 using a geomagnetic observation system with flux-gate magnetometers. This is an important finding: electromagnetic fields propagate from a source to an observation site at the light speed in the crustal materials. Further earthquake detection efforts can lead us to a new system for super-early warning of earthquake detection with the geomagnetic signal. However, the observed result with the earthquake was suggested that the geomagnetic field change accompanying fault movement, whose sources are the piezomagnetic effects, is very small and short term. Therefore, to develop an extremely important high-resolution magnetometer system, we first conducted long-term precise geomagnetic observations using a high-temperature superconductor based superconducting quantum-interference device (HTS-SQUID) magnetometer system. The HTS-SQUID magnetometer system had never been used for high-resolution geomagnetic observations outdoors. Since March 2012, we have observed geomagnetic field using the HTS-SQUID magnetometer at Iwaki observation site (IWK) in Fukushima, Japan. Comparison between the introduced HTS-SQUID magnetometer and conventional flux-gate clarified that the HTS-SQUID magnetometer in our system has higher resolution of magnetic field observation.

著者

Kotaro Matsuoka Yasutomo Yushima Ryo Hayakawa Riho Kawasaki Kazunori Hayashi Megumi Kaneko

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.5, no.5, pp.118-123, 2016 (Released:2016-05-01)

参考文献数

9

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This paper proposes a tag identification protocol built upon Boolean compressed sensing (CS) for radio frequency identification (RFID) systems. Unlike the conventional CS-based tag identification (CS-ID) protocol, the proposed protocol can cope with flat fading channels without explicit channel estimation. Simulation results show that the proposed scheme requires less amount of bits for successful identification than dynamic framed slotted ALOHA (DFSA) protocol, and that it even outperforms the conventional CS-ID protocol with perfect channel information.

著者

Yuta Seki Fumiyuki Adachi

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.2018XBL0028, (Released:2018-03-22)

被引用文献数

1

---

In this paper, we propose an adaptive minimum mean square error filtering combined with singular value decomposition (MMSE-SVD) for OFDM downlink multi-user multi-input multi-output (MU-MIMO) transmission. During data transmission, base station (BS) updates the multi-user MMSE transmit filter by using linear channel prediction, while user equipments (UEs) update their eigenmode receive filters, constructed by SVD, by using decision feedback adaptive channel estimation. The uncoded BER performance achievable by adaptive MMSE-SVD is evaluated by computer simulation. It is shown that proposed adaptive MMSE-SVD can increase an allowable maximum Doppler frequency (fDT) for keeping BER<10-2 by about 4 times.

著者

Isao Nakazawa Ken Umeno

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.6, no.12, pp.673-678, 2017 (Released:2017-12-01)

参考文献数

5

被引用文献数

2

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In this paper, we investigate the almost periodic frequency arrangement (APFA) asynchronous system for super-multi-access radio systems, and APFA configuration procedure on a frequency domain multiplex scheme by using almost periodic function (APF). We report on the relationship between the total number of prime numbers, the number of sub-carriers, and the normalized frequency standard deviation for a system with up to one million users. By using computer simulations, we show the multi-carrier modulation and asynchronous demodulation based on APFA, in which ICI interference by nonlinear elements is improved compared with the orthogonal frequency-division multiplexing (OFDM).

著者

Ken T. Murata Hidenobu Watanabe Kazunori Yamamoto Eizen Kimura Masahiro Tanaka Osamu Tatebe Kentaro Ukawa Kazuya Muranaga Yutaka Suzuki Hirotsugu Kojima

出版者

(社)電子情報通信学会

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.3, no.2, pp.74-79, 2014-02-25 (Released:2014-02-25)

参考文献数

6

被引用文献数

4 7

---

A variety of satellite missions are carried out every year. Most of the satellites yield big data, and high-performance data processing technologies are expected. We have been developing a cloud system (the NICT Science Cloud) for big data analyses of Earth and Space observations via spacecraft. In the present study, we propose a new technique to process big data considering the fact that high-speed I/O (data file read and write) is important compared with data processing speed. We adopt a task scheduler, the Pwrake, for easy development and management of parallel data processing. Using a set of long-time scientific satellite observation data (GEOTAIL satellite), we examine the performance of the system on the NICT Science Cloud. We successfully archived high-speed data processing more than 100 times faster than those on traditional data processing environments.

著者

Ryutaroh Matsumoto

出版者

(社)電子情報通信学会

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.2, no.8, pp.343-346, 2013-08-15 (Released:2013-08-15)

参考文献数

5

被引用文献数

4

---

We propose a Gilbert-Varshamov-type existential bound for the relative dimension length profile and the relative generalized Hamming weight of nested pairs of linear codes.

著者

Masanori Shinriki Hiroshi Takase

出版者

(社)電子情報通信学会

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.1, no.5, pp.165-170, 2012-10-16 (Released:2012-10-16)

参考文献数

4

---

Binary codes for a multi-range-resolution radar are proposed. Inverse filters can be then used for a multi-range resolution radar and compress the proposed codes to different pulse widths. These binary codes are compressed to several sub-pulses, only if a matched filter is applied. We describe that the compressed pulses have very small pulse compression losses and side-lobe amplitudes, even though the binary codes are compressed to the pulse width smaller than the reciprocal of the bandwidth of the codes. This fact is confirmed by computer calculations.

著者

Yohei Sakamaki Takeshi Kawai Tomoyoshi Kataoka Mitsunori Fukutoku

出版者

(社)電子情報通信学会

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.2, no.4, pp.148-153, 2013-04-15 (Released:2013-04-15)

参考文献数

8

---

We propose an intra-node arrayed optical amplifier (AOA) to improve the OSNR of received signals by reducing the insertion loss of multi-degree ROADM nodes. Our AOA shares a pump laser between several EDFAs with the aim of reducing the module size and manufacturing cost compared with the size and cost when only arraying discrete EDFA modules. We confirmed the feasibility of our fabricated AOA experimentally. The experimental results show that the pump power was properly distributed to each EDFA and the OSNR of the received signals was successfully improved for 128-Gbit/s PDM-QPSK signal transmission systems.