IEICE Transactions on Communications
Online ISSN : 1745-1345
Print ISSN : 0916-8516
Advance online publication
Showing 1-50 articles out of 75 articles from Advance online publication
  • Tomoki KANEKO, Noriyuki KAWANO, Yuhei NAGAO, Keishi MURAKAMI, Hiromi W ...
    Type: POSITION PAPER
    Article ID: 2019EBN0009
    Published: 2020
    [Advance publication] Released: July 01, 2020
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    This paper reports our new communication components and downlink tests for realizing 2.65 Gbps by utilizing two circular polarizations. We have developed an on-board X-band transmitter, an on-board dual circularly polarized-wave antenna, and a ground station. In the on-board transmitter, we optimized the bias conditions of GaN High Power Amplifier (HPA) to linearize AM-AM performance. We have also designed and fabricated a dual circularly polarized-wave antenna for low-crosstalk polarization multiplexing. The antenna is composed of a corrugated horn antenna and a septum-type polarizer. The antenna achieves Cross Polarization Discrimination (XPD) of 37 — 43 dB in the target X-band. We also modify an existing 10 m ground station antenna by replacing its primary radiator and adding a polarizer. We put the polarizer and Low Noise Amplifiers (LNAs) in a cryogenic chamber to reduce thermal noise. Total system noise temperature of the antenna is 58 K (maximum) for 18 K physical temperature when the angle of elevation is 90° on a fine winter day. The dual circularly polarized-wave ground station antenna has 39.0 dB/K of Gain - system-noise Temperature ratio (G/T) and an XPD higher than 37 dB. The downlinked signals are stored in a data recorder at the antenna site. Afterwards, we decoded the signals by using our non-real-time software demodulator. Our system has high frequency efficiency with a roll-off factor α = 0.05 and polarization multiplexing of 64APSK. The communication bits per hertz corresponds to 8.41 bit/Hz (2.65 Gbit / 315 MHz). The system is demonstrated in orbit on board the RAPid Innovative payload demonstration Satellite (RAPIS-1). RAPIS-1 was launched from Uchinoura Space Center on January 19th, 2019. We decoded 1010 bits of downlinked Rand L-channel signals and found that the downlinked binary data was error free. Consequently, we have achieved 2.65 Gbps communication speed in the X-band for earth observation satellites at 300 Mega symbols per second (Msps) and polarization multiplexing of 64APSK (coding rate : 4/5) for right- and left- hand circular polarizations.

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  • Hiraku OKADA
    Type: INVITED PAPER
    Article ID: 2020SEI0001
    Published: 2020
    [Advance publication] Released: July 01, 2020
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    In emergency communication systems research, aerial wireless relay networks (AWRNs) using multicopter unmanned aerial vehicles (UAVs) have been proposed. The main issue of the AWRNs is how to minimize the delay time of packet transmissions since it is not easy to supply many multicopters to cover a wide area. In this paper, we review the flight schemes and their delay time for the AWRNs. Furthermore, the network has specific issues such as multicopters' drops due to their battery capacity depletion and inclination of moving multicopters. The inclination of multicopters affects the received power, and the communication range changes based on the inclination as well. Therefore, we clarify the effect of these issues on the delay time.

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  • Huan SUN, Yuchun GUO, Yishuai CHEN, Bin CHEN
    Type: PAPER
    Article ID: 2020SEP0002
    Published: 2020
    [Advance publication] Released: July 01, 2020
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    Recently, the ECG-based diagnosis system based on wearable devices has attracted more and more attention of researchers. Existing studies have achieved high classification accuracy by using deep neural networks (DNNs), but there are still some problems, such as: imprecise heart beat segmentation, inadequate use of medical knowledge, the same treatment of features with different importance. To address these problems, this paper: 1) proposes an adaptive segmenting-reshaping method to acquire abundant useful samples; 2) builds a set of hand-crafted features and deep features on the inner-beat, beat and inter-beat scale by integrating enough medical knowledge. 3) introduced a modified channel attention module (CAM) to augment the significant channels in deep features. Following the Association for Advancement of Medical Instrumentation (AAMI) recommendation, we classified the dataset into four classes and validated our algorithm on the MIT-BIH database. Experiments showthat the accuracy of our model reaches 96.94%, a 3.71% increase over that of a state-of-the-art alternative.

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  • Hiroshi SAITO, Tatsuki OTAKE, Hayato KATO, Masayuki TOKUTAKE, Shogo SE ...
    Type: PAPER
    Article ID: 2020SEP0004
    Published: 2020
    [Advance publication] Released: July 01, 2020
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    Since wild animals are causing more accidents and damages, it is important to safely detect them as early as possible. In this paper, we propose two battery-powered wild animal detection nodes based on deep learning that can automatically detect wild animals; the detection information is notified to the people concerned immediately. To use the proposed nodes outdoors where power is not available, we devise power saving techniques for the proposed nodes. For example, deep learning is used to save power by avoiding operations when wild animals are not detected. We evaluate the operation time and the power consumption of the proposed nodes. Then, we evaluate the energy consumption of the proposed nodes. Also, we evaluate the detection range of the proposed nodes, the accuracy of deep learning, and the success rate of communication through field tests to demonstrate that the proposed nodes can be used to detect wild animals outdoors.

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  • Riichi Kudo, Matthew Cochrane, Kahoko Takahashi, Takeru Inoue, Kohei M ...
    Type: PAPER
    Article ID: 2020SEP0005
    Published: 2020
    [Advance publication] Released: July 01, 2020
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    Autonomous mobility machines, such as self-driving cars, transportation robots, and automated construction machines, are promising to support or enrich human lives. To further improve such machines, they will be connected to the network via wireless links to be managed, monitored, or remotely operated. The autonomous mobility machines must have self-status based on their positioning system to safely conduct their operations without colliding with other objects. The self-status is not only essential for machine operation but also it is valuable for wireless link quality management. This paper presents self-status-based wireless link quality prediction and evaluates its performance by using a prototype mobility robot combined with a wireless LAN system. The developed robot has functions to measure the throughput and receive signal strength indication and obtain self-status details such as location, direction, and odometry data. Prediction performance is evaluated in offline processing by using the dataset gathered in an indoor experiment. The experiments clarified that, in the 5.6 GHz band, link quality prediction using self-status of the robot forecasted the throughput several seconds into the future, and the prediction accuracies were investigated as dependent on time window size of the target throughput, bandwidth, and frequency gap.

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  • Quan TIAN, Tianshuang QIU, Jitong MA, Jingchun LI, Rong LI
    Type: PAPER
    Article ID: 2019EBP3016
    Published: 2020
    [Advance publication] Released: June 29, 2020
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    In array signal processing, many methods of handling cases of impulsive noise with an alpha-stable distribution have been studied. By introducing correntropy with a robust statistical property, this paper proposes a novel fractional lower order correntropy (FLOCR) method. The FLOCR-based estimator for array outputs is defined and applied with multiple signal classification (MUSIC) to estimate the direction of arrival (DOA) in alpha-stable distributed noise environments. Comprehensive Monte Carlo simulation results demonstrate that FLOCR-MUSIC outperforms existing algorithms in terms of root mean square error (RMSE) and the probability of resolution, especially in the presence of highly impulsive noise.

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  • Lijun GAO, Feng LIN, Maode MA
    Type: PAPER
    Article ID: 2020EBP3022
    Published: 2020
    [Advance publication] Released: June 29, 2020
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    In recent years, with the continuous development of the Internet of Things, radio frequency identification (RFID) technology has also been widely concerned. The computing power of low cost tags is limited because of their high hardware requirements. Symmetric encryption algorithms and asymmetric encryption algorithms, such as RSA, DES, AES, etc., cannot be suitable for low cost RFID protocols. Therefore, research on RFID security authentication protocols with low cost and high security has become a focus. Recently, an ultralightweight RFID authentication protocol LP2UF was proposed to provide security and prevent all possible attacks. However, it is discovered that a type of desynchronization attack can successfully break the proposed scheme. To overcome the vulnerability against desynchronization attacks, we propose here a new ultra-lightweight RFID two-way authentication protocol based on stream cipher technology that uses only XOR. The stream cipher is employed to ensure security between readers and tags. Analysis shows that our protocol can effectively resist position tracking attacks, desynchronization attacks, and replay attacks.

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  • Changsheng Yin, Ruopeng Yang, Wei Zhu, Xiaofei Zou, Junda Zhang
    Type: PAPER
    Article ID: 2020EBP3061
    Published: 2020
    [Advance publication] Released: June 29, 2020
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    Aiming at the problems of traditional algorithms that require high prior knowledge and weak timeliness, this paper proposes an emergency communication network topology planning method based on deep reinforcement learning. Based on the characteristics of the emergency communication network, and drawing on chess, we map the node layout and topology planning problems in the network planning to chess game problems; The two factors of network coverage and connectivity are considered to construct the evaluation criteria for network planning; The method of combining Monte Carlo tree search and self game is used to realize network planning sample data generation, and the network planning strategy network and value network structure based on residual network are designed. On this basis, the model was constructed and trained based on Tensorflow library. Simulation results show that the proposed planning method can effectively implement intelligent planning of network topology, and has excellent timeliness and feasibility

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  • Jedok Kim, Jangyong Ahn, Sungryul Huh, Kibeom Kim, Seungyoung Ahn
    Type: INVITED PAPER
    Article ID: 2019MCI0001
    Published: 2020
    [Advance publication] Released: June 26, 2020
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    This paper proposes a single coil active shielding method of wireless unmanned aerial vehicle charger for leakage magnetic field reduction. A proposed shielding system eliminates the leakage magnetic field generated from the transmitting and receiving coils by generating the cancelling magnetic field. In order to enhance shielding effectiveness and preserve power transfer efficiency, shielding coil design parameters including radius and turns will analyze. Based on the analysis of coil design, shielding effectiveness and power transfer efficiency will estimate. In addition, shielding current control method corresponding to leakage magnetic field strength and phase will describe. A proposed shielding system has verified by simulations and experiments in terms of the total shielding effectiveness and power transfer efficiency measurements. The simulation and experimental results show that a proposed active shielding system has achieved 68.85% of average leakage magnetic field reduction with 1.92% of power transfer efficiency degradation. The shielding effectiveness and power transfer efficiency variation by coil design has been experimentally verified.

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  • Shigeru KOZONO, Yuya TASHIRO, Yuuki KANEMIYO, Hiroaki NAKABAYASHI
    Type: PAPER
    Article ID: 2019EBP3171
    Published: 2020
    [Advance publication] Released: June 22, 2020
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    In a multiple-user MIMO system in which numerous users simultaneously communicate in a cell, the channel matrix properties depend on the parameters of the individual users in such a way that they can be modeled as points randomly moving within the cell. Although these properties can be simulated by computer, they need to be expressed analytically to develop MIMO systems with diversity. Given a small area with an equivalent multi-path, we assume that a user u is at a certain “user point” Puupup) in a cell, or (radius λup from origin, angle ξup) and that the user moves with movement Muumaxuv) around that point, or (Doppler frequency ƒumax, direction ξuv). The MU-MIMO channel model consists of a multipath environment, user parameters, and antenna configuration. A general formula of the correlation ρu-u'i-j,i'-j' (bm) between the channel matrix elements of users u and u' and one for given multipath conditions are derived. As a feature of the MU-MIMO channel, the movement factor Fu-u'un, ξuv), which means a fall coefficient of the spatial correlation calculated from only the user points of u and u', is also derived. As the difference in speed or direction between u and u' increases,Fu-u'un, ξuv) becomes smaller. Consequently, even if the path is LOS, ρu-u'i-j,i'-j' (bm) becomes low enough owing to the movement factor, even though the correlation in the single-user MIMO channel is high. If the parameters of u and u' are the same, the factor equals 1, and the channels correspond to the users' own channels and work like SU-MIMO channel. These analytical findings are verified by computer simulation.

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  • Shusuke NARIEDA, Daiki CHO, Hiromichi OGASAWARA, Kenta UMEBAYASHI, Tak ...
    Type: PAPER
    Article ID: 2019EBP3175
    Published: 2020
    [Advance publication] Released: June 22, 2020
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    This paper provides theoretical analyses for maximum cyclic autocorrelation selection (MCAS)-based spectrum sensing techniques in cognitive radio networks. The MCAS-based spectrum sensing techniques are low computational complexity spectrum sensing in comparison with some cyclostationary detection. However, MCAS-based spectrum sensing characteristics have never been theoretically derived. In this study, we derive closed form solutions for signal detection probability and false alarm probability for MCAS-based spectrum sensing. The theoretical values are compared with numerical examples, and the values match well with each other.

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  • Nozomi HAGA, Jerdvisanop CHAKAROTHAI, Keisuke KONNO
    Type: PAPER
    Article ID: 2019EBP3211
    Published: 2020
    [Advance publication] Released: June 22, 2020
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    The impedance expansion method (IEM) is a circuitmodeling technique for electrically small devices based on the method of moments. In a previous study, a circuit model of a wireless power transfer (WPT) system was developed by utilizing the IEM and eigenmode analysis. However, this technique assumes that all the coupling elements (e.g., feeding loops and resonant coils) are in the absence of neighboring scatters (e.g., bodies of vehicles). This study extends the theory of the IEM to obtain the circuit model of a WPT system in the vicinity of a perfectly conducting scatterer (PCS). The numerical results show that the proposed method can be applied to the frequencies at which the dimension of the PCS is less than approximately a quarter wavelength. In addition, the yielded circuit model is found to be valid at the operating frequency band.

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  • Xiaoxin QI, Bing ZHANG, Zhiliang QIU
    Type: PAPER
    Article ID: 2020EBP3016
    Published: 2020
    [Advance publication] Released: June 22, 2020
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    Low Earth Orbit (LEO) satellite networks serve as a powerful complement to the terrestrial networks because of their ability to provide global coverage. In LEO satellite networks, the network is prone to congestion due to several reasons. First, the terrestrial gateways are usually located within a limited region leading to congestion of the nodes near the gateways. Second, routing algorithms that merely adopt shortest paths fail to distribute the traffic uniformly in the network. Finally, the traffic input may exceed the network capacity. Therefore, rate control and load-balancing routing are needed to alleviate network congestion. Moreover, different kinds of traffic have different Quality of Service (QoS) requirements which need to be treated appropriately. In this paper, we investigate joint rate control and load-balancing routing in LEO satellite networks to tackle the problem of network congestion while considering the QoS requirements of different traffic. The joint rate control and routing problem is formulated with the throughput and end-to-end delay requirements of the traffic taken into consideration. Two routing schemes are considered which differ in whether or not different traffic classes can be assigned different paths. For each routing scheme, the joint rate control and routing problem is formulated. A heuristic algorithm based on simulated annealing is proposed to solve the problems. Besides, a snapshot division method is proposed to increase the connectivity of the network and reduce the number of snapshots by merging the links between satellites and gateways. The simulation results show that compared with methods that perform routing and rate control separately, the proposed algorithm improves the overall throughput of the network and provides better QoS guarantees for different traffic classes.

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  • Xue NI, Huali WANG, Ying ZHU, Fan MENG
    Type: PAPER
    Article ID: 2019EBP3262
    Published: 2020
    [Advance publication] Released: June 15, 2020
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    Low Probability of Intercept (LPI) radar waveform has complex and diverse modulation schemes ,which cannot be easily identified by the traditional methods. The research on intrapulse modulation LPI radar waveform recognition has received increasing attention. In this paper, we propose an automatic LPI radar waveform recognition algorithm that uses a multiresolution fusion convolutional neural network. First, signals embedded within the noise are processed using Choi-William Distribution (CWD) to obtain time-frequency feature images. Then, the images are resized by interpolation and sent to the proposed network for training and identification. The network takes a dual-channel CNN structure to obtain features at different resolutions and makes features fusion by using the concatenation and Inception module. Extensive simulations are carried out on twelve types of LPI radar waveforms, including BPSK, Costas, Frank, LFM, P1∼P4, and T1∼T4, corrupted with additive white Gaussian noise of SNR from 10dB to -8dB. The results show that the overall recognition rate of the proposed algorithm reaches 95.1% when the SNR is -6dB. We also try various sample selection methods related to the recognition task of the system. The conclusion is that reducing the samples with SNR above 2dB or below -8dB can eectively improve the training speed of the network while maintaining recognition accuracy.

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  • Takeshi Ishida, Osamu Fujiwara
    Type: PAPER
    Article ID: 2019EBP3191
    Published: 2020
    [Advance publication] Released: June 08, 2020
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    Air discharge immunity testing for electronic equipment is specified in the standard 61000-4-2 of the International Eelectrotechnical Commission (IEC) under the climatic conditions of temperature (T) from 15 to 35 degrees Celsius and relative humidity (RH) from 30 to 60 %. This implies that the air discharge testing is likely to provide significantly different test results due to the wide climatic range. To clarify effects of the above climatic conditions on air discharge testing, we previously measured air discharge currents from an electrostatic discharge (ESD) generator with test voltages from 2 kV to 15kV at an approach speed of 80 mm/s under 6 combinations of T and RH in the IEC specified range and non-specified climatic range. The result showed that the same absolute humidity (AH), which is determined by T and RH, provides almost the identical waveforms of the discharge currents despite different T and RH, and also that the current peaks at higher test voltages decrease as the AH increases. In this study, we further examine the combined effects of air discharges on test voltages, T, RH and AH with respect to two different approach speeds of 20 mm/s and 80 mm/s. As a result, the approach speed of 80 mm/s is confirmed to provide the same results as the previous ones under the identical climatic conditions, whereas at a test voltage of 15 kV under the IEC specified climatic conditions over 30 % RH, the 20 mm/s approach speed yields current waveforms entirely different from those at 80 mm/s despite the same AH, and the peaks are basically unaffected by the AH. Under the IEC non-specified climatic conditions with RH less than 20 %, however, the peaks decrease at higher test voltages as the AH increases. These findings obtained imply that under the same AH condition, at 80 mm/s the air discharge peak is not almost affected by the RH, while at 20 mm/s the lower the RH is, the higher is the peak on air discharge current.

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  • Yuta IDA, Takahiro MATSUMOTO, Shinya MATSUFUJI
    Type: PAPER
    Article ID: 2019EBP3216
    Published: 2020
    [Advance publication] Released: June 08, 2020
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    The spreading technique can improve system performance since it mitigates the influence of deeply faded subcarrier channels. Proposals for implementing orthogonal frequency division multiplexing (OFDM) systems include frequency symbol spreading (FSS) based on the Walsh-Hadamard transform (WHT) and the discrete Fourier transform (DFT). In a single carrier frequency division multiplexing (SC-FDMA), good performance is obtained by the interleaved subcarrier allocation. Moreover, in a multiple-input multiple-output (MIMO), interleaving the operation of the different transmit antennas is also effective. By combining these techniques, in this paper, we propose the different antenna interleaved allocation with the full and divided WHT/DFT spreading for a high time resolution carrier interferometry (HTRCI) MIMO-OFDM.

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  • Qingyuan Liu, Qi Zhang, Xiangjun Xin, Ran Gao, Qinghua Tian, Feng Tian
    Type: PAPER
    Article ID: 2019EBP3256
    Published: 2020
    [Advance publication] Released: June 08, 2020
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    This paper investigates the resource allocation problem for the downlink of non-orthogonal multiple access (NOMA) networks. A novel resource allocation method is proposed to deal with the problem of maximizing the system capacity while taking into account user fairness. Since the optimization problem is nonconvex and intractable, we adopt the idea of step-by-step optimization, decomposing it into user pairing, subchannel and power allocation subproblems. First, all users are paired according to their different channel gains. Then, the subchannel allocation is executed by the proposed subchannel section algorithm (SSA) based on channel priority. Once the subchannel allocation is fixed, to further improve the system capacity, the subchannel power allocation is implemented by the successive convex approximation (SCA) approach where the nonconvex optimization problem is transformed into the approximated convex optimization problem in each iteration. To ensure user fairness, the upper and lower bounds of the power allocation coefficients are derived and combined by introducing the tuning coefficients. The power allocation coefficients are dynamically adjustable by adjusting the tuning coefficients, thus the diversified quality of service (QoS) requirements can be satisfied. Finally, simulation results demonstrate the superiority of the proposed method over the existing methods in terms of system performance, furthermore, a good tradeoff between the system capacity and user fairness can be achieved.

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  • Yuto SAGAE, Takashi MATSUI, Taiji SAKAMOTO, Kazuhide NAKAJIMA
    Type: INVITED PAPER
    Article ID: 2019OBI0001
    Published: 2020
    [Advance publication] Released: June 08, 2020
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    We propose an ultra-low inter-core crosstalk (XT) multi-core fiber (MCF) with standard 125-μm cladding. We show the fiber design and fabrication results of an MCF housing four cores with W-shaped index profile; it offers XT of less than -67 dB/km over the whole C+L band. This enables us to realize 10,000-km transmission with negligible XT penalty. We also observe a low-loss of 0.17 dB/km (average) at a wavelength of 1.55 μm and other optical properties compatible with ITU-T G.654.B fiber. We also elucidate its good micro-bend resistance in terms of both the loss and XT to confirm its applicability to high-density optical fiber cables. Finally, we show that fabricating the MCF is feasible along with long-distance transmission by confirming the that the XT noise performance corresponds to transmission distances of 10,000 km or more.

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  • Yuki Osaka, Fumihiko Ito, Daisuke Iida, Tetsuya Manabe
    Type: PAPER
    Article ID: 2019OBP0002
    Published: 2020
    [Advance publication] Released: June 08, 2020
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    Mode-by-mode impulse responses, or spectral transfer matrix (STM) of birefringent fibers are measured by using linear optical sampling, with assist of polarization multiplexed probe pulse. By u sing the eigenvalue analysis of the STM, the differential mode delay and PMD vector of polarization maintaining fiber are analyzed as a function of optical frequency over 1 THz. We show that the amplitude averaging of the complex impulse responses is effective for enhancing the signal to noise ratio of the measurement, resulting in improving the accuracy and expanding the bandwidth of the measurement.

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  • Takaha Fujita, Kentaro Toba, Kariyawasam Indipalage Amila Sampath, Joj ...
    Type: PAPER
    Article ID: 2019OBP0008
    Published: 2020
    [Advance publication] Released: June 08, 2020
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    Impact of sampling frequency and the number of quantization bit of analog-to-digital conversion (ADC) in a direct detection lightwave system using Kramers-Kronig (KK) relation, which has been attracting attention in recent years, are numerically investigated. We studied the effect of spectral broadening caused by nonlinear operations (logarithm, square root) of the KK algorithm when the frequency gap (shift frequency) between the modulated signal and the optical tone is varied. We found that reception performances depend on both the ADC bandwidth and the relative positions of the optical tone and the spectrum. Spectral broadening caused by the logarithm operation of the KK algorithm is found to be the dominant factor of signal distortion in an ADC bandwidth limited system. We studied the effect of the number of quantization bit on the error vector magnitude (EVM) of KK relation based reception in a carrier-to-signal power ratio (CSPR) adjustable transmission system. We found that performances of KK relation based receiver can be improved by increasing the number of quantization bits. For minimum-phase-condition satisfied KK receiver, the required number of quantization bit was found to be 5 bits or more for detection of QPSK, 16-QAM and 64-QAM-modulated signal after 20-km transmission.

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  • Kazutaka HARA, Atsuko KAWAKITA, Yasutaka KIMURA, Yasuhiro SUZUKI, Sato ...
    Type: PAPER
    Article ID: 2019OBP0011
    Published: 2020
    [Advance publication] Released: June 08, 2020
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    A long-reach coexisting PON system (1G/10G-EPON, video, and TWDM-PON) that uses the Wavelength Selective Asymmetrical optical SPlitter (WS-ASP) without any active devices like optical amplifiers is proposed. The proposal can take into account the subscriber distribution in an access network and provide specific services in specific areas by varying the splitting ratios and the branch structure in the optical splitter. Simulations confirm the key features of WS-ASP, its novel process for deriving the splitting ratios and greater transmission distance than possible with symmetrical splitters. Experiments on a prototype system demonstrate how wavelengths can be assigned to specific areas and optical link budget enhancement. For 1G-EPON systems, the prototype system with splitting ratio of 60 % attains the optical link budget enhancement of 4.2 dB compared with conventional symmetrical optical splitters. The same prototype offers the optical link budget enhancement of 4.0 dB at the bit rate of 10G-EPON systems. The values measured in the experiment agree well with the simulation results with respect to the transmission distance.

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  • Ryo IGARASHI, Masamichi FUJIWARA, Takuya KANAI, Hiro SUZUKI, Jun-ichi ...
    Type: PAPER
    Article ID: 2019OBP0014
    Published: 2020
    [Advance publication] Released: June 08, 2020
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    Effective user accommodation will be more and more important in passive optical networks (PONs) in the next decade since the number of subscribers has been leveling off as well and it is becoming more difficult for network operators to keep sufficient numbers of maintenance workers. Drastically reducing the number of small-scale communication buildings while keeping the number of accommodated users is one of the most attractive solutions to meet this situation. To achieve this, we propose two types of long-reach repeater-free upstream transmission configurations for PON systems; (i) one utilizes a semiconductor optical amplifier (SOA) as a pre-amplifier and (ii) the other utilizes distributed Raman amplification (DRA) in addition to the SOA. Our simulations assuming 10G-EPON specifications and transmission experiments on a 10G-EPON prototype confirm that configuration (i) can add a 17 km trunk fiber to a normal PON system with 10 km access reach and 1:64 split (total 27 km reach), while configuration (ii) can further expand the trunk fiber distance to 37 km (total 47 km reach). Network operators can select these configurations depending on their service areas.

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  • Fukutaro Hamaoka, Takeo Sasai, Kohei Saito, Takayuki Kobayashi, Asuka ...
    Type: INVITED PAPER
    Article ID: 2019OBI0003
    Published: 2020
    [Advance publication] Released: May 29, 2020
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    We demonstrated 1-Tb/s-class transmissions of field-deployed large-core low-loss fiber links, which is compliant with ITU-T G.654.E, using our newly developed real-time transponder consisting of a state-of-the-art 16-nm complementary metal-oxide-semiconductor (CMOS) based digital signal processing application-specific integrated circuit (DSP-ASIC) and an indium phosphide (InP) based high-bandwidth coherent driver modulator (HB-CDM). In this field experiment, we have achieved record transmission distances of 1122 km for net data-rate 1-Tb/s transmission with dual polarization-division multiplexed (PDM) 32 quadrature amplitude modulation (QAM) signals, and of 336.6 km for net data-rate 1.2-Tb/s transmission with dual PDM-64QAM signals. This is the first demonstration of applying hybrid erbium-doped fiber amplifier (EDFA) and backward-distributed Raman amplifier were applied to terrestrial G.654.E fiber links. We also confirmed the stability of signal performance over field fiber transmission in wavelength division multiplexed (WDM) condition. The Q-factor fluctuations respectively were only less than or equal to 0.052 dB and 0.07 dB for PDM-32QAM and PDM-64QAM signals within continuous measurements for 60 minutes.

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  • Takeshi Umeki, Takayuki Kobayashi, Akihide Sano, Takuya Ikuta, Masashi ...
    Type: PAPER
    Article ID: 2019OBP0001
    Published: 2020
    [Advance publication] Released: May 22, 2020
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    We developed a polarization-independent and reserved-band-less complementary spectral inverted optical phase conjugation (CSI-OPC) device using dual-band difference frequency generation based on highly efficient periodically poled LiNbO3 waveguide technologies. To examine the nonlinearity mitigation in a long-haul transmission using a large number of OPCs, we installed a CSI-OPC device in the middle of a pure silica core fiber-based recirculating loop transmission line with a length of 320 km. First, we examined the fiber-input power tolerance after 5,120-km and 6,400-km transmission using 22.5-Gbaud PDM-16QAM 10-channel DWDM signals and found a Q-factor improvement of over 1.3 dB along with enhanced power tolerance thanks to mitigating the fiber nonlinearity. We then demonstrated transmission distance extension using the CSI-OPC device. The use of multiple CSI-OPCs enables an obvious performance improvements attained by extending the transmission distance from 6,400 km to 8,960 km, which corresponds to applying the CSI-OPC device 28 times. Moreover, there was no Q-factor degradation for the link in a linear regime after applying the CSI-OPC device more than 16 times. These results demonstrate that the CSI-OPC device can improve the nonlinear tolerance of PDM-16QAM signals without an excess penalty.

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  • Sun Zhao, Deng Shunge, Ma Xin, Luo Haimei, Li Xinwan
    Type: PAPER
    Article ID: 2019OBP0003
    Published: 2020
    [Advance publication] Released: May 22, 2020
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    Through novel rotation writing method of Bragg grating in multicore fiber, its strain vector characteristics are analyzed. The relation between the rotation angle and the strain curvature sensitivity is obtained. Reconstruction of strain vector is verified.

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  • Kensuke Ikeda, Christina Lim, Ampalavanapillai Nirmalathas, Chathurika ...
    Type: PAPER
    Article ID: 2019OBP0004
    Published: 2020
    [Advance publication] Released: May 22, 2020
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    Communication networks for wide-scale distributed energy resources (DERs) including photovoltaics (PVs), wind, storage and battery systems and electric vehicles (EVs) will be indispensable in future power grids. In this paper, we compare optical fronthaul networks using existing optical ground wires (OPGWs) for centralized radio access network (C-RAN) architecture to realize cost effective wireless communication network expansion including low population area. We investigate the applicability of optical data transport technologies of physical layer split (PLS), analog radio-on-fiber (ARoF), and common public radio interface (CPRI). The deployment costs of them are comparatively analyzed. It was shown that physical layer split and analog radio-on-fiber with subcarrier multiplexing (SCM) result in lower cost than other technologies.

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  • Takushi Kazama, Takeshi Umeki, Yasuhiro Okamura, Koji Enbutsu, Osamu T ...
    Type: PAPER
    Article ID: 2019OBP0005
    Published: 2020
    [Advance publication] Released: May 22, 2020
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    We evaluated the noise properties of a periodically poled lithium niobite phase-sensitive amplifier (PSA) using a phase-locked local oscillator as a pump generated by an optical phase-locked loop (OPLL-LO). To examine whether or not the LO pump generated by an OPLL degrades the noise figure (NF) of the PSA, we compared the noise levels of a PSA using an OPLL-LO with that of one using a master local oscillator (M-LO) that utilizes the master light itself as a pump in the electrical domain. With the OPLL, the phase-locked local light had almost the same frequency noise components as the master light. We observed almost the same output noise spectra for the OPLL-LO PSA and M-LO PSA and confirmed the absence of excess noise components in the OPLL-LO PSA in the 0.1 to 20-GHz range. The OPLL-LO PSA exhibited low-noise amplification with an average NF of 1.7-dB at a 23.2-dB gain within an input power range of -31 to -21 dBm, which is a feasible input power for repeater amplifiers used in the optical signal transmission systems. We also investigated the influence of the noisy master light, which emulates the accumulation of optical noise from the amplifiers in the transmission system. The OPLL-LO PSA was highly tolerant to the optical noise because the difference in the NF was negligibly small within a master light OSNR range of 5 to 55 dB. These results indicate that the OPLL-LO PSA will be useful as a low-noise repeater amplifier for the spectrally efficient large-capacity photonic networks of the future.

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  • Hitoro KAWAKAMI, Shoichiro KUWAHARA, Yoshiaki KISAKA
    Type: PAPER
    Article ID: 2019OBP0010
    Published: 2020
    [Advance publication] Released: May 22, 2020
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    We show that imperfection in an IQ-modulator degrades the accuracy of the auto bias control (ABC) circuit connected to the modulator's complementary port. Theoretical analyses show that the IQ -modulator constructed by a nested Mach-Zehnder modulator with a low extinction ratio can distort a constellation of modulated light observed at the complementary port. We propose an auto calibration technique for the ABC circuit that can effectively suppress this degradation. Experimental results using 32-Gbaud, 16-QAM signals showed the measured Q-factor improved by 0.5 dB with our proposed technique.

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  • Teruaki SHIKUMA, Yasuaki YUDA, Kenichi HIGUCHI
    Type: PAPER
    Article ID: 2019EBP3241
    Published: 2020
    [Advance publication] Released: May 20, 2020
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    We propose a novel non-orthogonal multiple access (NOMA)-based optimal multiplexing method for multiple downlink service channels to maximize the integrated system throughput. In the fifth generation (5G) mobile communication system, the support of various wireless communication services such as massive machine-type communications (mMTC), ultra-reliable low latency communications (URLLC), and enhanced mobile broadband (eMBB) is expected. These services will serve different numbers of terminals and have different requirements regarding the spectrum efficiency and fairness among terminals. Furthermore, different operators may have different policies regarding the overall spectrum efficiency and fairness among services. Therefore, efficient radio resource allocation is essential during the multiplexing of multiple downlink service channels considering these requirements. The proposed method achieves better system performance than the conventional orthogonal multiple access (OMA)-based multiplexing method thanks to the wider transmission bandwidth per terminal and inter-terminal interference cancellation using a successive interference canceller (SIC). Computer simulation results reveal that the effectiveness of the proposed method is especially significant when the system prioritizes the fairness among terminals (including fairness among services).

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  • Ryo SHIBATA, Gou HOSOYA, Hiroyuki YASHIMA
    Type: PAPER
    Article ID: 2019EBP3244
    Published: 2020
    [Advance publication] Released: May 20, 2020
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    For insertion and deletion channels, there are many coding schemes based on low-density parity-check (LDPC) codes, such as spatially coupled (SC) LDPC codes and concatenated codes of irregular LDPC codes and markers. However, most of the previous works have problems, such as poor finite-length performance and unrealistic settings for codeword lengths and decoding iterations. Moreover, when using markers, the decoder receives log-likelihood (LLR) messages with different statistics depending on code bit position. In this paper, we propose a novel concatenation scheme using protograph-based LDPC code and markers that offers excellent asymptotic/finite-length performance and a structure that controls the irregularity of LLR messages. We also present a density evolution analysis and a simple optimization procedure for the proposed concatenated coding scheme. For two decoding scenarios involving decoding complexity, both asymptotic decoding thresholds and finite-length performance demonstrate that the newly designed concatenated coding scheme outperforms the existing counterparts: the irregular LDPC code with markers, the SC-LDPC code, and the protograph LDPC code, which is optimized for an additive white Gaussian noise channel, with markers.

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  • Yifei Sun, Yasunori Kobori, Anna Kuwana, Haruo Kobayashi
    Type: PAPER
    Article ID: 2019EBP3263
    Published: 2020
    [Advance publication] Released: May 20, 2020
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    This paper proposes a noise reduction technology for a specific frequency band that uses the pulse coding controlled method to automatically set the notch frequency in DC-DC switching converters of communication equipment. For reducing the power levels at the frequency and its harmonics in the switching converter, we often use a frequency-modulated clock. This paper investigates a technology that prevents modulated clock frequency noise from spreading into protected frequency bands; this proposed noise reduction technology does not distribute the switching noise into some specified frequency bands. The notch in the spectrum of the switching pulses is created by the Pulse Width Coding (PWC) method. In communication devices, the noise in the receiving signal band must be as small as possible. The notch frequency is automatically set to the frequency of the received signal by adjusting the clock frequency using the equation Fn=(P+0.5)Fck. eere Fn is the notch frequency, Fck is the clock frequency, and P is a positive integer that determines the noise spectrum location. Therefore, simply be setting the notch frequency to the received signal frequency can suppress the noise present. We confirm with simulations that the proposed technique is effective for noise reduction and notch generation. Also we implement a method of automatic switching between two receiving channels. The conversion voltage ratio in the pulse width coding method switching converter is analyzed and full automatic notch frequency generation is realized. Experiments on a prototype circuit confirm notch frequency generation.

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  • Ryota TSUJI, Daisuke HISANO, Ken MISHINA, Akihiro MARUTA
    Type: PAPER
    Article ID: 2019OBP0016
    Published: 2020
    [Advance publication] Released: May 20, 2020
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    Wavelength division multiplexing (WDM) scheme is used widely in photonic metro-core networks. In a WDM network, wavelength continuity constraint is employed to simply construct relay nodes. This constraint reduces the wavelength usage efficiency of each link. To improve the same, an all-optical wavelength converter (AO-WC) has been attracting attention in recent years. In particular, an AO-WC is a key device because it enables simultaneous conversion of multiple wavelengths of signal lights to other wavelengths, independent of the modulation format. However, each AO-WC requires installation of multiple laser sources with narrow bandwidth because the lights emitted by the laser sources are used as pump lights when the wavelengths of the signal lights are converted by the fourwave mixing (FWM) process. To reduce the number of laser sources, we propose a remote pumped AO-WC, in which the laser sources of the pump lights are aggregated into several relay nodes. When the request for the wavelength conversion from the relay node without the laser source is conveyed, the relay node with the laser source transmits the pump light through the optical link. The proposed scheme enables reduction in the number of laser sources of the pump lights. Hereinwe analyze the distortion of the pump light by propagating it through the optical linkWe also evaluate the effect of the noise in optical amplifiers and nonlinearities in optical fibers using numerical simulations employing the representative parameters for a practical WDM network.

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  • Yuta KAIHORI, Yu YAMASAKI, Tsuyoshi KONISHI
    Type: INVITED PAPER
    Article ID: 2019OBI0002
    Published: 2020
    [Advance publication] Released: May 14, 2020
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    A high degree of freedom in spectral domain allows us to accommodate additional optical signal processing for wavelength division multiplexing in photonic analog-to-digital conversion. We experimentally verified a spectral compression to save a necessary bandwidth for soliton self-frequency shift based optical quantization through the cascade of the four-wave mixing based and the sum-frequency generation based spectral compression. This approach can realize 0.03 nm individual bandwidth correspond to save up to more than 85 percent of bandwidth for 7-bit optical quantization in C-band.

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  • Roberto Proietti, Xian Xiao, Marjan Fariborz, Pouya Fotouhi, Yu Zhang, ...
    Type: INVITED PAPER
    Article ID: 2019OBI0004
    Published: 2020
    [Advance publication] Released: May 14, 2020
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    This paper summarizes our recent studies on architecture, photonic integration, system validation and networking performance analysis of a flexible low-latency interconnect optical network switch (Flex-LIONS) for datacenter and high-performance computing (HPC) applications. Flex-LIONS leverages the all-to-all wavelength routing property in arrayed waveguide grating routers (AWGRs) combined with microring resonator (MRR)-based add/drop filtering and multi-wavelength spatial switching to enable topology and bandwidth reconfigurability to adapt the interconnection to different traffic profiles. By exploiting the multiple free spectral ranges of AWGRs, it is also possible to provide reconfiguration while maintaining minimum-diameter all-to-all interconnectivity. We report experimental results on the design, fabrication, and system testing of 8×8 silicon photonic (SiPh) Flex-LIONS chips demonstrating error-free all-to-all communication and reconfiguration exploiting different free spectral ranges (FSR0 and FSR1, respectively). After reconfiguration in FSR1, the bandwidth between the selected pair of nodes is increased from 50 Gb/s to 125 Gb/s while an all interconnectivity at 25 Gb/s is maintained using FSR0. Finally, we investigate the use of Flex-LIONS in two different networking scenarios. First, networking simulations for a 256-node datacenter inter-rack communication scenario show the potential latency and energy benefits when using Flex-LIONS for optical reconfiguration based on different traffic profiles (a legacy fat-tree architecture is used for comparison). Second, we demonstrate the benefits of leveraging two FSRs in an 8-node 64-core computing system to provide reconfiguration for the hotspot nodes while maintaining minimum-diameter all-to-all interconnectivity.

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  • Sugang Xu, Goshi Sato, Masaki Shiraiwa, Katsuhiro Temma, Yasunori Owad ...
    Type: PAPER
    Article ID: 2019OBP0007
    Published: 2020
    [Advance publication] Released: May 14, 2020
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    Large-scale disasters can lead to a severe damage or destruction of optical transport networks including the data-plane (D-plane) and control and management-plane (C/M-plane). In addition to D-plane recovery, quick recovery of the C/M-plane network in modern software-defined networking (SDN)-based fiber optical networks is essential not only for emergency control of surviving optical network resources, but also for quick collection of information related to network damage/survivability to enable the optimal recovery plan to be decided as early as possible. With the advent of the Internet of Things (IoT) technologies, low energy consumption, and low-cost IoT devices have been more common. Corresponding long-distance networking technologies such as low-power wide-area (LPWA) and LPWA-based mesh (LPWA-mesh) networks promise wide coverage sensing and environment data collection capabilities. We are motivated to take an infrastructure-less IoT approach to provide long-distance, low-power and inexpensive wireless connectivity and create an emergency C/M-plane network for early disaster recovery. In this paper, we investigate the feasibility of fiber networks C/M-plane recovery using an IoT-based extremely narrow-band, and lossy links system (FRENLL). For the first time, we demonstrate a field-trial experiment of a long-latency/loss tolerable SDN C/M-plane that can take advantage of widely available IoT resources and easy-to-create wireless mesh networks to enable the timely recovery of the C/M-plane after disaster.

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  • Yuta MATSUMOTO, Ken MISHINA, Daisuke HISANO, Akihiro MARUTA
    Type: PAPER
    Article ID: 2019OBP0015
    Published: 2020
    [Advance publication] Released: May 14, 2020
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    In inter-data center networks where high transmission capacity and spectral efficiency are required, a 16QAM format is deployed. On the other hand, in intra-data center networks, a PAM4 format is deployed to meet the demand for a simple and low-cost transceiver configuration. For a seamless and effective connection of such heterogeneous networks without using optical-electrical-optical conversion, an all-optical modulation format conversion technique is required. In this paper, we propose an alloptical PAM4 to 16QAM modulation format conversion using nonlinear optical loop mirror. The successful conversion operation from 2 × 26.6-Gbaud PAM4 signals to a 100-Gbps class 16QAM signal is verified by numerical simulation. Compared with an ideal 16QAM signal, the power penalty of the converted 16QAM signal can be kept within 0.51 dB.

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  • Hiroyasu Ishikawa, Yuki Horikawa, Hideyuki Shinonaga
    Type: PAPER
    Article ID: 2019CBP0007
    Published: 2020
    [Advance publication] Released: May 08, 2020
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    In the typical unmanned aircraft system (UAS), several unmanned aerial vehicles (UAVs) traveling at a velocity of 40-100 km/h and with altitudes of 150-1,000 m will be used to cover a wide service area. Therefore, Doppler shifts occur in the carrier frequencies of the transmitted and received signals due to changes in the line-of-sight velocity between the UAVs and the terrestrial terminal. By observing multiple Doppler shift values for different UAVs or observing a single UAV at different local times, it is possible to detect the user position on the ground. We conducted computer simulations for evaluating user position detection accuracy and Doppler shift distribution in several flight models. Further, a positioning accuracy index (PAI), which can be used as an index for position detection accuracy, was proposed as the absolute value of cosine of the inner product between two gradient vectors formed by Doppler shifts to evaluate the relationship between the location of UAVs and the position of the user.

    In this study, a maximum positioning error estimation method related to the PAI is proposed to approximate the position detection accuracy. Further, computer simulations assuming a single UAV flying on the curved routes such as sinusoidal routes with different cycles are conducted to clarify the effectiveness of the flight route in the aspects of positioning accuracy and latency by comparing with the conventional straight line fight model using the PAI and the proposed maximum positioning error estimation method.

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  • Zhi QUAN, Shuhua LV, Li JIANG
    Type: PAPER
    Article ID: 2019EBP3223
    Published: 2020
    [Advance publication] Released: May 08, 2020
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    Massive multiple-input multiple-output (MIMO) is an enabling technology for next-generation wireless systems because it provides significant improvements in data rates compared to existing small-scale MIMO systems. However, the increased number of antennas results in high computational complexity for data detection, and requires more efficient detection algorithms. In this paper, we propose a new data detector based on a box-constrained complex-valued dichotomous coordinate descent (BCC-DCD) algorithm for large-scale MIMO systems. The proposed detector involves two steps. First, a transmitted data vector is detected using the BCC-DCD algorithm with a large number of iterations and high solution precision. Second, an improved soft output is generated by reapplying the BCC-DCD algorithm, but with a considerably smaller number of iterations and 1-bit solution precision. Numerical results demonstrate that the proposed method outperforms existing advanced detectors while possessing lower complexity. Specifically, the proposed method provides significantly better detection performance than a BCC-DCD algorithm with similar complexity. The performance advantage increases as the signal-to-noise ratio and the system size increase.

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  • Takehiro SATO, Eiji OKI
    Type: PAPER
    Article ID: 2020EBP3001
    Published: 2020
    [Advance publication] Released: May 08, 2020
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    The machine-to-machine (M2M) service network platform that accommodates and controls various types of Internet of Things devices has been presented. This paper investigates program file placement strategies for the M2M service network platform that achieve low blocking ratios of new task requests and accommodate as many tasks as possible in the dynamic scenario. We present four strategies for determining program file placement, which differ in the computation method and whether the relocation of program files being used by existing tasks is allowed or not. Simulation results show that a strategy based on solving a mixed-integer linear programming model achieves the lowest blocking ratio, but a heuristic algorithm-based strategy can be an attractive option by allowing recomputation of the placement when the placement cannot be obtained at the timing of new task request arrival.

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  • Takaaki SAWA, Fujun HE, Akio KAWABATA, Eiji OKI
    Type: PAPER
    Article ID: 2020EBP3006
    Published: 2020
    [Advance publication] Released: May 08, 2020
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    This paper proposes two algorithms, namely Server-User Matching (SUM) algorithm and Extended Server-User Matching (ESUM) algorithm, for the distributed server allocation problem. The server allocation problem is to determine the matching between servers and users to minimize the maximum delay, which is the maximum time to complete user synchronization. We analyze the computational time complexity. We prove that the SUM algorithm obtains the optimal solutions in polynomial time for the special case that all server-server delay values are the same and constant. We provide the upper and lower bounds when the SUM algorithm is applied to the general server allocation problem. We showthat the ESUM algorithm is a fixed-parameter tractable algorithm that can attain the optimal solution for the server allocation problem parameterized by the number of servers. Numerical results show that the computation time of ESUM follows the analyzed complexity while the ESUM algorithm outperforms the approach of integer linear programming solved by our examined solver.

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  • Yoichi SUZUKI, Hisashi SUJIKAI
    Type: INVITED PAPER
    Article ID: 2019CBI0001
    Published: 2020
    [Advance publication] Released: April 21, 2020
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    4K/8K satellite broadcasting featuring ultra-high definition video and sound was launched in Japan in 2018. This is the first 8K ultra high definition television (UHDTV) broadcasting in the world, with 16 times as many pixels as HDTV and 3D sound with 22.2ch audio. The large amount of information that has to be transmitted means that a new satellite broadcasting transmission system had to be developed. In this paper, we describe this transmission system, focusing on the technology that enables 4K/8K UHDTV satellite broadcasting.

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  • Yang Nie, Xinle Yu
    Type: PAPER
    Article ID: 2019EBP3200
    Published: 2020
    [Advance publication] Released: April 21, 2020
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    This paper proposes a deterministic pilot pattern placement optimization scheme based on the quantum genetic algorithm (QGA) which aims to improve the performance of sparse channel estimation in orthogonal frequency division multiplexing (OFDM) systems. By minimizing the mutual incoherence property (MIP) of the sensing matrix, the pilot pattern placement optimization is modeled as the solution of a combinatorial optimization problem. QGA is used to solve the optimization problem and generate optimized pilot pattern that can effectively avoid local optima traps. The simulation results demonstrate that the proposed method can generate a sensing matrix with a smaller MIP than a random search or the genetic algorithm (GA), and the optimized pilot pattern performs well for sparse channel estimation in OFDM systems.

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  • Sho IWAZAKI, Shogo NAKAMURA, Koichi ICHIGE
    Type: PAPER
    Article ID: 2019EBP3213
    Published: 2020
    [Advance publication] Released: April 21, 2020
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    This paper presents a weighted spatial filter (WSF) design method based on direction of arrival (DOA) estimates for a novel array configuration called a sum and difference composite co-array. A sum and difference composite co-array is basically a combination of sum and difference co-arrays. Our configuration can realize higher degrees of freedom (DOF) with the sum co-array part at a calculation cost lower than those of the other sparse arrays. To further enhance the robustness of our proposed sum and difference composite co-array we design an optimal beam pattern by WSF based on the information of estimated DOAs. Performance of the proposed system and the DOA estimation accuracy of close-impinging waves are evaluated through computer simulations.

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  • Toshiro NUNOME, Suguru KAEDE, Shuji TASAKA
    Type: PAPER
    Article ID: 2019EBP3235
    Published: 2020
    [Advance publication] Released: April 21, 2020
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    In this paper, we propose a user-assisted QoS control scheme that utilizes media adaptive buffering to enhance QoE of audiovisual and haptic IP communications. The scheme consists of two modes: a manual mode and an automatic mode. It enables users to switch between these two modes according to their inclinations. We compare four QoS control schemes: the manual mode only, the automatic mode only, the switching scheme starting with the manual mode, and the switching scheme starting with the automatic mode. We assess the effects of the four schemes, user attributes, and tasks on QoE through a subjective experiment which provides information on users' behavior in addition to QoE scores. As a result of the experiment, we show that the user-assisted QoS control scheme can enhance QoE. Furthermore, we notice that the proper QoS control scheme depends on user attributes and tasks.

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  • Lu LU, Mingxing KE, Shiwei TIAN, Xiang TIAN, Tianwei LIU, Lang RUAN
    Type: PAPER
    Article ID: 2019EBP3237
    Published: 2020
    [Advance publication] Released: April 21, 2020
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    To tackle the distributed power optimization problems in wireless sensor networks localization systems, we model the problem as a hierarchical game, i.e. a multi-leader multi-follower Stackelberg game. Existing researches focus on the power allocation of anchor nodes for ranging signals or the power management of agent nodes for cooperative localization, individually. However, the power optimizations for different nodes are indiscerptible due to the common objective of localization accuracy. So it is a new challenging task when the power allocation strategies are considered for anchor and agent nodes simultaneously. To cope with this problem, a hierarchical game is proposed where anchor nodes are modeled as leaders and agent nodes are modeled as followers. Then, we prove that games of leaders and followers are both potential games, which guarantees the Nash equilibrium (NE) of each game. Moreover, the existence of Stackelberg equilibrium (SE) is proved and achieved by the best response dynamics. Simulation results demonstrate that the proposed algorithm can have better localization accuracy compared with the decomposed algorithm and uniform strategy.

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  • Yuya KASE, Toshihiko NISHIMURA, Takeo OHGANE, Yasutaka OGAWA, Daisuke ...
    Type: PAPER
    Article ID: 2019EBP3260
    Published: 2020
    [Advance publication] Released: April 21, 2020
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    Direction of arrival (DOA) estimation of wireless signals has a long history but is still being investigated to improve the estimation accuracy. Non-linear algorithms such as compressed sensing are now applied to DOA estimation and achieve very high performance. If the large computational loads of compressed sensing algorithms are acceptable, it may be possible to apply a deep neural network (DNN) to DOA estimation. In this paper, we verify on-grid DOA estimation capability of the DNN under a simple estimation situation and discuss the effect of training data on DNN design. Simulations show that SNR of the training data strongly affects the performance and that the random SNR data is suitable for configuring the general-purpose DNN. The obtained DNN provides reasonably high performance, and it is shown that the DNN trained using the training data restricted to close DOA situations provides very high performance for the close DOA cases.

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  • Nobuhiko ITOH, Takanori IWAI, Ryogo KUBO
    Type: PAPER
    Article ID: 2019EBT0007
    Published: 2020
    [Advance publication] Released: April 21, 2020
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    Road traffic collisions are an extremely serious and often fatal issue. One promising approach to mitigate such collisions is the use of connected car services that share road traffic information obtained from vehicles and cameras over mobile networks. In connected car services, it is important for data chunks to arrive at a destination node within a certain deadline constraint. In this paper, we define a flow from a vehicle (or camera) to the same vehicle (or camera) via an MEC server, as a mission critical (MC) flow, and call a deadline of the MCflow the MCdeadline. Our research objective is to achieve a higher arrival ratio within the MCdeadline for the MC flow that passes through both the radio uplink and downlink. We previously developed a deadline-aware scheduler with consideration for quality fluctuation (DAS-QF) that considers chunk size and a certain deadline constraint in addition to radio quality and utilizes these to prioritize users such that the deadline constraints are met. However, this DAS-QF does not consider that the congestion levels of evolved NodeB (eNB) differ depending on the eNB location, or that the uplink congestion level differs from the downlink congestion level in the same eNB. Therefore, in the DAS-QF, some data chunks of a MC flow are discarded in the eNB when they exceed either the uplink or downlink deadline in congestion, even if they do not exceed the MC deadline. In this paper, to reduce the eNB packet drop probability due to exceeding either the uplink and downlink deadline, we propose a deadline coordination function (DCF) that adaptively sets each of the uplink and downlink deadlines for the MC flow according to the congestion level of each link. Simulation results show that the DAS-QF with DCF offers higher arrival ratios within the MC deadline compared to DAS-QF on its own

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  • Naruto ARAI, Ken OKAMOTO, Jun KATO, Yoshiharu AKIYAMA
    Type: PAPER
    Article ID: 2019MCP0001
    Published: 2020
    [Advance publication] Released: April 08, 2020
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    This paper describes a method of measuring the unsymmetric voltage of conducted noise using a floating measurement system. Here, floating means that there is no physical connection to the reference ground. The method works by correcting the measured voltage to the desired unsymmetric voltage using the capacitance between the measurement instrument and the reference ground plane acting as the return path of the con ducted electromagnetic noise. The existing capacitance measurement instrument needs a probe in contact with the ground, so it is difficult to use for on site measurement of stray capacitance to ground at troubleshooting sites where the ground plane is not exposed or no ground connection point is available. The a uthors have developed a method of measuring stray capacitance to ground that does no t require physical connection of the probe to the ground plane. The developed method can be used to estimate the ca pacitance between the measurement instrument and ground plane even if the distance and relative permittivity of the space are unknown. And a method is proposed for correcting the voltage measured with the floating measurement system to obtain the unsymmetric voltage of the noise by using the measured capacitance to ground. In the experiment, the unsymmetric voltage of a sinusoidal wave transmitting on a co axial cable w as measured with a floating oscilloscope in a shield room and the measured voltage was co rrected to within 2 dB of expected voltage by using the capacitance measured with the developed method. In addition, the voltage of a rectangular wave measured with the floating oscilloscope, which displays sag caused by the stray capacitance to ground, was corrected to a rectangular wave without sag. This means that the phase of the unsymmetric voltage can also be corrected by the measured stray capacitance. From these results, the effectiveness of the proposed methods is shown.

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  • Sho Muroga, Motoshi Tanaka, Takefumi Yoshikawa, Yasushi Endo
    Type: PAPER
    Article ID: 2019MCP0002
    Published: 2020
    [Advance publication] Released: April 08, 2020
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    An effect of complex permeability of noise suppression sheets (NSS) on circuit parameters was investigated by a magnetic circuit analysis using cross-sectional size and material parameters. The series resistance and inductance of the coplanar waveguide (CPW) with a NSS considering the effect of the complex permeability of the NSS were quantitatively estimated. The result indicated that the imaginary and real part of the effective permeability affected the resistance and inductance, respectively. Furthermore, this analysis was applied to an 8-μm-wide CPW with a 0.5-μm-thick Co85Zr3Nb12 film for quantitative estimation of the resistance, the inductance and the characteristic impedance. The estimated parameters were almost similar to the measured values. These results showed that the frequency characteristics of the circuit parameters could be controlled by changing size and material parameters.

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  • Toshio CHIYOJIMA, Akihiro ODA, Go ISHIWATA, Kazuhiro TAKAYA, Yasushi M ...
    Type: PAPER
    Article ID: 2019MCP0003
    Published: 2020
    [Advance publication] Released: April 08, 2020
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    A method of determining emission limits was studied by using the amplitude probability distribution (APD) for low-probability pulsed electromagnetic disturbances due to discharge. The features of this method are 1) without using the previously reported relationship between APD and bit error rate, the limits are derived using the measured impact of a pulsed disturbance on various wireless communication systems having different bandwidths, and 2) disturbances caused by discharge with poor reproducibility are simulated by regularly repeated pulse-modulated sine waves to enable stable evaluation of the communication quality. APD-based limits are determined from the pulse repetition frequency of the simulated disturbance such that the block error rate (BLER) is less than a certain limit in wireless systems that are most sensitive to the pulsed disturbance. In the international standard CISPR 32 regulating electromagnetic disturbance, radiated disturbance due to discharge is excluded from the application of peak detection limits because of its low occurrence probability. In this paper we quantitatively determine appropriate criteria of the probability for the exclusion. Using the method, we measured the impact of low-probability pulsed interference on major wireless systems and found that GSM and WiFi systems were the most sensitive. New APD-based limits were derived on the basis of these findings. The APD-based limits determined by the proposed method enable a valid evaluation of low-occurrence-probability pulsed disturbances without unconditionally excluding the measurement.

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