Publications
As of October 09, 2024, we published and presented 1147 articles.
Please also refer to Okada Laboratory / Yamazato Laboratory research results page.
303
Peer-Reviewed Conference Papers
Low-Power Receiver Design with a Noise Enhanced 1-bit ADC and Signal Constellation Rearrangement for 16-QAM Transmitters
- A. Isozaki, T. Yamazato, Shan Lu, M. Saito
- IEEE Global Communications Conference (GLOBECOM) 2024, Capetown, South Africa
- Dec. 2024
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- This paper proposes a transmitter that rearranges the 16-QAM constellation for a 1-bit ADC receiver. A 1-bit ADC receiver is more eco-friendly and lower-cost than receivers with a high-resolution ADC. However, in conventional 1-bit ADC receivers, severe degradation of SER (Symbol Error Rate) in high Es/N0 poses a critical problem. This degradation is due to the lack of noise power in high Es/N0, which prevents the receiver from sufficiently benefiting from stochastic resonance. To solve this issue, we propose a novel transmitter that rearranges a 16-QAM constellation based on the probability density function of noise. The rearrangement of constellations mitigates the nonlinearity of a 1-bit ADC, enabling reliable demodulation of multilevel signals in high Es/N0. Numerical examples demonstrate that the proposed transmitter achieves good SER performance across a wide range of Es/N0, even when a 1-bit ADC receiver is employed, compared to conventional transmitters.
Noise Power Reducible In-Phase Combining for Signal-to-Power Ratio Improvement of Short-Term Power Delay Profile Estimation
- F. Ojika, T. Yamazato, M. Saito, H. Omote, A. Sato, S. Kimura, S. Tanaka, Ho-Yu Lin
- IEICE Transactions on Communications, Vol.J107-B,No.11,pp.-
- Nov. 2024
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- In mobile wireless communication systems, accurate channel characterization is crucial. Particularly in channel estimation, reducing noise power relative to the signal and utilizing low signal-to-noise ratio (SNR) signals are essential. Enabling communication in environments with low-SNR signals expands the coverage area of base stations. We propose a novel method for noise reduction utilizing short-term power delay profiles. To Validate its effectiveness, we conducted radio propagation measurements with deliberately weakened signals using attenuators. Assuming propagated paths originate from the same direction, our simulations confirm the feasibility of the proposed method. The method successfully improved the SNR of a 10 dB signal in the short-term power delay profile to 30 dB.
Synchronization method using Barker code in Event-Based-Camera Visible Light Communication using Walsh-Hadamard code
- R. Soga, S. Lu, T. Yamazato
- Enginnering Sciences Society Conference of IEICE, A-9-7, Saitama
- Sep. 2024
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- A. Isozaki, T. Yamazato, M. Saito
- Tokai-Section Joint Conference on Electrical, Electronics, Information, and Related Engineering, Gifu, Japan
- Aug. 2024
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Visible Light Communication Using Light Trails: An Overview and Prospects
- Z. Tang, S. Lu, T. Yamazato, S. Arai, T. Yendo
- IEICE Technical Report, WBS2024-26, pp.56-61, Nagoya
- Jul. 2024
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Analysis of error causes due to different blink angles in drone image sensor communication based on light trails
- C. Cao, Z. Tang, S. Lu, T. Yamazato
- IEICE Technical Report, WBS2024-27, pp.62-65, Nagoya
- Jul. 2024
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Relative Position Estimation Using Cross Filter for Rolling-Shutter Cameras
- D. Sekimoto, K. Kamakura, M. Kinoshita, T. Yamazato
- IEICE Technical Report, CS2024-36, pp.131-136
- Jul. 2024
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16 Quadrature Amplitude Modulation Orthogonal Frequency Division Multiplexing Receiver Using 1-bit ADC for Noise Utilization -Characterization in Fading Channels with Large Amplitude Fluctuations-
- A. Isozaki, T. Yamazato, M. Saito
- IEICE Communications Express
- Apr. 2024
- DOI:https://doi.org/10.23919/comex.2024TCL0018
- In this study, authors evaluate 1-bit ADC receivers proposed in previous studies in Rician and Rayleigh fading channels where the ampli- tude and phase of the signal fluctuate dynamically in terms of SNR (Signal- to-Noise Ratio) vs. BER (Bit Error Rate). We confirm that the 1-bit ADC receiver is effective even in such environments. However, the degree of degradation of SNR vs. BER due to variations in signal amplitude and phase depends on the demodulation method.
[Invited] Enhancing Mobile Vehicle Connectivity: Optimizing Visible Light Communication Signal Reception with Rolling Shutter Image Sensors
- T. Yamazato
- The 3rd ISA Global Annual LiFi Conference 2024
- Mar. 2024
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Demonstration of crossing the priority road using Sensor Sharing with Visible Light Communication
- K. Nakano, S. Lu, T. Yamazato
- General Conference of IEICE, A-13-18, Hiroshima, Japan
- Mar. 2024
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Performance Evaluation Simulation of NR-V2X using OMNeT++
- E. Go, T. Yamazato, S. Lu
- IEICE General Conference, A-13-17, Hiroshima
- Mar. 2024
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Recognition of the Environment around a Receiver using an Event Camera and Walsh-Hadamard Transform
- H. Nagai, D. Ehara, S. Lu, T. Yamazato
- IEICE General Conference, Hiroshima, Japan
- Mar. 2024
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Reducing Noise Power in Short-Term Power Delay Profiles with Weak Leading Edge
- F. Ojika, T. Yamazato, M. Saito, H. Omote, A. Sato, S. Kimura, S. Tanaka, H. Lin
- IEICE General Conference
- Mar. 2024
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Drone image sensor communication by LED propeller light-trails
- C. Cao, Z. Tang, J. Zheng, S. Lu, T. Yamazato
- IEICE General Conference, A-9-10, Hiroshima
- Mar. 2024
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A Testbed of Hybrid Private 5G Integrating Optical Wireless Communication for Coverage Expansion
- J. Zheng, S. Lu, T. Yamazato
- IEICE General Conference, A-9-13, Hiroshima
- Mar. 2024
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Vehicle to Infrastructure (V2I) Visible Light Communication System Using Rolling Shutter Image Sensor Driving at 50km/h
- R. Kondo, S. Lu, T. Yamazato
- IEICE General Conference
- Mar. 2024
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Experimental Demonstration of Optical OFDM Using Index Modulation in Rolling Shutter Based Visible Light Communication
- H. Shimizu, M. Kinoshita, K. Kamakura, T. Yamazato
- IEICE General Conference, A-9-16, Hiroshima
- Mar. 2024
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Communication Area Expansion in Rolling Shutter Based Visible Light Communication Using Parallel Delay Transmission
- H. Koga, R. Sugahara, M. Kinoshita, K. Kamakura, T. Yamazato
- IEICE General Conference, Hiroshima, Japan.
- Mar. 2024
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Experimental Study on Reception of IF Band 16-QAM/OFDM Signals with Noise and 1-bit ADC
- M. Saito and T. Yamazato
- IEICE General Conference, Hiroshima
- Mar. 2024
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Event-based Vision Sensor Visible Light Communication under Receiver Moving Environment with Multiple LEDs
- D. Ehara, Z. Tang, T. Yamazato, S. Lu
- IEICE General Conference, A-9-11, Hiroshima
- Mar. 2024
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Visible Light Communications
- T. Yamazato
- Presented at Multimedia Promotion Forum, Online
- Jan. 2024
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16QAM-OFDM Receiver Using 1-bit ADC that Utilizes Noise and Performs Frequency Conversion in the Digital Domain Characterization in a Frequency Flat Rician Fading Channel
- A.Isozaki, T.Yamazato, M.Saito
- International Conference on Emerging Technologies for Communications (ICETC)
- Dec. 2023
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- In this study, we propose the 1-bit ADC receiver that performs frequency conversion in the digital domain to simplify the circuitry in the receiver and reduce power consumption. Then, we evaluate the SNR vs. BER of the 1-bit ADC receiver we propose. In the proposed receiver, the average of the 1-bit ADC outputs in parallel is taken, the received signal is restored, and the baseband signal is demodulated by multiplying the restored received signal by the carrier wave.
High-Speed Image Sensor Communication Using High Dynamic Range Combining
- R. Huang, T. Yamazato, M. Kinoshita, H. Okada, S. Arai, K. Kamakura, T. Yendo, T. Fujii
- IEICE Communications Express
- Nov. 2023
- https://doi.org/10.1587/comex.2023XBL0075
- An essential issue in image sensor communication (ISC) is reliable and high-speed data transmission. In order to increase the data rate, this study uses pulse-width modulation (PWM). However, the symbol decision for PWM will become challenging with increasing numbers of luminance levels because of pixel saturation. In this study, we mitigate the pixel saturation problem by achieving high dynamic range (HDR) using two high-speed image sensors with varied exposure settings. Furthermore, we proposed HDR combining for signal demodulation. The field trial experiment results show that a throughput of higher than 87.5 kbps within the communication distance of 50 m can be achieved.
Image Sensor Communication Via Light Trail Using Propeller LED Transmitter
- Z. Tang, J. Zheng, T. Yamazato, S. Arai
- IEEE Photonics Journal, vol.15, no.5, pp.1-12
- Oct. 2023
- https://doi.org/10.1109/JPHOT.2023.3317082
- This paper proposes an image sensor communication (ISC) system based on light trails using rotary LEDs. The light trail refers to an optical phenomenon where light appears elongated and forms a trajectory due to the movement of luminous objects. In this study, we developed a propeller LED transmitter (P-Tx) that rotates LEDs with a propeller to generate and transmit light trail signals. According to the LED's rotation radius, the proposed system segments light trails to achieve high-capacity data transmission at short distances and high-trust transmission at long distances. In addition, we perform the rotation coordinates system conversion for the captured light trails to accurately and simply detect the signal LEDs' coordinates. We experimentally evaluate the proposed system's communication performance and data rate. The experimental results demonstrate that our system is capable of meeting communication requirements at various distances and exhibits significant potential in enhancing the data transmission rate of ISC.
Experimental Investigation of Weak Signal Enhancement through Iterative Short-Term Power Delay Profile Estimation
- F. Ojika, T. Yamazato, M. Saito, H. Omote, A. Sato, S. Kimura, S. Tanaka, H. Lin
- Communications Society Conference of IEICE, B-1-31, p.31
- Sep. 2023
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A Study on Ultrasonic-based Angle Measurement System and adding Communication Function
- S. Kitagawa, H. Hatano, K. Mori, K. Sanada, T. Kasashima, A. Tsujii, T. Yamazato
- Enginnering Sciences Society Conference of IEICE, A-13-7, p.108
- Sep. 2023
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Zone-segment transmission for light-trail based image sensor communication using propeller LED transmitter
- Z. Tang, J. Zheng, T. Yamazato, S. Arai
- Enginnering Sciences Society Conference of IEICE, A-9-5, p.68
- Sep. 2023
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Expanding Private 5G Coverage by Integrating Optical Wireless Communication
- J. Zheng, T. Yamazato
- Enginnering Sciences Society Conference of IEICE, A-9-4, p.67
- Sep. 2023
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Experimental Evaluation of Superimposed Iterative Transmission for Varying Communication Ranges in Rolling Shutter Based Visible Light Communication
- R. Maeda, M. Kinoshita, K. Kamakura, T. Yamazato
- Enginnering Sciences Society Conference of IEICE, A-9-11, p.74
- Sep. 2023
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Performance Evaluation of the Camera-Based Visible Light Communication Using Half-Wave Rectified Waveform
- H. Matsunaga, K. Kai, K. Fujii, T. Yendo, S. Arai, T. Yamazato
- Enginnering Sciences Society Conference of IEICE, A-9-13, p.76
- Sep. 2023
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Detecting Light-trail Signals Transmitted by LED Propeller in Drone-based Visible Light Communication
- C. Cao, Z. Tang, J. Zheng, T. Yamazato
- Enginnering Sciences Society Conference of IEICE, A-9-6, p.69
- Sep. 2023
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An Experimental Study on Visible Light Communication Based on High-Dynamic Range Images
- R. Huang, T. Yamazato, M. Kinoshita, H. Okada, K. Kamakura, S. Arai, T. Yendo, Fujii
- Enginnering Sciences Society Conference of IEICE, A-9-7, p.70
- Sep. 2023
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Tracking Multiple LEDs Using an Event Camera in a Receiver Moving Environment
- D. Ehara, Z. Tang, M. Kinoshita, T. Yamazato, H. Okada, K. Kamakura, S. Arai, T. Yendo, T. Fujii
- Enginnering Sciences Society Conference of IEICE, A-9-8, p.71
- Sep. 2023
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Achieving Successful VLC Signal Reception Using A Rolling Shutter Image Sensor While Driving at 40 km/h
- S. Kamiya, Z. Tang, T. Yamazato, M. Kinoshita, K. Kamakura, S. Arai, T. Yendo, T. Fujii
- IEEE Photonics Journal, vol. 15, no. 4, pp. 1-11
- Aug. 2023
- https://doi.org/10.1109/JPHOT.2023.3287211
- This paper presents the successful reception of visible light communication (VLC) signals, transmitted from an LED array, by an image sensor that utilizes a rolling shutter while driving at 40 km/h. The rolling shutter image sensors used in commercial cameras, such as those found in smartphones and dashcams, capture images line by line at a fast rate, allowing for VLC signal reception in vehicular environments. By analyzing the relationship between the signal reception rate for each line and the frame rate, we demonstrate that parallel VLC signals transmitted from the LED array can be received even while in motion. Notably, to our knowledge, this is the first time that an automobile moving at 40 km/h has successfully received a VLC signal.
Image Sensor Communication and its Transmitting Devices
- Z. Tang, T. Yamazato
- Elsevier, Optics Communications, vol. 541
- Aug. 2023
- https://doi.org/https://doi.org/10.1016/j.optcom.2023.129545
- This paper focuses on image sensor communication (ISC) using cameras to receive wireless signals transmitted by visible lights. We summarize the technical principles of ISC from the perspective of transmitting devices. An introduction to the development and applications of ISC was provided, starting with the history of image sensors and visible light communication (VLC). Moreover, the communication mechanism of ISC using complementary metal–oxide–semiconductor (CMOS) sensors is explained in this paper. Specifically, we investigate studies using an optical communication image sensor and the rolling shutter technique for high-speed ISC. Further, we highlight three distinctive transmitting devices in ISC: a LED array, rotating LEDs, and displays, and explain them in terms of structure and signal transmission methods. In particular, we present the parallel transmission of LED arrays and their application in traffic systems and introduce an optical flow-based signal transmission method using rotating LEDs. In addition, two visual transmission techniques in displays-based-ISC using brightness-difference and high-frequency flashing are introduced, respectively. This paper intuitively explains these ISC techniques and reveals ISC's high versatility.
MAP estimation using two temporally consecutive data for ultrasonic sensor arrays
- M. Hattori, A. Tsujii, T. Kasashima, H. Hatano, T. Yamazato
- IEICE Communications Express, vol.12, no.8, pp.444-449
- Aug. 2023
- https://doi.org/10.1587/comex.2023XBL0045
- This paper proposes MAP estimation using two temporally consecutive data using signals from eight ultrasonic sensors forming a linear array. First, we estimate the distance to the obstacle from the time difference between the eight received signals. Then, assuming that the ranging error follows a Gaussian distribution and that each of the eight ranging values is independent, we can get the existence probability of the obstacle’s position by a pair of two obtained distances. Finally, we estimate the position of the obstacle by multiplying 28 (8C2) existence probabilities obtained. The conventional method estimates the position of an obstacle by the above procedure. However, the estimation accuracy in the angular direction was poor, resulting in the spread of the existence probability in the horizontal direction. In the proposed MAP estimation using two temporally consecutive data, we obtain the existence probability of an obstacle by the procedure shown above, and then use it as a prior probability of the obstacle’s estimated position. Furthermore, we recursively perform the same process to obtain the existence probability of the obstacle. In this way, we improve the accuracy of the estimation of the position of the obstacle by the existence probability. We present the experiment results to show the effectiveness of the proposed method.
Experimental Evaluation of Rolling Shutter Based Optical OFDM Using Polarity Separated Transmission
- H. Shimizu, M. Kinoshita, K. Kamakura, T. Yamazato
- IEICE Technical Report, CS2023-20, pp.5-8
- Jul. 2023
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Communication Performance Evaluation of Dual Camera Receivers in M-PAM Rolling Shutter Based Visible Light Communication
- A. Takada, T. Saito, M. Kinoshita, K. Kamakura, T. Yamazato
- IEICE Technical Report, CS2023-21, pp.9-13
- Jul. 2023
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16QAM-OFDM Receiver Using a 1-bit ADC That Multiplies the Carrier Wave in the Digital Domain -Characterization in 2-pass Fading Channels and AWGN Channels-
- A. Isozaki, T. Yamazato, M. Saito
- IEICE Technical Report,CS2023-26, pp.30-34
- Jul. 2023
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Influence of Walsh-Hadmard codes Multiplied by pseudo-random sequences on Visible Light Communication Using an Event Camera
- D. Ehara, Z. Tang, M. Kinoshita, T. Yamazato, H. Okada, K. Kamakura, S. Arai, T. Yendo, T. Fujii
- IEICE Technical Report, CS2023-22, pp.14-17
- Jul. 2023
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- Visible light communication using an event camera in a receiver moving environment can transmit information by using Walsh-Hadmard codes. However, some parts of the Walsh-Hadmard code have a low spreading ratio and cannot be used for information transmission, which degrades communication performance. In this study, we introduced a spread spectrum communication scheme that multiplies Walsh-Hadmard codes with pseudo-random (PN) sequences and achieved improved communication performance.
A Testbed to Integrate Private 5G Networks with Visible Light Communication for Service Area Expansion
- J. Zheng, T. Yamazato, K. Naito
- IEEE Symposium on Computers and Communications (ISCC) Workshop on Optical Wireless Communications
- Jul. 2023
- https://doi.org/10.1109/ISCC58397.2023.10218188
- This paper reports an extension of the private 5G service area to the outside of the licensed area by integrating visible light communication (VLC). As VLC is license-free, integrating the VLC function into the private 5G networks gives a more flexible system design. For example, it will be possible to provide services to mobile vehicles and robots working outside the service area of a private 5G network. Alternatively, private 5G networks in different locations can be connected. A challenge is integrating the VLC function into a 5G core network. We successfully designed a testbed and an experiment using open-source 5G projects to evaluate and compare methods to integrate VLC and private 5G, including the simulation of poor network environments. Experimental results demonstrate the availability of integrating private 5G with VLC, which are compared with image-based methods and show better latency performance.
[Keynote] Visible light communication (VLC) for cars
- T. Yamazato
- IEEE Symposium on Computers and Communications (ISCC) Workshop on Optical Wireless Communications
- Jul. 2023
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- Visible light communications (VLC) is a promising technology for automotive applications because it offers several advantages over traditional wireless communication technologies using radio waves. For example, VLC is more secure, as it is difficult to intercept VLC signals, and VLC is more reliable, as VLC signals are less susceptible to interference from other signals. As a result of these advantages, VLC is being considered for various automotive applications, such as in-car infotainment and navigation systems, advanced driver assistance systems (ADAS), and autonomous driving. In this talk, he will explain VLC for cars using image sensor communication, one of the VLCs that use a camera as a receiver.
Simultaneous Visible Light Communication and Ranging Using High-Speed Stereo Cameras Based on Bicubic Interpolation Considering Multi-Level Pulse-Width Modulation
- R. Huang, M. Kinoshita, T. Yamazato, H. Okada, K. Kamakura, S. Arai, T. Yendo, T. Fujii
- IEICE Transactions on Fundamentals, vol.E106-A, no.7, pp.990-997
- Jul. 2023
- https://doi.org/10.1587/transfun.2022EAP1078
- Visible light communication (VLC) and visible light ranging are applicable techniques for intelligent transportation systems (ITS). They use every unique light-emitting diode (LED) on roads for data transmission and range estimation. The simultaneous VLC and ranging can be applied to improve the performance of both. It is necessary to achieve rapid data rate and high-accuracy ranging when transmitting VLC data and estimating the range simultaneously. We use the signal modulation method of pulse-width modulation (PWM) to increase the data rate. However, when using PWM for VLC data transmission, images of the LED transmitters are captured at different luminance levels and are easily saturated, and LED saturation leads to inaccurate range estimation. In this paper, we establish a novel simultaneous visible light communication and ranging system for ITS using PWM. Here, we analyze the LED saturation problems and apply bicubic interpolation to solve the LED saturation problem and thus, improve the communication and ranging performance. Simultaneous communication and ranging are enabled using a stereo camera. Communication is realized using maximal-ratio combining (MRC) while ranging is achieved using phase-only correlation (POC) and sinc function approximation. Furthermore, we measured the performance of our proposed system using a field trial experiment. The results show that error-free performance can be achieved up to a communication distance of 55 m and the range estimation errors are below 0.5 m within 60 m.
Reduction of Noise Power by Iterative Short-Term Power Delay Profile Estimation
- F. Ojika, T. Yamazato, M. Saito, H. Omote, A. Sato, S. Kimura, S. Tanaka, H. Lin
- IEEE Vehicular Technology Conference (VTC)
- Jun. 2023
- https://doi.org/10.1109/VTC2023-Spring57618.2023.10201065
- This paper proposes a new estimation method of short-term power delay profile to reduce the noise power included in the short-term power delay profile. By reducing the noise, the multipath signal components buried in the noise can be utilized, thereby reducing the transmitted signal power and extending the cell range of a mobile communications. The proposed method iteratively creates the short-term power delay profile while lowering the threshold which distinguishes between signal and noise. The purpose of the threshold is to suppress the noise in each profile and to extract the effective multipath components. Furthermore, the method aligns and averages the phase of each instantaneous delay profile. In this way, only the noise component can be reduced while maintaining a high multipath power. As a result, we successfully reduced the noise power by 15 dB by analyzing the raw data of 200 instantaneous delay profiles measured in the 50 MHz bands at 3.35 GHz. Furthermore, the delay spread increased from 0.66 μs to 1.47 μs.
Extended frequency coverage of clutter loss model for high base station environments
- H. Omote, A. Sato, S. Kimura, S. Tanaka, H. Y. Lin, T. Yamazato
- IEEE Vehicular Technology Conference (VTC), pp. 1-4
- Jun. 2023
- https://doi.org/10.1109/VTC2023-Spring57618.2023.10199433
- High-Altitude Platform Station (HAPS) has recently been attracting much attention as a new mobile communication platform for ultra-wide coverage areas and disaster-resilient networks since it can provide communication services from an altitude of approximately 20 km via a balloon, an Unmanned Aerial Vehicle (UAV) or other aircraft. In order to design efficient cell configurations for HAPS-based services, we need radio wave propagation models that consider various factors of vegetation, terrain, urban-suburban areas, and building entry loss. This paper focuses on propagation loss at high-elevation angles in urban and suburban areas. Recommendation ITU-R (International Telecommunication Union Radio communication sector) P.2108-1 describes the clutter loss model, which is the propagation loss caused by features such as buildings. The applicable frequency for ITU-R P.2108-1 is above 10 GHz; however, this model has no parameters for urban structure. Therefore, it needs to consider a correction for an urban structure to precisely evaluate clutter loss. We propose a new model that corrects Recommendation ITU-R P.2108 using shielding building heights as the urban structure. Since this new model was created based on measurements from 0.7 GHz to 5.7 GHz, the applicable frequencies are from 0.7 GHz to 5.7 GHz. Therefore, it is necessary to confirm whether the model applies to frequencies above 5.7 GHz. This paper compares the results of new propagation measurements at 29.3 GHz using a helicopter with the predicted results of the proposed model. The results show that the proposed model is applicable above 5.7 GHz.
Visible Light Communications
- T. Yamazato
- IEICE Tokai Section 2023 1st General Lecture
- Jun. 2023
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- This lecture introduces Visible Light Communication (VLC) using visible light (visible light). The principle of VLC and the application of VLC using a high-speed image sensor for automotive applications that the speaker is working on will be explained with the latest technological trends.
A Review on Image Sensor Communication and Its Applications to Vehicles
- R. Huang, T. Yamazato
- Photonics, vol.10, no.6, 617
- Jun. 2023
- https://doi.org/10.3390/photonics10060617
- Image sensor communication (ISC), also known as optical camera communication, is a form of visible light communication that utilizes image sensors rather than a single photodiode, for data reception. ISC offers spatial separation properties and robustness to ambient noise, making it suitable for outdoor applications such as intelligent transportation systems (ITSs). This review analyzes the research trends in ISC, specifically concerning its application in ITSs. Our focus is on various ISC receivers, including rolling shutter cameras, global shutter high-speed cameras, optical communication image sensors, and event cameras. We analyze how each of these receivers is being utilized in ISC vehicular applications. In addition, we highlight the use of ISC in range estimation techniques and the ability to achieve simultaneous communication and range estimation. By examining these topics, we aim to provide a comprehensive overview of the role of ISC technology in ITSs and its potential for future development.
Experimental Demonstration of Optical OFDM With Polarity-Separated Transmission in Rolling Shutter Based Visible Light Communication
- H. Shimizu, K. Kanata, M. Kinoshita, K. Kamakura, S. Arai, T. Yamazato
- 2023 IEEE International Symposium on Circuits and Systems (ISCAS)
- May 2023
- https://doi.org/10.1109/ISCAS46773.2023.10181518
- Using a rolling shutter camera as a receiver, visible light communication (VLC) can achieve a significantly higher sampling rate than the frame rate because of its sequential exposure mechanism. This study focuses on optical orthogonal frequency division multiplexing (OFDM) in a rolling shutter based VLC for further high-speed data rates. Because an image sensor is employed, conventional optical OFDM, such as DC-biased optical OFDM (DCO-OFDM), must fit in the grayscale range of 0–255 levels. Therefore, DCO-OFDM suffers from poor error performance owing to its high PAPR. To address this problem, we propose a polarity-separated transmission, in which the bipolar OFDM signal is separated into positive and negative parts and then transmitted by two LEDs simultaneously. Polarity-separated transmission is expected to double the grayscale range, i.e. 0–511, and improve error performance because it reconstructs the original bipolar signal by combining the received signals from two LEDs. We experimentally demonstrate and compare the symbol error rate (SER) performance of DCO-OFDM and polarity-separated transmissions. Consequently, polarity-separated transmission improved the SER performance by 10– 2 in the fundamental frequency range of 300–700 Hz when 16-PSK was adopted for subcarrier modulation.
Obstacle position estimation using measured distance with error in ultrasonic measurements
- A. Tsujii, T. Kasashima, H. Hatano, T. Yamazato
- IEICE General Conference, B-15-15, p.417
- Mar. 2023
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Proposal of a method to improve position estimation in multiple obstacles with ultrasonic arrays
- M. Hattori, A. Tsujii, T. Kasashima, H. Hatano, T. Yamazato
- IEICE General Conference, B-5-69, p.314
- Mar. 2023
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2D Encoding for Visible Light Communication Using Dual Orthogonal Rolling Shutter Image Sensors
- A. Otsuka,Z. Tang,T. Yamazato
- IEICE General Conference, A-9-4, p.83
- Mar. 2023
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Analysis of Event Occurrence under the Moving Situation of the Event-Based Camera
- K. Furukawa, T. Yamazato, D. Ehara, H. Okada, M. Kinoshita, T. Yendo, S. Arai, K. Kamakura, T. Fujii
- IEICE General Conference, A-9-3, p.82
- Mar. 2023
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Communication Performance Improvement for Rolling Shutter Based Visible Light Communication Using Polarity-Separated Optical OFDM
- H. Shimizu, K. Kaneda, M. Kinoshta, K. Kamakura, T. Yamazato
- IEICE General Conference, A-9-5, p.84
- Mar. 2023
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Evaluation of the effect of nonlinear amplifiers on the input/output analysis of 1-bit-ADC
- A.Isozaki, T.Yamazato, M.Saito, H.Hatano
- IEICE General Conference, B-5-19, p.264
- Mar. 2023
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16QAM/OFDM Signal Reception Experiment Using Noise and 1bit ADC
- T. Ohtaguro, M. Saito, T. Yamazato
- IEICE General Conference, B-5-20, p.265
- Mar. 2023
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2D coding to improve the communication speed of visible light communications using two orthogonally arranged rolling shutter cameras.
- A. Otsuka
- IEICE Tokai-Section, Graduation Research Presentation, 2-3
- Mar. 2023
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Analysis of changes in background brightness in a receiver moving environment using event cameras.
- K. Furukawa
- IEICE Tokai-Section, Graduation Research Presentation, 2-10
- Mar. 2023
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Evaluation of the impact of nonlinear amplifiers on 1-bit ADC receivers that take advantage of noise.
- A.Isozaki
- IEICE Tokai-Section, Graduation Research Presentation, 2-8
- Mar. 2023
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Experimental study on reception of 16QAM-OFDM signals using wideband noise and 1bit ADC
- T. Ohtaguro, M. Saito, T. Yamazato
- IEICE Technical Report, RCS2022-247, pp.1-8
- Mar. 2023
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Evaluation of Demodulation Error Performance for Parallel Transmission Image Sensor-based VLC Using M-point Combinatory Modulation
- T. Sato, K. Kamakura, M. Kinoshita, T. Yamazato
- IEICE Technical Report, CS2022-79, pp.35-40
- Mar. 2023
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[Invited Lecture] Image Sensor Communications These Days
- T. Yamazato
- IEICE Technical Report, WBS2022-43, pp. 48-53, Ritsumeikan University, BKC, EPOCH RITSUMEI 21, 3F
- Dec. 2022
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- Image sensor communication (ISC) is a visible light communication that uses a two-dimensional sensor such as a CMOS image sensor as a receiver. It is basically the same as optical camera communication (OCC) standardized in IEEE 802.15.7. However, we call it ISC in this paper after Mr. Nobuo Iizuka of Casio Computer Co. ISC is characterized by the use of two-dimensional sensors and therefore has spatial separation characteristics. Furthermore, by using LED arrays, spatial parallel transmission is possible. It also has unique characteristics not found in visible light communication that use a PD as a receiver, such as the ability to communicate and ranging (position estimation) simultaneously. This paper describes the outline of image sensor communication these days; visible light communication that uses a high-speed camera, a rolling shutter image sensor, and an event camera as receivers.
An Experimental Study on A Noise-aided 1-bit ADC Receiver for 4-PAM
- J. Zheng, T. Yamazato, M. Saito
- IEICE Communications Express, vol.11, no.12, pp.817-822
- Dec. 2022
- https://doi.org/10.1587/comex.2022COL0032
- 1-bit analog-to-digital converters (ADCs) have low power consumption and can easily speed up the analog-to-digital conversion and sampling. However, due to their resolution of only 1 bit, the nonlinearity between the input with multiple amplitude levels and output is large. With the method of utilizing noise proposed in previous studies, 1-bit ADCs can be linearized to demodulate signals with multi-level amplitude modulation like pulse amplitude modulation (PAM) and quadrature amplitude modulation (QAM). In this letter, we construct a receiver circuit using a 1-bit ADC, evaluate its performance, and show its availability through demodulation experiments on 4-PAM signals.
A. Tsujii, T. Kasashima, Y. Hatano, T. Yamazato
- Design and Evaluation of the Ultrasonic Sensor Array System for Low-Speed Vehicle
- IEICE Transactions on Communications, Vol.J105-B, No.12, pp.918-927
- Dec. 2022
- https://doi.org/10.14923/transcomj.2022JBP3008
- We aim to develop a system using ultrasonic sensors for an autonomous low-speed vehicle by solving ultrasonic sensors' detection distance and speed problems. The proposed system uses a fan-shaped beam that arrays the transmitters vertically to the detection plane. Experimental results show that the proposed system can detect and estimate the position of an obstacle driving at 20 km/h at a distance of 15 m. These results show that the proposed system is effective in low-speed driving conditions.
Position estimation method using recursive MAP estimation for ultrasonic sensor arrays
- M. Hattori, A. Tsujii, T. Kasashima, H. Hatano, T. Yamazato
- International Conference on Emerging Technologies for Communications (ICETC), O5-5, Waseda University
- Dec. 2022
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- We are working on the measurement of obstacle positions by an ultrasonic sensor array. This paper proposes a recursive position estimation method using signals from eight ultrasonic sensors forming a linear array. First, we estimate the distance to the obstacle from the time difference between the eight received signals. Then, assuming that the ranging error follows a Gaussian distribution and that each of the eight ranging values is independent, we can get the existence probability of the obstacle's position by a pair of two obtained distances. Finally, we estimate the position of the obstacle by multiplying 28 (8C2) existence probabilities obtained. The conventional method estimates the position of an obstacle by the above procedure. However, the estimation accuracy in the angular direction was poor, resulting in the spread of the existence probability in the horizontal direction. In the proposed recursive position estimation, we obtain the existence probability of an obstacle by the procedure shown above, and then use it as the prior probability of the obstacle's estimated position. Furthermore, we recursively perform the same process to obtain the existence probability of the obstacle. In this way, we improve the accuracy of the estimation of the position of the obstacle by the existence probability. We present the experiment results to show the effectiveness of the proposed method.
Influence of Walsh-Hadamard Code Sequency in Visible Light Communication Using an Event Camera
- D. Ehara, Z. Tang, M. Kinoshita, T. Yamazato, H. Okada, K. Kamakura, S. Arai, T. Yendo, T. Fujii
- International Conference on Emerging Technologies for Communications (ICETC), S9-5, Tokyo
- Dec. 2022
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[Technology Exhibit] An Implementation of Propeller-type Rotary LED Transmitter for Event Camera-based Image Sensor Communication
- Z. Tang, T. Yamazato, S. Arai
- IEICE Technical Report, SR2022-55, pp.52-57, Fukuoka
- Nov. 2022
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Synchronization Method for Time Division Multiplexed Image Sensor Communication with Phase Shift Keying
- H. Matsunaga, T. Yendo, S. Arai, T. Yamazato
- Multiple Innovative Kenkyu-kai Association for Wireless Communications (MIKA), Niigata
- Oct. 2022
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Considerations of Transmit Waveforms in Image Sensor Communications Based on I/Q Demodulator
- K. Kai, T. Yendo, S. Arai, T. Yamazato
- Multiple Innovative Kenkyu-kai Association for Wireless Communications (MIKA), Niigata
- Oct. 2022
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For an experimental verification of MIMO-OFDM signals reception using noise and 1-bit ADCs
- M. Saito, T. Yamazato
- Multiple Innovative Kenkyu-kai Association for Wireless Communications (MIKA), Niigata
- Oct. 2022
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LED Array Acquisition For Road-to-Vehicle Visible Light Communication Using Spatial-Temporal Gradient Values For a High-Speed Vehicle
- K.Nakamura,T.Yamazato,M.Kinoshita,H.Okada,K.Kamakura,S.Arai,T.Yendo,T.Fujii
- Multiple Innovative Kenkyu-kai Association for Wireless Communications (MIKA), Niigata,Japan
- Oct. 2022
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- For the development of Intelligent Transport Systems (ITS), road-to-vehicle Visible Light Communication(VLC) has been expected. In this study, we considered a case where the transmitter position in the captured image of the vehicle's receiver move at high speed. We propose a method to detect the amount of movement of the transmitter in the captured image by analyzing the time-gradient value of the parallel shift of the captured image using image processing. We conducted an experiment in a high-speed driving environment. We detected the movement of the transmitter in the captured image, corrected for the movement, and calculated the spatial-temporal gradient values. In this way, it is possible to acquire the LED array in the captured image. Furthermore, we confirmed that it is possible to demodulate data error-free from the acquired LED array.
A Study on Frequency Estimation by using Multiple Ultrasonic Sensors for Burst Signals
- T. Matsushima, H. Hatano, K. Sanada, K. Mori, A. Tsuji, T. Kasashima, T. Yamazato
- IEICE Technical Report, ITS2022-6, pp.1-6, Tokyo
- Sep. 2022
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A Study on Receiving SFBC-MIMO-OFDM Signals by 1bit ADC and Oversampling
- M. Saito, T. Yamazato
- Enginnering Sciences Society Conference of IEICE, A-9-8, p.54, online
- Sep. 2022
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Development of Rotary LED Transmitter for High-Speed Image Sensor Communication
- S. Arai, Z. Tang, T. Yamazato, T. Yendo
- Enginnering Sciences Society Conference of IEICE, AS-2-1, pp.S-4 - S-5, online
- Sep. 2022
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A Study on Communication Performance of PD-Type Visible Light Communication Using Stochastic Resonance
- H. Fujii, S. Arai, T. Yamazato, H. Hatano, M. Saito
- Enginnering Sciences Society Conference of IEICE, AS-2-3, pp.S-8 - S-9, online
- Sep. 2022
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Roadside LED Array Acquisition For Road-to-Vehicle Visible Light Communication Using Spatial-Temporal Gradient Values
- K. Nakamura, R. Huang, T. Yamazato, M. Kinoshita, K. Kamakura, S. Arai, T. Yendo, T. Fujii
- IEICE Communications Express, vol.X11-B, no.8, pp. -
- Aug. 2022
- https://doi.org/10.1587/comex.2022TCL0008
- Most of the previous research on the acquisition of the LED Array transmitter assumes that the onboard receiver approaches the LED transmitter from the car’s front. In this study, we considered a case where the vehicle’s receiver crosses the LED transmitter. This letter modifies the algorithm using spatial-temporal gradient values to detect LED arrays. As a result, we achieved error-free acquisition and successfully communicated up to 9728 [bits] at a vehicle speed of 25 [km/h].
Visible Light Communication System Using Rolling Shutter Image Sensor for ITS
- S. Kamiya, Z. Tang, T. Yamazato,
- IEEE ICC Workshop on Optical Wireless Communications (OWC), Seoul, South Korea
- May 2022
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- In this study, we investigate the application of visible light communication (VLC) to intelligent transport systems (ITS) using rolling shutter image sensors as receivers. The use of a global shutter high-speed image sensor as a receiver has been widely examined in ITS-VLC so far. However, this image sensor is impractical for general-purpose applications due to the high cost. This study aims to perform ITS-VLC using the rolling shutter image sensor. The rolling shutter image sensor is widely used in the smartphone camera. By using it as a receiver, ITS-VLC can be used in more opportunities. In this study, we propose a ITSVLC system using rolling shutter image sensor. The proposed system demodulates data from images captured in a moving environment. We evaluate the communication performance by measuring the bit error rate for the ITS-VLC experiments.
A Preliminary Investigation For Event Camera-Based Visible Light Communication Using The Propeller-type Rotary LED Transmitter
- Z. Tang,T. Yamazato, S. Arai
- IEEE ICC Workshop on Optical Wireless Communications (OWC), Seoul, South Korea
- May 2022
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- This study investigates a new communication scheme for the event camera-based visible light communication (VLC) using a propeller-type rotary LED transmitter. Conventional camera-based VLC suffers from low data rates and high latency due to the limited camera frame rates. To solve this problem, the event camera has been used as the receiver in VLC. Event cameras detect changes in brightness and asynchronously output these changes as events in microsecond order. The high temporal resolution gives the event camera-based VLC good potential in terms of high speed and low latency. However, when an event camera is used as the VLC receiver, the light of the transmitter needs to be changed constantly. If the transmitter LED is continuously in the same blinking state, the event camera may not output any events and the data could not be recovered until the blinking state changes. To transmit the optical signal for event cameras, we use a propeller-type rotary LED transmitter for the event camera-based VLC. The transmitter rotates the blinking LED in circles and uses the afterimage of LED light to transmit signals. The event camera detects the afterimages and constantly outputs them as a stream of events. We filter the noise events and recover data using signal events. This study verifies the operation for the proposed system through an implementation experiment. As a result, we achieved the communication in the proposed system and provided a basic evaluation in terms of communication speed and quality.
Performance Evaluation of RSSI-Based Positioning with Dither method by using Interference Signals
- S. Horiuchi, H. hatano, K. Sanada, K. Mori, T. Yamazato, S. Arai, M. Saito, K. Tadokoro, H. Tanaka
- IEICE General Conference, A-13-8, p.104, online
- Mar. 2022
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An Experimental Study on A Noise-aided 1-bit ADC Receiver for 4-PAM
- J. Zheng, T. Yamazato
- IEICE General Conference, B-8-24, p.148, online
- Mar. 2022
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Design of the ultrasonic sensor array system for slow vehicle
- A. Tsujii, T. Kasashima, H. Hatano, T. Yamazato
- IEICE General Conference, B-15-16, p.454, online
- Mar. 2022
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Reduction of Noise Power by Multi-stage Estimation of Delay Profile in 3.35 GHz Mobile Environment
- F.Ojika, T.Yamazato, M.Saito, S.Kimura, S.Tanaka, H.Lin, A.Sato, H.Omote
- IEICE General Conference, B-1-44, p.44, Online
- Mar. 2022
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Multi-stage estimation of delay profiles using phase estimation and phase correction in 3.35 GHz multipath environment
- F. Ojika
- IEICE Tokai Section Graduation Research Presentation, 5-4, p.67, online
- Mar. 2022
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Simplified Alamouti-Type Space-Time Coding for Image Sensor Communication Using Rotary LED Transmitter
- Z. Tang, S. Arai, T. Yamazato
- IEEE Photonics Journal, vol. 14, no. 1, pp. 1-7
- Feb. 2022
- https://doi.org/10.1109/JPHOT.2021.3137601
- This study proposes a simplified Alamouti-type space-time coding (STC), improving the performance of image sensor communication (ISC) using a rotary LED transmitter. The rotary LED transmitter was developed to increase the data rate of ISC using afterimages of LED lights. The transmitter simultaneously causes the LEDs to blink and rotates them around a vertical axis. Owing to the movement of the blinking LEDs that occurs within the exposure time of the camera, multiple blinking states are captured as afterimages, thus increasing the amount of information that can be received per image. However, with increasing communication distance, the size of the LED light captured on the image sensor decreases. In this case, it is difficult to distinguish each LED blinking state, leading to a degradation of the demodulation performance. To overcome this problem, the proposed STC encodes adjacent angular afterimages as symbol pairs and transmits these symbol pairs using two symbol times. In addition, we simplified the data decoding process by using normalized LED luminance values. We evaluate the demodulation performance of the proposed method through experiments. Compared with conventional coding methods, the proposed STC requires no channel estimation and significantly improves the demodulation performance.
Performance Enhancement of Rolling Shutter Based Visible Light Communication via Selective Reception Using Dual Cameras
LED array acquisition in Road to Vehicle Visible Light Communication when receiver crosses transmitter
- K. Nakamura, T. Yamazato, M. Kinoshita, K. Kamakura, S. Arai, T. Yendo, T. Fujii
- International Conference on Emerging Technologies for Communications (ICETC), online
- Dec. 2021
- https://doi.org/10.34385/proc.68.B3-5
- Intelligent Transport Systems Visible Light Communication (ITS-VLC) is attracting significant attention as a solution to solve various problems that vehicles have, or for the installation of new systems in the vehicles. In ITS-VLC, the acquisition of the VLC transmitter via
light-emitting diodes (LEDs) in the onboard camera’s captured image is the first and essential step when receiving the VLC signal. Most of the previous research on the acquisition of the LEDs assumes that the vehicles approach the LEDs source from the front of the vehicle. However, there are many situations in which vehicles cross the LEDs. In this study, we considered a case in which the vehicle’s receiver crosses the LED transmitter. We modified the acquisition algorithm based on the spatial-temporal gradient utilized in our model in which the transmitter and the receiver cross each other. We found that we can acquire the transmitter by correcting the difference of the ransmitter’s position in the captured image. When validating the specific signal, we achieved 100% acquisition success rate.
WWRF46 Panel Session
- T. Yamazato
- Wireless World Research Forum Meeting 46, Paris, France
- Dec. 2021
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- Optical wireless communication has been around since the 1980s. Why has its time come now in 5G/6G? What is the change?
Experimental Verification of 4-ary Pulse Amplitude Modulated Signal Receiver with Noise-added One-bit Analogue-to-digital Converter
- T. Ohtaguro, M. Saito, T. Yamazato
- International Conference on Materials and Systems for Sustainability (ICMaSS), online
- Nov. 2021
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A Cancellation of Inter-LEDs Interference Using Deconvolution In Visible Light Communication between LED Traffic Light and High-speed Image Sensor
- T. Yamamoto, T. Yamazato, H. Okada, M. Kinoshita, K. Kamakura, S. Arai, T. Yendo, T. Fujii
- IEICE Transactions on Communications, vol.J104-B, no.11, pp.938-948
- Nov. 2021
- https://doi.org/10.14923/transcomj.2021JBP3004
Experimental Study on Noise Aided 4PAM Receiver with 1bit ADC
- T. Ohtaguro, M. Saito, T. Yamazato
- Multiple Innovative Kenkyu-kai Association for Wireless Communications (MIKA), Naha/online
- Oct. 2021
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Can Optical Wireless Communication Be a Candidate for Post 5G or 6G?
- T. Yamazato, S. Arai, M. Kinoshita
- Communications Society Conference of IEICE, BI-5-5, pp.SS-69 - SS-70, online
- Sep. 2021
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Comparison of Distance Performances of Modulation Schemes in Intelligent Transport System Image Sensor Communication
- T. Yamamoto, T. Yamazato, H, Okada, M. Kinoshita, K. Kamakura, S. Arai, T. Yendo, T. Fujii
- IEICE Communications Express, vol.10, no.8, pp.498-504
- Aug. 2021
- https://doi.org/10.1587/comex.2021ETL0032
- This study describes intelligent transport image sensor communication (ITS-ISC) systems that use LED arrays as transmitters that imitate traffic lights. Three signal-transmission schemes -luminance modulation, spatial modulation, and combined luminance and spatial modulation- use LED array. However, their suitability for ITS-ISC has not been explored yet. Therefore, we compare the communication performance of these three systems under strong saturation and present the results.
[Poster Presentation] A Study on Signal Demodulation Method for LED Visible Light Communication Using Event Based Camera
- Y. Ohira, T. Yendo, T. Yamazato, S. Arai
- IEICE Technical Report, WBS2021-25, pp.19-23, online
- Jul. 2021
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[Poster Presentation] Multiple Access Method for Image-Sensor-Based Visible Light Communication Using Coded Exposure
- H. Matsunaga, T. Yendo, S. Arai, T. Yamazato
- IEICE Technical Report, WBS2021-29, pp.39-44, online
- Jul. 2021
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Visible Light Vehicle Ranging using High-speed Stereo Cameras
- Ruiyi Huang, Takaya Yamazato, Hiraku Okada, Masayuki Kinoshita, Shintaro Arai, Koji Kamakura, Tomohiro Yendo, Toshiaki Fujii
- IEICE Technical Report, CS2021-22, pp.33-37, Yakushima, Japan
- Jul. 2021
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- This study presents a performance evaluation of range estimation between vehicles and infrastructures in an ITS-VLC system. In the proposed ITS-VLC system, it is easy to simultaneously conduct communication and ranging using stereo cameras. However, the stereo camera calibration becomes a problem during simultaneous communication and ranging due to vehicle vibration. Using the data from LED transmitters and stereo cameras, it can obtain multiple measurements of distance. The monocular-stereo fusion algorithm is applied to visible light ranging in the proposed scheme using particle swarm optimization. We employed real data from the field trial experiment and achieved a ranging accuracy of 60 +- 1.0 m.
Light Sources Combination Modulation for Parallel Transmission Image Sensor-based Visible Light Communication
- T. Sato, K. Kamakura, M. Kinoshita, T. Yamazato
- IEICE Technical Report, CS2021-15, pp.9-14, online
- Jul. 2021
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Luminance Inversion for LCD and Camera Parallel Transmission Visible Light Communication
- K. Takahashi, K. Kamakura, M. Kinoshita, T. Yamazato
- IEICE Technical Report, CS2021-20, pp.25-30, online
- Jul. 2021
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Vehicle Distance Measurement based on Visible Light Communication Using Stereo Cameras
- R. Huang, T. Yamazato, M. Kinoshita, H. Okada, K. Kamakura, S. Arai, T. Yendo, T. Fujii
- IEEE Intelligent Vehicles Symposium, Nagoya, Japan
- Jul. 2021
- https://doi.org/10.1109/IV48863.2021.9575534
- Visible light communication based intelligent transportation systems (ITS-VLC) show great potential for future urban mobility. This study presents a performance evaluation of range estimation between vehicles and infrastructures in an ITS-VLC system. In the proposed ITS-VLC system, it is easy to simultaneously conduct communication and ranging using stereo cameras. However, the stereo camera calibration becomes a problem during simultaneous communication and ranging due to vehicle vibration. Using the data from LED transmitters and stereo cameras, it can obtain multiple measurements of distance. The monocular-stereo fusion algorithm is applied to visible light ranging in the proposed scheme using particle swarm optimization. We employed real data from the field trial experiment and achieved a ranging accuracy of 60±1.0 m.
Error Reduction Method employing Dither Method with Interfering Signals for Distance Estimation Technique
- S. Horiuchi, H. Hatano, K. Sanada, K. Mori, T. Yamazato, S. Arai, M. Saito, K. Tadokoro, H. Tanaka
- IEICE Technical Report, ITS2021-1, pp.1-6, online
- Jul. 2021
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Method for considering angle error in the position estimation of a moving target using ultrasonic array
- M. Hattori, A. Tsujii, T. Kasashima, H. Hatano, T.Yamazato
- IEICE Communications Express, vol.10, no.7, pp.374-379
- Jul. 2021
- https://doi.org/10.1587/comex.2021XBL0088
- In this study, we propose a method for reducing angle error in position estimation of a moving target. The distance between the transmitting array and target is approximated by two receiving sensors close to the transmitting array. This enables more accurate distance measurement between the receiving sensor and the target.
Initial Study of Demodulation Method for ITS Visible Light Communication Using Rolling Shutter Image Sensor
- S. Kamiya, T. Yamazato, H. Okada, T. Fujii, M. Kinoshita, K. Kamakura, S. Arai, T. Yendo
- IEICE Technical Report, RCS2021-52, pp.139-144, online
- Jun. 2021
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- This paper focuses on a receiver of image sensor communication for the intelligent transportation system (ITS). The use of a global shutter image sensor as a receiver has been widely examined in ITS Visible Light Communication so far. However, this image sensor has not been widely used due to its high cost. Therefore, in this paper, the initial study of ITS Visible Light Communication using the rolling shutter image sensor is performed. The rolling shutter method is also used in smart phones, and the ITS Visible Light Communication can be used in many occasions by using it as a receiver. In this study, the communication system using the LED array for the transmitter and the rolling shutter method image sensor for the receiver was constructed in the short distance static environment, and the influence that the photographing condition such as the exposure time gives to the communication quality was confirmed by doing the photographing experiment.
An experimental study on the demodulation of 4-PAM signals using 1bit ADC with noise
- T. Ohtaguro, M. Saito, T. Yamazato
- IEICE Technical Report, RCS2021-51, pp.133-138, online
- Jun. 2021
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Circuit Experiment of Photodiode-Type Visible Light Communication Using the Stochastic Resonance Generated by Interfering Light Noise
- S. Arai, W. Tamura, T. Yamazato, H. Hatano, M. Saito, H. Tanaka, and Y. Tadokoro
- IEEE International Symposium on Circuits and Systems (ISCAS), pp. 1-5, Daegu, Korea (On-site & Virtual)
- May 2021
- https://doi.org/10.1109/ISCAS51556.2021.9401452
- This study focuses on visible light communication (VLC) using a photodiode as a receiver. Accurate data transmission by this type of VLC is a challenge because the photodiode cannot detect weak light of subthreshold intensity owing to its insufficient light sensitivity. To overcome this problem, we employ a stochastic resonance, which is a nonlinear phenomenon in which the response characteristics of a system improve as its noise intensity increases, for the receiver of this VLC system. We also employ additive light-emitting diode light, which interferes in the photodiode as intentional noise. As an experimental result, the stochastic resonance was achieved by setting the parameters of the noise source appropriately, and we recovered the weak transmitting signal at the receiver.
Experimental evaluation of a long distance and high speed 8×8 MIMO optical wireless communication system
- T. Nakamura, C. Ben Naila, K. Kobayashi, H. Okada, M. Katayama
- IEICE General Conference, A-9-3, p.88, Online
- Mar. 2021
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A channel estimation and demodulation in a noise-aided 1bit ADC receiver
- Y. Nakashima, T. Yamazato, S. Arai, M. Saito, H. Hatano, H. Tanaka, Y. Tadokoro
- IEICE General Conference, B-8-27, p.148, online
- Mar. 2021
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Determination Method of Data Receiving Range for Alamouti-type Space-Time Coding in Image Sensor Communication Using a Rotary LED Transmitter
- Z. Tang, S. Arai, T. Yamazato
- IEICE General Conference, A-9-4, p.89, online
- Mar. 2021
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A Method for Improving Accuracy of Position Estimation of Moving Objects Using Ultrasonic Array
- M. Hattori
- IEICE Tokai Branch Graduation Research Meeting, 2-2, Online
- Mar. 2021
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A study of demodulation method in ITS visible light communication using rolling shutter type image sensor
- S. Kamiya
- IEICE Tokai Branch Graduation Research Meeting, 2-7, Online
- Mar. 2021
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[Poster Presentation] Experimental Evaluation for Alamouti-type Spatio-temporal Coding in Image Sensor Communication Using a Rotary LED Transmitter
- Z. Tang, S. Arai, T. Yamazato
- IEICE Technical Report, WBS2020-44, pp.86-91, online
- Mar. 2021
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[Poster Presentation] Performance Enhancement of Rolling Shutter Based Visible Light Communication by Selective Reception Using Dual Camera
- S. Ibaraki, T. Toguma, S. Yamaguchi, M. Kinoshita, K. Kamakura, T. Yamazato
- IEICE Technical Report, WBS2020-48, pp.110-114, online
- Mar. 2021
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LEO-MIMO transmission techniques using multiple Low Earth Orbit satellites
- D. Goto, F. Yamashita, T. Yamazato, R. Okema, H. Shibayama, K. Itokawa
- IEICE Technical Report, SAT2020-36, p.41, online
- Feb. 2021
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Optical Wireless Communication: A Candidate 6G Technology?
- S. Arai, M. Kinoshita, T. Yamazato
- IEICE Transactions on Fundamentals, vol.E104-A , no.1, pp.227-234
- Jan. 2021
- https://doi.org/10.1587/transfun.2020WBI0001
- We discuss herein whether an optical wireless communication (OWC) system can be a candidate for post 5G or 6G cellular communication. Almost once per decade, cellular mobile communication is transformed by a significant evolution, with each generation developing a distinctive concept or technology. Interestingly, similar trends have occurred in OWC systems based on visible light and light fidelity (Li-Fi). Unfortunately, OWC is currently relegated to a limited role in any 5G scenario, but the debate whether this is unavoidable has yet to be settled. Whether OWC is adopted post 5G or 6G is not the vital issue; rather, the aim should be that OWC coexists with 5G and 6G communication technologies. In working toward this goal, research and development in OWC will continue to extend its benefits and standardize its systems so that it can be widely deployed in the market. For example, given that a standard already exists for a visible-light beacon identifier and Li-Fi, a service using this standard should be developed to satisfy user demand. Toward this end, we propose herein a method for visible-light beacon identification that involves using a rolling shutter to receive visible-light communications with a smartphone camera. In addition, we introduce a rotary LED transmitter for image-sensor communication.
Deep Learning Detection for superimposed control signal in LEO-MIMO
- R. Okema, D. Goto, T. Yamazato, F. Yamashita, H. Shibayama
- IEEE Global Communications Conference (GLOBECOM), Taipei, Taiwan
- Dec. 2020
- https://doi.org/10.1109/GLOBECOM42002.2020.9348012
- Multiple-input multiple-output (MIMO) communication systems using multiple low-Earth orbital (LEO) satellites achieve higher capacity than conventional LEO systems. However, in previous research, control signals are allocated to a different frequency band for each satellite signal in order to estimate its Doppler frequency. The increase in the number of satellites reduces unoccupied MIMO signal bandwidth and hence the overall capacity. This study aimed to prevent such capacity reduction by introducing the superimposition of control signals. Such control signals occupy a frequency bandwidth of the equivalent of only one control signal; therefore, they can prevent the reduction of the overall capacity. The main challenge is estimating the satellites' Doppler frequencies from the waveforms of Doppler-affected superimposed control signals. To overcome this challenge, we propose the adoption of a deep learning technique.
Performance Evaluation of Range Estimation for Image Sensor Communication Using Phase-only Correlation
- R. Huang, M. Kinoshita, T. Yamazato, H. Okada, K. Kamakura, S. Arai, T. Yendo, T. Fujii
- IEEE GLOBECOM Workshop on Optical Wireless Communications (OWC), Taipei, Taiwan
- Dec. 2020
- https://doi.org/10.1109/GCWkshps50303.2020.9367540
- Stereo cameras, serving as the “eyes” of automotive vehicles, can determine the distance between objects and the vehicles. In this paper, stereo cameras are introduced into image-sensor-based visible light communication (IS-VLC) systems, in which the combination of VLC and stereo ranging shows promising prospects for intelligent transport systems. However, one of the problems of IS-VLC stereo ranging is that the luminance level of LEDs in the captured images would greatly affect disparity estimation, which would result in inaccurate range estimation. This paper gives the performance evaluation of this problem using phase-only correlation algorithm with luminance election. The proposed scheme using stereo cameras exhibited a ranging accuracy of 60±0.15 m in static conditions.
A Comparison of Distance Performances of Modulation Schemes in an ITS Image Sensor Communication
- T. Yamamoto, T. Yamazato, H, Okada, M. Kinoshita, K. Kamakura, S. Arai, T. Yendo, T. Fujii
- International Conference on Emerging Technologies for Communications (ICETC), B4-1, online
- Dec. 2020
- https://doi.org/10.34385/proc.63.B4-1
- Image sensor communication uses an LED light as a transmitter and an image sensor as a receiver. LED light sources are widely used in traffic lights and car tail lights. In addition, since image sensors are used for driving assistance and drive recorder applications, image sensor communication can be used in parallel with other intelligent transport systems(ITS) applications. This study describes an ITS image sensor communication (ITS-ISC) system, which uses an LED array as a transmitter to imitate traffic lights. There are three schemes of signal transmission using an LED array: luminance modulation, spatial modulation, and both luminance and spatial modulation. However, which of these schemes is the most suitable for ITS-ISC is not yet considered. In this study, we compare the communication performance of these three modulation schemes, present-ing the configuration of an LED array capture simulator and performance comparison results.
Method for considering angle error in the position estimation of a moving target using ultrasonic array
- M.Hattori, A. Tsujii, T. Kasashima, H. Hatano, T. Yamazato
- International Conference on Emerging Technologies for Communications (ICETC), I2-4, Online
- Dec. 2020
- https://doi.org/10.34385/proc.63.I2-4
- In this study, a method for reducing the angle error in the position estimation of a target is proposed. In this method, the distance between the transmitting array and the target approximates two receiving sensors close to the transmitting array. This enables the attainment of a more accurate distance between the receiving sensor and the target.
Preliminary Circuit Experiment of Photodiode-Type Visible Light Communication by Stochastic Resonance Using Interfering Light as Intentional Noise
- S. Arai, T. Yamazato, H. Hatano, M. Saito, H. Tanaka, Y. Tadokoro
- International Symposium on Nonlinear Theory and its Application (NOLTA), pp.97-100, online
- Nov. 2020
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RSSI-based Distance Estimation Enhanced by Interference Signals
- S. Horiuchi, H. Hatano, K. Sanada, K. Mori, T. Yamazato, A. Shintaro, M. Saito, Y. Tadokoro, H. Tanaka
- International Symposium on Nonlinear Theory and its Application (NOLTA), pp.101-104, online
- Nov. 2020
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A Study on Required FFT Sizes for Demodulation of OFDM Signals by Intentionally Added Noise and 1bit ADC
- M. Saito, T. Ohtaguro, Y. Nakashima, T. Yamazato, S. Arai, H. Hatano, H. Tanaka, Y. Tadokoro
- International Symposium on Nonlinear Theory and its Application (NOLTA), pp.105-108, online
- Nov. 2020
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Experimental Performance Evaluation of Image Sensor Based Visible Light Communication Using a DMD Projector in a Driving Condition
- T. Arisue, M. Kinoshita, T. Yamazato, H. Okada, K. Kamakura, S. Arai, T. Yendo, T. Fujii
- IEICE Transactions on Fundamentals, vol.J103-A, no.11, pp.283-286
- Nov. 2020
- https://doi.org/10.14923/transfunj.2020JAL2005
Image sensor communications for automotive intelligence
- T. Yamazato
- International Conference on Optoelectronic and Microelectronic Technology and Application 2020, Nanjing, China
- Oct. 2020
-
- Almost once per decade, cellular mobile communication is transformed by a significant evolution, with each generation developing a distinctive concept or technology.
Interestingly, similar trends have occurred in visible light communication systems and vehicle automation.
In this talk, the presenter looks back to the brief history of vehicle automation and related communication technologies. He then introduces visible light communication and its application for automotive intelligence. Some of his research results on VLC for automotive applications will also be provided.
Doppler frequency estimation of Superimposed Control Signal of multiple satellites by Deep Learning in LEO-MIMO
- R. Okema, D. Goto, T. Yamazato, F. Yamashita, K. Itokawa
- IEICE Technical Report, SAT2020-19, pp.47-52, online
- Aug. 2020
-
- This paper focuses on satellite MIMO (Multi-Input Multi-Output) technology to increase the capacity of Low Earth Orbit (LEO) satellite communications. In previous research, LEO-MIMO communication requires control signals to estimate the Doppler frequencies of each satellite. The control signal is allocated a different frequency band to avoid inter-carrier interference with other signals. However, as the number of communication LEO satellites increases, the bandwidth of the control signal becomes wider and the bandwidth for the MIMO signal becomes narrower. In other words, the problem is that the capacity of LEO-MIMO decreases with the increase in the number of communication LEO satellites. Therefore, this study attempts to suppress the communication capacity reduction by superimposing control signals. This technique can improve the bandwidth of the control signal is constant regardless of the number of satellites, and suppress capacity reduction regardless the number of satellites. On the other hands, superimposed control signals technique degrades the Doppler frequency estimation accuracy due to inter-carrier interference. To tackle of the problem, we propose the novel Doppler frequency estimation using Deep learning techniques. This paper deal with Doppler shift estimation for control signals with three or more superimposed waveforms and unlearned waveforms. In order to improve the estimation accuracy, we employed convolutional neural networks in addition to deep neural networks and compared their performance.
Sequential Maximum Likelihood Decoding Incorporating Reliability Determination for Image Sensor Communication
Current Status and Issues of Visible Light Communications
- T. Yamazato
- The 2nd Geospatial Information Seminar in FY2020 co-sponsored by Hokushinetsu Branch of the Japanese Society of Photogrammetry
- Jul. 2020
-
An Analysis of a Noise-aided One-bit Analog-to-Digital Converter for a Multi-Antenna Receiver
- Y. Nakashima, T. Yamazato, S. Arai, M. Saito, H. Hatano, H. Tanaka, Y. Tadokoro
- IEICE Technical Report, CS2020-20, pp.25-26
- Jul. 2020
-
Visible light beacon
- T. Yamazato
- Signal Processing in Photonic Communications (SPPCom), The 2020 OSA Advanced Photonics Congress, 2020., Online
- Jul. 2020
-
- Since the LED (light-emitting diode) is a semiconductor device, high-speed modulation is possible. The communication for transmitting information by blinking (modulating) the LED at such a high speed that the human eye cannot recognize is called visible light communication (VLC) [1]. The visible light beacon is an exciting application of VLC that transmits the short ID. In this article, the trend of the visible light beacon, a part of VLC is described.
Nonlinear Transform for Parallel Transmission for Image-Sensor-based Visible Light Communication
A Comparison between a Noise-Aided 1bit ADC Receiver and a Linear Receiver
- Y. Nakashima, T. Yamazato, S. Arai, M. Saito, H. Hatano, H. Tanaka, Y. Tadokoro
- IEICE General Conference, B-8-38, p.185, Hiroshima
- Mar. 2020
-
Distance and Velocity Measurement of Approaching Target Via 45 kHz Ultrasonic Sensor Array
- Y.H.J Lai, A. Tsujii, T. Kasashima, T. Yamazato, H. Hatano
- IEICE General Conference, A-4-2, p.35, Hiroshima, Japan
- Mar. 2020
-
- Ultrasonic sensors are an attractive option for target detection purposes due to their low cost, functionality in all light and weather conditions and easy implementation. Multiple ultrasonic sensors arranged in an array were shown to strengthen ultrasonic waves and increase detection range at static conditions in an indoor environment. In this article, we report a conducted experiment on a moving target in an outdoor environment to analyze its performance and will aim to use the obtained data for localization in future works.
Range Estimation of LED Transmitter Using Phase-Only Correlation for ITS-VLC System via High-speed Stereo Cameras
- R. Huang, M. Kinoshita, T. Yamazato, H. Okada, K. Kamakura, S. Arai, T. Yendo, T. Fujii
- IEICE General Conference, A-9-21, p.100, Hiroshima, Japan
- Mar. 2020
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A Study on FFT Sizes of Demodulating OFDM Signals by Intentionally Added Noise and 1bit ADC
- M. Saito, Y. Nakashima, T. Yamazato, S. Arai, H. Hatano, H. Tanaka, Y. Tadokoro
- IEICE General Conference, A-9-11, p.90, Hiroshima
- Mar. 2020
-
A Study on Photo-Diode-Type Visible Light Communication by Stochastic Resonance Using Interfering Light as Noise
- M. Takaki, S. Arai, T. Yamazato, H. Hatano, M. Saito, H. Tanaka, Y. Tadokoro
- IEICE General Conference, A-9-23, p.102, Hiroshima
- Mar. 2020
-
A Study on Applying Dither Method with Interference to RSSI Based Distance Estimation
- S. Horiuchi, H. Hatano, K. Sanada, K. Mori, T. Yamazato, A. Shintaro, M. Saito, Y. Tadokoro, H. Tanaka
- IEICE General Conference, A-14-1, p.118, Hiroshima
- Mar. 2020
-
Doppler Frequency Estimation of Two Superimposed LEO-MIMO’s Control Signals by Convolutional neural networks
- R. Okema, D. Goto, T. Yamazato, F. Yamashita, H. Shibayama
- IEICE General Conference, B-3-7, p.199, Hiroshima, Japan
- Mar. 2020
-
Visible Light Communications for Automotive Intelligence
- T. Yamazato
- The Optical Networking and Communication Conference & Exhibition (OFC2020), San Diego, USA
- Mar. 2020
-
BER Measurement for Transmission Pattern Design of ITS Image Sensor Communication Using DMD Projector
- T. Arisue, T. Yamazato, H, Okada, M. Kinoshita, S. Arai, T. Yendo, K. Kamakura, T. Fujii
- IEEE Consumer Communications and Networking Conference (CCNC), Las Vegas, US
- Jan. 2020
- https://doi.org/10.1109/CCNC46108.2020.9045147
- This paper presents an image sensor communication (ISC) using a digital micromirror device (DMD) projector as a transmitter. In particular, we focus on ISC for intelligent transport systems (ITSs) because DMD projectors are expected to be used in road traffic, such as vehicle headlights, street lights, and traffic signs. The DMD projector controls light patterns by switching tilt of micromirrors at high speed. Compared to the conventional LED array transmitter, DMD projector can design and alter the shape of the light pattern and data rate of transmission more easily. In the proposed system, the data rate can be easily increased by increasing the number of multiplexes. However, as the number of multiplexes is increased, the number of received pixels on the image sensor is decreased, and thus the performance of symbol detection deteriorates. Therefore, the purpose of this paper is to examine the relation between the num- ber of received pixels per cell and communication performance for transmission pattern design. Hence, we experimentally clarify this relation using our prototype system via a DMD projector and a high-speed camera.
Range Estimation for Traffic Light based on Visible Light Communication using Stereo Cameras
- R. Huang, T. Yamazato, H. Okada, M. Kinoshita, K. Kamakura, S. Arai, T. Yendo, T. Fujii
- Workshop on Optical Wireless Communication for Smart City (OWC2), pp.49-52, Toyota, Japan
- Dec. 2019
-
- The recognition of traffic light is important in self-driving cars nowadays. In this paper, we proposed a ranging method for traffic light on the road based on stereo ranging. By introducing the idea of visible light communication, it is simple to extract the traffic light from a complicated background. Experimental result shows that it can work well for the real traffic light.
Nonlinearity Mitigation of Received Luminance Using Inverse Pattern of the LED array in Image Sensor Communication
- T. Yamamoto, T. Yamazato, H, Okada, M. Kinoshita, K. Kamakura, S. Arai, T. Yendo, T. Fujii
- Workshop on Optical Wireless Communication for Smart City (OWC2), pp.53-56, Toyota, Japan
- Dec. 2019
-
- In this research, we describe visible light communication (VLC) using an LED array as a transmitter and a high-speed image sensor as a receiver. Such VLC is called an image sensor communication (ISC), and it assigns a symbol to the multilevel brightness of the LED. An issue is a nonlinearity caused by both LED and image sensors. In order to increase the data rate, it is necessary to handle this nonlinearity. In this paper, we first show the nonlinearity by experimental results. We then show that we can ease such nonlinearity by an introduction of an inverse pattern used to track the LED array. We show by the experimental result that the inverse pattern can mitigate the nonlinearity and thus improve the data rate.
Three-Frame Demodulation for Non-Synchronous Square Wave Quadrature Amplitude Modulation
- K. Yamamura, K. Kamakura, M. Kinoshita, T. Yamazato
- Workshop on Optical Wireless Communication for Smart City (OWC2), pp.33-36, Toyota, Japan
- Dec. 2019
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An Experiment of Image Sensor Communication Using Digital Micromirror Device Projector as a Vehicle Headlight
- T. Arisue, T. Yamazato, H, Okada, M. Kinoshita, S. Arai, T. Yendo, K. Kamakura, T. Fujii
- Workshop on Optical Wireless Communication for Smart City (OWC2), pp.1-4, Toyota, Japan
- Dec. 2019
-
- This paper presents an image sensor communication (ISC) using a digital micromirror device (DMD) projector as a transmitter. In particular, we focus on ISC for intelligent transport systems (ITSs). DMD projectors are expected to use in road traffic, such as vehicle headlights, street lights, and projectors of traffic signs. Our proposed system projects data patterns on a road or signage for transmission in addition to primary lighting/display function. In this paper, we report a basic experiment of the proposed system using the DMD projector as a vehicle headlight in driving conditions.
Nonlinear Companding Scheme for Parallel Transmission for Image-Sensor-Based Visible Light Communication
- K. Takahashi, K. Kamakura, M. Kinoshita, T. Yamazato
- Workshop on Optical Wireless Communication for Smart City (OWC2), pp.9-12, Toyota, Japan
- Dec. 2019
-
Performance Evaluation of Precoded Pulse Width Modulation for Visible Light Communicatino Using Image Sensor
- S. Kamegawa, M. Kinoshita, T. Yamazato, H. Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- IEICE Transactions on Communications, vol.J102-B, no.12, pp.962-965
- Dec. 2019
- https://doi.org/10.14923/transcomj.2019JBL4002
Calibration method for an integrated ranging and visible light communication system using stereo cameras
- R. Huang, M. Kinoshita, T. Yamazato, H. Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- International Conference on Materials and Systems for Sustainability (ICMaSS), Nagoya, Japan
- Nov. 2019
-
- Camera calibration is an essential part of stereo camera system. By using stereo cameras, it enables simultaneous range estimation and visible light communication (VLC) data transmission, and we can use them for VLC-based intelligent transport system (ITS-VLC).
The ranging accuracy greatly relies on the accurate camera calibration. As the range increases, the estimation error of calibration parameters will make the ranging result worse. In this paper, we introduce stereo cameras into ITS-VLC system, and discuss the calibration method for range estimation. Considering the effect of camera calibration, the proposed scheme using stereo cameras confirms a great ranging accuracy in a static condition, and the estimation errors of calibration parameters are given within 0.05%.
Analysis of Data Collected by the 700 MHz Band Intelligent Transport Systems for Reducing Ambulance Transportation Time
- T. Mitani, T. Yamazato, K. Naito, Y. Mori
- The 8th IEEE International Conference on Conected Vehicles and Expo (ICCVE), Gratz, Austlia
- Nov. 2019
- https://doi.org/10.1109/ICCVE45908.2019.8965232
- Emergency services around the world face the problem of increasing patient transportation times. The operation of emergency vehicles is fundamentally different from that of general vehicles ; hence, algorithms recommending optimal routes in a conventional way are not always applicable to emergency vehicles. In this study, we analyzed data of inter-vehicle and road-vehicle communication collected at 700 MHz band intelligent transport systems and demonstrated that the overall travel time of emergency vehicles can be reduced by decreasing their travel time at intersections.
Basic Experiment on ITS Visible Light Communication Transmitter Using DMD Projector Usable as Street Lights
- T. Arisue, T. Yamazato, H, Okada, M. Kinoshita, S. Arai, T. Yendo, K. Kamakura, T. Fujii
- Enginnering Sciences Society Conference of IEICE, A-9-1, p.64, Osaka, Japan
- Sep. 2019
-
Noise-aided linearization of a receiver with one-bit analog-to-digital converter
- Y. Nakashima, T. Yamazato, S. Arai, H. Tanaka, K. Tadokoro
- Communications Society Conference of IEICE,B-8-23,p97
- Sep. 2019
-
An analysis of a noise-aided linearization range on a receiver with one-bit analog-to-digital converter
- Y. Nakashima, T. Yamazato, S. Arai, H. Tanaka, K. Tadokoro
- IEICE Technical Report, RCS2019-149, pp.19-24
- Aug. 2019
-
- In this study, we assume the receiver with analog-to-digital converter(s) that has only one-bit resolution(1bit-ADC). The advantages of 1bit ADC are low power consumption, potential to realize high sampling rate, the simple structure and the small circuit area. Also, 1bit ADC does not need the gain control for the ADC dynamic range. However, the 1bit ADC has a nonlinearity and that cause the large amplitude distortion. Therefore, we focus on the noise-aided linearization known as stochastic resonance. the output of the 1bit ADC is stochastically linearized by noise and the amplitude distortion is restrained. In this paper, we shows an analysis for the stochastic input-output property of the 1bit ADC. The result shows the linearized range is decided from the distribution and the variance of the input noise.
Noise-aided demodulation of direct spread-code division multiple access signals with a 1bit analog-to-digital converter
Capacity Evaluation of Low-earth Orbit Satellite-MIMO Systems
- D. GOTO, H. SHIBAYAMA, F. YAMASHITA, R. OKEMA, T. YAMAZATO
- IEICE Transactions on Communications, Vol. J102B, No.8, pp.614-623
- Aug. 2019
- https://doi.org/10.14923/transcomj.2018WFP0016
- In this paper, we evaluate the transmission capacity of LEO-MIMO systems by low-earth orbit (LEO) satellite communication using Muti-Input/Multi-Output (MIMO). In LEO systems, Doppler shift is always caused by fluctuation of satellite orbit may affect the performance of LEO-MIMO. In this system, guard bands and control carriers are used for synchronization and channel estimation for MIMO demodulation. Simulation results show that MIMO transmission with five satellites at the center frequency of 12 GHz achieves the highest transmission capacity by approximately 2.7bps/Hz. And the transmission capacity with three satellites at 20GHz is maximized, approximately 1.6 bps/Hz.
High performance demodulation method with less complexity for image-sensor communication
- Y. Ohira, T. Yendo, S. Arai, and T. Yamazato
- Optics Express, vol.27, no.15, pp.21565-21578
- Jul. 2019
- https://doi.org/10.1364/OE.27.021565
- This study presents a novel method for signal demodulation for use with visible light communication systems composed of an image sensor as a receiver and light-emitting diode (LED) transmitters. Demodulation is a central challenge in the design of such a system, as the image captured at the image-sensor receiver is deteriorated by distance and noise. We propose a demodulation method that offers performance approaching that of the maximum-likelihood decoding (MLD) method and with significantly less complexity. The proposed method first applies the minimum mean square error (MMSE) method to each LED into reliable LEDs and unreliable LEDs according to the MMSE results and it demodulates the LEDs judged as reliable directly. Then, the MLD method is applied only to the unreliable LEDs to demodulate their signals. The results of numerical simulations and lab experiments are presented to evaluate the performance of this modified demodulation method.
[Invited Talk] Visible Light Communication and Ranging Using High-speed Stereo Cameras
- M. Kinoshita, K. Kamakura, T. Yamazato
- 2019 IEEE SUMMER TOPICALS MEETING SERIES, Photonics in Artificial Intelligence (Photonics-AI), Ft. Lauderdale, FL
- Jul. 2019
- https://doi.org/10.1109/PHOSST.2019.8794881
- We will introduce an integrated system of visible light communication (VLC) and ranging using high-speed stereo imaging. The system simultaneously decodes a VLC signal while its source tracking portion outputs ranging information. These image sensors are mainly used to provide visual information to the driver.
For the Applications of Stochastic Resonance in the Telecommunications
- Y. Tadokoro, T. Yamazato, H. Tanaka, S. Arai, Y. Nakashima, S. Hiraoka
- IEICE Transactions on Communications, vol.J102-B, no.6, pp.445-458
- Jun. 2019
- https://doi.org/10.14923/transcomj.2018JBR0001
- A nonlinear phenomenon of Stochastic resonance~(SR) was found in 1981 to describe the 100,000-year cycle of the ice age on Earth. In this framework, noise has an important role in the system behavior; the system response, especially response to weak signal, is strongly enhanced by exploiting noise. This unique feature has attracted interests in diverse fields, including biological systems, electron devices, and signal processing methods. For developing the future applications with SR in the telecommunication fields, this survey article provides the fundamental aspects and recent progress of SR. This article is divided into halves. The first part of the paper provides a review of the history, investigations, and fundamental theory of SR. The second part introduces practical applications of SR. To be more specific, the part describes an SR receiver for sub-threshold signal detection, its error rate analysis, and an example of implementation. A capacity analysis is also discussed using the derived error rate equation. Further, the part introduces multi-signal demodulation using one bit AD converter and hypothesis testing.
Detection of Two Superimposed LEO-MIMO’s Control Signals by Deep Learning
- R. Okema, D. GOoto, T. Yamazato, F. Yamashita, D. Shibayama
- IEICE Technical Report, SAT2019-3, pp.13-17, Nagoya,Japan
- May 2019
-
- A MIMO communication system using multiple low-earth orbital (LEO) satellites achieves higher capacity than a conventional LEO system.However, as it requires to allocate different frequency bandwidth for each satellite signal to estimate its Doppler-shift, increase in the number of satellites decreases occupied MIMO signal bandwidth, and hence lower the capacity.This paper tries to prevent such capacity reduction by an introduction of superimposition of the control signals. The superposition of the control signals occupy only a frequency bandwidth of one control signal, thus can prevent the capacity reduction. A challenge is how to estimate each satellites’ Doppler frequency from the superimposed control signal. In this paper, we propose to adopt deep learning to estimate each satellites’ Doppler frequency from the waveform of Doppler affected control signals. In particular, we consider the case of two superimposed control signal and show the result in terms of average frequency estimation error.
Maximum Likelihood Decoding Based on Pseudo-Captured Image Templates for Image Sensor Communication
- S. Arai, H. Matsushita, Y. Ohira, T. Yendo, D. He, T. Yamazato
- NOLTA, IEICE, vol.10, no.2, pp.173-189
- Apr. 2019
- https://doi.org/10.1587/nolta.10.173
- This paper focuses on an image sensor communication system that uses an LED as the transmitter and a high-speed image sensor (camera) as the receiver. Communication in this scheme depends on the quality of images transmitted from the LED to the sensor. If the image becomes unfocused on the way to the receiver, the LED luminance that make up the signal cannot be detected, so the receiver cannot demodulate the signal data. To overcome this problem, this study proposes a novel demodulation scheme to recover data from a degraded image, based on a maximum likelihood decoding (MLD) algorithm. The proposed method creates template images that imitate all possible blinking patterns produced by the LED transmitter, and then calculates the Euclidean distances between pixels in the captured image and the pseudo images for all possible blinking patterns. Finally, the algorithm chooses the image template with the smallest Euclidian distance from the received signal as the recovered data. Though an exhaustive set of image templates must be prepared for the proposed MLD, the number of templates depends on the number of LEDs on the transmitter. Thus, the computational complexity of this method increases as the number of transmitter LEDs increases. To reduce the computational complexity of the proposed MLD algorithm, the binary differential evolution (BDE) algorithm is used, which is a swarm intelligence technique. Computer simulations are used to evaluate the BDE algorithm's usefulness for reducing computational complexity and improving the BER of the communication system.
An LED Transmitter Detection using Linear SVM and CNN for ITS Image Sensor Communication
- M. Hori, M. Kinoshita, T. Yamazato, H. Okada, T. Fujii, K. Kamakura, T. Yendo, S. Arai
- 3rd International Conference and Exhibition on Visible Light Communications (ICELVC), Seoul, Korea
- Mar. 2019
-
- Image sensor communication (ISC) is a type of visible light communications (VLC) that has high affinity with the field of intelligent transport systems (ITSs). In an ISC, accurate detection of the transmitter from a captured image is critical, because the receiver uses pixels that sense VLC signal for data reception. The purpose of this study is to reduce the false-positive and the false-negative probabilities of the transmitter. To achieve this goal, we propose a novel LED transmitter detection method composed of two stages: the candidate extraction stage by a linear support vector machine (SVM) and the classification stage by a convolutional neural network (CNN). Then, we show that the proposed method is robust to vehicle vibration and other noises such as non-transmitter LED compared to the conventional method.
Employing the Arrayed Network Improves the Error Rate in the Receiver Exploiting Stochastic Resonance
- K. Tadokoro, H. Tanaka, Y. Nakashima, T. Yamazato, S. Arai
- IEICE General Conference, N-1-28, p.276, Tokyo
- Mar. 2019
-
Development of 45kHz ultrasonic sensor array system and experimental evaluation of obstacle position estimation method
- T.Nishio,A.Tsujii,T,Kasashima,H.Hatano,T.Yamazato
- Enginnering Sciences Society Conference of IEICE
- Mar. 2019
-
A demodulation for DS-CDMA signals with different intensities by 1bit analog-to-digital converter and noise
- Y. Nakashima, T. Yamazato, S. Arai, H. Tanaka, Y. Tadokoro
- IEICE General Conference, B-8-13, p.145, Tokyo
- Mar. 2019
-
Doppler Frequency Estimation of Two Superimposed LEO-MIMO's Control Signals by Deep Learning
- R.Okema,D.Goto,T.Yamazato,H.Shibayama,H.Yamashita
- IEICE General Conference
- Mar. 2019
-
Large Capacity MIMO Techniques Using Multiple Low Earth Orbit (LEO) Satellites
- D. Goto, H. Shibayama, F. Yamashita, R. Okema, T. Yamazato
- IEICE General Conference, B-3-20, p.210, Tokyo
- Mar. 2019
-
Experimental Evaluation of Visible Light Communication Performance Applying Pixel Selection / Maximal Ratio Combining Reception by High-speed Stereo Camera
- M. Kinoshita, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- IEICE Transactions on Communications, vol.J102-B,no.2,pp.90-97
- Feb. 2019
- https://doi.org/10.14923/transcomj.2018GTP0003
- In-vehicle cameras can be used as receivers for visible light communication in addition to their primary functions: for viewing assistance and object recognition. Because image sensor spatially separates transmission signals by image processing, it is attractive device for outdoor mobile environment in which number of noise sources (e.g. sunlight or street light) are existed, especially the field of intelligent transport systems. Most studies with this design perform tests via a single high-speed camera that is used as the receiver, but this study employs a receiver that uses a high-speed stereo camera. In the high-speed stereo camera, it is possible not only to estimate distance but also to improve the visible light communication performance by effectively utilizing the stereo image. In this paper, we propose pixel selection and maximum ratio combining as a reception method of high-speed stereo camera to improve visible light communication performance. Communication performance is then evaluated comparing to the conventional single-camera reception by experimental tests conducted under static and driving conditions.
Academic Databases and Search Tools
- T. Yamazato, F. Nishino, N. Kato, Y. Chimura
- The Journal of the Institute of Television Engineers of Japan, vol.73, no.1, pp.96-99
- Jan. 2019
-
Enhancing a BPSK receiver by employing a practical parallel network with Stochastic resonance
- Y. Tadokoro, H. Tanaka, Y. Nakashima, T. Yamazato, S. Arai
- NOLTA, IEICE, vol. E10-N, no. 1, pp. 106-114, 2019.
- Jan. 2019
- https://doi.org/10.1587/nolta.10.106
- Stochastic resonance (SR) is a noise-enhancement phenomenon that enables the detection of sub-threshold signals by adding noise and using nonlinear systems. This paper explores the applicability of SR in a BPSK receiver with sub-threshold signals. Although received signals are amplified as a result of the nonlinear behavior of the receiver, they are somewhat distorted. This results in the lower performance of SR receivers in comparison with linear receivers. Employing a parallel network of SR systems is expected to solve this problem. The present theoretical analysis demonstrates that in a certain noise intensity range, the output of the network can fully describe an input sub-threshold signal, and hence, the performance close to that of the linear receivers can be obtained. The effectiveness of the SR receiver was also demonstrated through a numerical example of the bit error rate (BER). However, achieving good BER performance requires an infinite number of arrayed SR systems, which is not realistic in practical systems. A design framework for an SR network with a finite number of elements and an appropriate noise intensity that can realize BER performance close to that in linear systems is also provided.
A Comparison of Reception Methods for Visible Light Communication Using High-speed Stereo Cameras
- M. Kinoshita, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- IEEE Global Communications Conference (GLOBECOM), Abu Dhabi, UAE
- Dec. 2018
- https://doi.org/10.1109/GLOCOM.2018.8647953
- In-vehicle cameras can be used as receivers for visible light communication in addition to their primary functions: for viewing assistance and object recognition.
Most studies with this design perform tests via a single high-speed camera that is used as the receiver, but this study employs a receiver that uses a high-speed stereo camera. The reception method developed in this paper effectively utilizes left and right stereo images to improve communication performance. Although the selective diversity reception method proposed in previous work improved communication performance, it cannot deal with cases wherein both the left and right cameras introduce errors. To further improve the communication performance of this system, maximal ratio combining (MRC) diversity is applied to the high-speed stereo camera in this study. Communication performance is then evaluated comparing to the selective diversity reception and conventional single-camera reception by experimental tests conducted under static and driving conditions.
LEO-MIMO Satellite Systems for High Capacity Transmission
Performance Evaluation of Precoded Pulse Width Modulation for Image Sensor Communication
- S. Kamegawa, M. Kinoshita, T. Yamazato, H. Okada, T. Fujii, K. Kamakura, T. Yendo, S. Arai
- IEEE GLOBECOM Workshop on Optical Wireless Communications, Abu Dhabi, UAE
- Dec. 2018
- https://doi.org/10.1109/GLOCOMW.2018.8644347
- Light-emitting diodes (LEDs) can add visible light communication (VLC) by high-speed blinking to their original lighting function. VLC using image sensors as receivers is referred to as image sensor communication (ISC). ISC eliminates noise and interference and enables multiple and simultaneous communication; hence it is suitable for outdoor mobile environments such as intelligent transport systems (ITSs). On the other hand, since the communication rate depends on the frame rate, it is difficult to increase. Therefore, the purpose of this study is to increase the communication rate by multilevel pulse width modulation (PWM). When the modulation level is increased, demodulation becomes difficult due to the bit per pixel (bpp) limitation of the image sensor. First, in order to perform efficient luminance extraction in limited bpp, we compare the maximum luminance extraction and the average luminance extraction. Then, we propose improving the nonlinearity between the transmitter and receiver, which is a problem in average luminance extraction suitable for a mobile environment, by applying precoded PWM. Finally, we evaluate effectiveness of precoded PWM experimentally.
Noise-aided Demodulation with One-bit ADC for Quadrature Amplitude Modulated Signals
- Y. Nakashima, T. Yamazato, S. Arai, H. Tanaka, Y. Tadokoro
- IEEE Global Communications Conference (GLOBECOM), Abu Dhabi, UAE
- Dec. 2018
- https://doi.org/10.1109/GLOCOM.2018.8648114
- This paper proposes a new demodulation method using a one-bit analog-to-digital converter (ADC).
With one bit resolution, a signal having a multilevel signal, such as a quadrature amplitude modulated (QAM) signal, is largely degraded by nonlinearity. To demodulate the signals, a high-resolution ADC is used to receive the signals with high linearity.
This study sets out to demodulate the QAM signals using a one-bit ADC, whose resolution is the lowest (one-bit) and possesses outputs of binary (nonlinear) values. We propose to solve the issue by focusing on the statistical characteristics of the output signals of the one-bit ADC combined with noise. The proposed demodulation method is based on maximum a posteriori (MAP) criterion. The theoretical analysis presented illustrates that reliable demodulation is possible even with the one-bit ADC, provided the output probability of the ADC corresponds to each transmitted symbol is known.
A Basic Study on Transmitting Pattern for ITS Visible Light Communication Using DMD Projector
- T. Arisue, M. Kinoshita, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- IEICE Technical Report, WBS2018-70, pp.237-241, Miyako, Japan
- Dec. 2018
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- This paper focuses on a transmitter of image sensor communication (ISC) for the intelligent transportation system (ITS). ISC is a kind of visible light communications (VLC) that use an image sensor as a reception device. A commonly used transmitter device for ISC is an LED array as it can transmit multiple data transmission. However, it is necessary to decide the design of LED array and its transmission pattern in advance. Therefore changing the LED design and transmission pattern is difficult. In this paper, we propose to use a DMD projector for the ISC transmitter which can easily design and change a shape of transmission pattern and data rate compared with the LED array. A headlight of a vehicle, street lights, a projector of road signage are a typical example of the DMD projector usage. We, therefore, assume that a transmission pattern is projected on a road or signage for communication. In this paper, we describe our prototype using DMD projector and a high-speed camera and report an essential examination of the transmission pattern.
Possibility of learning pathway analytics and AI conversion
- T. Yamazato and K. Takeda
- 2018 Axies Anual Conference, Sapporo, Japan
- Nov. 2018
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Interference-Aided Detection of Subthreshold Signal Using Stochastic Resonance Receiver ~ Characteristic Evaluation Using PSK Modulation Method ~
- S. Hiraoka, T. Yamazato, S. Arai, Y. Tadokoro, H. Tanaka
- IEICE Technical Report, RCS2018-179, pp.7-12, Naha, Japan
- Nov. 2018
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[Encouragement Talk] Vehicle Vibration Modeling Inducing Transmitter Displacement in Image Plane for ITS Image Sensor Communication
- M. Kinoshita, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- IEICE Technical Report, WBS2018-26, pp.47-52, Hiroshima
- Oct. 2018
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Noise-aided demodulation with one-bit comparator for multilevel pulse-amplitude-modulated signals
- Y. Nakashima, T. Yamazato, S. Arai, H. Tanaka, Y. Tadokoro
- IEEE Wireless Communications Letters, vol.7, no.5, pp.848-851
- Oct. 2018
- https://doi.org/10.1109/LWC.2018.2831683,28646
- This paper proposes a demodulation method using a one-bit comparator for signals processed by multilevel pulse amplitude modulation (PAM). The proposed method is simple and provides an alternative to using an analog-to-digital converter to describe multilevel input signals. Because of the noise present in the transmitted multilevel PAM signal, the two-level output of the one-bit comparator shows different statistical behavior for each level of the signal. Thus, it is possible to detect the signal level, or perform symbol decision, based on the maximum likelihood (ML) criterion. The present theoretical analysis reveals that reliable demodulation is possible even with a one-bit comparator if the probability mass function of the two-level outputs of each received symbol plus intentionally added noise is known.
[Poster Presentation]Experimental evaluation of the effect of asynchronous information exchanges in wireless feedback control of multiple machines
- M. Yamaguchi, K. Kobayashi, H. Okada, M. Katayama
- Multiple Innovative Kenkyu-kai Association for Wireless Communications 2018, no.4-14
- Sep. 2018
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Noise-aided demodulation of OFDM signals with a 1bit analog-to-digital converter
- Y. Nakashima,T. Yamazato, S. Arai, Y. Tadokoro, H. Tanaka
- Communications Society Conference of IEICE
- Sep. 2018
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A Validation of Synchronization and Channel Estimation Performance for Low Earth Orbit (LEO) MIMO Systems
- D. Goto, H. Shibayama, F. Yamashita, T. Yamazato
- Communications Society Conference of IEICE, B-3-2, p.196, Kanazawa
- Sep. 2018
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Detectability enhancement using interference signals in wireless communication systems
- S. Hiraoka, Y. Nakashima, T. Yamazato, S. Arai, Y. Tadokoro, H. Tanaka
- International Symposium on Nonlinear Theory and its Application (NOLTA), pp. 705-708, Tarragona, Spain
- Sep. 2018
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- We present a numerical study of an interference-aided detection of a weak (subthreshold) signal in a polarization diversity. We show that the nonlinear signal processing dramatically improves the detectability of the weak signal, supported by an interference signal generated by an appropriate beam control of the antenna arrays. The method takes advantage of subthreshold signal detection by the Stochastic resonance. To postulate a performance of the interference-aided detection, we numerically evaluate the channel capacity provided by the proposed diversity reception on a fading model. Through the numerical analysis, we find that the channel capacity depends on the threshold level of the detector and also the beam pattern determined by the diversity weights in the antenna arrays.
Interference-Aided Detection of Subthreshold Signal Using Beam Control in Polarization Diversity Reception
- S. Hiraoka, Y. Nakashima, T. Yamazato, S. Arai, Y. Tadokoro, H. Tanaka
- IEEE Communications Letters, vol.22, no.9, pp.1926-1929
- Sep. 2018
- https://doi.org/10.1109/LCOMM.2018.2851583,28616
- The present letter discusses a detectability enhancement induced by co-channel interference signals in the polarization diversity reception. The challenge is the detection of weak (subthreshold) signals, the level of which is less than the detection limit of radio receivers. To understand the theory underlying the mechanism in the presented diversity scheme, we introduce an analytic model of a dual polarized antenna array in the fading channel. In addition, the channel capacity in a binary data transmission is derived. As a result, we reveal that the interference-aided diversity reception enables us to detect signals even below the detection limit of the receiver. Moreover, the appropriate source code is needed to achieve the channel capacity because the transmission channel is asymmetric in the present reception scheme.
Image Sensor Communications for Automotive
- T. Yamazato
- Progress In Electromagnetics Research Symposium (PIERS), Toyama International Conference Center, Toyama, Japan
- Aug. 2018
-
- This article introduces image sensor communications (ISC), a subset of visible light communication (VLC), that use high-speed image sensor and its application to automotive. Li-Fi (light fidelity) and OCC (optical camera communication) or also know as CamCom are also VLC family. Li-Fi is a high-speed wireless system and is currently in the process of being standardized in IEEE 802.11. The OCC uses an ordinary camera, e.g. a smartphone camera, as a receiver while ISC uses a high-speed image sensor as a reception device. The principal component of a camera, an image sensor, is used for both ISC and OCC. The main difference is that ISC focuses on a high-speed image sensor while OCC concentrates on low-cost consumer applications using smartphones and similar contemporary devices. For automotive usage, a high-speed image sensor is the best choice for the VLC receiver because the image sensor has a spatial separation of noise and target source. The VLC family uses LED as the transmitter and LED light sources are everywhere on streets: in signs, traffic lights, street lights, and other stationary objects. So if we can send IDs or exact location data (latitude and longitude) by way of VLC from those LEDs, then they can be used as anchor nodes placed on roads, sidewalks, or landmarks. Those anchor nodes help autonomous cars and connected vehicle for robust navigation with centimeter accuracy. The image sensor is the suitable detection device as it can be used for both positioning and VLC data detection. The author has been working on ISC for automotive applications. In this article, some of the author research, as well as his findings, are introduced.
Overview of image-sensor communication
- T. Yamazato
- Visible Light Communications Workshop, Pacific Rim Conference on Lasers and Electro-Optics (CLEO-PR), Hong Kong Convention and Exhibition Centre, Hong Kong
- Jul. 2018
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- Back in 1998, Prof. Masao Nakagawa invented the concept of visible light communications (VLC) that adopts light emitting diodes (LEDs) as a transmitter. Twenty years of research progress make VLC attractive not only to researchers but also to practitioners. We are about to see blooms of VLC products. Image-sensor communication (ISC) is a form of VLC that uses image-sensor as a reception device. A particular advantage of ISC is an ability to spatially separate light sources. We can use ISC in the outdoor mobile environment. In this presentation, I will review ISC, its application, and future perspective. Some results from the author vis-a-vis ISC and its application to the automobile are also introduced.
Detection of Visible Light Communication Transmitter by Machine Learning using Time Gradient Feature
- M. Hori, M. Kinoshita, T. Yamazato, H. Okada, T. Fujii, K. Kamakura, T. Yendo, S. Arai
- IEICE Technical Report, ASN2018-30, pp.85-90, Hakodate, Japan
- Jul. 2018
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- In this paper, we focus on an image sensor visible light communication (VLC) for Intelligent Transport System (ITS). In this system, the transmitter is an LED array, and the receiver is a high-speed image sensor. To receive VLC signals, it is necessary to specify the position of the LED array transmitter from captured images. Previous studies showed that the transmitter has high time gradient values and low spatial gradient values, and proposed a transmitter detection method using these features. In this paper, we focus on time gradient periodicity, and use frequency component in addition to time gradient value and spatial gradient value. Then, we propose a transmitter detection method by machine learning with these features.
Application of Precoding for Image Sensor Based Visble Light Communication and Its Performance Evaluation in a Stationary Environment
- S.Kamegawa, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- , Hakodate,Japan
- Jul. 2018
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- In this paper, we compare the performance of two modulation schemes used for ITS image sensor communication. The one is a pulse-width modulation (PWM) that simply convert source data into a width of a pulse, and then convey the signal by the multi-level intensity of a LED. The other is a virtual sinusoidal wave, proposed to adopt amplitude and phase signal reception for the image sensor receiver. The wave can convey data mapped on both amplitude and phase signal. We compare those two schemes regarding data rate and error rate performance.
Image Sensor Communications for future ITS
- T. Yamazato
- 2018 Advanced Photonics Conference, ETH Zrich, Zrich, Switzerland
- Jul. 2018
-
- This article overviews image sensor communication (ISC), a subset of visible light communication (VLC) system that uses a high-speed image sensor as a reception device. Owing to a massive number of pixels and spatial separation of multiple light souces, ISC can be used in an outdoor mobile environment, suitable for automotive applications. The paper also introduces some results from the authors’ work on ISC and its application to vehicle-to-everything (V2X) communication.
Emergency vehicle data corrected by 700 MHz Intelligent Transport System and its analysis -Emergency vehicle location and speed analysis of the Nagoya-shi Showa-ku Yagoto Firefighting Station-
- T. Mitani, T. Yamazato
- IEICE Technical Report, SR2018-5, pp.29-34, Tokyo Big Sight
- May 2018
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- An issue of emeregency vehicle is that patient conveying time is increasing year by year. Here, the patient conveying time is defined as a time duration of the first emergency call and transport a patient to a hospital. It has been said that the half of the patient conveying time is the emergency vehicle traveling time. To analyze the patient conveying time, we focus on the data corrected by 700 MHz Intelligent Transport System and analyze the location and speed of emergency vehicle of the Nagoya-shi Showa-ku Yagoto Firefighting Station. In particular, we show the average communication time, vehicle speed histogram, vehicle speed heat-map to find the bottleneck of the emergency vehicle traveling time.
Communication performance enhancement by maximal ratio combining for ITS visible light communication using high-speed stereo camera
- M. Kinoshita, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- IEICE General Conference, A-9-8, p.95, Tokyo
- Mar. 2018
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A Demodulation Concept for 16QAM Signals by 1bit Analog to Digital Converter
- Y. Nakashima, S. Hiraoka, T. Yamazato, S. Arai, H. Tanaka, Y. Tadokoro
- IEICE General Conference, B-8-25, p.166, Tokyo
- Mar. 2018
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Image Sensor Communications for ITS
- T. Yamazato
- IEICE General Conference, CI-2-5, pp.SS-17 - SS-18, Tokyo
- Mar. 2018
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Performance Enhancement for Image Sensor Communication in an Intelligent Transport System Using a High-speed Stereo Camera
- M. Kinoshita, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- International Conference and Exhibition on Visible Light Communications (ICEVLC), Yokohama, Japan
- Mar. 2018
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- In this paper, we propose using a high-speed stereo camera as the image sensor communication (ISC) receiver of an intelligent transport system (ITS). The stereo camera is used for front recognition of the vehicle, making it possible to estimate distances and enabling an integrative system that comprises vehicle front recognition and communication. Furthermore, several stereo images from slightly different views can be obtained at the same time, which provides diversity. Thus the proposed method enhances communication performance owing to the stereo diversity. We also provide experimental results obtained using the high-speed stereo camera and compare them with that of a conventional single high-speed camera. The proposed method improves the bit error rate (BER) performance with respect to the conventional method.
High-speed image processing of VLC signals for automotive applications
- Takaya Yamazato
- International Conference on Optical Wireless Communications, Beijing, China
- Mar. 2018
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Technical Issues on IEEE 802.15.7m Image Sensor Communication Standardization
- T. Nguyen, A. Islam, T. Yamazato, Y. M. Jang
- IEEE Communications Magazine, vol. 56, no. 2, pp. 213-218
- Feb. 2018
- https://doi.org/10.1109/MCOM.2018.1700134
- This tutorial article presents an outline of image sensor communication (ISC) technologies realized by light sources and cameras. It discusses the revision of the IEEE 802.15.7-2011 standard, namely, the IEEE 802.15.7m Optical Wireless Communications Task Group, which has significantly influenced the development of the ISC technology. It also reviews the ISC technical proposals of the task group and compares them with related works. The essential technical considerations of the ISC specifications are presented, and the future directions of research and development are discussed.
[Invited] Stochastic resonance and its applicability to communication systems
- Takaya YAMAZATO, Yukihiro TADOKORO, Hiroya TANAKA, Hiroya TANAKA, Shintaro ARAI, Yasuo NAKASHIMA, and Shintaro HIRAOKA
- IEICE Technical Report, RCS2017-297, pp.167-174, Takamatsu, Japan.
- Jan. 2018
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- Stochastic resonance (SR) is a nonlinear phenomenon where system response can be boosted by adding noise. Traditionally, noise has been treated as a disturbance to a system, and therefore we remove the noise using a filter. In SR, we take a different approach that we give a positive role to the noise to increase the system response. For example, some creature use noise to detect a signal buried in noise. If we can use this mechanism, we may be able to detect a sub-threshold signal that can not be detected by an ordinary receiver. In this paper, we will present SR and its application to a communication system, with some reference to our research results.
Simplified Vehicle Vibration Modeling for Image Sensor Communication
- M. Kinoshita, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, vol.E101-A, no.1, pp.176-184
- Jan. 2018
- https://doi.org/10.1587/transfun.E101.A.176
- Image sensor communication (ISC), derived from visible light communication (VLC) is an attractive solution for outdoor mobile environments, particularly for intelligent transport systems (ITS). In ITS-ISC, tracking a transmitter in the image plane is critical issue since vehicle vibrations make it difficult to select the correct pixels for data reception. Our goal in this study is to develop a precise tracking method. To accomplish this, vehicle vibration modeling and its parameters estimation, i.e., representative frequencies and their amplitudes for inherent vehicle vibration, and the variance of the Gaussian random process representing road surface irregularity, are required. In this paper, we measured actual vehicle vibration in a driving situation and determined parameters based on the frequency characteristics. Then, we demonstrate that vehicle vibration that induces transmitter displacement in an image plane can be modeled by only Gaussian random processes that represent road surface irregularity when a high frame rate (e.g., 1000 fps) image sensor is used as an ISC receiver. The simplified vehicle vibration model and its parameters are evaluated by numerical analysis and experimental measurement and obtained result shows that the proposed model can reproduce the characteristics of the transmitter displacement sufficiently.
Practical Applications of Visible Light Communications
- T. Yamazato, H. Okada
- Journal of IEICE, vol.101, no.1, pp.59-65
- Jan. 2018
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V2X communications with an image sensor
- Takaya Yamazato
- Journal of Communications and Information Networks, vol.2, no.4, pp.65-74
- Dec. 2017
- https://doi.org/10.1007/s41650-017-0044-4
- This paper introduces infrastructure-to-vehicle and vehicle-to-vehicle communications using VLC. A VLC coupled with a high-speed image sensor is introduced (i.e., image sensor communication). The high-speed image sensors provide eyes for autonomous and connected vehicles. VLC imparts data reception capability to image sensors with necessary functions, which can then be provided to autonomous and connected vehicles. In this paper, some of our research on coupling VLC to high-speed image sensors is introduced, including our key findings: the basics of ISC, a vehicle motion model, and range estimation.
LED array detection method using SVM for ITS image sensor visible light communication
- M. Hori, M. Kinoshita, T. Yamazato, H. Okada, T. Fujii, K. Kamakura, T. Yendo, S. Arai
- IEICE Technical Report, Okinawa, Japan
- Dec. 2017
-
- In this paper, we focus on an image sensor visible light communication (VLC) for Intelligent Transport System (ITS). In this system, a transmitter is an LED array, and a receiver is a high-speed camera. To receive VLC signals, it is necessary to specify the position of the LED array transmitter from captured images. Previous studies showed that the LED array has a high temporal gradient value and a low spatial gradient value, and proposed an LED array detection method using these features. However, the method has difficulty to distinguish between information-contained LED array transmitter and an artificial light source without information. Also, since the number of pixels corresponding to the non-LED array is much larger than that of the LED array, such data imbalance should be considered. Therefore, in this paper, to detect LED array more accurately, we performed undersampling based on the k-means method. Then, we propose an LED array detection method using SVM model from these data.
Overview of visible light communications with emphasis on image sensor communications
- Takaya Yamazato
- Asia-Pacific Conference on Communications (APCC), Perth, WA, Australia
- Dec. 2017
- https://doi.org/10.23919/APCC.2017.8304093
- The concept of visible light communications (VLC) originates from an Asian professor and adopts light emitting diodes (LEDs) as a transmitter. Three Asian born Nobel Prize winners developed blue LEDs, key devices that produce white lighting. Consequently, VLC and its other forms can be considered as an Asian born wireless technology. This paper overviews VLC with emphasis on image sensor communication (ISC) that uses an image sensor as a reception device for VLC signals. Some results from the author vis-a-vis ISC and its application to automobile are also introduced.
A Stochastic Resonance Receiver for 4-PAM Signals
- Y. Nakashima, T. Yamazato, Y. Tadokoro, S. Arai
- International Symposium on Nonlinear Theory and its Application (NOLTA), pp.291-294, Cancun, Mexico
- Dec. 2017
-
- Stochastic Resonance (SR) is considered as a noise enhanced phenomenon, that a response of a nonlinear system is improved by noise. In previous studies, an application of SR for wireless communication has been discussed and an SR receiver, the receiver that demodulate a received signal by SR, was proposed. However, these studies have used a basic modulation signal and have not focused on a signal that transmit information by multi-level amplitude. In this paper, we consider an SR receiver for 4-pulse amplitude modulation (4-PAM) signals. By applying SR, it can demodulate 4-PAM signals by a 1-bit resolution device. We show the system model of the receiver, evaluate its performance by simulation, and show its availability.
N-Stream Superimposed System with m-Point DFT for Image-Sensor-Based Visible Light Communication
- S. Kibe, K. Kamakura, T. Yamazato
- IEEE Global Communications Conference (GLOBECOM), pp. 1-6, Singapore, Singapore
- Dec. 2017
- https://doi.org/10.1109/GLOCOM.2017.8254784
- This paper proposes an N-stream superimposed system for image-sensor-based visible light communications (ISbased VLC). Based on the principle of m-point discrete Fourier transform (DFT), a phase shift keying (PSK) signal is transmitted over m consecutive time slots mT, where T is a slot duration. In practice, the symbol rate of this paper is R/(m + 1) because a guard slot is inserted every m slots. In the superimposed system, N data streams where the symbol rate of the nth data stream, n = {1, 2, . . . , N}, is 1/(m + 1)n-1 times the symbol rate of the first data stream are combined to form a pulse-width modulated (PWM) wave with a period time T. An IS receiver with a camera operating at a frame rate of R/(m + 1)n-1 fps demodulates data streams whose symbol rate is R/m + 1)n symbol/s or lower. Our experimental results validate that from a superimposed PWM wave of 500-symbol/s and 125-symbol/s data streams, a 2000-fps camera receiver demodulates both of the two data streams and the 500-fps camera receiver does the 125-symbol/s data stream successfully, without shortening individual error-free transmission ranges, compared with non-superimposed systems in which 500-symbol/s and 125-symbol/s data streams are independently transmitted by different light emitting diode (LED) transmitters and received by 2000-fps and 500-fps camera receivers, respectively.
N-Stream Superimposed System with m-point DFT for Image-Sensor-Based Visible Light Communication
- S. Kibe, K. Kamakura, T. Yamazato
- IEICE Technical Report, CS2017-58, pp.21-2, Aso
- Nov. 2017
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The Uplink Visible Light Communication Beacon System for Universal Traffic Management
- T. Yamazato, N. Kawagita, H. Okada, T. Fujii, T. Yendo, S. Arai, K. Kamakura
- IEEE Access, vol.5, pp.22282-22290
- Oct. 2017
- https://doi.org/10.1109/ACCESS.2017.2759179
- This paper presents a feasibility study of the uplink visible light communication (VLC) beacon system for the universal traffic management system (UTMS). The UTMS is a traffic management system beneath the National Police Agency of Japan. Currently, 55 000 UTMS infrared beacon systems have been installed, and they provide expressway and ordinary road information to cars. However, the data rate is 1 Mbps, and a faster data rate is necessary to support automotive and smart mobility devices. In this paper, we propose an uplink V2I system for the UTMS. The system is designed to match the current beacon system as closely as possible, so that the system can easily be replaced and still provide sufficient bandwidth for future automotive and smart mobility devices. We adopt a photo diode (PD) as the VLC receiver and a commercially available off-the-shelf LED headlight as a transmitter. Unfortunately, the bandwidth of such an LED is usually small, so we consider applying a bit-loading algorithm to direct-current-biased optical orthogonal frequency division multiplexing. To reduce strong background noise, such as from the sun, we narrow down the field-of-view by applying a lens to the PD, which forms a tiny communication area, smaller than the current infrared beacon system. We then consider multiple PDs with the lens to create a similar communication area as the infrared beacon system. As a result, we achieve 3.1-Mbps throughput.
Modulation and coding for image sensor communication
- K. Kamakura, T. Yamazato
- IEEE Photonics Conference (IPC), pp.235-236, Orlando, FL, USA
- Oct. 2017
- https://doi.org/10.1109/IPCon.2017.8116086
- Most practical visible light communication (VLC) systems being currently deployed with image sensor receivers use intensity modulation and direct detection scheme for outdoor and indoor applications. A number of modulation and coding techniques that are used for image sensor-based VLC systems are presented.
Improvement of communication performance using high-speed stereo camera for ITS image sensor communication
- M. Kinoshita, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- IEICE Society Conference, A-9-7, p.92
- Sep. 2017
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A Feasibility Study on a Stochastic Resonance Receiver Based on Noise Level Control with Adaptive Array Antenna
- S. Hiraoka, Y. Nakashima, T. Yamazato, S. Arai, Y. Tadokoro, H. Tanaka
- IEICE Society Conference, N-2-3, p.196
- Sep. 2017
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Effect of a Root-Raised-Cosine Filter on a BPSK Stochastic Resonance Receiver
- Y. Nakashima, H. Tanaka, T. Yamazato, Y. Tadokoro, S. Arai
- NOLTA, IEICE, vol.E8-N, no.3, pp.204-214
- Jul. 2017
- https://doi.org/10.1587/nolta.8.204,26846
- Signal filtering is necessary for wireless communication. However it causes the signal amplitude to fluctuate and affects the performance of stochastic resonance (SR) receivers. In this study, we evaluate the bit error rate (BER) performance of filtered binary phase-shift keying (BPSK) on an SR receiver. The results show that filtering improves the BER performance of the SR receiver because the amplitude fluctuation contributes to improving the SR effect. We also evaluate the effect of the roll-off factor, which determines the bandwidth of the filter and the amplitude fluctuation. The results demonstrate the applicability of the SR receiver to bandlimited BPSK signals.
A Comparison of Transmission Methods to Accelerate Data Rate for Image Sensor Based Visible Light Communication in Intelligent Transport Systems
- S. Kamegawa, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- IEICE Technical Report,RCS2017-69, pp.115-120
- Jun. 2017
-
- In this paper, we compare the performance of two modulation schemes used for ITS image sensor communication. The one is a pulse-width modulation (PWM) that simply convert source data into a width of a pulse, and then convey the signal by the multi-level intensity of a LED. The other is a virtual sinusoidal wave, proposed to adopt amplitude and phase signal reception for the image sensor receiver. The wave can convey data mapped on both amplitude and phase signal. We compare those two schemes regarding data rate and error rate performance.
A Stochastic Resonance Receiver for 4 Pulse Amplitude Modulation
- Y. Nakashima, H. Tanaka, T. Yamazato, Y. Tadokoro, S. Arai
- IEICE NOLTA Society Conference, NLS-3, Nagoya, Japan
- Jun. 2017
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Modeling and Parameter Estimation of Vehicle Vibration Inducing Transmitter Displacement in ITS Image Sensor Communication
- M. Kinoshita, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- IEEE International Conference on Communications Workshop on Optical Wireless Communications, pp.144-149, Paris, France
- May 2017
- https://doi.org/10.1109/ICCW.2017.7962648
- Image sensor communication (ISC), which is derived from visible light communication (VLC), is a novel form of wireless communication that uses an image sensor as a receiver. ISC is an attractive solution for outdoor mobile environments and is particularly wellsuited to intelligent transport systems (ITS). The purpose of this paper is to derive the dominant components of vehicle vibrations and road surface irregularities that induce transmitter displacement in ITS-ICS in paved road scenarios. Such displacements make it difficult for a ISC receiver to select the correct pixels. We measured vehicle vibrations during an actual driving scenario using a sixaxis acceleration sensor installed in a smartphone. Using the results obtained, we performed a frequency analysis of the vehicle vibrations and determined the parameters of vehicle vibrations based on the frequency characteristics. This paper explains that the vehicle vibrations that affect the communication performance can be modeled by solely using Gaussian random processes when a high frame rate (e.g. 1000 fps) image sensor is used as the ISC receiver.
Prameter Estimation of the Channel Fluctuation Based on the Vehicle Vibration Measurement in ITS Image Sensor Communication
- M. Kinoshita, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- IEICE General Conference, A-9-14, p.123, Nagoya
- Mar. 2017
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Implementation of the Experimental System for Simultaneous Reception from Asynchronous Multiple Sources in ITS Image Sensor Communication
- T.Arai
- IEICE General Conference, A-9-15, p.124, Nagoya
- Mar. 2017
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An Examination of Transmission Methods to Accelerate Data Rate for Visible Light Communication Using Image Sensor
- S. Kamegawa, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- IEICE General Conference, A-9-13, p.122, Nagoya
- Mar. 2017
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Method to Detect Phase for Visible Light Communication using Normal Camera
- W. Kihara, T. Yendo, S. Arai, T. Yamazato, H. Okada, K. Kamakura
- IEICE General Conference, A-9-10, p.119, Nagoya
- Mar. 2017
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Spatial Modulation in Layered Space-Time Coding for Image-Sensor-Based Visible Light Communication
- K. Masuda, K. Kamakura, T. Yamazato
- IEICE General Conference, B-10-57, p.310, Nagoya
- Mar. 2017
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Wireless Communication System for Automotive
- T. Yamazato
- IEICE General Conference, BI-10-2, pp.SS-81 - SS-82, Nagoya
- Mar. 2017
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Internet Distribution of Teaching Materials and Copyright Movements
- T. Yamazato
- Nagoya University Library Research and Development Office Report Meeting
- Mar. 2017
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Simultaneous reception method of multiple transmitted signals asynchronous to each other in ITS image sensor visible light communication
- Y. Arai
- Graduation Research Presentation of IEICE Tokai Branch
- Mar. 2017
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The Impact on Increase of Penetration of the V2X System Based on ARIB STD-T109 on the Traffic Flow Management at an Intersection
- R. Ohno, T. Yamazato
- RISP International Workshop on Nonlinear Circuits, Communications and Signal Processing (NCSP), pp.81-84, Guam, USA
- Mar. 2017
-
- In this paper, we propose a traffic flow management at an intersection using the 760 MHz band V2X (Vehicle-to-X) system based on ARIB STD-T109. Using the V2X system, a road side unit (RSU) can obtain the vehicular information such as the vehicle position, speed and route. Based on the vehicular information, a ``support phase'' can be inserted to a cycle of traffic signal that controls traffic flow at an intersection. We define the “support phase” as the phase of changing the stop/go sign of the traffic signal on an intersection as necessary. In this way, it is expected to shorten the travel time of the vehicles. We evaluate the algorithm by a traffic simulator in terms of mean speed of all vehicles while passing through the intersection with considering V2X penetration rate.
Vehicle to Infrastructure Visible Light Communication using DCO-OFDM
- N. Kawagita, T. Yamazato, H. Okada, T. Fujii, S. Arai, T. Yendo, K.Kamakura
- RISP International Workshop on Nonlinear Circuits, Communications and Signal Processing (NCSP), pp.129-132, Guam
- Mar. 2017
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- In this paper, we focus on the vehicle to infrastructure visible light communication (V2I-VLC) for intelligent transportation systems (ITS). We propose a V2I-VLC system using LED headlights as transmitters and photodiodes (PDs) with an optical lens as receivers. We adopt DC biased optical orthogonal frequency division multiplexing (DCO-OFDM) as a modulation scheme in order to realize high speed communication. As a results of the data transmission experiments in the driving situation, we achieve data rate of 2.7 Mbps using 32QAM.
A Modulation Method to Detect Phase Shift from Asynchronous Camera Image for Visible Light Communication
- W. Kihara, T. Yendo, S. Arai, T. Yamazato, H. Okada, K. Kamakura
- RISP International Workshop on Nonlinear Circuits, Communications and Signal Processing (NCSP), pp.133-136, Guan, USA
- Mar. 2017
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Range Estimation Scheme for Integrated I2V-VLC using a High-Speed Image Sensor
- T. Yamazato
- Presentation at Professor Jean Armstrong's Laboratory, Monash University, Monash University, Australia.
- Mar. 2017
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Nagoya University's Approach to Copyright Handling
- T. Yamazato
- The 39th Tokai IS Conference, Nagoya University, Nagoya, Japan
- Feb. 2017
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Global Communications Newsletter -- Asia/Pacific Region Interview with Takaya Yamazato, Director of the AP Region --
- Stefano Bregni, Takaya Yamazato, Vasile Bota, Liangping Ma
- IEEE Communications Magazine, Vol. 55, No. 2, pp.13-16
- Feb. 2017
- https://doi.org/10.1109/MCOM.2017.7841463
- This is the fourth article in the series of eight, started in November 2016 and published monthly in the IEEE ComSoc Global Communi- cations Newsletter, which covers all areas of IEEE ComSoc Member and Global Activities. In this series of articles, I am introducing the six MGA Directors (Sister and Related Societies; Membership Services; AP, NA, LA, EMEA Regions) and the two Chairs of the Women in Communications Engineering (WICE) and Young Professionals (YP) Standing Committees. In each article, one by one they present their sector activities and plans. In this issue, I interview Takaya Yamazato, Director of the Asia/ Paci c Region (AP). Takaya is a professor at the Institute of Liberal Arts and Sciences, Nagoya University, Japan. He received the Ph.D. degree from Keio University, Yokohama, Japan, in 1993. From 1993 to 1998 he was an assistant professor in the Department of Information Electronics, Nagoya University, Japan. From 1997 to 1998 he was a visiting researcher in the Research Group for RF Communications, Department of Electrical Engineering and Information Technology, University of Kaiserslautern, Germany. In 2006 he received the IEEE Communication Society Best Tutorial Paper Award. He served as symposium co-chair of ICC 2009 and ICC 2011. From 2008 to 2010 he was the chair of the IEEE ComSoc Satellite and Space Communications Technical Committee and the editor-in-chief of the Japanese Section of IEICE Transactions on Communications. His research interests include visible light communication, intelligent transport systems, stochastic resonance, and open educational resources. It is a pleasure for me to interview Takaya for this issue and o er him this opportunity to outline his current activities and plans as Director of the AP Region.
A note on an application of space Time Block Coded DCO-OFDM to Vehicle to Infrastructure Visible Light Communication
- N. Kawagita, T. Yamazato, H. Okada, T. Fujii, S. Arai, T. Yendo, K.Kamakura
- Symposium on Information Theory and Its Applications (SITA), pp.555-560, Takayama, Japan
- Dec. 2016
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- This paper focuses on vehicle to infrastructure visible lightcommunication (V2I-VLC) using two LED headlights as transmitters and photodiodes (PDs) with an optical lens as receiver.We adopt DC-biased optical orthgonal frequency division multiplexing (DCO-OFDM) to realize high data rata V2I-VLC. In V2I-VLC,it is possible to remove background light noise sources by narrowing the receiver's field of view (FOV) by using an optical lens.However,small FOV causes received signal intensity fluctuations ,especially in a driving situation ,and performance may be degraded.To overcome the problem,we adopt a Alamouti-type Space Time Block Coding (STBC). In this paper, we experimentally demonstrate a 2×1 STBC performance and compare it with the conventional system which the same signals simultaneously transmitted from two headlights. Experimental results show that STBC can't improve bit-error-rate performance because two signals transmitted from each headlights have high space correlation.
Vehicle to Vehicle and Vehicle to Infrastracture Communication
- T. Yamazato
- Electromagnetic Environmental Engineering Information Monthly EMC, vol.29, no.8, pp.98-109
- Dec. 2016
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An Application of Collins Network to Stochastic Resonance Receiver
- H. Tanaka, Y. Nakashima, T. Yamazato, Y. Tadokoro, S. Arai
- The 39th Symposium on Information Theory and its Applications (SITA2016), pp.147-151, Gifu, Japan
- Dec. 2016
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- This paper presents an application of Collins Network to Stochastic Resonance Receiver. In stochastic resonance (SR) systems, sub-threshold signals can be detected by noise. This nonlinear phenomenon has been attracted much attention among many researchers. However, there has ever been no practical application of SR systems, because it is difficult to design them. In contrast to the conventional SR, the Collins network, which was proposed by Collins in 1995, is a good system with outstanding ability in detecting sub-threshold signals. The present paper evaluates the performance of the Collins network with in-out correlation.
Position estimation of LED matrix in image sensor communication
- T. Asai, T. Yendo, S. Arai, T. Yamazato, H. Okada, T. Fujii, K. Kamakura
- Asia-Pacific Signal and Information Processing Association Annual Summit and Conference (APSIPA), pp.1 - 5
- Dec. 2016
- https://doi.org/10.1109/APSIPA.2016.7820809
- We focus on the road-to-vehicle visible light communication (VLC) that system is composed of a LED matrix as a transmitter and a high-speed camera as a receiver. In this VLC system, intensity of each LED cannot be determined from received image directly in case that the receiver is distant from the transmitter. In previous research, a method to estimate intensity of the LED from received image is proposed. In this method, intensity of LED is estimated by using Moore-Penrose pseudo-inverse matrix of coefficient matrix, which expresses relation between intensity of LEDs and pixel values. However, the coefficient matrix changes every moment because it is determined by positional relation between the receiver and the LED traffic light in VLC system. In this paper, we propose a method to estimate position of the LED matrix using simulated images. We measure sensitivity distribution of image sensor to generate simulated images. We evaluated degree of similarity between simulated images and real images.
Vehicle Vibration Model that Induces Channel Fluctuation in ITS Image Sensor Communication
- M. Kinoshita, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- Cambodia-Japan Joint Workshop on Ambient Intelligence and Sensor Networks, シュムリアップ
- Dec. 2016
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- Image sensor communication (ISC) enables multiple and simultaneous signal reception because of its ability spatially separate multiple sources. Therefore, ISC is an attractive solution for an outdoor mobile environment, in particular, in the field of intelligent transport systems (ITS). In ISC, since a transmitter position moves in an image plane according to vehicle movement, detection and tracking of transmitter is critical issue for robust data reception. Such movement referred to as optical ow causes ISC channel to fluctuate and must be considered to receive the signal accurately. In this paper, we conducted vehicle vibration measurement in well paved road and analyzed the frequency characteristic. According to the measured result, we proposed a vehicle vibration model and determined its parameters.
[Poster Presentation] Evaluation of the video quality and communication quality in digital signage VLC using information embedding
- S. Sato, H. Okada, T. Yamazato, T. Wada, K. Kobayashi, M. Katayama
- VLCWS2016, Tokyo, Japan
- Nov. 2016
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Effect of a Root-Raised-Cosine Filtered BPSK Signal on a Stochastic Resonance Receiver
- Y. Nakashima, H. Tanaka, T. Yamazato, Y. Tadokoro and S. Arai
- International Symposium on Nonlinear Theory and its Application (NOLTA), pp.407-410, Yugawara,Japan
- Nov. 2016
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- Signal filtering is necessary for wireless communication however it fluctuates the signal amplitude and affects the performance of a stochastic resonance (SR) receiver. In this paper, we evaluate the bit error rate (BER) performance of filtered binary phase shift keying (BPSK) on an SR receiver. The result shows that filtering improves the BER performance of the SR receiver because the amplitude fluctuation contributes to improving the SR effect, indicating the applicability of the SR receiver to bandlimited BPSK signals.
Channel Measurement of Infrastructure-to-Vehicle Image Sensor Communication
- M. Kinoshita, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- 23rd World Congress on Intelligent Transport Systems , Melbourne, Australia
- Oct. 2016
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- In this paper, we focus on the visible light communication (VLC) for ITS application using LED light source as a transmitter and high-speed image sensor as a receiver (image sensor communication: ISC). In ISC, the data reception is performed by extracting luminance corresponding to the transmitter from captured images. However, since either transmitter, receiver, or both moves with vehicles, the transmitter position is moved between frames and it confuses receiver to select the correct pixels. Hence, we treat such movement referred to as optical flow as channel fluctuation. In our previous work, we proposed a model that expressed motion of transmitter in captured images by using a single pinhole camera. In this paper, we derive channel fluctuation characteristic by numerical analysis based on the proposed model and evaluate its validity by comparing with channel fluctuation characteristic obtained by actual measurement.
Performance Comparison of Stochastic Reosonance Receiver with BPSK and QPSK Modulations
- Y. Nakashima, H. Tanaka, T. Yamazato, Y. Tadokoro, S. Arai
- Communications Society Conference of IEICE, Sapporo,Hokkaido
- Sep. 2016
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Visible Light Communication Systems Using Blue Color Difference Modulation for Digital Signage
- S. Sato, H. Okada, K. Kobayashi, T. Yamazato, M. Katayama
- IEEE International Symposium on Personal, Indoor and Mobile Radio Communication (PIMRC), pp.1242-1247, Valencia, Spain
- Sep. 2016
- https://doi.org/10.1109/PIMRC.2016.7794761
- Digital signage, which is advertising media using a liquid crystal display (LCD), is increasing in popularity. One possible application is wireless communications between digital signage and viewers. We focus on image-sensor-based visible light communication (VLC). Image-sensor-based VLC requires only an image sensor (IS), which is common equipment in smart phones. In the proposed method, an nformation signal is displayed on LCD. However, embedding the information signal into an advertisement may decrease the quality. We propose blue color difference modulation to make such signals imperceptible. We implemented a VLC system between digital signage and IS to demonstrate, the effectiveness of the proposed modulation in a real environment.
Spatial Modulation in Layered Space-Time Coding for Image-Sensor-Based Visible Light Communication
Parameter Fitting of Vehicle Vibration and Road Surface Irregularity in ITS Image Sensor Communication
- M. Kinoshita, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- IEICE Technical Report, RCS2016-112, pp.99-103, Nagoya, Japan
- Jul. 2016
-
- Image sensor communication (ISC) enables multiple and simultaneous signal reception because of its ability spatially separate multiple sources. Therefore, ISC is an attractive solution for an outdoor mobile environment, in particular, in the field of intelligent transport systems (ITS). In ISC, since a transmitter position moves in an image plane according to vehicle movement, detection and tracking of transmitter is critical issue for robust data reception. Such movement referred to as optical flow causes ISC channel to fluctuate and must be considered to receive the signal accurately. In previous work, we have proposed a channel model focused on the motion of an LED transmitter in the image plane. However, vehicle vibration and road surface irregularity parameters have not been examined in detail. Therefore, in this paper, we estimated vehicle vibration and road surface irregularity parameters based on the measured data of vehicle vibration.
Performance comparison of stochastic resonance receiver with Schmitt trigger, comparator, and three-level device for subthreshold signal reception
- H. Tanaka, T. Yamazato, Y. Tadokoro, S. Arai
- Nonlinear Theory and Its Applications, IEICE, vol.7, no.3, pp.407-418
- Jul. 2016
- https://doi.org/10.1587/nolta.7.407
- This paper discusses the stochastic resonance (SR) effect in a binary communication system for subthreshold signal reception. We focus on the problem of no communication when received signal strength is below receiver sensitivity. Subthreshold signal reception requires a device that exhibits SR, such as a Schmitt trigger or a comparator. Previously, we proposed an alternative three-level device and demonstrated its high performance for subthreshold signal reception in an SR receiver. In the present study, we show that our proposed three-level device outperforms the three devices and discuss reasons for this superior performance. Contributions of our present paper are twofold: first, we analytically derive bit error rate (BER) performances of SR receivers installed with a Schmitt trigger and a comparator; second, we compare performances of the Schmitt trigger, comparator, and three-level device.
High-Speed Image Sensor Communications and Its Application to Vehicle-to-Vehicle and Vehicle-to-Infrastructure Communications
- T. Yamazato
- JIEP Advanced Electronics Packaging (JISSO) Technology Symposium, Tokyo Big Sight, Japan
- Jun. 2016
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A New Automotive VLC System Using Optical Communication Image Sensor
- Y. Goto, I. Takai, T. Yamazato, H. Okada, T. Fujii, S. Kawahito, S. Arai, T. Yendo, K. Kamakura
- IEEE Photonics Journal, vol.8, no.3
- Jun. 2016
- https://doi.org/10.1109/JPHOT.2016.2555582
- As a new technology for next-generation vehicle-to-everything (V2X) communication, visible-light communication (VLC) using light-emitting diode (LED) transmitters and camera receivers has been energetically studied. Toward the future in which vehicles are connected anytime and anywhere by optical signals, the cutting-edge camera receiver employing a special CMOS image sensor, i.e., the optical communication image sensor (OCI), has been prototyped, and an optical V2V communication system applying this OCI-based camera receiver has already demonstrated 10-Mb/s optical signal transmission between real vehicles during outside driving. In this paper, to reach a transmission performance of 54 Mb/s, which is standardized as the maximum data rate in IEEE 802.11p for V2X communication, a more advanced OCI-based automotive VLC system is described. By introducing optical orthogonal frequency-division multiplexing (opticalOFDM), the new system achieves a more than fivefold higher data rate. Additionally, the frequency response characteristics and circuit noise of the OCI are closely analyzed and taken into account in the signal design. Furthermore, the forward-current limitation of an actual LED is also considered for long operational reliability, i.e., the LED is not operated in overdrive. Bit-error-rate experiments verify a system performance of 45 Mb/s without bit errors and 55 Mb/s with BER < 10-5.
Range estimation scheme for integrated I2V-VLC using a high-speed image sensor
- T. Yamazato, A. Ohmura, H. Okada, T. Fujii, T. Yendo; S. Arai, K. Kamakura
- IEEE International Conference on Communications Workshops (ICC), pp.326-330, Kuala Lumpur, Malaysia
- May 2016
- https://doi.org/10.1109/ICCW.2016.7503808
- High-speed image sensors, designed for machine vision and control, provide the eyes for autonomous and connected vehicle. A noteworthy feature of high-speed image sensors is their ability to be used as a reception device for visible light communication (VLC) signals. Due to the massive number of pixels available and the ability to spatially separate sources, a signal-receiving pixel in the image sensor plane represents the actual position of the transmitter. The VLC signal can be represented not only by a VLC time domain signal but also by the position of the transmitter. In this paper, we propose a robust range estimation scheme that integrates with a VLC function for infrastructure-to-vehicle visible light communication (I2V-VLC). The scheme is composed of an LED array transmitter and a high-speed image sensor receiver. It measures a range by taking phase-only correlation (POC) and avoids vehicle vibration from road irregularity. Field trials confirm an accuracy range of 0.3 m, even on rough road conditions, with the measurement time of 2 ms, which is much faster than that of light detection and ranging (LIDAR).
A Study on Traffic Flow Management using 700MHz Band Vehicle-to-Infrastructure Cooperative System
- R. Ohno, T. Yamazato
- IEICE Technical Report, RCS2016-3, pp.13-18, Hirosaki, Japan
- Apr. 2016
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- In this paper, we propose traffic flow management using vehicle-to-infrastructure communication system. At present, traffic signals and traffic signs are used mainly to traffic flow management at the intersection. However, dynamic change of the signal phase in response to variation and congestion of traffic is not supported, and the indication displayed in the traffic signs are fixed. On the contrast, flexible traffic flow management is possible using vehicle-to-infrastructure communication system (V2I). For example, signal phase timing can be managed to achieve smooth and ecological driving depending on the traffic situation. In this paper, we aim to propose and consider the effectiveness of traffic flow management method which applies the 700MHz band vehicle-to-infrastructure cooperative system that has been introduced, researched and developed in Japan. As its initial investigation, we propose the algorithm applicable to a cross-shaped intersection of the straight lane. We consider the mixture case of that cars follow the indications transmitted via V2I and cars obey legacy traffic signals.
Free Educational Resources Provided by Nagoya University
- T. Yamazato
- Annals of Nagoya University Library Studies, No.13
- Apr. 2016
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- In this report, details of free educational resources and copyright issue are discussed. The report also introduces free educational resources provided by Nagoya University and presents the results of the ratio of the commercial textbook usages in Department of Science and Department of Engineering of Nagoya University. The results suggest that the percentages of lecturers who create their own teaching materials are rather high. So we are ready to publish open education materials. However, the launching of open educational resources does not advance because of lack of copyright clearance office. For launching of open educational resources, copyright clearance, a grant of the bibliography information (metadata), and appropriate platform that contributes to a wide recognition of the published contents are necessary. The author thinks that a university library should have this function. In this report, an opinion of the author on the opening of the educational materials and the role of the library is also described.
High Speed Image Sensor Based I2V-VLC Channel Modeling in Outdoor Mobile Environment
- M. Kinoshita, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- IEICE General Conference, AS-3-10, pp.S-53 - S-54, Fukuoka, Japan
- Mar. 2016
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BER Performance of NLOS Vehicle to Vehicle Visible Light Communication Using Optical OFDM
- N. Kawagita, T. Yamazato, H. Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- IEICE General Conference, A-9-17, p.153, Fukuoka,Japan
- Mar. 2016
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Performance Improvement of Stochastic Resonance Receiver by Uniform Noise and Binary Noise
- H. Tanaka, Y. Nakashima, T. Yamazato, Y. Tadokoro, S. Arai
- IEICE General Conference, NBS-1-1, pp.S-113 - S-114, Fukuoka, Japan
- Mar. 2016
-
erformance Evaluation of Stochastic Resonance Receiver in Bandlimited BPSK Modulations
- Y. Nakashima, H. Tanaka, T. Yamazato, Y. Tadokoro, S. Arai
- IEICE General Conference, N-2-2, p.369, Fukuoka, Japan
- Mar. 2016
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Preliminary Study of Platoon Management using 700 MHz Band Vehicle-to-Infrastructure Cooperative System
- R. Ohno, T. Yamazato
- IEICE General Conference, A-14-8, p.194, Fukuoka, Japan
- Mar. 2016
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Transmit diversity with single RF front-end using CIOD
- T. Yamaoka, T. Hara, A. Okazaki, T. Yamazato
- IEICE Communications Express, vol.5, no.2, pp.44-48
- Feb. 2016
- https://doi.org/10.1587/comex.2015XBL0170
- Complex interleaved orthogonal design (CIOD) can offers diversity gain to the part of the source in spatial modulation which has single radio frequency (RF) front-end at the transmitter despite multiple-inputmultiple-output, but emits the undesired component out-of-band. For the reducing out-of-band emission, we give up indicating the information source by the antenna switching and increase both the interleaver size and the antenna switching interval. The increase reduces the discontinuities in the waveform and out-of-band emission. We propose such a scheme as transmit diversity with single RF front-end using CIOD. The diversity gain of the proposed scheme is equivalent to the case for CIOD. Moreover, we evaluate the increase of out-of-band emission and confirm that of the proposed scheme compared to the ideal case is only 3dB.
Poor man’s Flipped Classroom
- T. Yamazato
- Nagoya Journal of Higher Education (in Japanese), No.16
- Feb. 2016
-
- This report introduces the active learning techniques employed by the author. Among a variety of active learning pedagogical methods, this report focuses on a flipped classroom. A lecture given during class time is self-learnt outside of a school hours, and typical learning that is completed outside the classroom is performed during in-class time. The spread of massive open online course (MOOC) promotes short video lectures to be viewed by students at home, and it is often seen as the key element in the flipped classroom. However, the production costs of the video lectures are usually high. So the author attempted a so-called “poor man’s flipped classroom.” Given it is an on-going trial it is too early to evaluate it; however, the author has a generally positive feeling about it. Various methods are available for active learning, and one may turn his or her thoughts to the meaning of related pedagogy. Those thoughts lead to questions about what we should be teaching and what students should learn at university. In this report, I also include my opinion with regards to the question.
Improving Communication Rate of Road-to-Vehicle Visible Light Communication System Using High-Speed Camera and LED Traffic Light
- D. Iwase, M. Kasai, T. Yendo, S. Arai, H. Okada, K. Kamakura, T. Fujii
- IEICE Transactions on Communications, vol.J99-B, no.2, pp.97-104
- Feb. 2016
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Novel Demodulation Scheme Based on Blurred Images for Image-Sensor-Based Visible Light Communication
- Y. Ohira, S. Arai, T. Yendo, T. Yamazato, H. Okada, T. Fujii and K. Kamakura
- IEEE GLOBECOM Workshop on Optical Wireless Communication, San Diego, CA, USA
- Dec. 2015
- https://doi.org/10.1109/GLOCOMW.2015.7414144
- This paper proposes a novel data detection scheme based on the occurrence of blurred output images in image-sensor-based visible light communication systems. This system's receiver suffers from an inability to detect correct LED luminance values and demodulation of data because the captured image blurs owing to defocusing. The proposed method assumes that the light emitted by all LEDs that is diffused by the blur can be approximated by applying a Gaussian filter and expressesall LED luminance values as convolution equations based on this diffusion of the LED light. We estimate each LED light's condition by simultaneously solving these convolution equations and recover data according to the estimated result. To confirm the accuracy of the proposed method, we conduct computer simulations and an implementation experiment to evaluate the bit error rate performance of the proposed method.
A note on subthreshold signal reception using stochastic resonance receiver - Comparison of dynamical and non-dynamical devices -
- H. Tanaka, T. Yamazato, Y. Tadokoro, S. Arai
- International Symposium on Nonlinear Theory and its Application (NOLTA), Hong Kong, China
- Dec. 2015
-
- Stochastic resonance (SR) is an interesting phenomenon in that noise enhances system responses. Despite an attractive phenomenon of SR that noise enhances a weak signal below a receiver sensitivity, few researchers have addressed the SR effect in communication systems. Previously, we proposed an analysis method for the SR receiver with a device exhibiting SR and evaluated its bit error rate (BER) performance. However, the device was limited to a non-dynamical device, and there is room for improving the performance of the SR receiver by changing the device. In this paper, we use two typical devices exhibiting SR, i.e., a comparator as a non-dynamical device and a Schmitt trigger as a dynamical device. We evaluate the BER performances of these devices with analysis methods and numerical simulations. A performance comparison of these devices is also shown.
Performance Analysis of Wireless Mesh Networks Using Forward/Reverse-Link Multi-User MIMO
- C. Fuwa, H. Okada, K. Kobayashi, M. Katayama
- International Symposium on EcoTopia Science (ISETS), no.P-6-2, Nagoya, Japan
- Nov. 2015
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- IEEE 802.11ac, which is the latest standard of IEEE 802.11, supports forward-link (downlink) MU (Multi-User)-MIMO (Multiple-Input Multiple-Output), and it can improve the transmission efficiency. IEEE 802.11ax, which is under standardization, is considered to apply reverse-link (uplink) MU-MIMO, and a further improvement of the efficiency is expected. In this paper, we propose to introduce reverse-link MU-MIMO in addition to forward-link MU-MIMO for wireless mesh networks, and evaluate the performance in terms of area transmission efficiency, which indicates a number of packets in a unit area. Then, we clarify that the proposed system achieves the higher area transmission efficiency than forward-link MU-MIMO.
I2V-VLC Vehicle Motion Modeling Using Actual Vehicle Vibration
- M. Kinoshita, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura
- International Workshop on Vision, Communications and Circuits (IWVCC) , Yokohama, Japan
- Nov. 2015
-
- Image-sensor-based visible light communications (IS-VLC), or also known as image sensor communication (ISC) and camera communications (CamCom), is one of emerging segment in the field of visible light communications (VLC). As the name indicates, IS-VLC uses light-emitting diodes (LEDs) or an LED array for the transmitter by modulating LED’s intensity at high speeds that are undetectable to the human eye. For the reception device, IS-VLC adopts image-sensor. In our previous work, we have proposed vehicle motion model that expresses the motion of VLC transmitter in image plane by single pinhole camera model. In this paper, we performed a simulation based on vehicle motion model for infrastructure-to-vehicle VLC (I2V-VLC) with actual vehicle vibration measured by 6- axis acceleration sensor of smartphone and evaluated its channel characterized by optical flow.
Performance Evaluation of Stochastic Resonance Receiver for Dynamical and Non-Dynamical Devices in QPSK Modulation
- H. Tanaka, T. Yamazato, S. Arai
- International Workshop on Vision, Communications and Circuits (IWVCC) , Yokohama, Japan
- Nov. 2015
-
- This paper evaluates the performance of the stochastic resonance (SR) receiver for subthreshold signal reception. We focus on the problem of no communication when received signal strength is below receiver sensitivity. Previously, we proposed a SR receiver installed with a typical device exhibiting SR in BPSK modulation and presented the performance improvement for subthreshold signals. However, the performances of other nonlinear devices exhibiting SR are not clear, and we require the performance evaluation for various nonlinear devices. And also, the performance evaluation in multi-level modulation is not presented. In this paper, we evaluate bit error rate (BER) performances of SR receivers installed with a three-level device, a Schmitt trigger and a comparator in QPSK modulation.
[Exhibition] An Optical Camera Communication System Using Digital Signage
- S. Sato, H. Okada, K. Kobayashi, T. Yamazato, M. Katayama
- International Conference and Exhibition on Visible Light Communications (ICEVLC), Yokohama, Japan
- Oct. 2015
-
Tracking of LED headlights considering NLOS for an image sensor based V2I-VLC
- Y. Kawai, T. Yamazato, H. Okada, T. Fujii, T. Yendo, S. Arai, K. Kamakura
- International Conference and Exhibition on Visible Light Communications (ICEVLC), Yokohama, Japan
- Oct. 2015
-
- This paper focuses on image sensor based vehicle-to-infrastructure visible light communication (V2IVLC) for Intelligent Transport Systems (ITSs). Because the image sensor can spatially separate multiple or noise sources, its receiver can simultaneously demodulate multiple sources. Thus, we consider multiple source reception from multiple vehicles. In image sensor based VLC, the transmitted data are received by extracting the luminance corresponding to the VLC transmitter from the captured image. Transmitter detection and tracking are an important requirement of these systems but are degraded by occlusion, which causes non-line of sight (NLOS). We focus on tracking of transmitters that may be occluded by moving vehicles in V2I-VLC. Our proposed method detects multiple LED headlights by combining a background difference method with an LED detection method based on time and space gradients. We also propose a tracking method based on optical flow-based tracking, which handles occlusion by linear or second-curve interpolation. The proposed methods were evaluated by a high-speed camera placed by the roadside. The false-positive and falsenegative tracking rates were 6.25% and 3.32%, respectively, at κ = 60 (where κ defines the permissible error in the optical flow).
[Invited Lecture] Optical Camera Communications Using Digital Signage
- H. Okada, S. Sato, T. Wada, T. Yamazato, M. Katayama
- ITE Technical Report, BCT2015-74, pp.21-24, Yamagata
- Oct. 2015
-
- In this paper, we discuss optical cammera communication systems using digital signage, which is composed of a liquid crystal display (LCD). The digital signage, which is used as a transmitter, displays advertisement contents as visual information. The optical camera communication system using digital signage has to transmit data information not to obstruct the visual information. In this paper, we propose blue color difference modulation for the optical camera communication system using digital signage. We clarify the performance of the proposed system by data transmission experiments.
Development of add-on stochastic resonance device for the detection of subthreshold RF signals
- K. Chiga, H. Tanaka, T. Yamazato, Y. Tadokoro, S. Arai
- Nonlinear Theory and Its Applications, IEICE, vol. 6, no. 4, pp. 520-533
- Oct. 2015
- https://doi.org/10.1587/nolta.6.520
- Stochastic resonance (SR) is a nonlinear phenomenon that, under certain conditions, can enhance system response by adding noise to the signals of some nonlinear system. A particular advantage of SR over conventional linear systems is that it is able to detect subthreshold signals that linear systems hardly sense. Unfortunately, most research of SR in wireless communication systems has focused on fundamental analysis, leaving work to be done in experimental SR research despite the attractiveness of its application. Few attempts have so far addressed the development of SR receivers to show the feasibility of subthreshold signal detection. Those receivers that have been developed are simple ones specially made to confirm the usefulness of SR without needing to support state-of-the-art wireless radio technology. The purpose of this study is to examine the feasibility of using an SR receiver to receive subthreshold radio frequency (RF) signals. A new add-on SR device is developed and confirmation that the SR phenomenon exists within RF is obtained when using software defined radio (SDR) as the post-processing receiver. Furthermore, bit error rate (BER) performance is mainly governed by the add-on SR device's output signal quality.
Performance Evaluation of Stochastic Resonance Receiver in QPSK Modulations
- Y. Nakashima, H.Tanaka, T.Yamazato, Y.Tadokoro,S.Arai
- Tokai-Section Joint Conference on Electrical, Electronics, Information and Related Engineering, K5-4, Nagoya
- Sep. 2015
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Vehicle Motion and Pixel Illumination Modeling for Image Sensor Based Visible Light Communication
- T. Yamazato, M. Kinoshita, S. Arai, E. Souke, T. Yendo, T. Fujii, K. Kamakura, H. Okada
- IEEE Journal on Selected Areas in Communications, vol.33, no.9, pp.1793-1805
- Sep. 2015
- https://doi.org/10.1109/JSAC.2015.2432511
- Channel modeling is critical for the design and performance evaluation of visible light communication (VLC). Although a considerable amount of research has focused on indoor VLC systems using singleelement photodiodes, there remains a need for channel modeling of VLC systems for outdoor mobile environments. In this paper, we describe and provide results for modeling image sensor based VLC for automotive applications. In particular, we examine the channel model for mobile movements in the image plane as well as channel decay according to the distance between the transmitter and the receiver. Optical flow measurements were conducted for three VLC situations for automotive use: infrastructure to vehicle VLC (I2V-VLC); vehicle to infrastructure VLC (V2I- VLC); and vehicle to vehicle VLC (V2V-VLC). We describe vehicle motion by optical flow with subpixel accuracy using phase-only correlation (POC) analysis and show that a single-pinhole camera model successfully describes these three VLC cases. In addition, the luminance of the central pixel from the projected LED area versus the distance between the LED and the camera was measured. Our key findings are twofold. First, a single-pinhole camera model can be applied to vehicle motion modeling of a I2V-VLC, V2I-VLC, and V2V-VLC. Second, the DC gain at a pixel remains constant as long as the projected image of the transmitter LED occupies several pixels. In other words, if we choose a pixel with highest luminance among the projected image of transmitter LED, the value remains constant, and the signal-to-noise ratio does not change according to the di