In this paper, we propose and validate an artificial neural network-based equalizer for the constant power 4-level pulse amplitude modulation in an optical camera communications system. We introduce new terminology to measure the quality of the communications link in terms of the number of row pixels per symbol Npps, which allows a fair comparison considering the progress made in the development of the current image sensors in terms of the frame rates and the resolutions of each frame. Using the proposed equalizer, we experimentally demonstrate a non-flickering system using a single light-emitting diode (LED) with Npps of 20 and 30 pixels/symbol for the unequalized and equalized systems, respectively. Potential transmission rates of up to 18.6 and 24.4 kbps are achieved with and without the equalization, respectively. The quality of the received signal is assessed using the eye-diagram opening and its linearity and the bit error rate performance. An acceptable bit error rate (below the forward error correction limit) and an improvement of ~66% in the eye linearity are achieved using a single LED and a typical commercial camera with equalization.

Department of Electromagnetic Field Faculty of Electrical Engineering Czech Technical University Prague 16627 Prague Czech Republic

Institute of Photonics University of Strathclyde Glasgow G1 1XQ UK

Instituto de Telecomunicações and Departamento de Electrónica Telecomunicações e Informática Universidade de Aveiro 3810 193 Aveiro Portugal

Optical Communications Research Group Faculty of Engineering and Environment Northumbria University Newcastle upon Tyne NE1 8ST UK

Zobrazit více v PubMed

Teli S.R., Zvanovec S., Ghassemlooy Z. Performance evaluation of neural network assisted motion detection schemes implemented within indoor optical camera based communications. Opt. Express. 2019;27:24082–24092. doi: 10.1364/OE.27.024082. PubMed DOI

Eso E., Ghassemlooy Z., Zvanovec S., Gholami A., Burton A., Hassan N.B., Younus O.I. Experimental Demonstration of Vehicle to Road Side Infrastructure Visible Light Communications; Proceedings of the 2019 2nd West Asian Colloquium on Optical Wireless Communications (WACOWC); Tehran, Iran. 27–28 April 2019; pp. 85–89.

Saeed N., Guo S., Park K.-H., Al-Naffouri T.Y., Alouini M.-S. Optical camera communications: Survey, use cases, challenges, and future trends. Phys. Commun. 2019;37:100900. doi: 10.1016/j.phycom.2019.100900. DOI

Younus O.I., Hassan N.B., Ghassemlooy Z., Haigh P.A., Zvanovec S., Alves L.N., Minh H.L. Data Rate Enhancement in Optical Camera Communications Using an Artificial Neural Network Equaliser. IEEE Access. 2020;8:42656–42665. doi: 10.1109/ACCESS.2020.2976537. DOI

Lee H.-Y., Lin H.-M., Wei Y.-L., Wu H.-I., Tsai H.-M., Lin K.C.-J. RollingLight: Enabling Line-of-Sight Light-to-Camera Communications; Proceedings of the 13th Annual International Conference on Mobile Systems, Applications, and Services; Florence, Italy. 18–22 May 2015; pp. 167–180.

Nguyen T., Islam A., Hossan T., Jang Y.M. Current Status and Performance Analysis of Optical Camera Communication Technologies for 5G Networks. IEEE Access. 2017;5:4574–4594. doi: 10.1109/ACCESS.2017.2681110. DOI

Bani Hassan N., Ghassemlooy Z., Zvanovec S., Biagi M., Vegni A.M., Zhang M., Luo P. Non-Line-of-Sight MIMO Space-Time Division Multiplexing Visible Light Optical Camera Communications. J. Lightwave Technol. 2019;37:2409–2417. doi: 10.1109/JLT.2019.2906097. DOI

Eso E., Teli S., Bani Hassan N., Vitek S., Ghassemlooy Z., Zvanovec S. 400  m rolling-shutter-based optical camera communications link. Opt. Lett. 2020;45:1059–1062. doi: 10.1364/OL.385423. PubMed DOI

Lauxtermann S., Lee A., Stevens J., Joshi A. Comparison of Global Shutter Pixels for CMOS Image Sensors; Proceedings of the 2007 International Image Sensor Workshop; Ogunquit, ME, USA. 7–10 June 2007.

Li X., Hassan N.B., Burton A., Ghassemlooy Z., Zvanovec S., Perez-Jimenez R. A Simplified Model for the Rolling Shutter Based Camera in Optical Camera Communications; Proceedings of the 2019 15th International Conference on Telecommunications (ConTEL); Graz, Austria. 3–5 July 2019; pp. 1–5.

Sturniolo A., Cossu G., Ciaramella E., Hassan N.B., Shou Z., Huang Y., Ghassemlooy Z. ROI Assisted Digital Signal Processing for Rolling Shutter Optical Camera Communications; Proceedings of the 2018 11th International Symposium on Communication Systems, Networks & Digital Signal Processing (CSNDSP); Budapest, Hungary. 18–20 July 2018; pp. 1–6.

Nguyen T., Islam A., Yamazato T., Jang Y.M. Technical Issues on IEEE 802.15.7m Image Sensor Communication Standardization. IEEE Commun. Mag. 2018;56:213–218. doi: 10.1109/MCOM.2018.1700134. DOI

Cahyadi W.A., Chung Y.H., Ghassemlooy Z., Hassan N.B. Optical Camera Communications: Principles, Modulations, Potential and Challenges. Electronics. 2020;9:1339. doi: 10.3390/electronics9091339. DOI

Goto Y., Takai I., Yamazato T., Okada H., Fujii T., Kawahito S., Arai S., Yendo T., Kamakura K. A New Automotive VLC System Using Optical Communication Image Sensor. IEEE Photonics J. 2016;8:1–17. doi: 10.1109/JPHOT.2016.2555582. DOI

Roberts R.D. Undersampled frequency shift ON-OFF keying (UFSOOK) for camera communications (CamCom); Proceedings of the 2013 22nd Wireless and Optical Communication Conference; Chongqing, China. 16–18 May 2013; pp. 645–648.

Luo P., Ghassemlooy Z., Le Minh H., Tang X., Tsai H. Undersampled phase shift ON-OFF keying for camera communication; Proceedings of the Sixth International Conference on Wireless Communications and Signal Processing (WCSP); Hefei, China. 23–25 October 2014.

Nguyen D.T., Chae Y., Park Y. Enhancement of Data Rate and Packet Size in Image Sensor Communications by Employing Constant Power 4-PAM. IEEE Access. 2018;6:8000–8010. doi: 10.1109/ACCESS.2018.2802948. DOI

Luo P., Ghassemlooy Z., Minh H.L., Tsai H., Tang X. Undersampled-PAM with subcarrier modulation for camera communications; Proceedings of the 2015 Opto-Electronics and Communications Conference (OECC); Shanghai, China. 28 June–2 July 2015; pp. 1–3.

Luo P., Zhang M., Ghassemlooy Z., Zvanovec S., Feng S., Zhang P. Undersampled-Based Modulation Schemes for Optical Camera Communications. IEEE Commun. Mag. 2018;56:204–212. doi: 10.1109/MCOM.2018.1601017. DOI

Rachim V.P., Chung W. Multilevel Intensity-Modulation for Rolling Shutter-Based Optical Camera Communication. IEEE Photonics Technol. Lett. 2018;30:903–906. doi: 10.1109/LPT.2018.2823784. DOI

Hu P., Pathak P.H., Zhang H., Yang Z., Mohapatra P. High Speed LED-to-Camera Communication using Color Shift Keying with Flicker Mitigation. IEEE Trans. Mobile Comput. 2020;19:1603–1617. doi: 10.1109/TMC.2019.2913832. DOI

Luo P., Zhang M., Ghassemlooy Z., Minh H.L., Tsai H., Tang X., Png L.C., Han D. Experimental Demonstration of RGB LED-Based Optical Camera Communications. IEEE Photonics J. 2015;7:1–12. doi: 10.1109/JPHOT.2015.2486680. DOI

Griffiths A.D., Herrnsdorf J., Strain M.J., Dawson M.D. Scalable visible light communications with a micro-LED array projector and high-speed smartphone camera. Opt. Express. 2019;27:15585–15594. doi: 10.1364/OE.27.015585. PubMed DOI

Liu L., Deng R., Chen L. Spatial and Time Dispersions Compensation With Double-Equalization for Optical Camera Communications. IEEE Photonics Technol. Lett. 2019;31:1753–1756. doi: 10.1109/LPT.2019.2945405. DOI

Haigh P.A., Ghassemlooy Z., Rajbhandari S., Papakonstantinou I., Popoola W. Visible Light Communications: 170 Mb/s Using an Artificial Neural Network Equalizer in a Low Bandwidth White Light Configuration. J. Lightwave Technol. 2014;32:1807–1813. doi: 10.1109/JLT.2014.2314635. DOI

Rajbhandari S., Ghassemlooy Z., Angelova M. Effective Denoising and Adaptive Equalization of Indoor Optical Wireless Channel with Artificial Light Using the Discrete Wavelet Transform and Artificial Neural Network. J. Lightwave Technol. 2009;27:4493–4500. doi: 10.1109/JLT.2009.2024432. DOI

Rajbhandari S., Faith J., Ghassemlooy Z., Angelova M. Comparative study of classifiers to mitigate intersymbol interference in diffuse indoor optical wireless communication links. Optik. 2013;124:4192–4196. doi: 10.1016/j.ijleo.2012.12.040. DOI

Willy Anugrah C., Yeon Ho C. Smartphone camera-based device-to-device communication using neural network-assisted high-density modulation. Opt. Eng. 2018;57:1–9.

Islam A., Hossan M.T., Jang Y.M. Convolutional neural networkscheme–based optical camera communication system for intelligent Internet of vehicles. Int. J. Distrib. Sens. Netw. 2018;14:1550147718770153. doi: 10.1177/1550147718770153. DOI

Liu L., Deng R., Chen L.-K. 47-kbit/s RGB-LED-based optical camera communication based on 2D-CNN and XOR-based data loss compensation. Opt. Express. 2019;27:33840–33846. doi: 10.1364/OE.27.033840. PubMed DOI

Younus O.I., Hassan N.B., Ghassemlooy Z., Zvanovec S., Alves L.N., Haigh P.A., Minh H.L. An Artificial Neural Network Equalizer for Constant Power 4-PAM in Optical Camera Communications; Proceedings of the 2020 12th International Symposium on Communication Systems, Networks and Digital Signal Processing (CSNDSP); Porto, Portugal. 20–22 July 2020; pp. 1–6.

Nguyen H., Pham T.L., Nguyen H., Jang Y.M. Trade-off Communication distance and Data rate of Rolling shutter OCC; Proceedings of the 2019 Eleventh International Conference on Ubiquitous and Future Networks (ICUFN); Zagreb, Croatia. 2–5 July 2019; pp. 148–151.

Chau J.C., Little T.D.C. Analysis of CMOS active pixel sensors as linear shift-invariant receivers; Proceedings of the 2015 IEEE International Conference on Communication Workshop (ICCW); London, UK. 8–12 June 2015; pp. 1398–1403.

Lehman B., Wilkins A., Berman S., Poplawski M., Miller N.J. Proposing measures of flicker in the low frequencies for lighting applications; Proceedings of the 2011 IEEE Energy Conversion Congress and Exposition; Phoenix, AZ, USA. 16–21 September 2011; pp. 2865–2872.

DiLaura D.L., Houser K.W., Mistrick R., Stey S.G. The Lighting Handbook Reference and Application. 10th ed. Illuminating Engineering Society of North America (IES); New York, NY, USA: 2011. p. 247.

Rajbhandari S., Chun H., Faulkner G., Haas H., Xie E., McKendry J.J.D., Herrnsdorf J., Gu E., Dawson M.D., O’Brien D. Neural Network-Based Joint Spatial and Temporal Equalization for MIMO-VLC System. IEEE Photonics Technol. Lett. 2019;31:821–824. doi: 10.1109/LPT.2019.2909139. DOI

ON Semiconductor. Semiconductor Components Industries, LLC; Aurora, CO, USA: 2017. [(accessed on 20 March 2021)]. 1.3Mp CMOS Digital Image Sensor. Application Note 98AON94065F. Available online: https://www.onsemi.com/pdf/datasheet/mt9m131-d.pdf.

Cossu G., Sturniolo A., Ciaramella E. Modelization and Characterization of a CMOS Camera as an Optical Real-Time Oscilloscope. IEEE Photonics J. 2020;12:1–13. doi: 10.1109/JPHOT.2020.3032951. DOI

AN 835: PAM4 Signaling Fundamentals. Intel. Intel Corporation; Santa Clara, CA, USA: 2019. [(accessed on 10 March 2021)]. Application Note AN-835. Available online: https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/an/an835.pdf.

Editorial to the Special Issue on "Visible Light Communications, Networking, and Sensing"