FIG. 1. Example of the total Nt = 16 LED array’s blinking sequence, based on the spatial intensity modulation (SIM) scheme with a 50% target dimming level ((8+ 6 +8 +10) / 4 /16×100 = 50%).
FIG. 2. Optimal turn-on probabilities maximizing the entropy, when (a) Nt = 4 and (b) Nt = 8.
FIG. 3. Binary tree of multilevel Huffman encoding ( Nt = 4, ζD = 0.775)
FIG. 4. Practical turn-on probabilities maximizing the entropy using multilevel inverse source coding, when (a) Nt = 4 and (b) Nt = 8.
FIG. 5. Achievable dimming level of the SIM scheme, when (a) Nt = 4 and (b) Nt = 8.
FIG. 6. Entropy versus the dimming ratio.
FIG. 7. Dimming capacity versus SNR, when the dimming level is (a) 48% and (b) 72%.
FIG. 8. Dimming capacity, depending on both SNR and dimming ratio.
TABLE 1. Example of multilevel Huffman coding ( Nt = 4, ζD = 0.775 )
TABLE 2. Example of multilevel inverse source coding ( Nt = 4, ζD = 0.781)
References
- A. Jovicic, J. Li, and T. Richardson, "Visible light communication: Opportunities, challenges and the path to market," IEEE Commun. Mag. 51, 26-32 (2013).
- H. Burchardt, N. Serafimovski, D. Tsonev, S. Videv, and H. Haas, "VLC: beyond point-to-point communication," IEEE Commun. Mag. 52, 98-105 (2014).
- S. H. Lee, S.-Y. Jung, and J. K. Kwon, "Modulation and coding for dimmable visible light communication," IEEE Commun. Mag. 53, 136-143 (2015).
- J.-H. Yoo and S.-Y. Jung, "Modeling and analysis of variable PPM for visible light communications," EURASIP EURASIP J. Wireless Commun. Netw. 9, 184-190 (2015).
- B. W. Kim and S.-Y. Jung, "Bandwidth-efficient precoding scheme with flicker mitigation for OFDM-based visible light communications," ETRI J. 37, 677-684 (2015). https://doi.org/10.4218/etrij.15.0114.0105
- H. D. Moon and S. Y. Jung, "Multi-coded variable PPM for high data rate visible light communications," J. Opt. Soc. Korea 16, 107-114 (2012). https://doi.org/10.3807/JOSK.2012.16.2.107
- J. Gancarz, H. Elgala, and T. Little, "Impact of lighting requirements on VLC systems," IEEE Commun. Mag. 51, 34-41 (2013).
- S. J. Song and H. Nam, "Visible light identification system for smart door lock application with small area outdoor interface," Curr. Opt. Photon. 1, 90-94 (2017). https://doi.org/10.3807/COPP.2017.1.2.090
- K. Choi, Y. Jang, M. Ju, and Y. Park, "Visible light communication with color and brightness control of RGB LEDs," ETRI J. 35, 927-930 (2013). https://doi.org/10.4218/etrij.13.0212.0425
- T. Fath and H. Haas, "Performance comparison of MIMO techniques for optical wireless communications in indoor environments," IEEE Trans. Commun. 61, 733-742 (2013). https://doi.org/10.1109/TCOMM.2012.120512.110578
- Y. Gong, L. Ding, Y. He, H. Zhu, and Y. Wang, "Analysis of space shift keying modulation applied to visible light communications," in Proc. International Conference on Information and Communication Technology (China, Apr. 2013), pp. 503-507.
- W. O. Popoola, E. Poves, and H. Haas, "Error performance of generalized space shift keying for indoor visible light communications," IEEE Trans. Commun. 61, 1968-1976 (2013). https://doi.org/10.1109/TCOMM.2013.022713.120501
- W. O. Popoola and H. Haas, "Demonstration of the merit and limitation of generalised space shift keying for indoor visible light communications," J. Lightw. Technol. 32, 1960-1965 (2014). https://doi.org/10.1109/JLT.2014.2310499
- S. P. Alaka, T. L. Narasimhan, and A. Chockalingam, "Generalized spatial modulation in indoor wireless visible light communication," in Proc. IEEE Global Communications Conference (USA, Mar. 2015), pp. 15820546.
- M. D. Renzo, H. Haas, A. Ghrayeb, S. Sugiura, and L. Hanzo, "Spatial modulation for generalized MlMO: Challenges, opportunities, and implementation," Proc. of the IEEE 102, 56-103 (2014). https://doi.org/10.1109/JPROC.2013.2287851
- J. K. Kwon, "Inverse source coding for dimming in visible light communications using NRZ-OOK on reliable links," IEEE Photon. Technol. Lett. 22, 1455-1457 (2010). https://doi.org/10.1109/LPT.2010.2062498