Solar LED Street Lamp System With Visible Light Communication

The solar LED street lamp,which realizes the high efficiency green energy conversion in the lighting scenarios,is a"green energy".Visible light communication?VLC?,which does not have the electromagnetic radiation in the communication,is a"green communication".In this paper,the solar street lamp and the VLC are combined to realize a“pure green”system with both"green energy"and"green communication".First of all,the hardware and software design of the intelligent controller,which is the core component of the street lamp system,is accomplished,and a platform controlled by the mobile APP is realized.Then,the VLC circuit is integrated into the solar LED street lamp system,which can realize the multiple function of lighting and communication and obtain the green energy conversion.We proposed a design rule of equalization circuit for VLC system to increase its 3-dB modulation bandwidth.By using the equalization circuit,the modulation bandwidth of the VLC system with a micro-size LED chip is increased from 94.2 to 815 MHz,and that with a commercial large-size LED chip is increased from 10 to 375 MHz.To evaluate the practical performance of the street lamps,a Bias-Tee based VLC system with 9W lighting LED lamp is tested.It is shown that the VLC system with an ordinary-type LED lamp cannot work.Nevertheless,the VLC system with a concentrate-type LED lamp works well.After the proper equalization circuit is added,the modulation bandwidth of the VLC system can be extended from 2.34 to 15.4 MHz;under the condition that the distance from the lamp to the detector is 6 m,the maximum data rate of the VLC system can be increased from 4 to 25 Mbps(the bit error rate below 3.8×10^-3).Finally,a MOSFET based VLC system is proposed to improve the system's communication distance and energy efficiency.Also,the 9W lighting LED lamp is used.If the ordinary-type LED street lamp is used,the GS-mode VLC system can get the eye diagram at the data-rate of 3 Mbps and the distance of 4 meters,while the GD-mode VLC system can only get the eye diagram at the data-rate of 2 Mbps and the distance of 1 meter.The energy efficiencies of the GS-mode and GD-mode VLC systems are 87.8%and 95.9%,respectively.If the concentrate-type LED street lamp is used,the stable eye diagram at the data-rate of 5 Mbps can be obtained in the two modes VLC system at the distance of 12 meters.The energy efficiencies of the GS-mode and GD-mode VLC systems are 89.2%and 96.0%,respectively.Our results show that the MOSFET-based scheme is a good solution for LED street lamp VLC system with high efficiency,low complexity,low cost and long distance.