Research On Visible Light Communication System Based On Vertical Structure GaN LED

As the next generation of mobile communication technology,6G has core requirements that include higher data rates,lower latency,better reliability,and broader coverage.Visible light communication(VLC)technology is one such technology that can provide important support for the implementation of 6G.By utilizing light signals emitted from sources such as LEDs,VLC technology can achieve high speed,low power consumption,resistance to interference,and security advantages.Compared to traditional wireless communication technologies,VLC technology does not produce electromagnetic interference and radiation,while also offering advantages such as high-density coverage,high-speed rates,and low cost.This paper first focuses on LED devices and designs blue and green vertical GaN LEDs on a 4-inch silicon substrate metal-bonded wafer,and briefly describes the wafer structure and fabrication process of the vertical GaN LED.The designed LED is then subjected to electrical and spectral testing,as well as communication performance testing,using measurement instruments.Based on the results of the LED testing,circuit designs for the transmission and reception ends of the optical communication system,video data processing,and main control chip selection are developed.Furthermore,theoretical analysis of the visible light communication channel model is conducted to determine the key technical requirements of the visible light communication system in different channel transmissions.Based on a comparison of different communication modulation schemes,2FSK is selected as the modulation method for the system due to its ease of bit synchronization,moderate bandwidth,and reduced system design complexity.Additionally,a low distortion and adjustable voltage transmission driver circuit is designed,as well as a high-gain,high-sensitivity,and low-noise receiving circuit,which are adjusted through waveform testing.The advantages of FPGA,including strong reconfigurability,high parallel processing capability,and low power consumption,are leveraged to select it as the main control circuit for the optical communication system.This enables functions such as Ethernet interface audio and video signal acquisition,data storage,subpacketization,signal RS encoding and decoding,and FSK modulation and demodulation,and establishes a verification testing platform for functional simulation testing of the corresponding codes.Finally,a full-duplex visible light communication system platform is established,and actual system testing is completed.According to the experimental results in this paper,it is shown that vertical junction GaN LEDs have higher luminous efficiency,greater efficiency and good heat dissipation rate compared with planar LED devices,and are compatible with the conventional sequenced list(pseudo-random binary sequence,PRBS)waveform speed.It can reach 20 Mbps,the power capacitance of a single LED is3 W when the system is working normally,and the normal working voltage of the system is 12V;at the same time,based on the progressive processing of audio and video digital codewords based on FPGA,blue and green GaN LEDs are used as emission sources.The 2 FSK signal optical communication with frequency modulation of 5Mbps and 10 Mbps was measured in a 2m water tank,and the full-duplex video communication test was realized.