| As the fourth generation of semiconductor lighting source, white LED has the advantages of long service life, high light intensity and energy efficiency, which is the lighting product actively promoted by country in the future. Meanwhile, in the background of radio spectrum resources increasingly depleted, VLC has many advantages:wide bandwidth with400THz, no need to apply for spectrum license, no electromagnetic interference and no harmless to the human body and so on. With the enhancement of LED manufacturing process, the current white LED has high response sensitivity (microseconds). Therefore, it can be used to transmit high-speed data. The VLC technology can achieve both lighting and indoor communication, which is a kind of indoor wireless broadband access technology in recent years. The study on VLC has important research value and application prospect.In our country, VLC is still in its infancy, while the current research Achievement mainly focused on channel model analysis and modulation methods. The research for error correction code technology and multi-receiver technology used in VLC is almost a white paper。The institutes that achieve VLC system are also numbered. The error correction code technology and multi-receiver technology applied VLC system has important significance.This paper presents a full-duplex VLC system model, common optical communication modulation technology (OOK, PPM and DPPM) and error correction code technology (Turbo code, LDPC code and RS code). We relize OOK, PPM modulation, and through comparative analysis, finally2-PPM modulation is the best choice for the system.A VLC system based on PPM modulation and RS error correction code is proposed in this paper. This paper designs and implements multipliers and RS (160,128) code based on Galois field GF(28), and verify the performance of RS code by Modelsim simulation tools. We complete system BER test between with RS code and without RS code, the following conclusions:BER performance with RS code is superior to the one without RS code at the distance of1.6m to2.8m. To ensure the BER of this VLC system is lower than10-6, the transmission distance is1.5m without RS code, while with RS code we can extend the distance to2.2m. However, due to a certain error correction threshold for RS code, it will be out of function beyond the distance of2.8m.A VLC system based on Ethernet is proposed in this paper. This paper designs and implements MII controller, including the MDIO interface control, the data transmission between MAC and PHY module,4B/5B encoding/decoding module and synchronization FIFO buffer module, and verify the correctness of the MII interface by Modelsim simulation tools. We complete720P HD video transmission test with10Mb/s transmission rate, and the communication distance is3.2m.This paper discusses the value of multi-receiver technology applied into VLC. We simulate the relationship of average Gain of each receiver vs.the number of receivers, and the BER performance vs.the number of receivers. Considering the cost and error rate of the receiver, this paper uses four receivers as the best solution. |
