Design and Analysis on FLIP-VLC-CC-CDMA Systems

Visible light communication (VLC) can be combined with Unmanned Aerial Vehicle (UA V) network technology, through the use of visible light band for data transmission, with fast transmission speed, strong anti- interference ability, high security advantages. Among them, anti- interference ability is extremely important for U A V applications, therefore, a suitable multi-access method is needed to eliminate interference. This paper designs a VLC code division multiple access (VLC-CDMA) using complementary codes (CCs). CCs have ideal autocorrelation and cross-correlation properties, which can be used to distinguish different users. The issues on periodicity and correlation of CCs in VLC-CDMA systems are discussed as preliminaries. The transmitter uses Light Emitting Diode (LEDs) of different wavelengths to separate different sub-codes in the CCs. The compensation circuit is used to synthesize white light and realize equal gain combination of the received signals. The receiver uses a filter with different central wavelength to separate signals transmitted by different sub-codes and convert them into electrical signals. B/U and U/B modules at transmitter and receiver are designed to complete the conversion between unipolar signals and bipolar signals. The anti-interference performance and a theoretical analysis on BER are conducted to verify the effectiveness. In addition, we compare the performance of VLC- CDMA systems using CC, Walsh sequences and Gold sequences, which shows that VLC-CDMA system using CCs can eliminate multi-user and multi-path interference.