Research On Interference Mitigation Method Based On Optical Camera Communication

With the advent of the Internet of Things era,global mobile data traffic is increasing excessively,so more spectrum resources are urgently needed to meet the needs of communication.Compared with millimeter wave communication and terahertz communication,visible light communication（VLC）has the advantages of high security,low cost and anti-electromagnetic interference.Recently,optical camera communication（OCC）has attracted the attention of many research teams due to the rising market share of light-emitting diodes（LED）and the popularization of smart mobile devices.It is a VLC technology with a complementary metal oxide semiconductor（CMOS）image sensor as the receiver.In this paper,considering the problems of inter-channel interference（ICI）and inter-symbol interference（ISI）in OCC system,the following works are carried out:1.An effective ID identification scheme and a sorting-based column matrix selection scheme are proposed to reduce the influence of ICI on the system,when the user moves to the LED radiation overlapping area.An improved sampling scheme based on length estimation is proposed to solve the problem of bright and dark fringes caused by overlapping row exposure times and user movement.The experimental results show that at the LED deployment interval of 20cm and the user moving speed of 80cm/s,the Bit Error Rate（BER）of the traditional demodulation scheme can be improved from 3.75×10^-2 improved to 10^-6using the proposed demodulation scheme.2.A demodulation scheme based on artificial neural network（ANN）is proposed to deal with the influence of ISI in the OCC systems based on pulse width modulation（PWM）.The BER performance of the system under different illumination and different data rates is studied.The experimental results show that the ANN scheme can significantly reduce the BER at the expense of smaller time cost and memory cost,compared with the traditional demodulation scheme and other machine learning schemes.Using the proposed scheme,the BER can be reduced to 1.78×10^-5 at the data rate of 15.84kb/s and the illumination of 2440lux.