Restarch On New Light Source Based On White LED And RGB LED In Visible Light Communication

With the continuous deepening of research on visible light communication(VLC),many research institutes have made breakthrough achievements in the field of VLC,but no researchers have combined white LED and RGB LED applied into VLC systems.Therefore,a new type of light source used in the VLC systems is proposed for the first time.The new light source is composed of a white LED and one or more sets of red,green and blue(RGB)LED,white LED provide the stable function of illumination,while RGB LED are utilized as antennas for information transmission in different combinations.There are seven combinations of RGB LED that can realize the communication function.This article mainly studies the color quality and communication performance of the new light source under the six combinations of RGB LED,and under the constraints of color rendering index of light source,the signal-to-noise ratio of the receiver,and bit error rate,the power ratio of the power of RGB LED and white LED is analyzed in different combinations.At the same time,on the basis of the new light source,two new modulation methods are proposed.One is based on the joint color shift keying(CSK)modulation and multi-pulse position modulation(MPPM)methods.The coding modulation process of the joint CSK modulation and MPPM modulation is deeply studied,and a specific example is given.The pseudo noise(PN)applied to the VLC system is proposed to recognize the time slot combination mode of MPPM.At the same time,the signal transmission,channel model and noise of the system are also analyzed.This paper is the first to study joint CSK modulation and MPPM methods,and it can be extended to other modulation methods.It provides a choice for the modulation method of the VLC system.The other is a joint step-by-step mapping spatial modulation method based on a novel light source.This modulation method combines the spatial modulation and different combinations of RGB LED for the first time,and implements the mapping process step by step to reduce the complexity of system modulation and demodulation.The different combinations of RGB LED are determined according to the color rendering index of the new light source and the range of the available power ratio to adapt to the communication of different scenarios.The new modulation method is used to transmit DCO-OFDM signals,and the effects of modulation order,DC offset,and transmitter layout on system performance are studied.