Research On Indoor Visible Light Positioning Based On PN Code

Indoor visible light positioning technology is indoor positioning technology based on visible light communication.This technology has the advantages of good confidentiality,high positioning accuracy,and both lighting and communication.In this thesis,the bit error rate of CDMA system under multi-access interference is analyzed.Then,based on the traditional positioning algorithm,an indoor visible light positioning algorithm based on PN code and CDMA modulation is proposed.Based on this algorithm,we continue to simplify and improve the operation.The specific research work of this thesis is as follows:First of all,on the basis of the predecessors,this thesis focuses on the estimation of bit error rate(BER)by using standard Gaussian approximation and simplified and improved Gaussian approximation.It is found that the simplified and improved Gaussian approximation method is more accurate for estimating the bit error rate of a CDMA system under multiple access interference when the number of users is small.And the standard Gaussian approximation method is not suitable for the central limit theorem due to the small number of users.So it has big deviation.Secondly,based on the RSS triangulation algorithm,this paper proposes an indoor visible light positioning technology based on PN code and CDMA modulation.The PN code is used as the spreading code to spread the ID location information that improve the anti-jamming capability.The receiver despreading access to each LED lamp corresponding to the ID location information,and then calculate the distance of the light source and the receiver.Finally,we use the RSS Triangle positioning algorithm to achieve precise positioning.Finally,on the basis of the above algorithm,a simplified and improved operation is carried out.the PN code is taken as a sign to identify different light sources,which not only saves the transmission of ID location information but also eliminates the need for frequency and despreading operations and simplify system complexity.At the same time,we further study the influence of the position of the reference point light source on the positioning accuracy.The research shows that the stability of the system can be effectively improved by uniformly distributing the position of the light source so that the light intensity is evenly distributed.