Visible Light Indoor Positioning Anti-interference Technology Based On Chirality

The popularity of light-emitting diode and smart phones has promoted the research of indoor positioning technology based on visible light communication,which has become one of the hotspots in indoor positioning technology.The indoor environment is complex.Mirror,glass,screen and other smooth objects will have specular reflection,generating pseudo light sources.Pseudo light source and real light source are specular symmetry.In the positioning process,if the position information of the pseudo light source is used for positioning,the wrong positioning coordinates will be obtained,and the reliability of positioning will be reduced.Starting from this factor,this paper focuses on how to identify real and pseudo light sources and eliminate specular interference.The main research contents are as follows:This paper proposes a design method of chiral light source.This paper studies the existing methods to identify the authenticity of the light source,and analyzes its limitations.In order to ensure that the receiver can identify the real and pseudo light sources in free attitude,the light source is designed as a small light source array composed of multiple light sources,in which the sub-light sources are arranged compactly and form a closed convex geometry.At the same time,the sub-light sources in the light source array are assigned ID according to the preset chiral order,so that they can identify the authenticity of the light source in the actual indoor environment.Based on the light source array,this paper proposes a light source authentication algorithm based on vector product.According to the ID of the sub-light source in the light source array,the algorithm uses the imaging coordinates of the sub-light source to determine two vectors,and uses the outer product of the vectors to determine the chirality of the light source array,and then determine the authenticity of the light source array.The algorithm is simulated and analyzed from three aspects: the accuracy of the algorithm,the scope of the algorithm and the comparison with the positioning success rate of the existing algorithm.From the perspective of increasing the number of IDs,this paper proposes a light source authentication algorithm based on the delay and sum of the light source emission sequence.In this algorithm,the light source array uses the same pseudo-random sequence,and the sub-light source emission sequence is obtained by cyclic shifting different bits of the sequence.At the receiving end,after the sub-light source emission sequence is obtained,the cross-correlation operation of the adjacent sub-light source emission sequence is performed according to the chirality,and the emission sequence delay of the adjacent sub-light source is obtained.This algorithm identifies the authenticity of the light source array by calculating the relationship between the sum of all the emission sequence delays and the sequence length.Consistent with the vector product algorithm,the algorithm is simulated and analyzed from different aspects.On the premise of meeting the normal illumination,the available length of the emission sequence is deduced according to the rolling shutter characteristics of CMOS image sensor.In this paper,the error rate estimation method is designed for the above two light source identification algorithms.According to the possible error reasons of the imaging geometric distribution analysis algorithm of the light source array,an estimation method of the error rate of the algorithm is proposed,which provides an idea for subsequent research.To sum up,this paper endows the light source with chiral characteristics,and proposes two kinds of light source identification algorithms,which can effectively eliminate the interference of pseudo-light source on the positioning under free attitude and improve the positioning reliability.