| People have long been eager for indoor positioning technology.With the increasing application range of LED lamps and its dual functions of illumination and communication,it has laid a good foundation for LED-based visible light communication,followed by visible light.Indoor positioning has also attracted the attention of researchers at home and abroad,and has gradually become a research hotspot.This paper first briefly describes the application prospects of indoor visible light and some existing shortcomings.At the same time,it introduces several common positioning algorithms used in visible light indoor positioning technology,especially the positioning algorithm that uses the received signal to reach the intensity RSS;The RSS positioning algorithm requires at least three LED lights to illuminate at the same time in the positioning process.A visible light localization technique based on code division multiple access(CDMA)is proposed,and the basic principle of CDMA technology is introduced in detail,and its inherent multiple access interference is introduced.Based on the predecessors,the calculation formula of the multiple access interference power in the visible light localization system is given,and the influence of the positioning error caused by the multiple access interference is analyzed.Then,the m sequence,the gold sequence,the walsh sequence and the pseudo random sequence are analyzed.The frequency ratio and the transmission power of the LED lamp cause several degrees of influence on the average positioning error caused by the system,and the simulation data is verified.In the case of the ideal channel model,considering the influence of multiple access interference and the influence of Gaussian noise,a channel model more suitable for the actual situation is established,which makes the model of this paper more practical.Due to the influence of multiple access interference and environmental noise,the measured value of RSS and the actual value have different degrees of deviation,so that the calculated distance between the LED and the PD is deviated from the actual distance,and finally the positioning error is caused.Therefore,based on the traditional correction positioning algorithm,an improved error self-correction algorithm is proposed.Without changing the original hardware facilities,the room is first divided into regions,the reference points are selected in each region,and then the test is to be tested.The RSS value of the point is compared with the reference point RSS value in the area to select the nearest reference point,calculate the correction factor,correct the measured distance calculated by the receiving end to be closer to the actual value,and then use the least squares.Finally,the estimated position closer to the real position is obtained,and this method can improve the positioning accuracy to a certain extent.Therefore,the improved algorithm is applied to the model of this paper,and the feasibility of the algorithm is verified by simulation.Simulation experiments show that the gold sequence is superior to the other two kinds of spreading sequences as the spreading sequence.At the same time,the improved error self-correction algorithm and the traditional correction algorithm are compared and found that the improved error self-correction algorithm is superior to the traditional correction algorithm. |
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