Error Modeling And Performance Analysis Of TOA-Based Indoor Visible Light Positioning

With the development of technology,a variety of mobile terminals are rapidly flooding into the market.Various services based on positioning have become an indispensable part of social life.Global Positioning System(GPS)and BeiDou Navigation Satellite System(BDS)are widely used in outdoor scenarios.However,due to the signal blocking and multipath effect,they cannot provide reliable positioning services in indoor scenarios.In recent years,visible light has received extensive attention due to its high bandwidth and rich spectrum resources.Visible indoor positioning technology is expected to become one of the major indoor positioning technologies in the future.This work mainly studies the error modeling of the indoor visible light positioning system based on time-of-arrival(TOA)and compares the performance of various positioning algorithms.The effects of limited sampling rate at the receiving end and the time synchronization between the transmiter and the receiver are also studied respectively.The main contributions of this thesis are as follows:·It establishes an indoor visible light signal receiving model.Based on this model,the direct positioning method using the received signal to directly estimate the position of the target is explored.The maximum likelihood(ML)estimation result is given and the complexity of the estimation algorithm is analyzed.The Cramer-Rao low bound(CRLB)based on the direct positioning method is also derived.·In order to reduce the complexity of the algorithm,we consider estimating the position in two steps.In the first step,the TOA parameters are estimated,the variance of time delay estimation is derived and affecting factors are analyzed based on the indoor visible light signal propagation model.An error model which better describes the practical positioning system is further established.In the second step,the maximum likelihood method and the least square(LS)method are adopted to estimate the target position.Lacking analytical results of the positioning error,the explicit expressions of the mean square error(MSE)of the LS and ML methods are derived based on the first-order perturbation theory.The error performance is studied by simulation.·The effects of the nonideal factors on the positioning performance including limited sampling rate and synchronization error are investigated.First,the effects of transmission waveform and sampling rate of the analog-to-digital converter at the receiver on the postioning accuracy are studied.Then the positioning performance in the presence of the system synchronization error is explored,and effects of noise and synchronization error on the positioning accuracy are analyzed.Positioning accuracies of different positioning algorithms under these factors are further compared.