Indoor Visible Light Localization Algorithm Based On Received Signal Strength

With the development of wireless communication and the popularization of mobile terminals,location based service(LBS)has attracted increasing attention.Indoor localization is a key technology of indoor LBS.Indoor visible light localization is a promising candidate for indoor localization.It is based on the visible light communication(VLC)system,and utilizes the visible light signals to implement localization.It is capable of high accurate localization,has economical and dense infrastructure due to the wide adoption of light-emitting diodes(LED)and can be free employed in electromagnetic sensitive environments.The topic of this thesis comes from the Huawei Innovation Research Program(HIRP)(No.20150101).The received signal strength(RSS)algorithm is the most widely used kind of indoor visible light localization algorithm.However,existing RSS algorithms usually require the receiver orientation limiting or knowing,and their coverage is not high.To address the problems above,we proposed three kinds of RSS algorithms for different system models,and combined them as a multi-model localization scheme.Main research contents of this paper are listed as follows:1.In the improvement of the transmitter,a multiple directional LED array(MDLA)consisting of multiple LEDs pointing to different directions is designed as the transmitter.Furthermore,a localization algorithm based on RSS with MDLA is proposed,which utilize the received signal strength ratio(RSSR)to localize the photodiode(PD).Using the proposed algorithm,a PD only requires to detect one MDLA for 2-dimensional(2-D)localization and two for 3-dimensional(3-D)localization.The proposed algorithm can attain high accuracy without limit to or need for the knowledge of the PD orientation,and can cover more locations and orientations of the receiver compared to the conventional RSS algorithm using the triangulation method with the lamp structure of a single LED.Simulation results show that when the tilt angle of LEDs is 15°,in the proposed algorithm for 3-D localization,the errors of 95%localization results are below 19cm,and it can cover 11.1%more locations and 13.1%more orientations of the receiver than the conventional triangulation2.In the improvement of the receiver,a multiple directional PD array(MDPA)consisting of multiple PDs pointing to different directions is designed as the receiver.Furthermore,a localization algorithm based on RSS with MDPA is proposed,which involves two phases:the incidence angle estimation based on RSSR with the relative orientation of PD with respect to the MDPA,and then the location estimation based on RSS with the estimate of the incidence angle.Using the proposed algorithm,a MDPA only requires to detect three LEDs for 3-D localization.The proposed algorithm can attain centimeter-level accuracy without limit to or need for the knowledge of the orientation of the MDPA(or the PD).Simulation results show that when the tilt angle of PDs is 15°,the errors of 95%localization results are below 5cm.3.Furthermore,combining the research results above,employ the MDLA as the transmitter and the MDPA as the receiver simultaneously in the localization system.Firstly,in the case of using only one MDLA,a localization algorithm based on RSS with MDLA and MDPA is proposed,which involves three phases:the irradiance angle estimation based on RSSR,the incidence angle estimation based on RSSR,and then the location estimation based on RSS.Using the proposed algorithm,a MDPA only requires to detect one MDLA for 3-D localization,and there is no iterative procedure in the computation.The proposed algorithm can attain centimeter-level accuracy without limit to or need for the knowledge of the orientation of the MDPA(or the PD).Simulation results show that when the tilt angle of the LEDs in MDLA and the PDs in MDPA are both 15°,the errors of 95%localization results are below 8cm.Secondly,in the case that multiple MDLA exsit,the three kinds of localization algorithms proposed above are combined as a MDLA-MDPA multi-model localization scheme,using which the three different localization algorithms can be employed for three different signal receiving conditions.The MDLA-MDPA multi-model localization scheme can not only give full play to the advantages of these three algorithms,but also possess higher cover than anyone of them.