Abstract
There are several technologies and techniques available when developing indoor positioning systems (IPS). Recently, the development of positioning systems based on optical signals has aroused great interest, mainly those using visible light from the lighting infrastructure. In this work, we analyze which techniques give better results to lay the foundations for the development of a Visible Light Positioning system (VLP). Working only with a receiver, it is analyzed what the result of determining the position of different emitters is when they emit simultaneously and without any synchronism. The results obtained by Frequency Division Multiple Access (FDMA) (with digital bandpass filters, I/Q demodulation, and FFT) and Code Division Multiple Access (CDMA) are compared. The interference between signals when emitted simultaneously from multiple emitters is analyzed as well as the errors they cause and how these effects can be mitigated. As a result of the research, the advantages and disadvantages using different multiple-access determination techniques are determined. In addition, advantages and disadvantages of using FDMA and CDMA techniques as well as hardware requirements that make one more feasible than the other are presented. The system behavior, in terms of errors, is established using FDMA and different configurations such as: I/Q, RMS, or FFT. The work also determines the error rates that can be obtained with the different FDMA and CDMA configurations, considering different error scenarios and integration time. Synthetic emulations and empirical tests were performed, which concluded that IPS systems based on optical signals and PSD sensors can achieve very high measurement accuracies and a high measurement rate. Obtained positioning errors in a room of 3 m height are less than 1 cm when working in noisy environments.
Highlights
Different applications have been developed based on Indoor Positioning Systems (IPS) to assist people [1] to locate users in large indoor environments in both professional and leisure activities [2,3].They are used in logistic applications for intelligent factories [4] to perform different tasks such as moving objects within an environment [5].It can be seen that IPS is already well established in daily activities [6,7,8,9]
Our research group has worked in the development of optical IPS systems for more than a decade, carrying out work based on measuring the phase shift of the signal on arrival at detectors and determining the angle of arrival of the signal
Focusing in IPS based on PSD, we have proposed an IPS [22] based on the angle of arrival (AoA)
Summary
Different applications have been developed based on Indoor Positioning Systems (IPS) to assist people [1] to locate users in large indoor environments in both professional and leisure activities [2,3].They are used in logistic applications for intelligent factories [4] to perform different tasks such as moving objects within an environment [5].It can be seen that IPS is already well established in daily activities [6,7,8,9]. Different applications have been developed based on Indoor Positioning Systems (IPS) to assist people [1] to locate users in large indoor environments in both professional and leisure activities [2,3]. The following is an outline of the IPS proposed in [22]: knowing the impact point on the PSD, we can obtain the equation of the LOS to the emitter from the calibrated optical system. Knowing this line and knowing that our emitter is always moving in the same plane, the position of the emitter is given by the intersection of this line with that plane. The main advantages of IPS based on PSD sensor are accuracy, precision, range, and obtaining the impact point on the sensor surface with continuous resolution
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