Metameric indoor localization schemes using visible lights

In indoor environments, visible light communications paradigm is emerging as a viable promising solution complementary to well-known radio frequency technology. At the same time, the information about user's location is useful for accessing the medium via space-division multiplexing, handling over or providing access to location-based contents. In this paper, we present two localization mechanisms based on the wavelength domain by assuming that each anchor point uses a spectrally dedicated signature for the user to readily identify it. The first approach, i.e., wavelength-based localization, assumes a simultaneous transmission of three different pulse streams emitted by the red-green-blue (RGB) light emitting diodes (LEDs). The second method, i.e., color-based localization, considers the subsequent transmission of RGB pulses. Localization is then computed through traditional received signal strength and time difference of arrival approaches. Moreover, we resort to the properties of metamerism so that the red, green, and blue components used by LEDs provide the white light sensation to the human eye. The performances of the two proposed schemes are close to theoretical bounds. Even in the worst cases, the estimation error variance is in the order of $10^{-4}$ m$^2$. Finally, the signaling request for estimating user position is less than others in the literature and is independent from the number of anchor points.