Fine-grained indoor localization: optical sensing and detection

A LED-assisted navigation system for large indoor environments is proposed. White LEDs are used both for illumination purposes and as transmitters. On-off keying modulation scheme is used to broadcast the information together with the identifiers, IDs, related to the physical location of the transmitters. The mobile receiver is implemented using a double p-i-n/pin SiC photodetector with light controlled filtering properties. Coded multiplexing techniques for supporting communications and navigation concomitantly on the same channel are analysed. Fine-grained indoor localization is demonstrated. Different indoor layouts, using as position technique a four-code assignment for the LEDs, are proposed. Square and hexagon mesh are tested, and a 2D localization design, demonstrated by a prototype implementation, is presented. The key differences between both topologies are discussed. The location and motion information is calculated by position mapping and estimating the location areas along the time. In both topologies, the transmitted data information, indoor position and motion direction of the mobile device are determined. The results showed that the LED-aided VLC navigation system make possible not only to determine the position of a mobile target inside the unit cell but also in the network and concomitantly to infer the travel direction along the time.