Indoor Position Tracking Using Multiple Optical Receivers

An indoor positioning system is a key component in enabling location-based services in future wireless networks. The need for a highly accurate indoor positioning system is rapidly increasing. In the past couple of years, several positioning systems based on visible light communications that achieve good positioning accuracy have been proposed. Some of these systems are based on assumptions such as complete knowledge of the height of the receiver, and exact alignment of the transmitter and receiver normals to the normal of the ceiling. Some other systems do not support user mobility because they require a user to vary the receiver orientation at a fixed location. Another common assumption is that the transmitters are at the same height from the ground. In order to support user mobility, this paper proposes a novel positioning system using multiple optical receivers that provides coordinates and an orientation of the mobile receiver. The remarkable features of the system are as follows: 1) the receiver can be mobile; 2) the positioning is done within 2.5 ms in our experimental setup; 3) the heights of the transmitters need not be the same; 4) the receiver's height need not be known; and 5) the receiver's normal need not be aligned with those of the transmitters. Experimental results show that mean position errors of less than 0.06 m is achievable even when the average receiver speed is 1.3 m/s.