Demodulation method for distorted carrier of visible light communication in indoor positioning for autonomous robots

Visible light positioning offers some advantages not to be substituted by the traditional wireless positioning. However, visible light positioning systems are subjected to the problem of the optical communication carrier distortion caused by the nonlinear characteristics of light-emitting diodes. A phase-sensitive detection demodulation technique is therefore proposed to address this problem. This technique makes use of the distorted signal frequency spectrum characteristics and relies on the phase-sensitive detection demodulation method to suppress the harmonic interferences of higher orders. Dispensing with the need for hardware predistortion in the emitter, this technique simplifies substantially the complexity of the positioning system. Simulations show that the bit error rates of 1, 1.5, and 2 MHz/s carrier data are less than 10−6 in indoor environments, satisfying the requirement of indoor visible light positioning for autonomous robots.