Interference Rejection Using Filter-Based Sensor Array in VLC Systems

With the recent development of solid-state lighting (SSL) technologies, visible light communication (VLC) systems using light-emitting diodes (LEDs) has been a promising technology to complement wireless communication. While LEDs offers advantageous properties such as high brightness, lower power consumption, long lifetime, and short transient time for high transmission rates, few researches have been exploited on the receiver side. Conventionally, photoelectric-diodes are implemented to convert optical signals into electronic signals. Since conventional photoelectric-diodes cannot distinguish inputs of different spectra, using conventional photoelectric-diodes have the disadvantage that the system is vulnerable to interference, and that it is hard to achieve wavelength-division-multiplexing (WDM) for light sources of different wavelengths. In this work, a spectrum sensor array is proposed to be implemented on the receiver side to achieve interference rejection. Due to recent advances in semiconductor technologies, spectrum sensors with different spectral transmission properties can be integrated into a chip-scale sensor-array. By proper design of the weightings for individual spectrum sensor, the effective output signal-to-interference ratio (SIR) can be maximized. Following the concept of coherent multi-antenna communication systems, signal fusion algorithms are presented. Our simulation is conducted based on the specification of a prototype filter-array spectrum sensor from nanoLambda. Simulation results demonstrate that robust interference rejection is possible using the low-cost spectrum sensor array.