Researchers Obtain Patent in Visible Light Communication

Achievement date: 

A professor and researcher at member institutions of the NSF-funded Engineering Research Center for Lighting Enabled Systems & Applications (LESA), headquartered at Rensselaer Polytechnic Institute (RPI), were jointly awarded a patent for their work in visible light communication (VLC) on Optical Orthogonal Frequency Division Multiplexing (O-OFDM).


VLC provides high data communication rates with low power requirements, has an unregulated bandwidth, creates no interference with radio frequency (RF) systems, is low cost, and does not pose any known health concerns. The basic OFDM method overcomes bandwidth limitations of LEDs, providing a 3X to 5X improvement in data rates.


In VLC, the light data wave form is modulated onto the instantaneous power of the optical carrier, and an optical detector generates a current proportional to the received instantaneous power. The O-OFDM the researchers patented is an efficient coding platform that is fully compatible with pulse width modulation (PWM) SSL dimming, and color control methods widely used in lighting.

O-OFDM is a now a patented parallel data transmission technique where high data rates can be achieved by transmitting on orthogonal subcarriers. O-OFDM systems do not require complex channel equalizers because the time varying channel can be easily estimated using frequency domain channel estimation, and because adaptive modulation can be applied based on the up- link/down-link requested data rates.