Gigabit-class optical wireless communication system at indoor distances (1.5 ÷ 4 m)

Area of Science:

• Optoelectronics
• Wireless Communication
• Optical Networking

Background:

• Optical Wireless Communication (OWC) offers a high-bandwidth alternative to traditional radio frequency communication.
• Visible Light Communication (VLC) systems, utilizing Light Emitting Diodes (LEDs), are gaining traction for indoor networking.
• Integrating uplink and downlink capabilities in OWC systems is crucial for full-duplex communication.

Purpose of the Study:

• To experimentally demonstrate a bidirectional OWC link utilizing a multi-channel visible LED board and wavelength division multiplexing (WDM).
• To achieve high data rates for both downlink (visible LEDs) and uplink (infrared LED) communication within typical indoor distances.
• To optimize system parameters such as LED working current and modulation depth for enhanced performance.

Main Methods:

• Implementation of a bidirectional OWC link using a four-channel visible LED board for downlink and an infrared LED for uplink.
• Exploitation of wavelength division multiplexing (WDM) to enable multiple data channels within the visible spectrum.
• Careful selection of LED emission wavelengths and optical filter spectra to minimize interference and maximize signal quality.
• Investigation of optimal LED working current and modulation depth to enhance data rates and maintain low bit error ratios.

Main Results:

• Achieved a downlink data rate exceeding 5 Gbit/s using the visible LED board with WDM.
• Achieved an uplink data rate of 1.5 Gbit/s using an infrared LED.
• Demonstrated reliable communication at common indoor distances (1.5 to 4 meters).
• Maintained bit error ratios (BER) below the forward error correction (FEC) limit of 3.8·10⁻³ for all channels.

Conclusions:

• The developed bidirectional OWC system successfully demonstrates high-speed indoor wireless communication.
• The strategic use of WDM with visible LEDs and an infrared uplink offers a viable solution for enhanced OWC.
• Optimized LED parameters and optical components are key to achieving robust performance and exceeding target data rates.