Utilization of Optical OFDM Modulation on Blue LED VLC Datacom Without Equalization for 4 m Wireless Link

Area of Science:

• Optoelectronics
• Wireless Communication
• Optical Engineering

Background:

• Visible light communication (VLC) systems commonly use wide bandwidth light-emitting diodes (LEDs) and spectral efficiency modulation for high traffic capacity.
• Achieving high data rates in VLC systems is crucial for next-generation indoor wireless networks.

Purpose of the Study:

• To demonstrate a visible light communication (VLC) system capable of achieving over 1 Gbit/s capacity using a single blue LED.
• To evaluate the performance of an orthogonal frequency division multiplexing quadrature amplitude modulation (OFDM-QAM) system with bit- and power-loading algorithms under low illumination conditions.

Main Methods:

• Application of orthogonal frequency division multiplexing quadrature amplitude modulation (OFDM-QAM) with bit- and power-loading algorithms on a single blue LED.
• Utilizing a 400 MHz bandwidth avalanche photodiode (APD)-based receiver (Rx) for decoding the optical signal.
• Testing the system's performance over wireless link lengths of 1 to 4 meters with illumination levels ranging from 255 to 40 lux.

Main Results:

• Achieved a data rate exceeding 1 Gbit/s (0.962 to 1.057 Gbit/s) using a single blue LED and OFDM-QAM.
• Demonstrated successful decoding with a 400 MHz bandwidth APD receiver under poorly illuminated indoor conditions.
• Confirmed the effectiveness of the high-sensitivity APD in compensating for wireless VLC link length.

Conclusions:

• A single blue LED VLC system can achieve high data rates (>1 Gbit/s) suitable for indoor access networks.
• The proposed OFDM-QAM system with APD receiver is effective even in low-light environments without analog equalization.
• This technology offers a viable solution for enhancing indoor wireless communication capacity.