Light Fidelity (Li-Fi) is an emerging wireless communica-tion technology that utilizes visible light high-speed

data transmission, offering an efficient alternative to conventional radio frequency systems. This research

presents the design and implementation of a Li-Fi-based audio communication system using both LED and Laser

as optical transmitters. [1] The study focuses on a comparative analysis of these two light sources in terms of

transmission range, signal strength, direc-tionality, and overall performance. The system converts audio signals

into modulated light, which is transmitted through LED and Laser sources and received by a solar cell, then

amplified and reproduced via a speaker. Experimental results demonstrate that LEDs provide wider coverage

with moderate signal strength, whereas lasers offer long-distance, focused transmission with improved

Communication (OWC) and Visible Light Communication (VLC), where data is transmitted by rapidly

modulating the intensity of light sources such as LEDs and lasers, which is not visible to the human eye. This

technology offers high-speed, secure, and interference-free communication, making it suitable for environments

where RF communication is restricted or inefficient.. [1]

Traditional wireless systems using RF suffer from band-width limitations, electromagnetic interference, and

spectrum congestion. [2] Li-Fi eliminates these issues by using light-emitting diodes (LEDs) to transmit

information via intensity variations that are imperceptible to the human eye.

The objective of this project is to design a Li-Fi Audio Transmission Working Model Kit that demonstrates the

trans-mission of analog audio signals using light. [2] The model showcases real-time audio transfer, reflecting

the feasibility of Li-Fi for short-range, secure communication.

compared to traditional Wi-Fi. The IEEE

802.15.7 standard governs VLC operation, defining its phys-ical and MAC layer specifications for reliable

indoor data transmission. [1].

Li-Fi, short for Light Fidelity, extends the VLC concept into a complete communication network capable of two-

way high-speed data transfer. O’Brien et al. (2020) demonstrated that Li-Fi can reach speeds up to 10 Gbps using

micro-LEDs. [1] The system works by varying LED light intensity to represent digital data, while a photodiode

at the receiver converts these optical variations back into electrical signals. Because light cannot penetrate opaque

surfaces, Li-Fi communication remains confined within a closed environment, ensuring data privacy and

preventing external interference

[4] These studies confirm Li-Fi’s ability to deliver clear, low-latency audio transmission using cost-effective

hardware

Efficient modulation and detection are vital for improving Li-Fi system performance. On-Off Keying (OOK),

Pulse Po-sition Modulation (PPM), and Orthogonal Frequency Division Multiplexing (OFDM) are widely used

techniques. Research by Alsaadi (2022) shows that OFDM provides higher spectral efficiency and better noise

tolerance, particularly in environ-ments with variable lighting. At the receiver, photodiodes or avalanche

photodiodes (APDs) detect the light’s intensity variations and convert them into electrical signals for demod-

ulation and reconstruction. [5]

Li-Fi provides strong physical-layer security since its optical signals are confined within illuminated regions and

cannot pass through walls. Studies by Ahangama et al. (2025) confirm that Li-Fi offers stable, interference-

resistant connectivity and minimal electromagnetic radiation. [5]Additionally, Li-Fi net-works enable high data

density because each light source can serve as an independent communication hotspot, enhancing bandwidth

utilization and reducing latency for multiple users.

The Li-Fi Audio Transmission System is designed using a simple, low-cost hardware architecture that enables

wireless communication through visible light. The proposed system consists of a transmitter and receiver module

Transmitter Section:The transmitter consists of an audio source (mobile phone), LED and Laser modules, and

a Li-ion battery as a power supply. The audio signal from the mobile is directly used to modulate the intensity

of both the LED and Laser.

Receiver Section: The receiver consists of a solar cell (or photodiode), an audio amplifier, and a speaker. The

Power Supply: The system uses a Li-ion battery for the transmitter side and a 3.7V DC power supply for the

receiver section. These power sources ensure stable operation of the LED/Laser transmitters and the amplifier

circuit, making the system portable and efficient.

Based on the architectural diagram (Fig. 1), the registration process follows these steps:

Audio Input:The sound signal from the mobile phone or audio source is connected to the transmitter circuit

through an auxiliary cable.It acts as the primary source of information by providing voice or music signals in

Audio Amplifier : The amplifier increases the strength of the weak electrical signal received from the solar cell.

Speaker:The speaker converts the amplified electrical signal into audible sound, reproducing the original audio.

Interruption Effect: If an opaque object (such as cardboard) blocks the light path, the signal is interrupted, and

sound transmission stops immediately.

Re-Establishment of Communication: Once the obsta-cle is removed, the photodiode immediately resumes

detection, and the sound continues without delay, confirming real-time communication capability.

Environmental Sensitivity: The system performance slightly varies with external light intensity; in darker envi-

ronments, the signal is clearer, while in strong ambient light, minor distortion may occur due to background

interference.

Power Supply (Receiver): The 3.7V supply powers the amplifier and receiver circuit.

with laser

The receiver circuit processes the optical signal through the following stages:

Photodiode Detection: Converts varying light intensity into an electrical current.

Filtering and Amplification: Removes noise and strength-ens the weak signal.

Output Stage:Drives a speaker or earphones for audio playback.

Physical Layer Security::Li-Fi communication is naturally secure because visible light cannot penetrate opaque

surfaces such as walls or doors. This restricts signal access to the area illuminated by the LED, preventing

external interception or unauthorized data capture. It offers enhanced privacy com-pared to radio-based systems.

Signal Integrity: The use of analog intensity modulation ensures that the transmitted audio closely resembles

the input waveform with minimal distortion. Stable voltage regulation and filtering circuits maintain consistent

output even with small variations in light intensity.

Access Control: Optical filtering and shielding techniques reduce interference from ambient light sources such

as sunlight or fluorescent lamps.

Energy Efficiency: The system uses low-power LEDs and simple amplifier circuits, making it cost-effective

and suitable for educational and experimental use.

The Li-Fi Audio Transmission System was experimentally tested to evaluate its performance under various

The Li-Fi Audio Transmission setup was developed using readily available low-cost components, including

LEDs, resis-tors, capacitors, photodiodes, and transistors. The estimated cost breakdown is as follows: