Visible light communication
Visible light communication (VLC) is a wireless optical communication technology that transmits data using the visible light spectrum, spanning wavelengths from approximately 400 to 800 nanometers, by modulating the intensity of light emitted from sources such as light-emitting diodes (LEDs), with photodetectors or image sensors serving as receivers to decode the signals.[1][2] This approach leverages existing lighting infrastructure for dual purposes of illumination and high-speed data transfer, offering an alternative to traditional radio frequency (RF) systems.[3] The roots of light-based communication trace back to ancient civilizations, such as the Greeks who used polished bronze shields to reflect sunlight for signaling over distances, and extend to 19th-century innovations like Alexander Graham Bell's photophone in the 1880s, which modulated sunlight for voice transmission.[2] Modern VLC emerged in the early 2000s, driven by advancements in solid-state lighting and efficient LEDs, with key milestones including the first demonstrations in Japan around 2000 and the initial establishment of the IEEE 802.15.7 standard in 2011, with revisions in 2018 and an amendment in 2024, to define physical layer and medium access specifications for short-range optical wireless communications.[2][1][4] VLC provides significant advantages over RF technologies, including access to an unlicensed bandwidth of about 300 terahertz in the visible spectrum, complete immunity to electromagnetic interference, and inherent security since light signals do not penetrate opaque walls.[3][1] Additionally, it enables energy-efficient operation, with LED-based systems consuming up to 75% less power than traditional incandescent lamps while supporting data rates from gigabits per second in practical deployments to over 10 gigabits per second in advanced setups, and theoretical potentials exceeding 15 gigabits per second or even terabits per second; as of 2025, laboratory demonstrations have achieved over 50 Gbps.[2][5][1][6] Notable applications of VLC encompass indoor networking for high-speed internet access in environments like offices and hospitals, vehicular-to-vehicular (V2V) and infrastructure-to-vehicle (I2V) communications to enhance traffic safety and autonomous driving, underwater data transmission where RF signals falter, and integration with Internet of Things (IoT) devices in smart homes and cities for positioning accurate to centimeters.[3][5][2] Despite these benefits, VLC systems contend with challenges such as the necessity for line-of-sight propagation, which limits range and coverage; interference from ambient light sources like sunlight; and issues with mobility and shadowing in dynamic environments.[3][1][5] Ongoing research focuses on hybrid VLC-RF architectures and advanced modulation techniques, such as orthogonal frequency-division multiplexing (OFDM), to mitigate these limitations and broaden practical adoption.[5][3]Fundamentals
Definition and Principles
Visible light communication (VLC) is a form of bidirectional, high-speed wireless communication that utilizes the visible light spectrum, spanning wavelengths from approximately 380 nm to 780 nm, to transmit data via light sources such as light-emitting diodes (LEDs). These LEDs serve the dual purpose of providing illumination while simultaneously encoding and transmitting information, enabling data rates that can reach several gigabits per second in controlled environments. Unlike traditional radio frequency (RF) systems, VLC operates without the need for spectrum licensing, leveraging the vast, unregulated bandwidth of the visible light spectrum, which extends up to approximately 300 THz.[7] The fundamental principles of VLC rely on intensity modulation/direct detection (IM/DD), where the light intensity from the source is rapidly modulated to encode data without producing perceptible flicker to the human eye, typically by operating at frequencies above 200 Hz. Propagation in VLC primarily occurs via line-of-sight (LOS) paths, where the transmitter and receiver maintain a direct optical link to ensure reliable signal reception, although non-line-of-sight (NLOS) components can contribute in indoor settings through reflections. At the receiver, photodetectors such as photodiodes convert the modulated optical signal back into an electrical signal for data decoding. This approach exploits the high modulation bandwidth of LEDs, often exceeding hundreds of MHz, allowing VLC to achieve superior data rates compared to RF alternatives constrained by licensed spectrum and interference.[7] A key metric for the theoretical maximum data rate in VLC systems is derived from Shannon's capacity formula, adapted for optical IM/DD channels:R = \frac{1}{2} B \log_2 (1 + \text{SNR})
where R is the data rate, B is the channel bandwidth, and SNR is the signal-to-noise ratio. This expression accounts for the baseband nature of the optical signal and the real-valued constraints of intensity modulation, providing an upper bound on achievable throughput under additive white Gaussian noise assumptions. VLC distinguishes itself from infrared (IR) or ultraviolet (UV) communication systems by its exclusive use of the visible spectrum, which inherently supports simultaneous illumination and data transfer, thereby integrating seamlessly into existing lighting infrastructure without compromising visual comfort.