ITU-T G.9991, provisionally known as G.vlc, is an international standard developed by the International Telecommunication Union Telecommunication Sector (ITU-T) for high-speed line-of-sight optical networking, commonly referred to as Light Fidelity (LiFi).[ [1] ]
LiFi gained attention after Harald Haas’s 2011 TED Talk[ [2] ] demonstrated data transmission via visible light, sparking interest in optical wireless communication as a secure and spectrum-efficient alternative to RF. The ITU-T, recognizing the potential of VLC, began exploring standardization to ensure interoperability and scalability.
In 2016, the ITU-T Study Group 15 (SG15) began developing G.9991 under the G.hn standard family to define physical and data link layers for VLC systems. The standard was developed to define a physical layer (PHY) and data link layer (DLL) for VLC systems, ensuring high-speed, secure communication using visible light (380–780 nm). The first version of G.9991 was published in March 2019, specifying data rates up to several Gbps, support for multiple users, and integration with existing lighting infrastructure.
Since its initial release, G.9991 has been updated to refine its specifications, including support for infrared (IR) light in addition to visible light, to enhance performance and reduce interference from ambient light. The standard leverages Orthogonal Frequency Division Multiplexing (OFDM) and supports features like spatial multiplexing and wavelength division multiplexing (WDM) to increase capacity.
G.9991 emerged alongside the IEEE 802.11bb LiFi standard (published in 2023), creating a competitive landscape. While 802.11bb aligns with WiFi ecosystems and focuses on VLC for higher theoretical speeds (up to 9.6 Gbps), G.9991 prioritizes secure, stable deployments, with speeds typically in the multi-gigabit range.[ [3] ] The theoretical speeds 802.11bb have not been realized, and existing products built to G.9991 have been faster.[ [4] ]
Several companies are at the forefront of developing and commercializing LiFi products that adhere to the ITU G.9991 standard. The most prominent among them are:
Signify (formerly Philips Lighting)[ [5] ]
Oledcomm[ [7] ]
Fraunhofer Heinrich Hertz Institute (Fraunhofer HHI)[ [9] ]
Terra Ferma[ [10] ]
Other LiFi Vendors and Research Groups: Multiple vendors and academic groups have adopted G.9991, leveraging its compatibility with G.hn chipsets and its robust, standardized approach to optical wireless networking.
HomeGrid Forum[ [11] ]
The HomeGrid Forum, which promotes G.hn standards, supports G.9991 adoption. Members like MaxLinear and Microchip Technology integrate G.9991 into their chipsets for LiFi-enabled devices, targeting smart homes, industrial IoT, and enterprise networks. These chipsets enable manufacturers to build G.9991-compliant LiFi solutions.
Enterprise and Industrial Sectors:
Companies in sectors requiring secure, RF-free communication—such as manufacturing, healthcare, and finance—use G.9991-based systems. [12] For instance, G.9991 is deployed in factories to connect IoT devices without RF interference, and in hospitals to avoid disrupting sensitive medical equipment.
Government and Defense:
Government agencies and defense organizations adopt G.9991 for its security benefits. The standard’s line-of-sight nature prevents signal interception, making it ideal for secure communication in sensitive environments. The Dutch Ministry of Defense uses Signify’s TruLiFi (based on G.9991) for secure office connectivity. [13] The US Government has implemented Terra Ferma LiFi Access Points and Controllers into several Government and Military Projects.
ITU-T G.9991 (provisionally known as G.vlc) is a standard developed by ITU-T for line-of-sight optical networking. [14] [15]
G.9991 was approved in March 2019. [16]