Gigabit Home Networking (G.hn) is a specification for wired home networking that supports speeds up to 2 Gbit/s and operates over four types of legacy wires: telephone wiring, coaxial cables, power lines and plastic optical fiber. Some benefits of a multi-wire standard are lower equipment development costs and lower deployment costs for service providers (by allowing customer self-install).^[1]

G.hn offers enhanced immunity to power line disturbances compared to other connection technologies. It serves as a bridge, connecting older systems prevalent in industrial settings with modern technologies that can revolutionize operations. While many machines and devices have transitioned to wireless, wired legacy systems remain integral for communication in industrial contexts. In the industrial realm, swift and dependable connectivity is crucial for seamless machine-to-machine interactions. Absence of this can lead to operational halts or reduced service quality. G.hn stands as a pivotal infrastructure for time-sensitive and safety-critical tasks, boasting strong features that support vital communications and a network's ability to auto-recover. ^[2]

G.hn was developed under the International Telecommunication Union's Telecommunication Standardization sector (the ITU-T) and promoted by the HomeGrid Forum and several other organizations. ITU-T Recommendation (the ITU's term for standard) G.9960, which received approval on October 9, 2009,^[3] specified the physical layers and the architecture of G.hn. The Data Link Layer (Recommendation G.9961) was approved on June 11, 2010.^[4]

Prominent organizations, including CEPca, HomePNA, and UPA, who were creators of some of these interfaces, rallied behind the latest version of the standard, emphasizing its potential and significance in the home networking domain.^[5] Moreover, the ITU-T extended the technology with multiple input, multiple output (MIMO) technology to increase data rates and signaling distance.^[6] This new feature was approved in March 2012 under G.9963 Recommendation.

The development and promotion of G.hn have been significantly supported by the HomeGrid Forum and several other organizations.^[7] The technology was not only designed to address home-networking challenges but also found applications beyond this initial scope, showcasing its versatility and potential in the networking domain.^[8]

The major motivation for wired home networking technologies was IPTV, especially when offered by a service provider as part of a triple play service, voice and data service offering such as AT&T's U-Verse.^[37] Smart grid applications like home automation or demand side management can also be targeted by G.hn-compliant devices that implement low-complexity profiles.^[38]

1. IPTV: In many customers' homes the residential gateway that provides Internet access is not located close to the IPTV set-top box. This scenario becomes very common as service providers start to offer service packages with multiple set-top boxes per subscriber. G.hn can connect the residential gateway to one or more set-top boxes, by using the existing home wiring. Using G.hn, IPTV service providers do not need to install new Ethernet wires, or 802.11 wireless networks. Because G.hn supports any kind of home wiring, end users might install the IPTV home network by themselves, thus reducing the cost to the service provider.^[39]
2. Home networks: Although Wi-Fi technology is popular for consumer home networks, G.hn is also intended for use in this application. G.hn is an adequate solution for consumers in situations in which using wireless is not needed (for example, to connect a stationary device like a TV or a network-attached storage device), or is not desired (due to security concerns) or is not feasible (for example, due to limited range of wireless signals).
3. Consumer electronics: Consumer electronics (CE) products can support Internet connectivity using technologies such as Wi-Fi, Bluetooth or Ethernet. Many products not traditionally associated with computer use (such as TVs or hi-fi equipment) provide options to connect to the Internet or to a computer using a home network to provide access to digital content. G.hn is intended to provide high-speed connectivity to CE products capable of displaying high-definition television. Integrating the power connection and the data connection provides potential energy savings in CE devices. Given that CE devices (such as home theater receivers) very often run on standby or "vampire power", they represent major savings to homeowners if their power connection is also their data connection - the device could reliably be turned off when it is not displaying any source.
4. Smart grid: Because G.hn can operate over wires including AC and DC power lines, it can provide the communication infrastructure required for smart grid applications. A comprehensive smart grid system requires reaching into every AC outlet in a home or building so that all devices can participate in energy conserving strategies. In September 2009, the US National Institute of Standards and Technology included G.hn as one of its standards for the smart grid "for which it believed there was strong stakeholder consensus", as part of an early draft of the "NIST Framework and Roadmap for Smart Grid Interoperability Standards".^[40] In January 2010 G.hn was removed from the final version of the "Standards Identified for Implementation".^[41]

G.hn technology facilitates the connection of devices across various network types using different wiring options, including coax, phone lines, power lines, and optical fiber. Initially designed for home networking, its applications expanded to encompass a broad spectrum of industrial scenarios.^[15]

1. Smart elevators: Contemporary elevators are equipped with numerous sensors and actuators that ideally communicate via IP. Leveraging G.hn for communication between these dispersed IP nodes can lead to significant reductions in wiring during installation.
2. Intelligent lighting systems: In the realm of smart cities, lighting systems are evolving into interactive platforms that interact with their surroundings. This might encompass nodes linked to street signage, light modulation, water monitoring, atmospheric sensors, pedestrian communication systems, vehicle charging stations, imaging units, and audio systems.
3. Airport navigation lights: Utilizing the right signal coupler allows the existing infrastructure to be repurposed with the G.hn PLC profile, simplifying the communication system setup.
4. Charging stations: Charging station networks, encompassing quick payment, user-friendly queries, operations, station oversight, and cloud-based control, can efficiently repurpose existing powerline infrastructure for data transfer.
5. Industrial facilities: G.hn components can be integrated to function alongside industrial control systems through the power bus. The employment of coaxial cables is seen as beneficial due to their durability in challenging conditions, reducing the need for protective conduits.
6. Fiber solutions for harsh conditions: G.hn access systems come with an industrial profile, allowing them to function in challenging conditions like flooding or extreme temperature fluctuations.

The ITU-T endorsed G.hn technology stands out as today's most adaptable and dependable network backhaul for multi-gigabit connectivity, spanning from residential and business applications to industrial and smart grid scenarios. G.hn is consistently advancing across various media, including coax, copper pairs, powerlines, and plastic optical fibers, as well as LiFi communication systems using visible light, ultraviolet, and infrared spectrums. This supports the industry's digital transformation. HomeGrid Forum members champion the worldwide adoption of G.hn, a unified networking technology with multiple sources.

• IEEE 1901
• HD-PLC