G.hn Standard & FAQs
1. What is G.hn Standard?
The G.hn standard (Ghn) is a specification for home networking with data rates up to 2 Gbps and operation over different types of copper wires, including telephone wiring (phone lines), coaxial cables (coax cables), power-lines and twisted-pair cables (UTP/2-Wire). A single G.hn wired communication or home network device is able to provide multi-node Ethernet communication and connectivity over any of the supported home wire types. Some benefits of a multi-wire standard are lower equipment development costs and lower deployment costs for service providers (by allowing customer self-install).
The G.hn standard supports multiple profiles for optimal performance over different media. The profiles include power-line, phone line, and coax cables. There are also multiple band plans in each profile.
The G.hn standard is developed under the International Telecommunication Union’s Standardization arm (ITU-T) and promoted by the HomeGrid Forum along with global telecom carriers, semiconductor companies, system vendors, academic institutes. ITU-T Recommendation (the ITU’s term for standard) G.9960 received approval on October 9, 2009, which specified the physical layers and the architecture of the standard. The Data Link Layer (Recommendation G.9961) was approved on June 11, 2010. The ITU-T extended the technology with multiple-input, multiple-output (MIMO) technology to increase data rates and signaling distance. This new feature was approved in March 2012 under G.9963 Recommendation. Amendments to the main G.9960/G.9961 added new functionalities to the base standard, including neighboring domains interference mitigation (distributed NDIM), power-saving modes, PSD management, new transmission profiles, and Layer 2 configuration management protocol LCMP.
G.hn specifies a single physical layer based on fast Fourier transform (FFT) orthogonal frequency-division multiplexing (OFDM) modulation and low-density parity-check code (LDPC) forward error correction (FEC) code. G.hn includes the capability to notch specific frequency bands to avoid interference with amateur radio bands and other licensed radio services. G.hn includes mechanisms to avoid interference with legacy home networking technologies and also with other wireline systems such as VDSL2 or other types of DSL used to access the home. OFDM systems split the transmitted signal into multiple orthogonal sub-carriers, and each one of the sub-carriers is modulated using QAM. The maximum QAM constellation supported is 4096-QAM (12-bit QAM).
The G.hn Media Access Control is based on a time division multiple access (TDMA) architecture, in which a “domain master” schedules Transmission Opportunities (TXOPs) that can be used by one or more devices in the “domain”. There are two types of TXOPs, Contention-Free Transmission Opportunities (CFTXOP) and Shared Transmission Opportunities (STXOP). The CFTXOPs have a fixed duration and are allocated to a specific pair of transmitter and receiver. CFTXOP are used for implementing TDMA Channel Access for specific applications that require quality of service (QoS) guarantees. The STXOPs are shared among multiple devices in the network. STXOP are divided into Time Slots (TS). There are two types of TS: Contention-Free Time Slots (CFTS) for implementing “implicit” token passing Channel Access. In G.hn, a series of consecutive CFTS is allocated to a number of devices. The allocation is performed by the “domain master” and broadcast to all nodes in the network. There are pre-defined rules that specify which device can transmit after another device has finished using the channel; and Contention-Based Time Slots (CBTS) for implementing CSMA/CARP Channel Access. In general, CSMA systems cannot completely avoid collisions, so CBTS are only useful for applications that do not have strict Quality of Service requirements.
G.hn technology is a complementary counterpart to WiFi because it can enable a reliable high-speed Internet backhaul based on existing home wires. Although WiFi technology is popular for consumer home networks, G.hn is an adequate supplementary solution for consumers in situations in which WiFi 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, poor performance, or instability of wireless signals).
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2. What media can be used with G.hn Standard?
G.hn can support different media such as power-lines, coaxial cables, and phone lines. In fact, it can be used for any transmission lines that have differential properties, such as flat cable, Ethernet cable, UTP/STP, 2-wire, DC lines, etc. The signal attenuation may be quite different for different transmission media, resulting in variations of transmission distance and performance.
3. Can G.hn Standard be used for access networks?
Yes it can. G.hn technology-driven phone line and coaxial cable media can be used for telecom carrier access networks. Multiple carriers and cable operators have already adopted access network or WiFi distribution services or solutions based on the G.hn access technology.
4. Why is G.hn disruptive to existing home networking technologies?
- The capability to use all existing wires/media available at home to establish stable, high-speed, multi-node network backhaul
- No need to re-wire the existing homes and no attenuation going through walls or floors/ceilings
- Higher performance (up to 2Gbps) compared to legacy wired communication technologies
- Reliable, pervasive connectivity everywhere inside the home
- Provides BW and QoS to enable HD video delivery
- Enables end-to-end solution with one silicon
- Enhance mesh WiFi user experience by reliable network connection between WiFi APs and home gateways
5. Why did you choose G.hn Standard?
- The technology barrier for power-line communication, Ethernet over coax, and phone line communication is very high, which will block lots of potential “copy cats” from entering the market.
- G.hn will create lots of innovative home network applications in the market, such as smart home connectivity, smart home appliances, AR/VR applications, and 4K/8K video streaming.
- The IPs we develop and invent will help to develop more derivative modules, products, and solutions in a timely and cost-effective fashion.
- Huge market potential in smart home, smart city, and wired commercial/industrial IoT markets will help us generate sustainable revenue growth.
6. Who will benefit from G.hn Standard?
Because the G.hn standard is aimed to deliver a single unified home networking technology that can run over coax, power-lines and phone lines, a wide range of companies – including service providers, electronics manufacturers and CE companies– will benefit. Consumers will also see significant benefits. G.hn enables service providers to deploy new offerings including IPTV more cost-effectively; and it allows consumer electronics manufacturers to provide powerful devices for connecting all types of entertainment, home automation, smart energy management, and security products throughout the house. Coupled with the HomeGrid certification program, this greatly simplifies consumer purchasing and installation processes.
7. Why do global tier 1 carriers prefer G.hn Standard?
- Existing Home Networking technologies created a fragmented market – Slow Adoption
- Multiple silicon technologies for the same target market→higher solution cost
- Non-interoperability among vendors of the same technology→Slower customer adoption
- Low bandwidth→Not suitable for video
- Media specific→Limited bundling of services→Lower revenue potential for carriers
- ITU-T makes the G.hn a universal standard enabling a single chip to work on all wires. From the technical point of view, it is a new version of polished and improved home networking and wired communication solution for PLC/Coax/Phone Line, and it is more suitable for large scale deployment across the whole world.
8. Why is G.hn so hot today?
- The dramatically increased access bandwidth to home by FTTH/FTTB/G.fast deployment is creating an urgent demand for efficient, reliable, high-performance home networking solutions. G.hn will best serve the market needs due to its higher performance, improved reliability, and better QoS.
- G.hn will enable pervasive HD/4K/8K video distribution and pervasive connectivity within the home
- G.hn is the ultimate solution to achieve convergence of three networks, the Internet of things (IoT) at home and intelligence home management.
- G.hn can be extended to many commercial or industrial applications, such as building automation, IP intercom, smart grid, video surveillance camera, underground mining, etc.
9. Does G.hn compete with WiFi?
No. As a wired home networking technology, G.hn is complementary to WiFi. Due to severe attenuation of 2.4GHz/5.2GHz RF signals by concrete and brick walls, QoS (Quality of Service) issues, and security concerns experienced by WiFi, an ideal network model is to use G.hn as wired backbone to connect WiFi APs in different rooms whereas a G.hn + WiFi bridge is used to set up WiFi environment within each room. Carriers have been adopting such G.hn + WiFi bridge solutions since it is more advantageous than WiFi in terms of scalability, stability, and performance as the home network backbone.
10. Is G.hn mature from a technology point of view?
Yes. G.hn is an emerging technology ONLY in the sense that it is a brand new standard that enables single device for three media (Power line/Coax/Phone line) at home. There are lots of successful deployments based on single medium Home Networking technologies (PLC, MoCA, and HomePNA), but the market is fragmented mainly because of single medium and lacking of Interoperability. G.hn takes advantage of the learning from those technology developments and has matured much faster than those single media technologies. ITU-T makes the G.hn a universal standard. From the technical point of view, it is a new version of polished and improved Home Networking solution for PLC/Coax/Phone Line, and it is more suitable for large scale deployment across the whole world.
Today, five silicon vendors, including us, have developed and released G.hn silicon. With multiple vendors’ efforts, there is a huge selection of G.hn-enabled devices or solutions already successfully deployed in all continents by either telecom carrier or retail channels.
11. Why is G.hn a better standard than HomePlugAV for power line?
The differences between HomePlugAV and G.hn are in the PHY layer, the MAC layer, and networking features. G.hn utilized the latest state-of-the-art networking technology that HPAV lacks due to its legacy technology. There are also several significant improvements on the PHY technology such as LDPC error correction technology in G.hn vs. old Turbo code in HPAV, MAC and Networking technologies, dealing with multicast, broadcast, security, QoS etc., are where G.hn shines brightly. In addition, G.hn enables neighboring domain interference mitigation (NDIM), which essentially solves the issue when the PLC networks conflict between neighbors.
12. What is the International Telecommunication Union (ITU)?
The ITU is a global standards body that is under the auspices of the United Nations. Comprising more than 185 member countries, the ITU sets standards for global networks. The ITU’s Telecommunications division (ITU-T) produces more than 200 standards recommendations each year in the converging areas of telecommunications, information technology, consumer electronics, broadcasting and multimedia communications.
13. What is the ITU-T G.hn Standard effort?
ITU-T G.hn is a next-generation wired home networking technology that enables transmission of video, audio and data over existing coax, phone line and power line wires in the home. The G.hn recommendation consists of five components: G.9960 (PHY), G.9961 (MAC), G.9962 (MIMO), G.9963 (PSD) and G.9972 (coexistence mechanism)
14. Who performs certification of G.hn products?
The HomeGrid Forum and the Broadband Forum collaborate to set a complete certification and interoperability program for silicons and products.
The HomeGrid Forum is a non-profit organization promoting G.hn technologies and products. It provides technical and marketing efforts, addresses certification and interoperability, and cooperates with complementary industry alliances. HomeGrid Forum members include Actiontec Electronics, Inc., Allion Test Labs, Inc., ARRIS, AT&T, BC Institute of Technology, Best Buy, British Telecom (BT), Chunghwa Telecom, COMTREND Corporation, Holland Electronics, LLC, Institute for Information Industry (III), Korea Electrotechnology Research Institute (KERI), Korea Polytechnic University (KPU), Kwangwoon University, LAN S.A.R.L, Marvell, Metanoia Communications, Inc., MitraStar, Sigma Designs, Teleconnect GmbH, Telefónica, The University of British Columbia, TRaC Global, and Xingtera Inc.
15. Is G.hn stable under power line environment?
Yes. A lot of practical experience in the industry has proved that the wideband PLC technology is mature and stable. It can support power line environment in different countries / regions and real-time high data-rate multimedia streaming such as IPTV and 4K/8K HDTV.
16. Will my neighbors’ PLC adapters interfere mine?
Yes and no. Because all power lines are interconnected, your neighbor’s PLC signals may enter your home environment and therefore cause interference. In most environments, there are a pair of circuit breakers, a pair of electric meters, and a power line of a certain distance between your PLC adapters and your neighbor’s PLC adapters, which could introduce 30 ~ 80dB attenuation. When attenuation is small, the interference between neighbors can cause decline in PLC performance.
Fortunately, the problem of neighboring interference has been taken into account in the early stage of G.hn development. Therefore, the neighboring domain interference mitigation (NDIM) protocol in the standard ensures that the interference will not cause a large impact on the performance or experience within the neighborhood. For typical user application, there will be no noticeable difference even when your neighbor is also using the same technology.
17. Is G.hn PLC technology secure?
Yes. G.hn employs the Advanced Encryption Standard (AES) encryption algorithm (with a 128-bit key length) using the CCMP protocol to ensure confidentiality and message integrity. Authentication and key exchange is done following ITU-T Recommendation X.1035. The standard specifies point-to-point security inside a domain, which means that each pair of transmitter and receiver uses a unique encryption key which is not shared by other devices in the same domain. For example, if node A sends data to node B node C (in the same domain as A and B) will not be able to easily eavesdrop their communication.
18. Does G.hn comply with EN50561?
Yes. G.hn supports EN50561 specified PSD, AR notch standards and etc. To fully comply with EN50561 standard, one needs to take into consideration of a few design factors including the peripheral circuit electromagnetic compatibility requirements, strengthening filtering, and shielding design.
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