G.hn
Encyclopedia
G.hn is the common name for a home network
technology family of standards developed under the International Telecommunication Union
's Standardization arm (ITU) and promoted by the HomeGrid Forum. and several other organizations.
The G.hn specification defines networking over power lines, phone lines and coaxial cables with data rates up to 1 Gbit/s.
ITU Recommendation (the ITU's term for standard) G.9960, which received approval on October 9, 2009, specifies the Physical Layer and the architecture of G.hn. The Data Link Layer (Recommendation G.9961) was approved on June 11, 2010. The work was done in the ITU-T
Telecommunication Standardization Sector, Study Group 15, Question 4. Over 20 companies participated regularly, including some large telephone companies, communication equipment companies, and home networking technology companies.
wireless products. G.hn targets gigabit per second data rates and operation over three types of legacy home wires: telephone wiring, coaxial cables and power lines. As the majority of devices in which G.hn may become embedded (such as televisions, set-top boxes, residential gateways, personal computers or network-attached storage
devices) will be AC-powered, configurations that have at least one power line networking interface are likely to become the most common. This will also facilitate integration with home control and demand side management applications for AC-powered appliances.
The ITU-T extended the technology with multiple input, multiple output
(MIMO) technology. This aims for more noise robustness, higher data rates, and extended signalling distances. The work on MIMO for G.hn at ITU-T is under the G.9963
standard. This is the first standards development organization (SDO) to have defined a MIMO technology standard for a powerline application.
By developing dual mode devices, G.hn proponents believe it can provide an evolution path from today's incompatible wired home networking technologies including Multimedia over Coax Alliance
(MoCA), HomePNA
3.1 over coax and phone wires (already an ITU standard G.9954), and HomePlug
AV, Universal Powerline Association
(UPA) and HD-PLC over powerline. In February 2009 the key promoters of two of these interfaces united behind the latest version of the standard. Others are pursuing different initiatives, such as IEEE 1901, MoCA 2 and HomePlug AV2.
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. In G.hn each one of the sub-carriers is modulated using QAM. The maximum QAM constellation supported by G.hn 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:
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
.
G.hn 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 Alice sends data to node Bob, node Eve (in the same domain as Alice and Bob) will not be able to eavesdrop their communication.
G.hn supports the concept of relays
, in which one device can receive a message from one node and deliver it to another node further away in the same domain. Relaying provides extended range for large networks. To ensure security in scenarios with relays, G.hn specifies end-to-end encryption, which means that if node Alice sends data to node Bob using node Mallory as an intermediate relay, the data is encrypted in such a way that Mallory cannot decrypt it or modify it.
Examples of G.hn devices based on high complexity profiles are Residential Gateways or Set-Top Boxes. Examples of G.hn devices based on low complexity profiles are home automation, home security and Smart Grid devices.
G.hn specifies the Physical Layer
and the Data Link Layer
, according to the OSI model
.
The PMD sub-layer is the only sub-layer in the G.hn stack that is "medium dependent" (i.e., some parameters may have different values for each media - power lines, phone lines and coaxial cable). The rest of sub-layers (APC, LLC, MAC, PCS and PMA) are "medium independent".
The interface between the Application Entity and the Data Link Layer is called A-interface. The interface between the Data Link Layer and the Physical Layer is called Medium Independent Interface (MII). The interface between the Physical Layer and the actual transmission medium is called Medium Dependent Interface (MDI).
Recommendation G.9961 received Approval on June 11, 2010. During that meeting, concerns about regulatory conformance were raised and an amendment to the G.hn standard was proposed that eliminated the passband (100 MHz to 200 MHz) and reduced the baseband operational spectrum (from 100 MHz to 80 MHz). Other changes included in the amendment included a reduction of transmit power to meet regulatory complaints raised at the meeting. In June 2011, during a joint Forum held by ITU-T, ITU-R and other organizations, it was recognized that "ITU-T G.hn was considered to have electromagnetic compatibility (EMC) and mitigation techniques that go well beyond those considered essential for protecting radio services", and that "Non-ITU compliant home network equipment may cause problems".
In October 2010, Sigma Designs announced the first G.hn-compliant chipset, called CG5110. In January 2011, Lantiq introduced a family of G.hn-compliant chips, called HNX176 and HNX156.
In June 2011, four silicon vendors (Lantiq, Marvell Semiconductor, Metanoia and Sigma Designs) announced their participation in an open interoperability plugfest in Geneva, hosted by Homegrid Forum, Broadband Forum and ITU.
HomeGrid Forum members are Intel, Lantiq
, Panasonic
, Best Buy
, British Telecom, K-Micro, Ikanos Communications
, Aware, Marvell
, Sigma Designs
, Holland Electronics, Telefonica
, Comtrend, University of British Columbia
, BC Hydro
, University of New Hampshire InterOperability Laboratory
(UNH-IOL), LAN S.A.R.L, IC Plus Corp, Korea Electrotechnology Research Institute
(KERI), Metanoia, Xingtera and Polaris Networks.
Other silicon vendors actively involved in the development of G.hn include DSL vendors Lantiq
and Metanoia, microprocessor manufacturer Intel (which on June 2009 said "[...] a single networking technology for all three types of existing home wiring will make it easier to expand the market for Intel’s home networking products"), and SoC
vendor Sigma Designs
, which on July 2009 said "Sigma intends to support the proliferation of G.hn-based products starting with reference platforms that will power the next-generation of home content delivery".
press release, AT&T
(which makes extensive use of wireline home networking as part of its U-Verse
IPTV
service) expressed support for the work developed by ITU-T creating standards for home networking, including G.hn.
Service providers like AT&T will benefit from G.hn for several reasons:
Other Service Providers that are active contributors to the work being done by ITU-T Study Group 15, Question 4, include British Telecom, NTT
, Telenor
, Qwest
, Telefonica
, Portugal Telecom
and China Telecom
. However, to date only AT&T and BT have expressed public interest in potentially deploying G.hn devices.
es for the service provider market, expressed its support for the unified standard:
(which is the largest retailer of consumer electronics
in the United States
) joined the board of directors of HomeGrid Forum and expressed its support for G.hn technology as the single standard for wired home networks:
Panasonic
, one of the largest manufacturers of consumer electronics, is also a contributor member of HomeGrid Forum.
said:
On December 2008, Joyce Putscher, Principal Analyst at market research firm In-Stat, said:
On December 2008, Kurt Scherf, analyst with market research firm Parks Associates, said:
On December 2008, Steve Rago, principal analyst at market researcher iSuppli, said:
and the Universal Powerline Association
), announced that they had agreed to work with Homegrid Forum to promote G.hn as the single next-generation standard for wired home networking, and to work to ensure coexistence with existing products in the market.
On October 2008, the Continental Automated Buildings Association
(CABA) and HomeGrid Forum signed a liaison agreement to support HomeGrid Forum’s efforts in conjunction with ITU-T G.hn to make it easy for consumers worldwide to connect devices and enjoy innovative applications using existing home wiring.
On July 2009, HomeGrid Forum and DLNA signed a liaison agreement "setting the stage for collaboration between the two organizations and the approval of G.hn as a DLNA-recognized Physical Layer technology".
On June 2010, Broadband Forum and HomeGrid Forum signed an agreement to deliver a global compliance and interoperability testing program for products using G.hn technology. The Broadband Forum will support HomeGrid Forum's validation of G.hn products, their promotion of product conformance and interoperability, and help expedite the total time to market for HomeGrid Forum Certified products. On May 2011, both organizations jointly announced the first open G.hn plugfest.
ITU G.9970
(also known as G.hnta) is a Recommendation developed by ITU-T that describes the generic architecture for home networks and their interfaces to the operators' broadband access networks.
ITU G.9972
(also known as G.cx) is a Recommendation developed by ITU-T that specifies a coexistence mechanism for home networking transceivers capable of operating over power line wiring. The coexistence mechanism would allow G.hn devices which implement G.9972 to coexist with other devices implementing G.9972 and operating on the same power line wiring.
(especially IPTV offered by a service provider as part of a triple play service
, voice and data service offering (such as AT&T
's U-Verse
)), it is expected that G.hn will also become the dominant wired networking standard for other markets such as the PC and CE industries. Smart Grid applications like home automation
or demand side management can also be targeted by G.hn-compliant devices that implement low-complexity profiles.
services is that in many customers' homes the Residential gateway
that provides connectivity with the Broadband access network is not located in close proximity 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 solves the problem of connecting the Residential Gateway to one or more Set-top boxes, by using the existing home wiring. Using G.hn, IPTV service providers don't need to install new Ethernet
wires, and don't need to use 802.11 wireless networks, which usually don't provide the Quality of Service
and Security
required for IPTV. Because G.hn supports any kind of home wiring, end users will often be able to install the IPTV home network by themselves, thus reducing the cost to the service provider.
technology is today the most popular choice 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 NAS
device), or is not desired (due to security
concerns) or is not feasible (for example, due to limited range of wireless signals).
(CE) is connectivity. It's usual for many CE products to include 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) now 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 (HD).
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.
and DC
power lines), it can provide the communication infrastructure required for Smart Grid applications in residential, commercial and industrial environments. 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.
On September 2009, NIST included G.hn as one of the "Standards Identified for Implementation" 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". In January 2010 this "strong stakeholder consensus" collapsed when G.hn was removed from the final version of the "Standards Identified for Implementation". Additional standards which are relevant to integrating G.hn with the Smart Grid are mentioned in the NIST report.
The broad concept of Smart Grid includes applications with overlapping scopes such as Demand side management (DSM), Energy conservation
measures (ECM), Advanced Metering Infrastructure (AMI) and Home Area Networks.
Because G.hn natively supports popular protocols like Ethernet
, IPv4
and IPv6
, G.hn-based Smart Grid networks can easily be integrated with IP-based networks. Well-known network management protocols like SNMP
can be used to manage large-scale IP networks including G.hn devices.
for powerline and Multimedia over Coax Alliance
(MoCA) for coaxial cable. There are millions of deployed devices in the market that are based on these two standards and future G.hn-based products will not interoperate with any of these. Opponents also believe that a single standard for the three different wired mediums will result in a lowest common denominator solution that offers lower performance on all of the wires as compared to current wireline standards that optimize communications for the specific wired environment (i.e. HomePlug AV and IEEE1901 for powerline, MoCA for coax).
The G.hn effort has been criticized by most proponents of other wired technologies, notably MoCA and HomePlug technologies. Some industry analysts have questioned the potential adoption of G.hn. Critics argue that G.hn is incompatible with the established technologies in the market, including HomePlug AV and MoCA. Some claim that the G.hn specification is not sufficient as a next generation technology and that G.hn will be outperformed by backwards-compatible technologies developed by these groups. HomePlug proponents point out that G.hn claims of gigabit-level powerline performance were and are made based on the most optimistic of theoretical calculations and do not take into account the realities of actual powerline networking that must conform to various regulatory restrictions.
Criticism of the G.hn standard also includes the general nature of the document which totals about 300 pages. The HomePlug AV and IEEE1901 standards contain very detailed technical specifications and range to about 1,300 pages. Critics say that the G.hn standard is too general and that the wide technical latitude it affords could cause multi-vendor interoperability issues whenever products are deployed. Parks Associates analyst Kurt Scherf, after recent conversations with European service providers, is convinced that HomePlug has strong backing from that industry. "I do not think that the G.hn effort will fully succeed until they take into account HomePlug and build in some compatibility with it," Scherf is quoted to have said.
In a June 15 article bylined by Stephen Lawson of IDG News Service, Scherf is quoted as saying, “The bottom line is that MoCA and HomePlug work -- and seem to work well -- for the service providers that have chosen them. They'd be very reluctant to make a wholesale move to a technology that's not proven in large field deployments."
EDN Analyst Brian Dipert for instance believed that G.hn would not be adopted as a powerline technology "With DS2's demise. if the rumors are correct, seemingly also go the powerline portions of the ITU's G.hn standards group. That is, unless G.hn faces up to de facto standardization reality and incorporates HomePlug AV into its specifications instead." Other analysts and vendors in 2010 believed that G.hn will face an uphill climb to gain industry adoption.
By May 2011, the press noted "the complexity of handling three types of networks, plus the small size of many of the early vendors in this space, partly caused the slow movement".
Home network
A home network or home area network is a residential local area network . It is used for communication between digital devices typically deployed in the home, usually a small number of personal computers and accessories, such as printers and mobile computing devices...
technology family of standards developed under the International Telecommunication Union
International Telecommunication Union
The International Telecommunication Union is the specialized agency of the United Nations which is responsible for information and communication technologies...
's Standardization arm (ITU) and promoted by the HomeGrid Forum. and several other organizations.
The G.hn specification defines networking over power lines, phone lines and coaxial cables with data rates up to 1 Gbit/s.
ITU Recommendation (the ITU's term for standard) G.9960, which received approval on October 9, 2009, specifies the Physical Layer and the architecture of G.hn. The Data Link Layer (Recommendation G.9961) was approved on June 11, 2010. The work was done in the ITU-T
ITU-T
The ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....
Telecommunication Standardization Sector, Study Group 15, Question 4. Over 20 companies participated regularly, including some large telephone companies, communication equipment companies, and home networking technology companies.
Unified communication
G.hn is a specification for existing-wire home networking. It is a wired and complementary counterpart to the popular Wi-FiWi-Fi
Wi-Fi or Wifi, is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point. An access point has a range of about 20...
wireless products. G.hn targets gigabit per second data rates and operation over three types of legacy home wires: telephone wiring, coaxial cables and power lines. As the majority of devices in which G.hn may become embedded (such as televisions, set-top boxes, residential gateways, personal computers or network-attached storage
Network-attached storage
Network-attached storage is file-level computer data storage connected to a computer network providing data access to heterogeneous clients. NAS not only operates as a file server, but is specialized for this task either by its hardware, software, or configuration of those elements...
devices) will be AC-powered, configurations that have at least one power line networking interface are likely to become the most common. This will also facilitate integration with home control and demand side management applications for AC-powered appliances.
The ITU-T extended the technology with multiple input, multiple output
MIMO
In radio, multiple-input and multiple-output, or MIMO , is the use of multiple antennas at both the transmitter and receiver to improve communication performance. It is one of several forms of smart antenna technology...
(MIMO) technology. This aims for more noise robustness, higher data rates, and extended signalling distances. The work on MIMO for G.hn at ITU-T is under the G.9963
G.9963
Recommendation G.9963 is a home networking standard under development at ITU-T.It was begun in 2010 by ITU-T to add multiple-input and multiple-output capabilities to the G.hn standard originally defined in Recommendation G.9960. The standard is also known as "G.hn-mimo".As part of the family of...
standard. This is the first standards development organization (SDO) to have defined a MIMO technology standard for a powerline application.
By developing dual mode devices, G.hn proponents believe it can provide an evolution path from today's incompatible wired home networking technologies including Multimedia over Coax Alliance
Multimedia over Coax Alliance
Multimedia over Coax Alliance is a trade group promoting a standard that uses coaxial cables to connect consumer electronics and home networking devices in homes. It allows both data communication and the transfer of audio and video streams....
(MoCA), HomePNA
HomePNA
The HomePNA Alliance is an incorporated non-profit industry association of companies that develops and standardizes technology for home networking over the existing coaxial cables and telephone wiring within homes.-Overview:HomePNA does not manufacture products, although its members do...
3.1 over coax and phone wires (already an ITU standard G.9954), and HomePlug
HomePlug
HomePlug is the family name for various power line communications specifications that support networking over existing home electrical wiring. Several specifications exist under the HomePlug moniker, with each offering unique performance capabilities and coexistence or compatibility with other...
AV, Universal Powerline Association
Universal Powerline Association
The Universal Powerline Association was a trade association that covered power line communication markets and applications. The UPA promoted and certified power line communication technology from 2004 to 2010.-History:...
(UPA) and HD-PLC over powerline. In February 2009 the key promoters of two of these interfaces united behind the latest version of the standard. Others are pursuing different initiatives, such as IEEE 1901, MoCA 2 and HomePlug AV2.
One device, any wire
G.hn proponents hope one semiconductor device can be used for networking over any home wire. Some benefits of a multi-wire standard might be lower equipment development costs and lower deployment costs for service providers (by allowing customer self-install).Technical overview
G.hn specifies a single Physical LayerPhysical layer
The physical layer or layer 1 is the first and lowest layer in the seven-layer OSI model of computer networking. The implementation of this layer is often termed PHY....
based on fast Fourier transform
Fast Fourier transform
A fast Fourier transform is an efficient algorithm to compute the discrete Fourier transform and its inverse. "The FFT has been called the most important numerical algorithm of our lifetime ." There are many distinct FFT algorithms involving a wide range of mathematics, from simple...
(FFT) orthogonal frequency-division multiplexing
Orthogonal frequency-division multiplexing
Orthogonal frequency-division multiplexing is a method of encoding digital data on multiple carrier frequencies. OFDM has developed into a popular scheme for wideband digital communication, whether wireless or over copper wires, used in applications such as digital television and audio...
(OFDM) modulation and low-density parity-check code
Low-density parity-check code
In information theory, a low-density parity-check code is a linear error correcting code, a method of transmitting a message over a noisy transmission channel, and is constructed using a sparse bipartite graph...
(LDPC) forward error correction
Forward error correction
In telecommunication, information theory, and coding theory, forward error correction or channel coding is a technique used for controlling errors in data transmission over unreliable or noisy communication channels....
(FEC) code. G.hn includes the capability to notch specific frequency bands to avoid interference with amateur radio
Amateur radio
Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...
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. In G.hn each one of the sub-carriers is modulated using QAM. The maximum QAM constellation supported by G.hn is 4096-QAM (12-bit QAM).
The G.hn Media Access Control
Media Access Control
The media access control data communication protocol sub-layer, also known as the medium access control, is a sublayer of the data link layer specified in the seven-layer OSI model , and in the four-layer TCP/IP model...
is based on a time division multiple access
Time division multiple access
Time division multiple access is a channel access method for shared medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession, one after the other, each using its own time slot. This...
(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), which 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 serviceQuality of serviceThe quality of service refers to several related aspects of telephony and computer networks that allow the transport of traffic with special requirements...
(QoS) guarantees. - Shared Transmission Opportunities (STXOP), which 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), which are used for implementing "implicit" token passingToken passingIn telecommunication, token passing is a channel access method where a signal called a token is passed between nodes that authorizes the node to communicate. The most well-known examples are token ring and ARCNET....
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. As all devices know "who is next", there is no need to explicitly send a "token" between devices. The process of "passing the token" is implicit and ensures that there are no collisions during Channel access. - Contention-Based Time Slots (CBTS), which are used for implementing CSMA/CARPCSMA/CARPIn computer networking, Carrier Sense Multiple Access With Collision Avoidance and Resolution using Priorities is Channel access method. CSMA/CARP is similar in nature to the CSMA/CD Channel access method used in Ethernet networks, but CSMA/CARP provides no detection of network collisions...
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.
- Contention-Free Time Slots (CFTS), which are used for implementing "implicit" token passing
Optimization for each medium
Although most elements of G.hn are common for all three media supported by the standard (power lines, phone lines and coaxial cable), G.hn includes media-specific optimizations that ensure that performance is maximized when operating over each media. Some of these media-specific parameters include:- OFDM Carrier Spacing: 195.31 kHz in coaxial, 48.82 kHz in phone lines, 24.41 kHz in power lines.
- FEC Rates: G.hn's FEC can operate with code rates 1/2, 2/3, 5/6, 16/18 and 20/21. Although these rates are not media specific, it's expected that the higher code rates will be used in cleaner media (such as coaxial) while the lower code rates will be used in noisy environments such as power lines.
- Automatic repeat request (ARQ) mechanisms: G.hn supports operation both with and without ARQ (re-transmission). Although this is not media specific, it's expected that ARQ-less operation is sometimes appropriate for cleaner media (such as coaxial) while ARQ operation is appropriate for noisy environments such as power lines.
- Power levels and frequency bands: G.hn defines different power masks for each media.
- MIMO support: Recommendation G.9963G.9963Recommendation G.9963 is a home networking standard under development at ITU-T.It was begun in 2010 by ITU-T to add multiple-input and multiple-output capabilities to the G.hn standard originally defined in Recommendation G.9960. The standard is also known as "G.hn-mimo".As part of the family of...
includes provisions for transmitting G.hn signals over multiple AC wires (phase, neutral, ground), if they are physically available.
Security
G.hn uses the AESAdvanced Encryption Standard
Advanced Encryption Standard is a specification for the encryption of electronic data. It has been adopted by the U.S. government and is now used worldwide. It supersedes DES...
encryption algorithm (with a 128-bit key length) using the CCMP
CCMP
Counter Mode with Cipher Block Chaining Message Authentication Code Protocol or CCMP is an encryption protocol designed for Wireless LAN products that implement the standards of the IEEE 802.11i amendment to the original IEEE 802.11 standard...
protocol to ensure confidentiality
Confidentiality
Confidentiality is an ethical principle associated with several professions . In ethics, and in law and alternative forms of legal resolution such as mediation, some types of communication between a person and one of these professionals are "privileged" and may not be discussed or divulged to...
and message integrity. Authentication
Authentication
Authentication is the act of confirming the truth of an attribute of a datum or entity...
and key exchange
Key exchange
Key exchange is any method in cryptography by which cryptographic keys are exchanged between users, allowing use of a cryptographic algorithm....
is done following ITU-T
ITU-T
The ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....
Recommendation X.1035
X.1035
ITU-T Recommendation X.1035 specifies a password-authenticated key agreement protocol that ensures mutual authentication of two parties by using a Diffie–Hellman key exchange to establish a symmetric cryptographic key...
.
G.hn 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 Alice sends data to node Bob, node Eve (in the same domain as Alice and Bob) will not be able to eavesdrop their communication.
G.hn supports the concept of relays
Repeater (disambiguation)
A repeater is a telecommunications device that amplifies a signal.Broadcast relay stations, cellular repeaters, microwave radio relays, tunnel transmitters, radio repeaters, amateur radio repeaters and communications satellite transponders all act as repeaters in that they receive and amplify a...
, in which one device can receive a message from one node and deliver it to another node further away in the same domain. Relaying provides extended range for large networks. To ensure security in scenarios with relays, G.hn specifies end-to-end encryption, which means that if node Alice sends data to node Bob using node Mallory as an intermediate relay, the data is encrypted in such a way that Mallory cannot decrypt it or modify it.
Profiles
The G.hn architecture includes the concept of profiles. Profiles are intended to address G.hn nodes with significantly different levels of complexity. In G.hn the higher complexity profiles are Proper supersets of lower complexity profiles, so that devices based on different profiles can interoperate with each other.Examples of G.hn devices based on high complexity profiles are Residential Gateways or Set-Top Boxes. Examples of G.hn devices based on low complexity profiles are home automation, home security and Smart Grid devices.
Protocol stack
Physical layer
The physical layer or layer 1 is the first and lowest layer in the seven-layer OSI model of computer networking. The implementation of this layer is often termed PHY....
and the Data Link Layer
Data link layer
The data link layer is layer 2 of the seven-layer OSI model of computer networking. It corresponds to, or is part of the link layer of the TCP/IP reference model....
, according to the OSI model
OSI model
The Open Systems Interconnection model is a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a prescription of characterizing and standardizing the functions of a communications system in terms of abstraction layers. Similar...
.
- The G.hn Data Link LayerData link layerThe data link layer is layer 2 of the seven-layer OSI model of computer networking. It corresponds to, or is part of the link layer of the TCP/IP reference model....
(Recommendation G.9961) is divided into three sub-layers:- The Application Protocol Convergence (APC) Layer, which accepts frames (usually in EthernetEthernetEthernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
format) from the upper layer (Application Entity) and encapsulates them into G.hn APC Protocol data units (APDUs). The maximum payload of each APDU is 214 bytes. - The Logical Link ControlLogical Link ControlThe logical link control data communication protocol layer is the upper sub-layer of the data link layer in the seven-layer OSI reference model...
(LLC), which is responsible for encryptionEncryptionIn cryptography, encryption is the process of transforming information using an algorithm to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information...
, aggregationPacket aggregationIn a packet-based communications network, packet aggregation is the process of joining multiple packets together into a single transmission unit, in order to reduce the overhead associated with each transmission....
, segmentationPacket segmentationIn a data communications networks, packet segmentation is the process of dividing a data packet into smaller units for transmission over the network...
and Automatic repeat-request. This sub-layer is also responsible for "relaying" of APDUs between nodes that may not be able to communicate through a direct connection. - The Medium Access Control (MAC), which schedules Channel Access.
- The Application Protocol Convergence (APC) Layer, which accepts frames (usually in Ethernet
- The G.hn Physical LayerPhysical layerThe physical layer or layer 1 is the first and lowest layer in the seven-layer OSI model of computer networking. The implementation of this layer is often termed PHY....
(Recommendation G.9960) is divided into three sub-layers:- The Physical Coding Sub-layer (PCS), responsible for generating PHYPHYPHY is an abbreviation for the physical layer of the OSI model.An instantiation of PHY connects a link layer device to a physical medium such as an optical fiber or copper cable. A PHY device typically includes a Physical Coding Sublayer and a Physical Medium Dependent layer. The PCS encodes and...
headers. - The Physical Medium Attachment (PMA), responsible for scramblingScramblerIn telecommunications, a scrambler is a device that transposes or inverts signals or otherwise encodes a message at the transmitter to make the message unintelligible at a receiver not equipped with an appropriately set descrambling device...
and FECForward error correctionIn telecommunication, information theory, and coding theory, forward error correction or channel coding is a technique used for controlling errors in data transmission over unreliable or noisy communication channels....
coding/decoding. - The Physical Medium Dependent (PMD), responsible for bit-loading and OFDM modulationModulationIn electronics and telecommunications, modulation is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with a modulating signal which typically contains information to be transmitted...
.
- The Physical Coding Sub-layer (PCS), responsible for generating PHY
The PMD sub-layer is the only sub-layer in the G.hn stack that is "medium dependent" (i.e., some parameters may have different values for each media - power lines, phone lines and coaxial cable). The rest of sub-layers (APC, LLC, MAC, PCS and PMA) are "medium independent".
The interface between the Application Entity and the Data Link Layer is called A-interface. The interface between the Data Link Layer and the Physical Layer is called Medium Independent Interface (MII). The interface between the Physical Layer and the actual transmission medium is called Medium Dependent Interface (MDI).
Status
Recommendation G.9960 (Physical Layer) was granted Approval at the October 2009 Study Group 15 plenary meeting.Recommendation G.9961 received Approval on June 11, 2010. During that meeting, concerns about regulatory conformance were raised and an amendment to the G.hn standard was proposed that eliminated the passband (100 MHz to 200 MHz) and reduced the baseband operational spectrum (from 100 MHz to 80 MHz). Other changes included in the amendment included a reduction of transmit power to meet regulatory complaints raised at the meeting. In June 2011, during a joint Forum held by ITU-T, ITU-R and other organizations, it was recognized that "ITU-T G.hn was considered to have electromagnetic compatibility (EMC) and mitigation techniques that go well beyond those considered essential for protecting radio services", and that "Non-ITU compliant home network equipment may cause problems".
In October 2010, Sigma Designs announced the first G.hn-compliant chipset, called CG5110. In January 2011, Lantiq introduced a family of G.hn-compliant chips, called HNX176 and HNX156.
In June 2011, four silicon vendors (Lantiq, Marvell Semiconductor, Metanoia and Sigma Designs) announced their participation in an open interoperability plugfest in Geneva, hosted by Homegrid Forum, Broadband Forum and ITU.
HomeGrid Forum
The HomeGrid Forum is a global, non-profit trade group promoting the International Telecommunication Union’s G.hn standardization efforts for next-generation home networking. HomeGrid Forum promotes adoption of G.hn through technical and marketing efforts, addresses certification and interoperability of G.hn-compliant products, and cooperates with complementary industry alliances.HomeGrid Forum members are Intel, Lantiq
Lantiq
Lantiq is an international fabless semiconductor business of approximately 1,000 people. It was formed in 2009 when Infineon Technologies sold its Wireline Communications Division....
, Panasonic
Panasonic
Panasonic is an international brand name for Japanese electric products manufacturer Panasonic Corporation, which was formerly known as Matsushita Electric Industrial Co., Ltd...
, Best Buy
Best Buy
Best Buy Co., Inc. is an American specialty retailer of consumer electronics in the United States, accounting for 19% of the market. It also operates in Mexico, Canada & China. The company's subsidiaries include Geek Squad, CinemaNow, Magnolia Audio Video, Pacific Sales, and, in Canada operates...
, British Telecom, K-Micro, Ikanos Communications
Ikanos Communications
Ikanos Communications Inc. is a leading provider of advanced broadband semiconductor and software products for the digital home...
, Aware, Marvell
Marvell Technology Group
Marvell is an American producer of storage, communications and consumer semiconductor products.Founded in 1995, Marvell Technology Group Ltd. has operations worldwide and approximately 5,700 employees. Marvell’s U.S. operating subsidiary is based in Santa Clara, California and Marvell has...
, Sigma Designs
Sigma Designs
Sigma Designs is an American public corporation that designs and builds high-performance system-on-a-chip semiconductor technologies for Internet-based set-top boxes, DVD players/recorders, high-definition televisions, media processors, digital media adapters, portable media players and home...
, Holland Electronics, Telefonica
Telefónica
Telefónica, S.A. is a Spanish broadband and telecommunications provider in Europe and Latin America. Operating globally, it is the third largest provider in the world...
, Comtrend, University of British Columbia
University of British Columbia
The University of British Columbia is a public research university. UBC’s two main campuses are situated in Vancouver and in Kelowna in the Okanagan Valley...
, BC Hydro
BC Hydro
The BC Hydro and Power Authority is a Canadian electric utility in the province of British Columbia generally known simply as BC Hydro. It is the main electric distributor, serving 1.8 million customers in most areas, with the exception of the Kootenay region, where FortisBC, a subsidiary of Fortis...
, University of New Hampshire InterOperability Laboratory
University of New Hampshire InterOperability Laboratory
The University of New Hampshire InterOperability Laboratory provides independent, broad-based interoperability and standards conformance testing for data, telecommunications and storage networking products and technologies...
(UNH-IOL), LAN S.A.R.L, IC Plus Corp, Korea Electrotechnology Research Institute
Korea Electrotechnology Research Institute
The Korea Electrotechnology Research Institute is a non-profit government-funded research institute in Republic of Korea...
(KERI), Metanoia, Xingtera and Polaris Networks.
Silicon and IP Vendors
Immediately after G.hn's consent five vendors, Aware, CopperGate, DS2, Ikanos and TangoTec announced support for the new G.hn standard.Other silicon vendors actively involved in the development of G.hn include DSL vendors Lantiq
Lantiq
Lantiq is an international fabless semiconductor business of approximately 1,000 people. It was formed in 2009 when Infineon Technologies sold its Wireline Communications Division....
and Metanoia, microprocessor manufacturer Intel (which on June 2009 said "[...] a single networking technology for all three types of existing home wiring will make it easier to expand the market for Intel’s home networking products"), and SoC
System-on-a-chip
A system on a chip or system on chip is an integrated circuit that integrates all components of a computer or other electronic system into a single chip. It may contain digital, analog, mixed-signal, and often radio-frequency functions—all on a single chip substrate...
vendor Sigma Designs
Sigma Designs
Sigma Designs is an American public corporation that designs and builds high-performance system-on-a-chip semiconductor technologies for Internet-based set-top boxes, DVD players/recorders, high-definition televisions, media processors, digital media adapters, portable media players and home...
, which on July 2009 said "Sigma intends to support the proliferation of G.hn-based products starting with reference platforms that will power the next-generation of home content delivery".
Service providers
On February 26, 2009, as part of a HomePNAHomePNA
The HomePNA Alliance is an incorporated non-profit industry association of companies that develops and standardizes technology for home networking over the existing coaxial cables and telephone wiring within homes.-Overview:HomePNA does not manufacture products, although its members do...
press release, AT&T
AT&T
AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...
(which makes extensive use of wireline home networking as part of its U-Verse
U-Verse
AT&T U-verse is a registered service mark under which AT&T offers Internet access, television, and telephone services in various parts of the United States. It began in 2008 to serve mostly residences and small businesses in urban and suburban areas.-Services:...
IPTV
IPTV
Internet Protocol television is a system through which television services are delivered using the Internet protocol suite over a packet-switched network such as the Internet, instead of being delivered through traditional terrestrial, satellite signal, and cable television formats.IPTV services...
service) expressed support for the work developed by ITU-T creating standards for home networking, including G.hn.
Service providers like AT&T will benefit from G.hn for several reasons:
- Connect to any room no matter what the wiring type may be.
- Enable customer self-install
- Built-in diagnostic information and remote management
- Multiple silicon and equipment suppliers
Other Service Providers that are active contributors to the work being done by ITU-T Study Group 15, Question 4, include British Telecom, NTT
Nippon Telegraph and Telephone
, commonly known as NTT, is a Japanese telecommunications company headquartered in Tokyo, Japan. Ranked the 31st in Fortune Global 500, NTT is the largest telecommunications company in Asia, and the second-largest in the world in terms of revenue....
, Telenor
Telenor
Telenor Group is the incumbent telecommunications company in Norway, with headquarters located at Fornebu, close to Oslo. Today, Telenor Group is mostly an international wireless carrier with operations in Scandinavia, Eastern Europe and Asia, working predominantly under the Telenor brand...
, Qwest
Qwest
Qwest Communications International, Inc. was a large United States telecommunications carrier. Qwest provided local service in 14 western U.S. states: Arizona, Colorado, Idaho, Iowa, Minnesota, Montana, Nebraska, New Mexico, North Dakota, Oregon, South Dakota, Utah, Washington, and Wyoming.On April...
, Telefonica
Telefónica
Telefónica, S.A. is a Spanish broadband and telecommunications provider in Europe and Latin America. Operating globally, it is the third largest provider in the world...
, Portugal Telecom
Portugal Telecom
Portugal Telecom is the largest telecommunications service provider in Portugal. Although it operates mainly in Portugal and Brazil, it has also a significant presence in Guinea-Bissau, Cape Verde, Mozambique, Timor-Leste, Angola, Kenya, the People's Republic of China, and São Tomé and...
and China Telecom
China Telecom
China Telecom Corp. Ltd. is a Chinese state-owned telecommunication company. It is the largest fixed line service and 3rd largest mobile telecommunication provider in the People's Republic of China.-Sectors:...
. However, to date only AT&T and BT have expressed public interest in potentially deploying G.hn devices.
Equipment vendors
On April 2008, during the first announcement of HomeGrid Forum, Echostar, a manufacturer of set-top boxSet-top box
A set-top box or set-top unit is an information appliance device that generally contains a tuner and connects to a television set and an external source of signal, turning the signal into content which is then displayed on the television screen or other display device.-History:Before the...
es for the service provider market, expressed its support for the unified standard:
Consumer Electronics
On March 2009, Best BuyBest Buy
Best Buy Co., Inc. is an American specialty retailer of consumer electronics in the United States, accounting for 19% of the market. It also operates in Mexico, Canada & China. The company's subsidiaries include Geek Squad, CinemaNow, Magnolia Audio Video, Pacific Sales, and, in Canada operates...
(which is the largest retailer of consumer electronics
Consumer electronics
Consumer electronics are electronic equipment intended for everyday use, most often in entertainment, communications and office productivity. Radio broadcasting in the early 20th century brought the first major consumer product, the broadcast receiver...
in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
) joined the board of directors of HomeGrid Forum and expressed its support for G.hn technology as the single standard for wired home networks:
Panasonic
Panasonic
Panasonic is an international brand name for Japanese electric products manufacturer Panasonic Corporation, which was formerly known as Matsushita Electric Industrial Co., Ltd...
, one of the largest manufacturers of consumer electronics, is also a contributor member of HomeGrid Forum.
Industry Analysts
On June 2008, Michael Wolf, director at ABI ResearchABI Research
ABI Research is a marketing research firm based in New York. It was founded in 1990. The organization provides research on the following areas:* Mobile Devices, Networks and Services* Telematics & Navigation* Digital Home* Wireless Connectivity...
said:
On December 2008, Joyce Putscher, Principal Analyst at market research firm In-Stat, said:
On December 2008, Kurt Scherf, analyst with market research firm Parks Associates, said:
On December 2008, Steve Rago, principal analyst at market researcher iSuppli, said:
Other organizations
On February 25, 2009, three home networking organizations that promoted previously incompatible technologies (CEPCA, HomePNAHomePNA
The HomePNA Alliance is an incorporated non-profit industry association of companies that develops and standardizes technology for home networking over the existing coaxial cables and telephone wiring within homes.-Overview:HomePNA does not manufacture products, although its members do...
and the Universal Powerline Association
Universal Powerline Association
The Universal Powerline Association was a trade association that covered power line communication markets and applications. The UPA promoted and certified power line communication technology from 2004 to 2010.-History:...
), announced that they had agreed to work with Homegrid Forum to promote G.hn as the single next-generation standard for wired home networking, and to work to ensure coexistence with existing products in the market.
On October 2008, the Continental Automated Buildings Association
Continental Automated Buildings Association
The Continental Automated Buildings Association is a not-for-profit industry association dedicated to the advancement of intelligent home and intelligent building technologies in North America....
(CABA) and HomeGrid Forum signed a liaison agreement to support HomeGrid Forum’s efforts in conjunction with ITU-T G.hn to make it easy for consumers worldwide to connect devices and enjoy innovative applications using existing home wiring.
On July 2009, HomeGrid Forum and DLNA signed a liaison agreement "setting the stage for collaboration between the two organizations and the approval of G.hn as a DLNA-recognized Physical Layer technology".
On June 2010, Broadband Forum and HomeGrid Forum signed an agreement to deliver a global compliance and interoperability testing program for products using G.hn technology. The Broadband Forum will support HomeGrid Forum's validation of G.hn products, their promotion of product conformance and interoperability, and help expedite the total time to market for HomeGrid Forum Certified products. On May 2011, both organizations jointly announced the first open G.hn plugfest.
Related standards
ITU G.9970
G.9970 is a Recommendation developed by ITU-T that describes the generic transport architecture for home networks and their interfaces to a provider's access network.G.9970 was developed by Study Group 15, Question1...
(also known as G.hnta) is a Recommendation developed by ITU-T that describes the generic architecture for home networks and their interfaces to the operators' broadband access networks.
ITU G.9972
ITU G.9972
G.9972 is a Recommendation developed by ITU-T that specifies a coexistence mechanism for networking transceivers capable of operating over electrical power line wiring...
(also known as G.cx) is a Recommendation developed by ITU-T that specifies a coexistence mechanism for home networking transceivers capable of operating over power line wiring. The coexistence mechanism would allow G.hn devices which implement G.9972 to coexist with other devices implementing G.9972 and operating on the same power line wiring.
Potential Applications
Although the major driver for wired home networking technologies has been IPTVIPTV
Internet Protocol television is a system through which television services are delivered using the Internet protocol suite over a packet-switched network such as the Internet, instead of being delivered through traditional terrestrial, satellite signal, and cable television formats.IPTV services...
(especially IPTV offered by a service provider as part of a triple play service
Triple play (telecommunications)
In telecommunications, triple play service is a marketing term for the provisioning of two bandwidth-intensive services, high-speed Internet access and television, and a less bandwidth-demanding service, telephone, over a single broadband connection. Triple play focuses on a combined business...
, voice and data service offering (such as AT&T
AT&T
AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...
's U-Verse
U-Verse
AT&T U-verse is a registered service mark under which AT&T offers Internet access, television, and telephone services in various parts of the United States. It began in 2008 to serve mostly residences and small businesses in urban and suburban areas.-Services:...
)), it is expected that G.hn will also become the dominant wired networking standard for other markets such as the PC and CE industries. Smart Grid applications like home automation
Home automation
Home automation is the residential extension of "building automation". It is automation of the home, housework or household activity. Home automation may include centralized control of lighting, HVAC , appliances, and other systems, to provide improved convenience, comfort, energy efficiency and...
or demand side management can also be targeted by G.hn-compliant devices that implement low-complexity profiles.
IPTV Home Networks
One of the problems faced by most providers of IPTVIPTV
Internet Protocol television is a system through which television services are delivered using the Internet protocol suite over a packet-switched network such as the Internet, instead of being delivered through traditional terrestrial, satellite signal, and cable television formats.IPTV services...
services is that in many customers' homes the Residential gateway
Residential gateway
A residential gateway is a home networking device, used as a gateway to connect devices in the home to the Internet or other WAN.It is an umbrella term, used to cover multi-function networking computer appliances used in homes, which may combine a DSL or cable modem, a firewall, a consumer-grade...
that provides connectivity with the Broadband access network is not located in close proximity to the IPTV Set-top box
Set-top box
A set-top box or set-top unit is an information appliance device that generally contains a tuner and connects to a television set and an external source of signal, turning the signal into content which is then displayed on the television screen or other display device.-History:Before the...
. This scenario becomes very common as service providers start to offer service packages with multiple Set-Top Boxes per subscriber.
G.hn solves the problem of connecting the Residential Gateway to one or more Set-top boxes, by using the existing home wiring. Using G.hn, IPTV service providers don't need to install new Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
wires, and don't need to use 802.11 wireless networks, which usually don't provide the Quality of Service
Quality of service
The quality of service refers to several related aspects of telephony and computer networks that allow the transport of traffic with special requirements...
and Security
Security
Security is the degree of protection against danger, damage, loss, and crime. Security as a form of protection are structures and processes that provide or improve security as a condition. The Institute for Security and Open Methodologies in the OSSTMM 3 defines security as "a form of protection...
required for IPTV. Because G.hn supports any kind of home wiring, end users will often be able to install the IPTV home network by themselves, thus reducing the cost to the service provider.
Consumer Home Networks
Although Wi-FiWi-Fi
Wi-Fi or Wifi, is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point. An access point has a range of about 20...
technology is today the most popular choice 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 NAS
Network-attached storage
Network-attached storage is file-level computer data storage connected to a computer network providing data access to heterogeneous clients. NAS not only operates as a file server, but is specialized for this task either by its hardware, software, or configuration of those elements...
device), or is not desired (due to security
Wireless security
Wireless security is the prevention of unauthorized access or damage to computers using wireless networks.Many laptop computers have wireless cards pre-installed. The ability to enter a network while mobile has great benefits. However, wireless networking is prone to some security issues...
concerns) or is not feasible (for example, due to limited range of wireless signals).
Consumer Electronics devices
A recent trend in many types of Consumer ElectronicsConsumer electronics
Consumer electronics are electronic equipment intended for everyday use, most often in entertainment, communications and office productivity. Radio broadcasting in the early 20th century brought the first major consumer product, the broadcast receiver...
(CE) is connectivity. It's usual for many CE products to include Internet connectivity using technologies such as Wi-Fi
Wi-Fi
Wi-Fi or Wifi, is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point. An access point has a range of about 20...
, Bluetooth
Bluetooth
Bluetooth is a proprietary open wireless technology standard for exchanging data over short distances from fixed and mobile devices, creating personal area networks with high levels of security...
or Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
. Many products not traditionally associated with computer use (such as TVs or Hi-Fi equipment) now provide options to connect to the Internet or to a computer using a home network
Home network
A home network or home area network is a residential local area network . It is used for communication between digital devices typically deployed in the home, usually a small number of personal computers and accessories, such as printers and mobile computing devices...
to provide access to digital content.
G.hn is intended to provide high-speed connectivity to CE products capable of displaying High definition (HD).
Integrating the power connection and the data connection provides potential energy savings in CE devices. Given that CE devices (such as Home theater
Home cinema
Home cinema, also commonly called home theater, are home entertainment set-ups that seek to reproduce a movie theater experience and mood with the help of video and audio equipment in a private home....
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.
Smart Grid
Because G.hn can operate over any type of wire (including ACAC power
Power in an electric circuit is the rate of flow of energy past a given point of the circuit. In alternating current circuits, energy storage elements such as inductance and capacitance may result in periodic reversals of the direction of energy flow...
and DC
Direct current
Direct current is the unidirectional flow of electric charge. Direct current is produced by such sources as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type. Direct current may flow in a conductor such as a wire, but can also flow through...
power lines), it can provide the communication infrastructure required for Smart Grid applications in residential, commercial and industrial environments. 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.
On September 2009, NIST included G.hn as one of the "Standards Identified for Implementation" 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". In January 2010 this "strong stakeholder consensus" collapsed when G.hn was removed from the final version of the "Standards Identified for Implementation". Additional standards which are relevant to integrating G.hn with the Smart Grid are mentioned in the NIST report.
The broad concept of Smart Grid includes applications with overlapping scopes such as Demand side management (DSM), Energy conservation
Energy conservation
Energy conservation refers to efforts made to reduce energy consumption. Energy conservation can be achieved through increased efficient energy use, in conjunction with decreased energy consumption and/or reduced consumption from conventional energy sources...
measures (ECM), Advanced Metering Infrastructure (AMI) and Home Area Networks.
Because G.hn natively supports popular protocols like Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
, IPv4
IPv4
Internet Protocol version 4 is the fourth revision in the development of the Internet Protocol and the first version of the protocol to be widely deployed. Together with IPv6, it is at the core of standards-based internetworking methods of the Internet...
and IPv6
IPv6
Internet Protocol version 6 is a version of the Internet Protocol . It is designed to succeed the Internet Protocol version 4...
, G.hn-based Smart Grid networks can easily be integrated with IP-based networks. Well-known network management protocols like SNMP
Simple Network Management Protocol
Simple Network Management Protocol is an "Internet-standard protocol for managing devices on IP networks. Devices that typically support SNMP include routers, switches, servers, workstations, printers, modem racks, and more." It is used mostly in network management systems to monitor...
can be used to manage large-scale IP networks including G.hn devices.
Criticism
G.hn opponents believe that this standard has a major deficiency in that it won’t interoperate with legacy wireline standards such as HomePlugHomePlug
HomePlug is the family name for various power line communications specifications that support networking over existing home electrical wiring. Several specifications exist under the HomePlug moniker, with each offering unique performance capabilities and coexistence or compatibility with other...
for powerline and Multimedia over Coax Alliance
Multimedia over Coax Alliance
Multimedia over Coax Alliance is a trade group promoting a standard that uses coaxial cables to connect consumer electronics and home networking devices in homes. It allows both data communication and the transfer of audio and video streams....
(MoCA) for coaxial cable. There are millions of deployed devices in the market that are based on these two standards and future G.hn-based products will not interoperate with any of these. Opponents also believe that a single standard for the three different wired mediums will result in a lowest common denominator solution that offers lower performance on all of the wires as compared to current wireline standards that optimize communications for the specific wired environment (i.e. HomePlug AV and IEEE1901 for powerline, MoCA for coax).
The G.hn effort has been criticized by most proponents of other wired technologies, notably MoCA and HomePlug technologies. Some industry analysts have questioned the potential adoption of G.hn. Critics argue that G.hn is incompatible with the established technologies in the market, including HomePlug AV and MoCA. Some claim that the G.hn specification is not sufficient as a next generation technology and that G.hn will be outperformed by backwards-compatible technologies developed by these groups. HomePlug proponents point out that G.hn claims of gigabit-level powerline performance were and are made based on the most optimistic of theoretical calculations and do not take into account the realities of actual powerline networking that must conform to various regulatory restrictions.
Criticism of the G.hn standard also includes the general nature of the document which totals about 300 pages. The HomePlug AV and IEEE1901 standards contain very detailed technical specifications and range to about 1,300 pages. Critics say that the G.hn standard is too general and that the wide technical latitude it affords could cause multi-vendor interoperability issues whenever products are deployed. Parks Associates analyst Kurt Scherf, after recent conversations with European service providers, is convinced that HomePlug has strong backing from that industry. "I do not think that the G.hn effort will fully succeed until they take into account HomePlug and build in some compatibility with it," Scherf is quoted to have said.
In a June 15 article bylined by Stephen Lawson of IDG News Service, Scherf is quoted as saying, “The bottom line is that MoCA and HomePlug work -- and seem to work well -- for the service providers that have chosen them. They'd be very reluctant to make a wholesale move to a technology that's not proven in large field deployments."
EDN Analyst Brian Dipert for instance believed that G.hn would not be adopted as a powerline technology "With DS2's demise. if the rumors are correct, seemingly also go the powerline portions of the ITU's G.hn standards group. That is, unless G.hn faces up to de facto standardization reality and incorporates HomePlug AV into its specifications instead." Other analysts and vendors in 2010 believed that G.hn will face an uphill climb to gain industry adoption.
By May 2011, the press noted "the complexity of handling three types of networks, plus the small size of many of the early vendors in this space, partly caused the slow movement".
External links
- ITU-T Study Group 15 Question 4
- ITU-T Recommendation G.9960
- ITU-T Recommendation G.9961
- ITU-T Recommendations: Series G
- The HomePNA Blog contains general information about home networking and G.hn
- The HomeGrid Forum Blog, A forum for discussion of ITU-T G.hn
- Everywire, Your Definitive Source for All Things G.hn
- Bluehelmets care for homenetworks - a translated report from Tom's Networking Guide Germany