G.hn Technology2023-08-10T09:13:11-04:00

G.hn Access Technology

The ITU-T G.9960 G.hn Wave-2 standard is designed to leverage the existing phone lines (CAT-3) CAT-5/5e/6 wiring, or RG-6/RG-11/RG-59 coaxial cable to deliver a Gigabit Internet service to each subscriber. Reuse of the existing wiring eliminates the complexity and delays associated with in-building fiber installation.

G.hn is used as an access technology by Broadband Service Providers (including telcos, cable companies, ISPs, and WISPs) looking to extend Gigabit services serving properties via Fiber or FWA over the in-building wiring. G.hn is a highly scalable, wired, Ethernet-based technology that greatly simplifies the access network and backend infrastructure. With G.hn, operators deliver advanced Gigabit Ethernet connectivity and managed Wi-Fi without the high capital and operational expenses associated with a fiber retrofit.

Each G.hn subscriber port supports up to 1.7 Gbps of dynamically allocated bandwidth for near symmetric Gigabit services. Each G.hn link is encrypted with 128-bit keys for additional security. The GAM operates in point-to-point mode over telephone wiring and also supports point-to-multipoint operation over coaxial cabling by leveraging the existing CATV splitters and taps. The Positron GAM solution is ideally suited to deliver data connectivity and Ethernet services in MDU, MTU, and Hospitality deployments.

Point to Point over Phone Line Pairs

Each port of the GAM can transmit over one or two unshielded copper telephone pairs. In single-pair mode (SISO – Single Input Single Output), G.hn utilizes up to the full 3.5MHz to 200MHz spectrum to achieve up to 1.7Gbps of aggregate payload bandwidth (upstream plus downstream). In dual-pair mode (MIMO – Multiple Input Multiple Output), G.hn splits the bandwidth between the two pairs, leveraging the 3.5MHz to 100 MHz spectrum for each pair to extend the reach of a Gigabit service by about 60%. Because signal attenuation increases with frequency, the use of the lower end of the spectrum on each pair in MIMO mode means that G.hn is able transmit the same bandwidth at a further distance. Each port of a Positron GAM can be set to either SISO or MIMO mode independently from other ports.

G.hn employs several techniques to optimize performance over twisted pair. Each port’s upstream and downstream throughput demands are monitored in real time on a synchronized basis. Using Collective Dynamic Transmit Allocation (cDTA), the GAM automatically adjusts the upstream/downstream bandwidth allocation of each G.hn port in response to the instantaneous directional needs of each subscriber. By adjusting the bandwidth ratio identically and simultaneously across all ports, interference is reduced (and thus performance enhanced) since ports within the binder group are not transmitting in the same bands as received signals on other ports.  

Although G.hn allows for the allotment of frequency channels up to 200MHz (SISO mode) or 100MHz (MIMO mode) to achieve the 1.7Mpbs throughput, actual spectrum allocation is performed in a more elegant manner on a port-by-port basis. The GAM enhanced the VectorBoost function for more robust handling of bad pairs. VectorBoost monitors the real-time bandwidth needs of each user as well as the interference levels being induced by the other pairs in the same copper binder to set the optimal spectrum (or Boost level) of each user to one of five different frequency plans. Each consecutive plan utilizes a greater number of channels (up to the maximum allowed spectrum). This technique minimizes the crosstalk amongst users by lowering the power spectral density to the level necessary to meet each port’s actual real-time needs.  

Point to Multi-Point over Coax

While G.hn can operate in a Point-to-Point mode over coaxial cabling, it is very advantageous  to use the existing CATV passive coax splitters originally installed in buildings to bring the CATV signal to multiple tenants (subscribers). The G.hn standard takes advantage of this Point to Multipoint (P2MP) architecture to serve up to 16 individual subscribers from a single coaxial GAM port.  Each of the Endpoints sharing the same coax splitter has a unique MAC address to identify the recipient of the data. In P2MP mode, the Domain Master and each Endpoint collaborate to control the allocation of the bandwidth and to isolate the traffic of each subscriber sharing the same G.hn coax port. Endpoint devices receiving data not addressed to them will simply discard the encrypted frames, very much like GPON access networks using passive optical splitters.  

When operating over coaxial cable, G.hn Independent Dynamic Transmit Allocation (iDTA) optimizes the bandwidth allocation to each user and in each direction sharing the same GAM port over a standard coax splitter. The GAM ensures that this dynamic bandwidth allocation remains optimal even when there is a significant discrepancy in the quality of the signal of each subscriber. This ensures the maximal bandwidth in each direction while handling any oversubscription of the total capacity over the coax cable for each G.hn port.

Very Low Latency and Jitter

The G.hn standard is designed to provide low latency communication for gigabit home networking and applications such as multimedia streaming, online gaming, and real-time control of home automation devices. To achieve low latency, various techniques such as time synchronization and packet prioritization are used. In practice, the latency added by the GAM is typically 1 msec. The G.hn chipset uses advanced buffering techniques coupled with the efficient dynamic bandwidth allocation method to reduce jitter which averages 1 msec.

Q-in-Q VLAN and Full Quality of Service (QOS) Support

G.hn and the GAM fully support single and dual (Q-in-Q) VLAN with comprehensive Ethernet Quality of Service (QoS) mechanisms to prioritize and control network traffic. This ensures a consistent and predictable level of service for different types of traffic. Traffic classification methods, traffic prioritization levels (up to 8), and rate control techniques such as traffic shaping are all used by the GAM.

A Bright Future

G.hn Wave-2 is recognized as the most efficient Gigabit Ethernet technology over legacy wiring.  The Wave-3 standard, also known as G.hn2, was ratified by the ITU in March of 2020, marking a major milestone. Silicon vendors anticipate the availability of chips supporting this standard by 2025, paving the way for their release to match the anticipated deployment of 50 Gigabit PON solutions.

Wave 3 will leverage a wider frequency spectrum with increased transmission efficiency and advanced coding techniques to achieve an interface connection speed of up to 10Gbps over coax and 5Gbps over copper.  Wave-3 will be backwards compatible with Wave-2!

Empowering Reliable and High-Bandwidth Ethernet Services

G.hn technology serves as the advanced foundation that empowers the Positron GAM to provide reliable and high-bandwidth Ethernet-based services over copper and coaxial cables. As the recognized industry leader, Positron has made significant strides in enhancing G.hn while ensuring strict compliance with the ITU-T standard. These enhancements have not only improved performance but also simplified usability and established greater levels of integration and interoperability with other key technologies like XGS-PON and Wi-Fi 6.

Wave-3 is poised to further revolutionize the capabilities of G.hn for hospitality sector stakeholders and MDUs, enabling them to deliver even more remarkable digital experiences to their tenants and guests in the years to come. Positron’s commitment to innovation will continue to drive the next generation of G.hn forward.

GAM copper indoor scaled

GAM for Copper Indoor

GAM Copper Outdoor

GAM for Coax Indoor

GAM for COAX indoor scaled

GAM for Copper

GAM for COAX Outdoor

GAM for Coax

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