Hybrid Fibre Coaxial

What is hybrid fibre-coaxial?

A hybrid fibre-coaxial network is a common telecommunications network that combines both optical fibre and copper cables (coaxial). The optical fibre typically ends near to home or a commercial businesses, then the final connection to the premises is made using coaxial cables. HFC networks, are capable of serving millions of users and provide internet, FM radio, analog television, subscription digital television and public telephony. HFC networks are capable of theoretical speeds up to 10GB/s.

In New Zealand, a typical hybrid fibre coaxial connection is installed when an existing Pay TV cable can be used to make the final part of the network connection from the nearest available fibre node.

Where is HFC available in New Zealand?

HFC networks are generally available throughout New Zealand’s capital cities, and you may be connected in Brisbane, Sydney, Melbourne, Adelaide, Perth, Canberra, Hobart, and Darwin, among other major cities and metropolitan areas across New Zealand. In New Zealand, there are currently a number of network operators providing HFC networks including OptiComm.

How does HFC compare to other network types?

HFC vs FTTP

Across New Zealand, the common standard for home premises connection is fibre-to-the-premises (FTTP). FTTP is a dedicated fibre cable direct to your home to access the internet and telecommunications services. HFC, on the other hand, is used when FTTP is not possible and fibre-to-the-node (FTTN) exists, with the remaining connection made by using an existing hybrid fibre-coaxial network to connect to households the fibre at the node.

HFC vs FTTC

HFC and fibre-to-the-curb (FTTC) are both hybrid connection technologies that employ existing telecommunications infrastructure to finish the connection to served residences. As such, they are conceptually similar. The key distinction between HFC and FTTC is the distance of the non-fibre portion of the connection, even though both use the hybrid fibre-coaxial network. Compared to FTTC, which runs fibre to the kerbside telecommunications box, a connection to the next node for HFC may just require a few meters of existing wiring. HFC is a very close competitor to FTTC in terms of delivered network speeds.

HFC vs FTTB

Another hybrid connection technique is fibre-to-the-building (FTTB). FTTB runs fibre into the communications room of a building housing several dwellings, such as an apartment complex. Individual premises are then connected using the telecoms wiring already present in the building. FTTB can often be a full fibre connection from the home to the network provider’s access network because the in-building cabling may already be fibre (instead of copper wiring) or can be upgraded to fibre. New multi-dwelling builds are typically installed with fibre nowadays.

Although HFC cabling is a more recent technology than copper wiring, certain HFC connections have reportedly experienced reliability issues, which prevent the technology from reaching its full potential. You are also at the mercy of the coaxial wire because of the distance between the fibre hub and the coaxially linked residence.

HFC vs FTTN

HFC is a more reliable, future proof network than fibre-to-the-node (FTTN). They are similar in that optical fibre is used to connect to a central node, however they differ in the last part of the connection to the premises. HFC uses existing hybrid fibre-coaxial cables to finish the connection where FTTN uses copper telephone cabling.

HFC Signal Transmission

The term “HFC” can also be used to suggest the means through which signals are transmitted over the network. Each and every one of the HFC networks jams information into the available spectrum slots in a cable plant by employing frequency division multiplexing. Spectrum refers to the range of frequencies used to transmit this type of data, which in the United States is 52MHz to 1004MHz in the forward direction (from headend to subscriber) and 5MHz to 42MHz in the reverse direction (from subscriber to headend). Spectrum allocations and frequency partitions might differ from one country to the next. These bands are also referred to as the “downstream” and “upstream” bands, respectively.

Transported signals from the headend to the subscriber can be either analog or modified with a quadrature amplitude modulation technique (QAM). QAM signals are created by sampling the original signal (which could be an analog speech or video signal) and modulating a carrier with the resulting digital representation. Because of its enormous capacity, the resulting QAM signal must be carefully managed to ensure a high signal-to-noise ratio (SNR). In comparison, the SNR equivalent requirements for a digital optical signal, such as that used in GEPON or GPON (gigabit passive optical networks), are far less stringent.

Data Over Cable Service Interface Specification (DOCSIS) is the standard that governs QAM transfer, and it is controlled by CableLabs, a non-profit industry-funded R&D group. DOCSIS 3.0 is currently the most used standard. By increasing the downstream to 1200MHz and beyond and the upstream to 85MHz and beyond, the latest version of DOCSIS, DOCSIS 3.1, greatly enhances modulation rates and data throughput to subscribers.