NBN and Optical Fibre - An overview
- Optical fibre
- Telephony on the NBN
- Answers to questions about NBN
- NBN Multi-technology mix (MTM)
- The future of NBN?
Optical fibre (fiber in USA) - OF - is a preferred cable technology for transmission over long distances. OF is not new. I worked on short and long haul OF systems in Australia from the late 1980s. The advantages of modern OF systems compared to copper cable include much lower signal loss over long distances, higher frequency (i.e. higher data speed) and immunity from electrical interference.
An interesting introduction to the principles and technology of OF can be viewed at:
This following youtube video by Corning gives more information about fibre principles and technology:
The National Broadband Network is an integrated high speed digital data communications network that replaces the customer access network (CAN). The CAN is/was the existing, copper wire, street cabling between the telephone exchange and customer premises. NBN will ultimately connect all Australian premises to the Internet via a mixture of transmission technologies but based on an optical fibre backbone. NBN Co Limited is the wholly Government owned business enterprise formed to build and operate the wholesale-only national broadband network across Australia.
Who owns the CAN?
Historically, Telstra and its predecessors, Telecom Australia/PMG, owned the customer access network but this is changing. Control is progressively being handed over to NBN Co Ltd and predicted to be completed by 2020. This is spelt out at:
The idea of using OF in the CAN in Australia is not new. I am reliably informed that Telecom Australia (the government owned forerunner of today's Telstra) started planning an OF CAN in the mid 1980s. The preferred principles, at the time, appear to be similar to the current fibre to the curb/kerb - FTTC (see below).
A lot of these plans stalled with the deregulation of the Australian telecommunications industry in the 1990s but Telstra persisted with OF in some new areas (search for "Telstra Velocity" on the internet). It even proposed a FTTN system in 2005/6 but reneged when confronted with regulatory/competition issues. See:
Implemented by the Kevin Rudd Labor Government a couple of years after its election in 2007, the NBN was to connect the majority of Australian premises directly to the Internet via high speed optical fibres. It was a heroic project predicted to cost many tens of billions of dollars and take a couple of decades to complete. The (Liberal) conservative government (2013-), initially led by Tony Abbott but now by Malcolm Turnbull (Jan. 2018), has since reviewed this project and implemented ways to try and reduce the costs, so the performance outcomes will probably not meet original expectations.
The original plan was to connect to the majority of premises with optical fibre and those in low population, outlying areas with radio or satellite feeds. Since 2014 the preferred option has been the multi-technology mix (MTM - below) which minimises the use of fibre to the premises (FTTP) in favour of a hybrid system comprising a backbone fibre network but final customer feeds using existing copper cable in various configurations (see HFC, FTTN, FTTC below).
Telephony on the NBN
Telephone services are also available over the NBN/Internet. The transmission technology is digital VoIP (see link below) rather than traditional analogue telephony. Customers wishing to retain their familiar analogue telephones should be able to choose a telephone service that is connected via the analogue ports provided on the NBN terminal equipment. This is still VoIP telephony but converted in the NBN terminal equipment (see ATA below). For further information on telephony on NBN go to this page
Background information on analogue and digital telephony, ATA and VoIP can be found here
When the NBN is fully implemented (2020?), our familiar analogue Public switched telephone network (PSTN) will be completely shut down.
Answers to questions about NBN
I have not fully checked the veracity of this document but on the face of it appears to be useful and accurate. Certainly worth reading: http://registeredcablers.com.au/101%20Booklet-web.pdf
NBN multi-technology mix (MTM)
The multi-technology mix is the Coalition Government (2013-) policy on NBN distribution methods, replacing the former Labor Government’s mostly FTTP system. The MTM technologies are summarised below. This writer acknowledges and thanks Mr Ian Milner and the Telit cabling Newsletter (TITAB Australian Cabler Registry Services) as the source of much of this information.
There are seven transmission technologies currently in the multi-technologies-mix.
- FTTP: Fibre to the premises
- Fixed wireless
- FTTB: Fibre to the building/basement
- FTTN: Fibre to the node
- FTTC: Fibre to the curb (kerb) AKA Fibre to the distribution point (FTTdp)
- HFC: Hybrid fibre coax
These transmission technologies are briefly described below.
The implementation of the "NBN multi-technology mix" (MTM) is briefly described at: https://www.youtube.com/watch?v=cg0fsyWm7Io
Added 14 Aug 2017. According to a "Choice" article published in June 2017, the projected % mix of technologies in the MTM is as follows:
FTTP to 2.4 million premises, or 20% of the network.
Fixed wireless to 600,000 premises in regional areas.
Satellite to 400,000 rural and remote premises.
FTTN/B to 4.5 million premises, or 38% of premises.
HFC to 3.3 million premises, or 34% of the network (I think this should read 28% - JP)
FTTC to 700,000 premises from the HFC footprint.
It is interesting to note that FTTP (fibre to the premises) will now service 20% of the network compared to 93% in the original plan.
FTTP (fibre to the premises): Sometimes called fibre to the home, this is the previous Labor Government (2007-2013) model that originally intended to cover 93% of customers. The optic fibre is connected directly to the interface (a network terminating device - NTD) in the customer’s premises and there is no copper wire in the link. This option has now been largely superseded by FTTN (below) so FTTP services are now in the minority (approx. 20%).
What an NBN FTTP installation looks like can be seen at this site:
Infrastructure information about the NBN FTTP can be found at:
Fixed wireless: An alternative where cable distribution is difficult. Radio base stations, similar to those used in mobile telephony, are installed. The customer will have an antenna and network terminating device (NTD) providing the broadband. If an analog telephone service is required, the existing copper PSTN service will be retained for the time being.
Fixed wireless was part of the original NBN proposal to cover the 7% not met by FTTP and is retained in the MTM model.
Satellite: Offering similar service to the above fixed wireless system but for remote or inaccessible locations. NBNCo can provide a satellite dish and NTD that links to one of two available satellites. The NBN "Sky Muster" satellites were launched in 2015/2016. More information on satellite NBN can be found at http://www.nbnco.com.au/learn-about-the-nbn/network-technology/sky-muster-explained.html
Satellite was part of the original NBN proposal to cover the 7% not met by FTTP and is retained in the MTM model.
A simple introduction to the FTTP, wireless and satellite systems can be seen at: https://www.youtube.com/watch?v=IqXy804y20c
This 2014 video is now somewhat outdated because it was produced before the MTM was implemented but is a good introduction to the above-mentioned three technologies.
FTTB (fibre to the building/basement): Typically for apartment and business complexes, the fibre will terminate on a “node” (contains optical/electrical converters and multiplexers) near the building MDF and then distributed to the customers via the building’s existing copper cable network. FTTB is functionally equivalent to FTTN so will not be discussed further here.
FTTN (fibre to the node): Similar to FTTB but the node is located in the street near an existing telecommunications pillar. The final distribution to the premises, (houses, apartments or small businesses) will be by the existing copper CAN. It is theoretically possible to service up to 384 customers with one node.
It is interesting to note that Telstra proposed a FTTN system in 2005 so it is quite old technology. The majority of services in the MTM will be FTTN.
In FTTN, the optical fibres terminate at a node (usually in a roadside metal cabinet). The node is mains powered and contains interface equipment (DSLAM) to convert/multiplex the optical and electrical digital signals. The final connections to the customers are over existing underground copper cable pairs. A VDSL2 modem is required at the customer end.
The following images show FTTN topology, a couple of views of typical Node cabinets and a typical VDSL modem setup.
From the customer's perspective, the FTTN/B technology is similar, in principle, to a naked DSL service except the DSLAM is no longer in the exchange building but closer to the customer in a node and the modem operates at higher frequencies/speed. The FTTN service may suffer similar cable quality issues to naked DSL.
This Telstra video describes basic set up of an FTTN/B modem:
NBN FTTN Performance
There is a lot of debate about the effectiveness of the FTTN model. Offering a completely informed opinion about the performance of NBN FTTN is beyond my personal expertise but some interesting articles can be found at:
FTTC (fibre to the curb):
Added 28 November 2016: I prefer Fibre to the Kerb. NBNCo calls it "curb" but I intensely dislike American English usurping our language! Also known as fibre to the distribution point this is yet another distribution option to the MTM trialled/implemented from late 2016. Fibre cable is provided in the streets adjacent to the customers' premises and there is a "distribution point unit' (DPU) in each pit. The customers' existing copper lead-in cables are used between the DPU and the premises.
FTTC is a variation of the FTTN principle except that the DPU only services a few premises (typically 4). Another cost-saving measure is that the DPU is power-fed via the copper lead-in cable using a 'reverse power feeder" (RPF) located in the customers' premises and not separately mains powered like FTTN. As well as the RPF, a VDSL, or similar, modem (as in FTTN) is required in the premises. An overview can be found at:
Another article describing FTTC can be seen at:
Added 8 Dec 2016: A possible snag with FTTC rollout regarding the legality of RPF?
HFC (hybrid fibre/coax): The broadband services will be provided over existing copper pay TV infrastructure. An NBNCo article on HFC can be seen at: http://www.nbnco.com.au/learn-about-the-nbn/network-technology/hybrid-fibre-coaxial-explained-hfc-3.html.
The HFC rollout may be reduced in favour of FTTN or FTTC according to this commentary of August 2016: https://www.itnews.com.au/news/nbn-co-shrinks-hfc-footprint-expands-fttn-rollout-435117
More issues have been reported recently which impact the HFC rollout. See:
The future of NBN?
5G mobile technology is looming - predicted to be in place in Australia by 2020 (about the same time the NBN project will be nearing completion). 5G is expected to offer much greater data speeds compared to current NBN plans and there is a lot of speculation about its effect on the viability of the NBN.
What is 5G?
5G is next generation mobile technology. It operates in the SHF radio band and trials suggest its data speed will be prodigious compared to existing technologies. A good introduction to 5G appears on this site:
NBNCo refutes the above claims about the impact of 5G and recently published the following response. Although the gist of their reply suggests that things could change within a few years.