It’s time to zoom in and take a closer look at the some of the technology being used in the construction of the National Broadband Network. In order to understand the differences between the various types of cables and connections used in the multi-technology rollout, we get into the nitty gritty of how they work and what role they will play.
A multi-technology mix
The mixed-technology NBN rollout ordered by the Federal Government in April 2014 allows NBN Co to choose the technology and infrastructure used in each area, as long as it conforms to a number of criteria. The rollout must provide a download speed of at least 25 megabits per second (Mbps) to all premises and 50Mbps to 90 per cent of premises and be delivered within the constraints of a public equity capital limit of $29.5 billion.
In addition to the expansion of the fibre network footprint, the mixed-technology rollout will involve the extension of the satellite, hybrid fibre coaxial (HFC) cable and fixed wireless programs to areas outside the fibre footprint.
Current broadband speeds
The Government’s 2013 Broadband Availability and Quality: Summary Report provided a detailed spatial analysis of the coverage and quality of existing broadband customer access networks across Australia. As a measure of quality the analysis estimated the possible achievable speeds given known constraints.
The reported stated, “Broadband services are delivered using a range of technologies to homes and businesses across the country. The infrastructure most often used to provide broadband includes asymmetric digital subscriber line (ADSL) technology over the copper access network, the 3G and 4G mobile networks, HFC networks originally rolled out for subscription television, fibre-to-the-node (FTTN) networks and fibre-to-the-premises (FTTP) networks. In addition to these terrestrial networks, all Australian premises are covered by satellite broadband networks.“
The key findings included:
• 9.9 million premises (91 per cent) have access to fixed line broadband services delivered via digital subscriber line technology.
• 3.1 million premises (28 per cent) have access to a high speed broadband platform, including FTTN networks, HFC networks and fixed wireless networks.
• 8.8 million premises (81 per cent) have access to 3G mobile broadband services and 6.4 million premises (59 per cent) have access to 4G services.
• 1.4 million premises (13 per cent) across Australia are in areas where less than 40 per cent of premises can access a fixed broadband service.
• 3.1 million premises (28 per cent) have access to peak download speeds of between 25Mbps to 110Mbps.
• 7.1 million premises (65 per cent) are in areas that have access to peak median download speeds of less than 24Mbps over the copper network.
• 700,000 premises (six per cent) are unable to get access to a fixed broadband service.
• Of the premises with access to xDSL broadband services over copper, 3.7 million of these are located in areas with an estimated peak median download speed of less than 9Mbps, and 920,000 have an estimated peak median download speed of less than
Therefore, for the majority of Australians, the minimum 25Mbps speeds to be offered by the NBN should be a vast improvement on their existing connection.
Contrasting fibre optic cable and copper
The largest component of the NBN rollout is the construction of the fibre network, which will replace much of the existing copper-based telecommunications network. This includes replacing the existing copper cables with fibre optic cable, either all the way to the premises for an FTTP connection; to a node servicing an area for an FTTN connection; or to the boundary of a building for a fibre-to-the-building/basement (FTTB) connection. In the case of FTTN and FTTB, the final connection to each premise is made via non-optical means such as the existing copper connection, twisted pairs or wireless.
Both newer fibre optic technology and older copper based cables have an important role to play in the revised NBN rollout. Much of the discussion surrounding the NBN rollout has focused on the far superior data transfer speeds offered by fibre optic cable compared to copper. But why is fibre optic technology faster? What are the main differences between the two?
In the end it primarily comes down to the material from which the cables are made and how they transfer information.
Traditional copper wires transfer data in the form of electrical currents, while fibre optic cables transfer information as pulses of light, which are then converted back into electrical information at the end of the line. The amount of data that can be transferred per unit of time is known as the ‘throughput’ and is determined by the bandwidth, the range of frequencies that the cable can carry. The higher the bandwidth the more data can be transferred at a given time.
Fibre optic cables have a much higher bandwidth than copper cables and therefore can transfer information faster and over longer distances. Typically fibre cable bandwidth is cited at around ten times that of copper coaxial cable in a similar system and much higher speeds have been recorded. However, it must be stated that the actual upload or download speed experienced by the end user is also heavily dependent on the equipment at each end of the fibre and a variety of other variables.
Fibre optic cable can carry higher frequency ranges than copper without degradation and can carry signals for around 200km without losing quality. Copper cables, on the other hand, begin to lose signal strength over relatively short distances. Due to the difference in the type of signal being transferred (light versus electrical), fibre optic technology is also less susceptible to electromagnetic interference.
These advantages provide the rationale for many developed countries choosing to transition their telecommunications infrastructure to a primarily fibre-based network.
Fibre optic technology also looks set to keep improving into the future. For instance, it is likely that higher quality glass will offer even further improvements in data transfer speeds. Copper networks have also been augmented over the years to improve their throughput, although they rarely reach comparable speeds.
The role of fibre and copper in the NBN
The fibre optic network will be connected to premises in a number of different ways throughout the fixed fibre footprint of the revised NBN. As mentioned the primary connection types will be FTTP, FTTN and FTTB.
In an FTTN connection the fibre optic network terminates at a self-contained node servicing each area and the remaining distance to each premise is covered by non-optical means, such as the existing copper connection. This type of connection is currently being trialled by NBN Co and is expected to be rolled out extensively within the fixed fibre footprint.
Using FTTP technology, the primary connection type of the former government’s NBN rollout plan, each premises is directly connected to the network via optic fibre. This type of connection will still be used in the revised rollout plan for new developments or where the rollout has progressed too far to make utilising the existing copper infrastructure viable. According to NBN Co CEO Bill Morrow, this connection type will also be used by the company to connect buildings in potentially profitable areas as part of the company’s plan to counter TPG’s rival FTTB rollout, until NBN Co’s own FTTB product is ready. (For more information on FTTB and infrastructure competition, see The Race to the Basement in the May 2014 issue of Utility.)
FTTB connections involve fibre optic cable extending to the boundary of a building, such as the basement of a large apartment building. The final connection to each premises inside the building is made via non-optical means. This type of connection is currently being trialled by NBN Co and may be used to connect large buildings in the revised rollout.
Therefore, while much of the copper network will be replaced, copper will likely still play a vital role in a mixed-technology rollout, bridging the gaps between the fibre network nodes and each premises for FTTN connections and possibly connecting some premises in FTTB connections. Australia’s copper-based telecommunications network is currently owned by Telstra, and NBN Co is negotiating a contract with the company for access to its infrastructure.
Due to the higher bandwidth of fibre optic cables, generally, the closer the fibre optic cable comes to each premises, the greater the download and upload speeds. Therefore, FTTP has the fastest potential download speeds at around 1,000Mbps. Preliminary trials of FTTB have reached download speeds of around 108Mbps and upload speeds of 48Mbps, and initial trials of FTTN using the existing copper network have been reported to deliver download speeds up to 105Mbps and upload speeds of up to 45Mbps.
Due to the difference in potential data transfer speeds between fibre and copper, the speeds of FTTN connections (and FTTB connections utilising the copper infrastructure) will be limited by the data transfer speeds obtainable over the copper. Premises closer to the node (where less distance must be covered by copper) are likely to receive greater speeds than those further away, while premises connected by FTTP technology may have significantly greater speeds overall. FTTP speeds may also continue to rise as upgrades require only the replacement of the equipment at each end of the fibre and not the fibre itself. High speed broadband network rollouts overseas suggest that the FTTN connections may eventually need to be replaced with FTTP connections as data volume increases into the future.
Three main contractors provide the fibre optic cable and passive equipment for the NBN project.
In 2011, NBN Co awarded a major contract for the supply of fibre optic cables to Prysmian Telecom Cables & Systems Australia, a global manufacturer of telecommunications cabling with manufacturing facilities in Dee Why and Liverpool, NSW. The contract was valued at up to $300 million over five years, with an initial purchase order of $150 million. The cables provided included a wide range of ribbon and multi-fibre communication cables including termite resistant, rodent-proof and high strength cables.
NBN Co also secured a commitment from Prysmian to source approximately 80 per cent of the value of its contract with NBN Co in Australia. As a result Prysmian invested approximately $11 million in expanding its cable plant in Dee Why on new equipment to manufacture specialised ‘ribbon’ cable locally, and to expand its cable sheathing operations. Ribbon cable involves twelve individual fibres being spliced together at once, allowing faster and easier installation and maintenance, and saving space in comparison to splicing each fibre individually. This type of cable was used in Australia for the first time for the NBN project. All the rodent proof and high strength cables are manufactured in the Australian plants.
Despite the change of government and revised rollout plan involving less FTTP connections, Prysmian specialist fibre optic cables will be installed underground in up to 80 per cent of suburban Australia in NSW, QLD, the NT, WA and the ACT.
Victorian fibre optic equipment manufacturer Warren & Brown Technologies was also awarded an equipment contract worth up to $110 million over five years to provide optical distribution frames and sub-racks to connect NBN Co’s equipment to external cabling. These products require sheet metal manufacture and assembly of fibre optic connectors. It is not yet clear if or how this contract may be renegotiated with the revised rollout requiring less FTTP infrastructure.
NBN Co also awarded a contract for multiple types of equipment (including street side fibre distribution hubs) worth up to $1.2 billion over five years to Corning, a world leader in the manufacture of fibre optic cabling. In 2013, Corning opened a new facility at their Clayton site, as part of a $40 million local investment in additional local production capacity.
All in all, fibre optic technology looks set to continue to evolve into the future and pave the way for future innovation. The revised NBN project, utilising both copper and fibre optic cable, represents a merging of old and new technology. While the final shape of the NBN is yet to be seen, it will almost certainly incorporate a variety of different connection types, the final speeds of which will be determined by a number of factors. Not the least of these will be the key attributes of the copper and fibre cables used.