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George Georgevits
sufficient to support 10G Ethernet.
However, if the maximum link length
is restricted to ~50m (as suggested in
the TIA TSB155 document), then a
Cat 6 link can be re-tested to Cat 6A
requirements (500MHz) and if it passes,
support for 10G Ethernet can be
guaranteed in many cases.
In summary, for any particular type of
cable, the shorter the link, the higher the
bandwidth it will support.
FTTN BASICS
The bandwidth-reach product for fibre
cabling far exceeds that of its copper
cable counterpart, particularly so for
single mode fibre.
Also, a large percentage of the cost
of implementing FTTP is associated
with the last mile, where the cable is
distributed to and terminated in the
customer’s premises.
Given the above, a compromise
solution, in terms of cost versus
performance, for attaining relatively
high speed internet access at the
customer’s premises can be realised by
running fibre for most of the way and
completing the last mile of each link
with existing Telstra’s copper telephone
cabling network.
This is the essence of FTTN. The ‘node’
is the name given to the equipment
that terminates the fibre cabling
that serves the neighbourhood. This
equipment also drives the copper
telephone cabling for the final leg of the
link to the customer’s premises.
The maximum internet speeds
achievable with FTTN are not as great
as that achievable with the all fibre
solution (i.e. FTTP), but they are still a
big improvement on the various existing
all copper telephone cabling network
based solutions (e.g. ADSL), because
with FTTN, the length of the copper
cabling component for each link is
relatively short.
NBN IMPLEMENTATION USING FTTN
NBN implementation is simpler for
FTTN than for FTTP, and consequently
the projected rollout for the NBN is
now projected to be on a much faster
timescale.
One of NBN Co.’s objectives is to ensure
that by 2020, all homes, businesses and
communities across Australia can access
high speed broadband. FTTN will make it
much easier to achieve this goal.
Also, installation costs will be
significantly lower than that projected for
the original FTTP based NBN.
RECENT DEVELOPMENTS
Late last year, NBN Co announced
a multi-technology approach to NBN
deployment for most households and
businesses, as follows:
>
Those already served by the Optus or
Telstra Hybrid Fibre Coaxial (HFC) cable
networks, will receive fast broadband
over an upgraded HFC network;
>
Where the NBN FTTP network has been
deployed or is in advanced stages of
being built, they will remain part of the
FTTP rollout;
>
Where the NBN fixed wireless or
satellite networks are earmarked for
deployment, they will remain part of the
fixed wireless or satellite rollout.
>
All other communities are likely to
receive fast broadband over FTTN and,
in the case of multi-dwelling units
such as apartment blocks, Fibre to the
Basement (FTTB).
Last October, NBN Co revealed details of
the first 140 suburbs set to receive FTTN
technology over the NBN.
The company released a list of areas
where work is underway to bring the
NBN to more than 200,000 homes and
businesses in parts of the Central Coast,
Newcastle and Lake Macquarie regions in
New South Wales as well as the Greater
Brisbane, Moreton Bay and Wide Bay
Burnett regions in Queensland.
In keeping with the above plan, in
December 2014 NBN Co. announced
that it had entered into agreements
with Telstra and Optus to make use of
their existing HFC networks, albeit in
an upgraded form. Making use of this
existing high-speed network technology
will speed up the transition to NBN in
areas presently served by these networks.
DOWNLOAD SPEEDS
With regards to projected NBN
download speeds, it is NBN Co.’s stated
goal to provide all homes and businesses
with access to download data rates of at
least 25Mbps by 2020.
The majority of premises in the fixed
line footprint (i.e. those not served by
a wireless or satellite implementation
of NBN) are planned to have access to
download data rates of at least 50Mbps.
CONCLUSIONS
Implementing an NBN using
FTTP technology has the benefit of
providing very fast internet access to
the customer’s premises; however, it
has the disadvantages of very high
implementation cost and a very long
deployment time.
FTTN offers more modest performance
in terms of access speed, but still far in
excess of what many customers present
experience via their existing copper
telephone cable based service.
In addition, the planned NBN rollout will
be achieved on a much faster timescale,
and at a fraction of the cost.
George Georgevits manages his own
communications engineering consultancy
firm, Power and Digital Instruments Pty Ltd
(PDI). Established in 1980, PDI specialises
in lab and field transmission testing and
troubleshooting of cabling systems and
components, as well as provision of
consulting engineering services. You can
contact PDI on +61 2 9411 4442.