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Aurora Networks, Inc.Aurora Networks, Inc.
July 2009
WHITE PAPER 16
2009 Aurora Networks, Inc. All rights reserved.
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2009 Aurora Networks, Inc. All rights reserved.2
Thinking Green Strengthens the Case for Fiber Deep in Cable
Aurora Networks, Inc.
5400 Betsy Ross Drive
Santa Clara, CA 95054
Tel 408.235.7000Fax 408.845.9045
www.aurora.com
Copyright 2009 Aurora Networks, Inc. All rights reserved.
All rights reserved. No part of this document may be reproduced, stored in a retrieval
system, or transmitted in any form by any means, electronic, mechanical, photographic,
magnetic, or otherwise without the prior written permission of Aurora Networks.
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Thinking Green Strengthens Case for Fiber Deep in Cable
INTRODUCTION
As cable operators intensify their search
for efficiencies in energy consumption,
operations costs and bandwidth utiliza-
tion, the case for rapid migration of their networks
to Fiber Deep architectures is becoming more
compelling than ever.
This is especially apparent now that the effort to
combat global climate change has become a major
priority worldwide. Amid mounting green
sensibilities among regulators, industries and the
general public worldwide, the cable industrys
drive for energy efficiency is not just about saving
costs. It has also become a matter of social
responsibility, which a few network service
providers from both the cable and telco sides have
begun to stress in their public messaging and in
the specifications they set for new equipment.
Fiber Deep architecture stands out as a uniquely
advantageous approach for cable operators given
that it delivers major efficiencies across all these
areas of concern, including net gains to the bottom
line, customer satisfaction and corporate standing
with the public and regulators. By leveraging
existing HFC infrastructure to radically reduce the
number of customers served by a single node,
Fiber Deep raises the proportion of available
bandwidth on a per-household basis, cuts plant
power consumption, reduces maintenance costs,
lowers the amount of gas consumed in truck rolls
and provides cable operators the results they need
to take credit for significant greening of their
operations.
THE CABLE GREEN MANDATE
The past year has witnessed emergence
of government and public consensus on
the urgency of global warming and, with
it, an expansion of green initiatives on the part of
regulators, institutions and businesses everywhere.
Cable operators and network service providers
in general are no exception. In growing numbers
they are taking proactive steps to reduce energy
consumption and to educate their customers on
best practices with respect to use and disposal of
consumer electronics equipment. And some are
making environmental considerations a key part
of their equipment purchasing decisions as well.
Consumer electronics is an especially high-profile
early indicator of the role environmental issues
will play in cable operators thinking about their
responsibilities and public positioning in the
months and years ahead. For example, the
Environmental Protection Agency has launched a
program known as Energy Star, which rates the
energy efficiency of set-top boxes and encourages
cable operators, telcos and DBS providers to
commit to purchasing Energy Star-qualified
terminals. The EPA estimates that energy savings
amounting to $2 billion per year could be realized
if all set-tops in the U.S. met these requirements.
Resulting reductions in green house emissions
would equal the annual emissions of 2.5 million
vehicles, the EPA says.
Working in tandem with these goals, cable
interests in 2008 launched the Screen to Green
Aurora Networks Solution Maximizes Energy Efficiencieswhile Minimizing Capital and Operating Expenses
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Thinking Green Strengthens the Case for Fiber Deep in Cable
initiative with events and dissemination of
information educating consumers to the dangers
ofTVs in landfills and on how to dispose of
equipment in an environmentally responsible way.Comcast Colorado took a proactive role in Screen
to Green by promoting a Recycling Rally in Denver
via messages in bills, on-screen alerts and
commercials co-produced with Discovery
Communications Planet Green channel. The
cable operator also promoted attendance by
sponsoring a drawing at the rally with an HDTV
set and one-year service subscription as the
prizes.
One of the early leaders in cable industry efforts
to emphasize responsible environmental behavior
is Cox Enterprises, which launched its Cox
Conserves initiative in 2007. Promoting
responsible disposal of consumer electronics
equipment is an important part of the effort. But
Cox, which has holdings in newspaper publishing
and other businesses as well as cable, is also
focusing on its own efforts to conserve. Thecompany says it cut energy consumption by 10
percent between 2000 and 2007 while sustaining
an annual corporate growth rate of 12 percent,
and it says it intends to cut energy consumption
by additional 20 percent by 2017. These efforts
include use of fuel-efficient vehicles, exploration
of solar and other energy-saving technologies and
promotion of energy-saving behavior on the part
of its 80,000 employees.Network equipment is now becoming the focus
of green initiatives as well, most notably through
theIEEEs Energy Efficient Ethernet Committee,
which is tasked with suggesting ways to minimize
Ethernet network equipment power consumption
during periods of low link usage. The committee
estimates that one percent of all power
consumption in the U.S. is attributable to the
operations of telecommunications network
equipment of all types. It says inefficiencies inEthernet equipment alone waste up to 5.8
terawatt-hours annually at a cost of about $450
million.
These various individual and group initiatives are
just the beginning of what is sure to be a
groundswell of activity and publicity focused on
energy savings in telecommunications. Fortunately
for cable operators, deployment of Fiber Deep,
arguably the most cost-efficient step they can taketoward addressing long-term bandwidth needs,
also happens to offer major benefits when it
comes to reducing energy consumption, increasing
operational efficiency and positioning cable
operators as leaders in the greening of telecom-
munications. This is why Fiber Deep, especially
when deployed using the innovations provided by
Aurora Networks, has emerged as the logical next
step in cable network evolution.From a green perspective, the benefits of Fiber
Deep are extensive. In the Aurora Networks
architecture extension of fiber to where there is
no longer a need for RF amplifiers in the coaxial
plant serves to cut the number of active devices
in the distribution portion of the network by 70
percent. This results in a 50 percent reduction in
power consumption and significant reductions in
the maintenance requirements, including truckrolls.
Of course, the radical reduction in the number of
active devices in Fiber Deep networks has a major
impact on other maintenance requirements as well.
All told, the savings in plant maintenance and
power costs averages out to over $5 per house-
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hold passed per year, based on analysis of field
data generated from Aurora Networks Fiber
Deep deployments over the past several years.
Equally important, Fiber Deep has major impli-cations for the operators ability to demonstrate
significant reductions in energy usage. Analysis
shows that a typical Aurora Fiber Deep deploy-
ment results in an annual reduction in plant power
consumption of about 25.8 kilowatt hours per
household passed in comparison to power
consumption over an average HFCnetwork. And
fewer truck rolls results in significant reductions
in fuel consumption and therefore generation ofgreenhouse emissions.
THE GREEN BENEFITS OF FIBER DEEP
With Auroras Fiber Deep platform
now widely deployed around the
world, there is an abundance of data
attesting to the technologys dramatic impact on
energy consumption. One example of how thisimpact has been calculated is summarized in the
following tables.
This analysis compares a one-year period ofHFC
operations with a one-year period of Fiber Deep
on a network passing 70,000 households. It
should be noted that the households passed
(HHP) ratio of this particular Fiber Deep
deployment averaged 84 per node.Even so, the data amassed by this operator offers
dramatic proof of the green benefits to be realized
from Fiber Deep. As shown in Summary Table 5,
the company reports a net savings of $618,667
in combined costs of maintenance and power
consumption for Fiber Deep compared to HFC
over the course of one year. This translates to a
savings of $619 per mile or $8.84 per home
passed. The green impact, in terms of powerconsumption, is undeniable, with a wattage
variance of 185,478 Watts and a savings in
kilowatt-hours per year of 1,805,314, adding up
to a power cost savings of $234,691 in favor of
Fiber Deep.
Table 1. Node Maintenance Table 2. RF Active Maintenance
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Thinking Green Strengthens the Case for Fiber Deep in Cable
A UNIQUE FIBER DEEP SOLUTION
Generically Fiber Deep refers to any num-
ber of vendor solutions that serve to ex-
tend fiber deeper into the coaxial plant
than is typically the case in HFC architectures.
However, the Aurora Networks Fiber Deep
solution is a unique, widely deployed approach
which relies on key innovations, such as AuroraNetworks patented digital return path technology,
Virtual Hubs (VHub) and remote optical power
balancing, to deliver the highest possible perfor-
mance at construction costs that are comparable
to a typical HFC new build/rebuild.
A representative diagram of one portion of a
typical Fiber Deep network is shown in Figure 1.
The largest Fiber Deep project underway in North
America, encompassing the 1.8-million household
Videotron network in Montreal, is based on the
Aurora Networks platform. This is an especially
important indicator of future trends, where, along
with new builds and rebuilds, Fiber Deep hasbecome the architecture of choice for the evolution
of a state-of-the-art 1,000 MHz HFC network
serving a major metropolitan area.
Aurora Networks approach to Fiber Deep entails
use of existing fiber and coaxial plant to deliver
Table 3. Power Supply Maintenance Table 4. Network Power Costs
Table 5. Summary
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Figure1.
RepresentativeFiberDeepNetw
ork
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Thinking Green Strengthens the Case for Fiber Deep in Cable
signals optically to strand-mounted,
environmentally hardened optical nodes that are
positioned to eliminate all RF amplifiers and most
power supplies. Depending on neighborhooddensities, the resulting node service area might
serve anywhere from 50 to 200 households. The
average benchmark is 125 households.
Typically, in a 1,000 MHz plant this configuration
results in the provision of 25 megabits per second
or more of dedicated narrowcast capacity per
subscribing household in the downstream,
depending on service penetration and simulta-
neous usage rates, and about 2.1 Mbps of dedi-cated capacity per household in the upstream. And
because the elimination of RF amplifiers on the
coaxial plant serves to expand the potential coaxial
capacity to as much as 1.5 GHz, the proportion
of dedicated downstream and upstream band-
width can be significantly increased beyond these
ratios.
The VHub (Virtual Hub)
The linchpin to cost-effective reuse of existing
plant to achieve this level of fiber penetration is
the Aurora Networks Virtual Hub, a fully opera-
tional hub encased in environmentally hardened
strand- or pedestal-mounted node housing.
Through innovative use of passive optical modules
in the downstream and digital multiplexing in the
return path this architecture radically reduces the
number of active components not only in the
coaxial portion of the network but in the optical
distribution portion as well.
In the Aurora Networks Fiber Deep architec-
ture signals are distributed and returned optically
over multiple wavelengths to and from Virtual
Hubs using either dense or course wavelength
division multiplexing technology (DWDM or
CWDM). DWDM, because it allows use of more
wavelengths and is compatible with optical power
amplification, is the preferred mode, especially inlarger cable systems and in any systems where
operators will require dedicated service capacity
and sufficient light power to support eventual
migration of fiber to the home.
Fed by as few as two fibers, a Virtual Hub can
serve up to 24 optical nodes (or downstream
service groups), with four fibers needed if includ-
ing redundant routes for downstream and upstream
signals. A single fiber serving a cluster of up to 12nodes delivers a unique combination of broad-
cast and narrowcast channels over two wave-
lengths to each node with a separate fiber to carry
the return signals. The highly compact Virtual Hub,
along with housing all the combiners, splitters,
redundant switching and other modules, can also
accommodate an optical amplifier (EDFA) if
needed to maximize the distribution reach of
optical signals.
Efficiencies in the Downstream
In the downstream, the Aurora Networks DWDM
platform delivers RF-modulated narrowcast sig-
nals in the 1531-1571 nm spectrum window and
broadcast signals in the 1565 nm. window to each
Virtual Hub. At the Virtual Hub Aurora Networks
passive Light-Plex broadcast/narrowcast
modules combine each narrowcast wavelengthwith the broadcast wavelength into separate op-
tical outputs. One combiner can create up to eight
such outputs to support delivery of a unique
combination of narrowcast and broadcast services
over a single fiber to each node or service group.
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The VHub can support up to three Light-Plex
modules to distribute signals to up to 24 service
groups, which, at 125 households per node with
four nodes per service group, translates to aservice area of 12,000 households per VHub.
This unique approach to optically passing signals
from the Virtual Hub to Fiber Deep nodes
eliminates the need for signal regeneration and RF
combining at the hub, as is the norm in HFC or
other approaches to Fiber Deep distribution.
Upstream Efficiencies
A key innovation in this architecture is the
technique Aurora Networks has developed to
allow the return signals to be combined from all
the nodes served by a single fiber link. Rather
than employing RF combining at each node,
Aurora Networks uses a patented digital return
technology which digitally combines or
concatenates the signals at each node. At the
Virtual Hub each set of concatenated return signals
are multiplexed together for transmission back to
primary hubs and ultimately the master headend.
This approach to delivering return signals not only
lowers initial capital costs of field distance
limitation / link budget concerns and headend
optics; it greatly reduces power consumption on
the return path. In addition, with Aurora
Networks Digital Return the network is future-
proofed; Digital Return can provide sufficient
system performance to support DOCSIS 3.0
channel-bonding.
Remote Optical Power Balancing andRoute Redundancy
The Aurora Networks system supports remote
optical power balancing at the virtual hubs to
maintain precise broadcast/narrowcast ratios
across all receivers at the final node points. The
Light-Plexs built-in optical power level manage-
ment capabilities greatly simplify the installation,
set up and maintenance of the Fiber DeepDWDM
architecture. As operators add new video or data
carriers, they can realign power levels remotely
via an SNMP interface to an element manage-
ment system, eliminating the need to coordinatebetween headend and field technicians. And they
can add optical wavelengths without interrupting
existing narrowcast services to their subscribers.
Cost-effective redundant routing is also essential
to a robust Fiber Deep architecture. Aurora
Networks unique optical switch, which can
reroute signals with very low insertion loss at
switching speeds of less than 5 milliseconds, is
housed in the secondary headend, eliminating the
need for separate switching facilities. The switch
can simultaneously protect both forward and return
signal flow over the alternately routed fiber.
Moreover, remote power level management
allows operators to set new power levels to
maintain required broadcast/narrowcast ratios
over alternate routes that may vary in distance
from the primary route. This flexibility in alternative
route selection lowers the costs of providinginfrastructure support for route redundancy.
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Thinking Green Strengthens the Case for Fiber Deep in Cable
Migration Flexibility
Aurora Networks approach to Fiber Deep also
serves to cut costs with regard to operators flex-
ibility to configure serving areas in the downstream
and upstream differently and to provision for low-
cost migration to all-fiber networks. For example,
if the upstream segmentation provides a dedicated
return path for each 125-household node serving
area, but the downstream partitioning of optical
signals is designed so that each combination of
dedicated narrowcast and broadcast signals is
distributed to two nodes serving a total of 250
households. This allows the company to peg itsinitial costs to actual demand for narrowcast ser-
vices while holding in reserve the ability to easily
move to partitioning of the downstream carriers
on a 125-home-per-node basis.
Moreover, through use ofDWDM, the potential
cost of fiber extension to the home can be
lowered. By installing EDFAs in the Virtual Hubs
and implementing additional wavelengths per
service area, it is possible to maximize use of
existing infrastructure to deliver signals optically
to the premises without having to incur the costs
of optical signal regeneration.
CONCLUSION
Even without the energy savings to be re-
alized with Fiber Deep, operators have
every reason to move in the direction of
Fiber Deep, given the great service benefits to be
gained in the context of the low deployment and
maintenance costs associated with the Aurora
Networks solution. With the green attributes the
case for Fiber Deep will only grow stronger as
energy conservation becomes a major strategic
priority for cable operators.
There is no better way to cost-effectively meet
the three inter-related goals of bandwidth
efficiency, operations efficiency and energy
efficiency. By taking steps now to exploit these
immediate benefits operators will also position
themselves to greatly reduce the costs and hassles
of making the inevitable migration toFTTP.
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Aurora Networks, Inc.
5400 Betsy Ross Drive
Santa Clara, CA 95054
Tel 408.235.7000
Fax 408.845.9043
www.aurora.com