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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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White Paper 16

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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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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White Paper 16

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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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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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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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

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