WhitePaper017 RevA CellTowerBackhaul

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Aurora Networks, Inc.Aurora Networks, Inc.

July 2009

WHITE PAPER 17

2009 Aurora Networks, Inc. All rights reserved.


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2009 Aurora Networks, Inc. All rights reserved.2

Real at Last: Cable's Opportunity in Cell Tower Backhaul

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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2009 Aurora Networks, Inc. All rights reserved. 3

White Paper 17

Real at Last: Cables Opportunity in Cell Tower Backhaul

Aurora Networks Provides Cable Operators the Technical Foundation

to Meet Wireless Industry Requirements

INTRODUCTION

After several years of rising expectations,

cable operators are finally in a strong

position to capitalize on what is shaping

up to be a far more explosive opportunity in mobile

backhaul services than many analysts anticipated.

While mobile backhaul has long been a discus-sion point in the outlook for cable commercial

services, several factors have served to delay a

full-scale push into this arena, notwithstanding

occasional cable operator successes at winning

backhaul contracts with mobile providers in various

localities. Most significantly, cables presumed

ability to leverage a ubiquitous fiber presence to

deliver backhaul services cost effectively has been

encumbered by the absence of cable-optimized

transport platforms that could meet the rigorous

performance requirements set by mobile

operators.

Cable operators could work around these

technical limitations by building dedicated

networks to support wireless backhaul service,

but they could not justify the aggressive market-

ing and service support initiatives that were

required to make this niche a high-priority targetsegment for their commercial services divisions.

Moreover, as long as the lions share of capacity

expansion requirements between cellular base

stations and base station controllers was tied to a

need for more T1 or E1 lines, the market demand,

while significant, was not factoring in a major need

for the Gigabit Ethernet-carrying capacity that

would play to cables fiber advantage over

competitors.

The good news for cable operators is that all these

barriers have fallen. The key technology issue has

been eliminated with the availability of equipment

supplied by Aurora Networks that meets or

surpasses mobile industry quality and reliability

standards across all performance metrics. Cable

operators can now use their fiber networks to

deliver carrier-grade Ethernet services that not

only provide the IP transport capacity required

by next-generation mobile networks; they can use

the superior Metropolitan Ethernet Forum (MEF)-

compliant circuit emulation capabilities made

possible through Aurora Networks technology

advances to support cost-effective expansion ofT1/E1 capacity over those Ethernet links as well.

Coinciding with this technology development,

demand forIP transport is taking off, fueled by a

sudden surge in consumer demand forIP-based

services over 3G networks and by an accelera-

tion in 4G infrastructure buildout schedules on the

part of mobile operators. Moreover, major cable

operators themselves have become part of this

4G acceleration, in some cases through partici-

pation in the Clearwire venture and in others by

virtue of acquisition of mobile spectrum on which

to launch LTE (Long Term Evolution)-based 4G

services. Taking steps essential to competing for

mobile backhaul services from current providers


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will position cable operators to compete success-

fully for backhaul business from their own mobile

units.

As a result of these developments the momenthas arrived for cable companies to move aggres-

sively to make delivery of mobile backhaul

services a core segment of their commercial

service operations. Targeting and winning

customers in this space will not only ensure cable

operators are positioned to benefit from the

coming explosion in wireless backhaul require-

ments; it will greatly enhance their ability to win

enterprise customers in the lucrative private lineservices market across all industry sectors.

THE FAST-CHANGING WIRELESSBACKHAUL SCENARIO

F

or some time research organizations have

been generating projections showing a

steep demand curve for wirelessbackhaul, based in part on escalating numbers of

cell tower base stations and in part on anticipated

increases in transport capacity over links connect-

ing those base stations to base station controllers.

For example, two years ago Infonetics Research

predicted global spending by mobile providers

on backhaul equipment and services would jump

from $20 billion in 2006 to $32 billion in 2009.

In another report on the cellular backhaul marketthe Heavy Reading research unit of publisher Light

Reading said the U.S. share of backhaul spending,

pegged at $2.8 billion in 2007, would jump to

$15 billion in 2011. Whereas the average number

ofT1/E1connections per base station was running

at 3 lines per site in 2007, Heavy Reading

predicted the average would hit 10 lines per site

in 2011.

Looking at the 2007-2009 timeframe, Infonetics

Research foresaw a near doubling of bandwidthrequirements per backhaul link, going from about

5 megabits per second to 9 megabits per second.

Infonetics projected that worldwide Ethernet

backhaul would grow to nearly 543,000 new

connections between 2007 and 2011, represent-

ing a 235 percent CAGR(cumulative annual

growth rate).

As aggressive as these projections were, the latest

developments involving accelerated rollouts of3G and 4G infrastructure together with

ongoing buildouts of 3G infrastructure suggest

backhaul capacity expansion will move at an even

faster pace. Even though just 11 percent of the

worlds cellular population has access to 3G,

carriers are already contracting forLTEinfrastruc-

ture, with major contracts now awarded in the

U.S., Japan, Sweden, Norway and Singapore,

according to research from In-Stat. And mobileWiMAX rollouts are underway or about to get

underway in several cities served by the partners

in the Clearwire venture. Both 4G platforms boast

peak downstream data rates in excess of 100

megabits per second.

Verizon Wireless says it will reach 20 to 30

markets with LTE-based services by the end of

2010. AT&T Mobile, with its own LTE deploy-

ments schedule to begin in 2011, recentlyannounced that, rather than waiting until then to

take the next leap in mobile bandwidth, it would

implement HSPA (High Speed Packet Access)

7.2 Mbps upgrades starting in the second half of

2009, thereby doubling its current peak rates over

the 3G HSPA network infrastructure. The


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White Paper 17

company also announced it would nearly double

its 3G wireless spectrum in conjunction with

expanding 3G availability to another 20 metro

areas, bringing the total to nearly 370 cities byyears end.

These sudden leaps in mobile speeds are the

carriers market-driven responses to a much

greater consumer demand for Internet and multi-

media services than most observers anticipated.

The phenomenal success of Apples iPhone has

been accompanied by a surging demand for

applications from the Apple app store, with the

company reporting over one billion apps down-loaded worldwide within nine months of the stores

launch. Inspired by Apples success, various

handset makers and other players now offer an

aggregate of about 70 app stores around the

globe, according to the latest count from AT&T.

Other signs of surging demand for mobile access

capacity abound. U.K. researcher Ovum projects

that mobile broadband revenues, which topped

$30 billion in 2008, will jump to $137 billion by2014. Strategy Analytics forecasts there will be

an installed base of 100 million connected

consumer electronics devices beyond traditional

handsets by 2014, and another study from Rethink

Wireless forecasts operator revenues from such

non-handset devices will hit $90 billion in 2013.

Lending credibility to such projections, AT&T

Mobile has launched an emerging embedded

devices business unit with a mandate to build newecosystems and service models around mobile-

connected netbooks and MIDcomputers, e-read-

ers, automobiles and much else.

The impact of this surge in mobile bandwidth

consumption on backhaul requirements portends

to an even greater impact on backhaul capacity

requirements than researchers envisioned. Traffic

sampling undertaken by the Metropolitan Ethernet

Forum shows that in contrast to the 16 kilobits

per second of bandwidth required for the averagemobile voice call, Web browsing consumes at

minimum 128-384 Kbps per session and multi-

media streaming can consume anywhere from 2

to 15 Mbps.

Whereas Ethernet connections have accounted

for a very minor portion of wireless backhaul

capacity over the past few years, In-Stat predicts

the ramp-up in capacity requirements will result

in Ethernet links accounting for over half of allmobile backhaul capacity by the end of 2011.

Moreover, In-Stat notes, this shift to Ethernet is

not just for the purposes of accommodating the

surge in IP traffic; it is also a function of mobile

operators growing acceptance of the latest circuit

emulation capabilities over Ethernet as being

adequate to meeting the needs for more T1/E1

connections. As shall be seen, this has crucial

implications for cable operators who make useof the circuit emulation capabilities built into Aurora

Networks wireless backhaul solution.

KEYS TO CABLES SUCCESS INCOMPETING FOR WIRELESS

BACKHAUL BUSINESS

Clearly, the greater-than-expected near-

term leap in backhaul capacity needscreates a new measure of urgency

behind cables opportunity to play a significant

role in this market. In its 2007 report on wireless

backhaul trends and opportunities forMSOs,

Heavy Reading said, IfMSOs don't make cell

backhaul a top priority soon, they could find


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themselves limited to just a small slice of the market

if not shut out altogether. Given the pace at

which capacity demands are outstripping

projections from Heavy Reading and others, thestatement has more validity now than ever.

Needless to say, the surge in backhaul capacity

demand represents larger opportunities for all

suppliers of such services, not just cable. This

means cable operators must take advantage of

all the means at their disposal to deliver competi-

tively priced wireless backhaul services that meet

or exceed all the performance requirements set

by mobile carriers.Presently, according to New Paradigm Resources

Group, at least 85 percent of all U.S. cell sites

are served solely by local exchange carriers

copper plant. At the same time, according to

Insight Research, over 90 percent of U.S. wireless

backhaul traffic is served by leased private lines,

which means wireless carriers prefer to lease

capacity even though microwave options are

available that would allow them to own their ownbackhaul infrastructure. According to ABI

Research, the high costs of real estate for mounting

antennas combined with high per-megabit costs

of microwave technology will continue to be

barriers to wireless carriers use of this option,

especially in North America, even as high-speed

Ethernet connectivity becomes a major increment

of ongoing capacity requirements.

Thus, wireless carriers must either continue to relyon local exchange carriers as capacity needs

outstrip the usefulness ofT1/E1 connectivity or

find alternative providers who can meet the need

for both T1/E1 and high-speed IP transport

capacity cost effectively. While competition has

forced LECs to reduce T1 line rates, in some

cases into the $300-per-month range, telco prices

for fiber-based private line services have remained

high, with specific rates depending on transmis-

sion speed, a fixed rate for central office termina-tion and a mileage charge for the fiber transport

distance. These pricing trends have the effect of

driving demand for ever more T1 lines as long as

TDM-based transport is a viable option, while

leaving a cost chasm in instances where the high-

bit-rate requirements ofIPservices call for fiber-

based connectivity.

Mobile carriers can ill afford such increases in

backhaul expenses. Already, backhaul operationsaccount for up to 30 percent of mobile operators

total operations costs, according to Infonetics

Research.

Cables chief advantage in taking on the

entrenched dominance of the telcos as private line

service providers to the wireless backhaul market

rests on the proximity of cable fiber nodes to

mobile base stations, which means operators are

frequently in a position to extend fiber to basestations at far lower costs than can be achieved

by telco competitors. By several estimates, cable

fiber nodes are in close proximity to 70-80 percent

of the businesses in their markets, most of which

are situated in the commercially zoned locations

where base stations are most likely to be found.

Now cable operators finally have the technologi-

cal means to exploit this fiber advantage in the

wireless backhaul market. Thanks to theavailability of cable-optimized optical transport

technology from Aurora Networks as described

below, cable operators can employ Ethernet

transport across their existing fiber infrastructure

to provide a cost-competitive combination of

multiple T1/E1 links and multi-megabit Ethernet


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White Paper 17

connectivity to accommodate both the voice and

IP-traffic demands of mobile carriers.

Mobile carriers who are faced with charges for

comparable services from LECs that can run tomany thousands of dollars per month per base

station will be able to obtain these services from

cable operators at much lower rates. Given this

cost advantage, cable operators are well

positioned to compete for wireless carrier

business, even in instances where the mobile

providers are units of the LECs. Bottom-line-

driven business practices that value cost savings

and migration flexibility over loyalty to any onesupplier will always prevail.

However, it is essential that cable operators enter

into competition for this business as full-service

private line market providers with the commit-

ment of technical staff, sales and customer service

personnel as well as marketing clout that conveys

a sense of dedication to the wireless segment.

Because the technical foundation enabling delivery

of private line backhaul services positions cableoperators to compete for private line business in

general, operators stand to gain not only new

revenues from other enterprise segments but also

greater credibility in the eyes of potential wireless

customers to the extent they are viewed as major

competitors for private line business in the

enterprise marketplace.

THE TECHNOLOGY FOUNDATION TOCABLES OPPORTUNITY IN WIRELESS

BACKHAUL

While there has been a long-held pre-

sumption that cable operators could

use existing fiber plant, including

HFC distribution fiber, to support wireless

backhaul services, the fact is that crucial technol-

ogy advancements were needed to ensure that

solutions supporting cables participation in this

market met all performance requirements. Aurora

Networks has met these requirements by

combining its Ethernet-over-cable transport know-how with Ethernet service capabilities that comply

with the rigorous standards set by the Metro

Ethernet Form and the mobile industry.

Most significantly, these include the T1/E1 circuit

emulation requirements embodied in the MEF-8

and MEF-18 specifications. To achieve MEF-18

certification Aurora Networks next-generation

TDM-over-packet GT3410A T1/E1 solution had

to pass a set of 334 stringent test cases that are

designed to ensure that a provider of Circuit Emu-

lation Services over Ethernet (CESoETH)

conforms to market requirements.

Aurora Networks is one of only three vendors

that have been certified to be compliant withMEF-

18 and theonlyone to date found to be compliant

forbothT1 and E1 circuit emulation. Aurora

Networks has also been certified on the key

Ethernet User Network Interface and Traffic

Management metrics contained in the MEF-9 and

MEF-14 specifications.

The benchmarks set by MEF-18 represent a

significant advance over the capabilities of various

pseudo-wire solutions that have been in the


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marketplace several years but which, in general,

have fallen short of the performance requirements

set by mobile carriers for backhaul applications.

TheMEF-18 tests provide assurance that the jitter,wander, frame loss and packet delay metrics on

a per-link and aggregate backhaul network basis

are well within tolerance levels set for all

generations of GSM, CDMA and WiMAX

networks.

Synchronization of clock timing, inherent to the

mechanisms in a T1 orE1 copper link, has been

one of the biggest hurdles for Ethernet circuit

emulation techniques when applied to mobilebackhaul. Each cell site must use a clock source

that is synchronized with the overall network clock

so as to produce minimum wander, which is a

measure of how far clocks move out of sync over

a given timeframe, and jitter or packet delay

variation, which measures the impact of timing on

a per-link, per-flow basis.

Given the fact that the typical local radio access

network backhaul infrastructure can consist of oneto two network controller sites serving anywhere

from hundreds to thousands of base stations,

maintaining clock synchronization across the entire

backhaul system is an especially daunting

challenge. According to the MEF, most mobile

networking applications require a frequency

accuracy of 50 parts per billion.

Packet-based synchronization operates indepen-

dently of the physical layer by applying sophisti-cated algorithms to reconstruct the time and

frequency information from the packet flow. To

be certified compliant with MEF-18, Auroras

GT3410A platform had to meet the stringent

standards set by the ITUs G.823 and G.824 jitter

and wander requirements.

The GT3410A achieves the required synchroni-

zation accuracy by applying Adaptive Clock

Recovery methods, where end points measure

the inter-arrival time of the received packets toreconstruct the original frequency information. All

elements across the TDM and packet network

are thus tightly synchronized to the primary clock

reference positioned at the cable headend or wire-

less base station controller. Critically, this in-band

clock synchronization approach eliminates the

need for additional synchronization equipment and

minimizes packet overhead related to timing, which

makes it more efficient and cost effective as

compared to alternative methods. This schema

is graphically depicted in Figure 1.

But accuracy through packet-based synchroni-

zation can only be maintained to the extent that

the system maintains rigorous Layer 2

performance levels with regard to packet

impairments such as end-to-end delay, delay

variations and frame loss. Auroras GT3410A

platform is designed to maintain sub-millisecondtransport delay over point-to-point links, thereby

ensuring packet-based synchronization meets the

rigorous requirements ofTDMclock synchroni-

zation.

This Layer 2 performance has important implica-

tions for circuit emulation over cellular backhaul

links, where the total end-to-end delay threshold

encompassing all system components cannot

exceed 8 milliseconds. Because the introductionof Aurora-based CESoETH technology

contributes just a sub-millisecond delay element,

the solution is eminently suited for use on legacy

CDMA T1/E1 cell site and controller interfaces.

Each GT3410Amodule has fourT1/E1 interfaces

and serves to aggregate that traffic into the one


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White Paper 17

Gigabit Ethernet Fiber interface for transport over long

backhaul distances, thereby functioning as an inter-

networking agent between the T1/E1 and metro

Ethernet clouds in conformance with theMEFs Generic

Inter-working Function (GIWF). The GT3410A also

has one 10/100/1000 copper interface that can be

utilized for back-hauling high speed data traffic in the

vicinity of cell tower thus adding more flexibility to cable

operators solution portfolio.

By employing the GT3410A across all wireless

backhaul end points cable operators can provide a

solution that allows wireless carriers to support

and expand legacy PDH (Packet Digital

Hierarchy) T1/E1 connections while providing

them a one Gigabit Ethernet interface to accom-

modate IP traffic flows.

When installed in a 3RU CH3000 chassis (as

shown in Figure 2) for deployment at base station

controllers or the cable headend, multiple

GT3410A modules provides support for up to 80

T1ports in a single chassis. The GT3410Amodule

can also be installed as a single module in the 1RU

Figure 1. In-band Clock Synchronization Based on Adaptive Clock Recovery

Figure 2. GT3410A T1/E1 Access Modules Installed in the 1RU CH1301 CPE Chassis (at left)

and Pictured with the 3RU CH3000 Chassis (at right)


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CH1301 CPE chassis for placement at base

stations. Several such individual GT3410A units

(inCH1301Bchassis) can be daisy-chained together

to connect into the cable operators access fiberover separate CWDM wavelengths, thereby

allowing more efficient use of fiber at base station

sites with high densities ofT1/E1 ports.

A reference drawing for one possible architecture

is shown in Figure 3.

TheGT3410A is fully compatible with the cable

network-optimized Fast Ethernet and Gigabit

Ethernet capabilities widely used with Aurora

Networks solutions such as Fiber On Demandand its family ofSMART Media Converters.

These transport capabilities provide CWDM and

DWDM Ethernet conduits over the existing fiber

distribution and metro backbone plant, allowing

the operator to aggregate and terminate all base

station traffic on the CH3000 at the headend or atthe wireless operators base station controller.

This flexibility in Ethernet-over-cable architecture

gives operators the option to serve base station

controllers directly in regions where the cable

metro fiber plant is proximate to controllers or to

hand off aggregated base station traffic from the

headend to other providers of high-capacity links

between the headend and the controller site.

Operators, of course, can also terminate theEthernet traffic at the headend and build out their

own or lease TDM DS3 orOC-12 links to reach

the controller.

Figure 3. Reference Architecture


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CONCLUSION

The accelerated pace of 4G deployments

amid ongoing 3G expansion worldwide

is compounding an already difficult

backhaul capacity conundrum for mobile service

providers. Legacy backhaul infrastructure

suppliers with their dependence on TDM-based

connectivity over copper and their inflated pricing

for fiber access are not well positioned to serve

these expansion needs, especially if cable

operators can provide the wireless industry with

options that prevent backhaul costs from

becoming an even larger share of wireless carrieroperating budgets.

But wireless carriers cant be expected to wait

for these alternative solutions to emerge over time.

With researchers predicting the average number

ofT1/E1backhaul ports per base station will more

than double over the next two years as the need

for high-speed IP packet throughput jumps to a

significant share of overall backhaul capacity its

clear the wireless players will be locking down

on these next-gen needs very quickly.

Cable operators now have the means at their

disposal to address this market with an integrated

fiber-based solution that leverages existing

network resources to meet the full range of wire-

less backhaul requirements. Aurora Networks

MEF-18 certified GT3410A solution provides

wireless carriers the assurance they need to exploit

the tremendous cost savings made possible

through use of Ethernet-based circuit emulationto deliverTDM traffic over high-capacity Ethernet

fiber. Thus, by deploying the GT3410A platform

at base stations and base station controllers, cable

operators can take advantage of Aurora

Networks market-proven Ethernet-over-cable

transport capabilities to deliver both the T1/E1

and the pure Ethernet support wireless carriers

are looking for.

Moving in this direction to serve the private line

transport needs of the wireless industry also

positions cable operators to compete aggressively

for other segments of the private line business.

Cable operators ability to leverage their fiber in-

frastructure in conjunction with use of the Aurora

Networks GT3410A platform to aggregate PBX

voice traffic overT1 circuit emulation interfaces

with LAN traffic on the Ethernet interface gives

them entre to one of the hottest markets in

commercial services.

The magnitude and urgency of the wireless

backhaul market represents a huge opportunity

for cable operators to be players in a $40-billion

global market. There has seldom been so

promising a point of entry into a new market for

the cable industry.


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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

WhitePaper017 RevA CellTowerBackhaul

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