Tài liệu Delivering Services over FTTP pdf

case study
Delivering Services over FTTP
the Home Town Way
Situation
Home Town Cable Plus is an integrated service provider operating in the city of Port St. Lucie as well
as in the county of St. Lucie in Florida. Just three years ago, the new company embarked upon its
plan to build a passive optical network (PON) to link homes and businesses in its service area to the
company data center. Home Town officially opened for business in September 2003 with a bundle
that includes standard POTS as well as alarm and monitoring services. In addition, Home Town offers
217 channels of SDV (switched digital video) and gigabit Ethernet high-speed Internet service over
the advanced IP-based network.
As Home Town management drew-up its business and operating plans, it was clear that offering highly
competitive pricing and operating profitably was going to require long term cost containment. In addi-
tion, as a pioneer in delivering services over a fiber-to-the-premise network, it was also clear that Home
Town’s PON architecture was unique. It was going to require a different approach in the outside plant
and more than off-the-shelf solutions to maintain reliable service levels and speed service turn-up.
Figure 1: PON Design for Home Town Cable Plus
A Design Takes Shape
The Home Town network was conceived as a
two-fiber system—one fiber for voice and data
and one for video. In addition, planners elected
to aggregate drop cables in fewer points in
neighborhoods, a design resulting in far fewer
above ground terminals that would appeal to
both builders and homeowners.
The PON was designed around two major com-
ponents: Neighborhood Access Points (NAP) and
Local Conversion Points (LCP), each of which
feeds multiple NAPs, shown in Figure 1. LCP and
NAP cabinets would house splitters, splices and
distribution panels. As with any PON, all active

equipment is centralized in the headend and
splitters deployed in the field so that PON cards
in the headend are purchased and activated in
unison with take rates, effectively deferring capi-
tal purchases closer to revenue.
Referring to Figure 1, the design calls for fiber
feeder cable from the headend to be spliced
to rear input ports on splitters in the LCP.
Distribution cables from NAPs are terminated
by splice on the rear of distribution panels in
the LCP. This configuration allows cross connect-
ing between input side of splitters and output
side of distribution panels by use of simple
jumper cables.
NAPs, which are deployed deeper in the network
and designed to support 32 or 64 homes, have a
similar design. Distribution cable from the LCP is
spliced to rear input ports of splitters and at
service turn-up, drop cable is spliced to the out-
put side of a distribution panel. Once fiber drop
cable is blown to the premise in pre-installed
conduit and spliced at the NAP, service connec-
tion in the field is completed with a fiber jumper
in the cross connect.
The design for the outside plant was future
thinking. With splitters in the PON rather than
centralized in the headend, the company was
able to reduce fiber count and construction costs.
Upfront costs were also reduced by use of guide
tubes and blown fiber for drop cables. By invest-

ing an additional 1% to 2% of total project costs
in a cross-connect architecture for the PON,
Home Town expects to generate long-term oper-
ational savings by reducing the time required for
activation and troubleshooting. This small invest-
ment reduces capital investment by full utilization
of PON card ports in the headend, which would
not be possible with an all-spliced PON. With a
design in hand, the task turned to finding a ven-
dor to supply LCPs and NAPs.
PON Products Engineered
Specifically for Home Town
Bill Flanagan, Director of Operations for Home
Town Cable Plus, has worked on fiber projects for
over 20 years before joining the start-up Home
Town. From initial investigations, it was evident
there were no products existing from any vendor
to meet Home Town’s needs. Yet he knew from
first-hand experience of ADC’s track record for
innovation and service both in the headend and
the outside plant. When it came time to find
products for the PON, he invited ADC to the table.
After listening and discussing objectives with
Home Town, ADC offered solutions for both
LCPs and NAPs that combined components from
existing ADC product lines. The proposal called
for ACE100, ACE200 and ADCE400 outside
plant cabinets retrofitted with VAM (Value-
Added Modules) splitter modules as well as dis-
tribution panels, splice wheels, and cable stor-

age modules from the OMX
™
line of optical dis-
tribution frames.
In all, ADC designed five different cabinets for
Home Town—all from existing products. ADC’s
ability to come up with just the right cabinets for
Home Town’s requirements was due to inherently
modular product lines, savvy engineering support
and, most important, highly flexible manufactur-
ing processes. As a vertically integrated manufac-
turer and provider of mass-customized products
for the past 60 years, ADC was able to tailor
products to Home Town’s needs.
“We had several companies out to visit with us
and they all had good products. But the others
couldn’t produce exactly what we wanted. ADC’s
manufacturing expertise impressed us enough to
know they could successfully combine several
off-the-shelf products into a solution for us,”
said Flanagan.
ADC Telecommunications, Inc., P.O. Box 1101, Minneapolis, Minnesota USA 55440-1101
Specifications published here are current as of the date of publication of this document. Because we are continuously improving our products, ADC
reserves the right to change specifications without prior notice. At any time, you may verify product specifications by contacting our headquarters
office in Minneapolis. ADC Telecommunications, Inc. views its patent portfolio as an important corporate asset and vigorously enforces its patents.
Products or features contained herein may be covered by one or more U.S. or foreign patents. An Equal Opportunity Employer
1288842 4/04 Original © 2004 ADC Telecommunications, Inc. All Rights Reserved
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Conquering Density with Proper Cable
Management
For ADC engineering, NAP design posed a dual chal-
lenge. On one hand, Home Town wanted small above
ground cabinets in neighborhoods. On the other, cab-
inets were going to be highly dense with either 32 or
64 two-fiber drops per NAP cabinet. Adding to high
fiber count are splitters, splices and cross-connect
panels, all of which could converge into a potentially
unmanageable cabinet.
In light of these challenges, making both NAPs and
LCPs technician-friendly and highly reliable meant
paying close attention to the details of cable manage-
ment. Clamping, drop cable routing within the cabi-
net, cross-connect jumper management, fiber feeder
and distribution cable entrance and exit, splice stor-
age, bend radius protection, choice of connector—
these were all critical issues evaluated by ADC engi-
neers for Home Town.
The solution started with standard ACE series outside
plant cabinets. Designed to meet Telcordia GR487
and NEMA 4 specifications, the cabinets offer proven
durability and protection. Engineers then found that
the highly modular components of the OMX optical
distribution frame system were well suited for the
project. To manage splices, OMX splice wheels were
specified. Each splice wheel provides not only splicing
but also ready storage for up to 3 meters of slack,
allowing technicians to move splice wheels away from
the cabinet to a proper position for effective splicing.

Also brought into the solution were OMX storage
modules for secure storage of cross-connect jumpers.
Finally, pre-terminated OMX distribution modules ori-
ented specifically for the right side of the cabinet,
along with VAM splitter modules, provided the ability
to cross connect in cabinets.
Taken together, advanced cable management and
cross-connect functionality offered Home Town the
right features for operational efficiency and reliability
in the PON. "Design of the cabinets addressed both
density and cable management issues," said
Flanagan. "We will realize lower operating costs
because we’re going to take less time to activate, test
and troubleshoot," he said.
Connectors in the PON Add Flexibility
Home Town expects to gain operational efficiency due
to use of cross-connects rather than all-splices for acti-
vation and rearrangements in the PON. Feeder and
distribution cables are spliced behind distribution pan-
els and, once spliced, are never touched again. Service
turn-up and other rearrangements are conducted by
placing jumpers on the front of cross-connect panels
rather than pulling fibers out, breaking splices, resplic-
ing, and pushing fibers back into place—an operation
that risks damage to adjacent fibers, too. Given that
fibers are inherently fragile, use of cross-connects in
both LCPs and NAPs increases service life of fibers and
minimizes risk of disruptions.
The choice of connector style was an important con-
sideration, too. For the harsh environment of the out-

side plant, Home Town chose ADC’s LX.5 small form
factor connector. From a fiber management perspec-
tive, use of LX.5 supported Home Town’s two-fiber
system because two LX.5 connectors are housed in
the same space normally occupied by a single SC type
connector.
In addition, the integral shutter of the LX.5 connec-
tor, which automatically closes when the connector is
removed, protects ferrules from dirt and dust. This
simple feature ensures high fiber performance in an
environment that is subject to contaminants.
Combined with thorough bend radius protection
within each cabinet, the quality and consistency of
pre-terminated distribution panels ensure low signal
attenuation when introducing connectors in the PON.
Conclusion
From a capital and operating perspective, the overall
network design works. Use of cross-connects rather
than splices in the PON allows Home Town Cable Plus
to maximize port usage on expensive PON cards while
streamlining activation and troubleshooting. As an
early adopter of the PON architecture for FTTP, Home
Town did not have the luxury to choose from a suite
of existing products. Instead, Home Town relied on
experience, flexibility and manufacturing prowess of
ADC to help build the PON.