Tài liệu Future-Proofing BPON Architectures for Tomorrow’s GPON and N-GPON pdf

WHITE PAPER
Future-Proofing BPON
Architectures for Tomorrow’s
GPON and N-GPON
Future-Proofing BPON
Architectures for Tomorrow’s GPON and N-GPON
As the final touches are added to Gigabit Passive Optical Network (GPON)
standards and with next-generation GPON (N-GPON) standards already
underway, it should be clear to service providers that additional network
upgrades are imminent as demand for bandwidth continues to increase. Today’s
fiber-to-the-premise (FTTP) architectures, deployed with broadband PON (BPON)
technology, are meeting the needs of small business and residential customers,
but are they being constructed with easy upgradeability once bandwidth usage
demands it?
ADC believes there will be a logical migration from BPON to GPON architectures
in coming years, followed by a similar move to N-GPON for even more
bandwidth delivery. The question for service providers and network engineers is
simple – have you considered the necessary steps for today’s BPON to enable the
smoothest, most cost effective migration to GPON and, ultimately, N-GPON?
The ultimate goal
When deploying PON architectures, much of the cost is directed toward the
infrastructure of fiber deployment and electronics. With that in mind, ADC is
alerting network planners that the ultimate goal is to build PONs so the next
upgrade is only a matter of replacing the electronics at each end of the network.
Adding new services to the existing network should be achieved without having
to change or re-deploy any infrastructure between the central office (CO) and
the premise.
The motivation for migration to GPON lies in its additional capabilities. As
demand for bandwidth and cutting edge services rises, GPON offers many
advantages. One of these advantages is a significantly higher data rate. BPON
transports data at 622 Mbits/sec downstream and 155 Mbits/sec upstream. A

move to GPON would increase those rates to 2.4 Gbits/sec downstream and 1.2
Gbits/sec upstream.
GPON also provides for higher split ratios to service more homes. A centralized
BPON system uses 1x32 splitters to service up to 32 customers. GPON offers
a 1x64 split enabling up to 64 customers to be serviced from a single splitter.
This splitter upgrade makes it relatively easy for service providers to opt for
centralized splitter configurations. However, it could involve a significantly higher
investment for service providers deploying cascaded splitter architectures, such as
1x4 splitters feeding 1x8 splitters – another important consideration for network
architects deploying new PONs.
GPON is expected to span greater distances, an ongoing issue in FTTP
deployments. The GPON standard promises enhanced interoperability, support
for legacy services, and physical interconnect conformance and performance.
Each of these issues makes it important for service providers to ensure the PON
networks they are deploying today will easily and cost effectively scale to GPON
and other future standards.
Page 3
Future-Proofing BPON Architectures for Tomorrow’s GPON and N-GPON
The actual components deployed in today’s PON systems
– connectors, cables, splitters, etc. – are already GPON-
capable. These components have the capacity to carry
many types of signals, from BPON to GPON. This could
hold true for migration to N-GPON as well. Discussions
about adding CWDM as one method of N-GPON
migration could present additional technical challenges.
Adding WDM to PON architectures will present
significant issues, such as different band passes, using
low water peak fiber, splitters for specific transmission
ranges, and the need to accomplish testing in different
band passes. For example, today’s BPON and GPON

systems operate in the 1310 and 1490 nm ranges (and
sometimes at 1550 nm in the case of video overlays).
N-GPON may introduce new band pass ranges. ADC
products already support wavelength ranges from 1260
to 1625 nm.
However, even if the equipment can handle new band
pass ranges, it’s still critical for network planners to look
ahead toward other issues associated with migrating
the network to GPON or N-GPON. For example, when
BPON customers demand new services associated with
GPON technology, the network should be as prepared
as possible to accommodate them. Choosing the proper
fiber distribution hub (FDH) – one with extra splitter slots
for easy expansion – and the right splitter modules for
BPON will decrease costs associated with future upgrades
to GPON or N-GPON.
Getting GPON services to BPON customers
The real challenge lies in how quickly and easily the
service provider can bring new GPON services to
customers that demand them – and how to handle
customers who are happy with the current services
and don’t want to upgrade. Once the decision has
been made to upgrade from BPON to GPON, the cost
of delivering new services falls on either the customer
or the service provider – and some customers won’t be
willing to pay for services they don’t need. Therefore, it’s
important to plan a migration to GPON that will ensure
the satisfaction of all customers – and that will depend
on how the BPON is constructed from day one.
For example, a service provider for a 5000-home

community has a very high take rate – 4500 homes
are purchasing BPON services today. In-house marketing
studies indicate that as many as 40%, would be willing
to purchase additional services associated with a GPON
upgrade. During the marketing campaign, the first 10%
of those customers indicated they would be ready to
purchase services within the first few months. This
poses an interesting scenario – one that is entirely
dependent on how the BPON was originally designed
within the network.
The first step is to install a GPON-capable optical line
terminal (OLT) in the CO to support the new GPON
services. The 10% of customers taking the services would
need their BPON optical network terminals (ONTs) at the
side of their homes replaced with GPON ONTs. This will
also require going to the FDH to install a new splitter
associated with the GPON card.
The distribution fiber (F1) now extends from the CO to
the FDH and through the new GPON splitter. The final
step is to switch each customer connection from the
BPON splitter – thus removing that BPON port from
service – to a new GPON splitter port. Although this
may seem relatively easy, the service provider could
incur significant expense during this process if the
FDH was not installed with a migration in mind.
The migration-minded FDH
The first consideration for a migration-ready FDH is to
ensure crossconnect capability – the ability to connect
from any splitter port to any customer. Installing a
centralized splitter architecture from the start will make

this a much easier – and less costly – process. Individual
drop cables can simply be swapped from BPON to GPON
splitter ports for customers desiring the new services.
A second consideration can be easily overlooked during
an original PON deployment, but becomes clear when
faced with a future upgrade to GPON. Ensuring that
extra splitter slots are available in the FDH to enable easy
installation of new GPON splitters – without having to
remove BPON splitters to free up slots.
Without spare splitter slots, a high take rate would
require waiting until 32 customers were ready to
upgrade, taking them all out of service, and replacing
a BPON splitter with a GPON splitter in the same slot.
The alternative would be to simply convert from
BPON to GPON for all customers, even those that do
not desire new services. However, that would also
require changing out the ONT at every home – a very
expensive proposition.
The importance of extra splitter slots in the FDH is
clear to allow easy and efficient migration of individual
customers from BPON to GPON. In fact, ADC suggests as
much as a 50% increase in available splitter slots to allow
fast and affordable upgrades. Extra splitter space also
enables providers to reclaim BPON splitters for future use
in other portions of the network. These benefits can only
be realized by deploying an FDH with additional splitter
slots available.
Finally, there may also be a need for additional “parking
space” in the FDH to enable easier crossconnect activity.
A parking lot can be used to place out-of-service

cables temporarily while maintenance and customer
churn issues are resolved. It not only provides an extra
convenience to the technician, but helps keep connectors
free of debris that could affect operating performance.
WHITE PAPER
Website: www.adc.com
From North America, Call Toll Free: 1-800-366-3891 • Outside of North America: +1-952-938-8080
Fax: +1-952-917-3237 • For a listing of ADC’s global sales office locations, please refer to our website.
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
106061AE 2/08 Original © 2008 ADC Telecommunications, Inc. All Rights Reserved
WHITE PAPER
Extra is better
ADC’s message to service providers is simple – plan for the future. Deploy PON systems with
interconnect capability in architectures that achieve the highest reliability and flexibility. Add extra
slots in each FDH for additional splitters and more parking space for easy access and to accommodate
any foreseeable take rate during an upgrade. Consider the cost savings of reclaiming used splitters for
future use.
It may be ten years away – or perhaps less than five – but sooner or later every FTTP network will
require some type of upgrade. Planning for an upgrade as an inevitable reality, rather than just a remote
possibility, is ADC’s position. Proper planning can make the transition faster, less expensive, and increase
customer satisfaction. Ensuring the FDH is migration-ready will make all the difference.