ADC KRONE - Guide Book - FTTP - The Efficient Service Delivery Architecture for OSP network

Fiber-to-the-premises FTTP systems, based on passive optical network PON architecture, provide the access piece to traditional OSP networks for bringing multiple services to multiple bus

OmniReach™: The Efficient

Service Delivery Architecture for OSP Networks

Current outside plant (OSP) networks, particularly those deploying fiber, were designed primarily with transport and backhaul in mind – a means to carry telecommunications traffic on and off a larger transport system and usually over long distances There was little demand for actual service delivery to multiple end users, although an occasional large business customer might require as much as an OC-3 or OC-48, Megabit Ethernet, Fibre Channel, or other connection for day-to-day business operations

Times have changed Today, fiber is being deployed much deeper into the network, both for business and residential consumers The demand for high-speed voice, data, and video services is escalating, and new distribution architectures must be added to OSP networks

to reach these customers However, serving the small business and residential customer requires architecture that can efficiently connect millions of users onto a local network Fiber-to-the-premises (FTTP) systems, based on passive optical network (PON) architecture, provide the access piece to traditional OSP networks for bringing multiple services to multiple business and residential customers

PON – Catalyst for the FTTP Revolution

PON architectures are optical transmission systems designed to carry transmission signals via fiber-optic cable from the central office (CO) directly to the end user – such as a business, multi-tenant unit, or individual home The network is passive because once the signal leaves the central office, there are no powered electronics or optical components involved The signal is guided through the fiber to the end user by connecting and splitting components, traveling up to, and in some cases, exceeding 20 km At the end user, the optical signal is converted back to electrical by an optical network terminal (ONT) for use as telephony, Internet, or video

for OSP Networks

Central Office

Splice Case

Splice Case

Fiber Distribution Terminal

Drop Cable

Fiber Access Terminal Distribution

Cable

Information from the end user flows from the premises

back through the PON to the CO, using wavelength

division multiplexing (WDM) WDM enables different

wavelengths of light to be transmitted over a single fiber

in either direction PON offers distinct advantages over

competing technologies because of its passive nature,

such as eliminating the need for any electrical power

unit PON can function in the OSP under environmental

extremes, and its low maintenance and data independent

nature provides significant operational and upgrade cost

benefits to telecom providers

A New Way of Thinking

With the introduction of FTTP architectures comes a new

set of issues and concerns to challenge networking

engineers Large-scale FTTP networks require providers to

ask some tough questions about their traditional

methods of building, operating, and maintaining the OSP

network Which overall design, particularly in terms of

which splitter approach to use, will be most cost-efficient

in a particular deployment scenario? Which will provide

the necessary flexibility – connectorization or splicing?

What components will provide the best performance?

How many access points will be needed for testing and

maintaining the system? How much training will

technicians need to ensure proper cable management

and slack storage? How does one deal with the new

implications posed by FTTP for the central office?

There are various answers for every decision Choosing

the wrong answer can be the difference between an

efficient, revenue-generating network versus one that

will constantly require upgrades and overhauls as

demand and technology moves forward ADC has

introduced craft-friendly access networks based on many

years of experience in addressing these and other

concerns posed by customers

PON architectures require key decisions that depend

heavily on service area considerations, such as physical

proximity of end users and service take rates, to

determine what components are optimal and their

placement within the network This paper will address

pros and cons, as well as solutions, to the challenges

faced by today’s forward-thinking service providers who

view FTTP as the next major marketplace for increased

revenues through superior service offerings

Higher OLT Efficiency is a ‘Splitter’ Decision

There are two main approaches to FTTP optical splitters: centralized and cascaded Through research, statistical data, and lessons learned, ADC has concluded that in most cases, a 1x32 centralized splitter configuration provides distinct advantages over a cascaded splitter approach The first reason for choosing a centralized splitter approach is to obtain the highest possible efficiency of the optical line terminal (OLT) cards Each PON card services a maximum of 32 end users, providing

an optical signal to each ONT at the premises

A cascaded approach, however, requires dedication, or

“hard-wiring,” of fibers to certain locations, leaving a real possibility of stranded connections whenever take rates are not high – making additional (and expensive) PON cards necessary A centralized approach makes use

of all 32 connections on each PON card, resulting in maximum efficiency and the need for fewer cards Additionally, the 1x32 centralized splitter provides for a modular build that enables budgeting costs with revenue growth

Testing also becomes a challenge with a cascaded approach To use an optical time-domain reflectometer (OTDR) for testing multiple splitters, each fiber must be characterized with certain identifiable traits for recognition by the OTDR From a centralized point, it is also difficult to see through an array of splitters down individual fiber lengths In a centralized system, all troubleshooting is done from a single, centralized point

A centralized splitter also provides better overall loss measurements compared to the cascaded approach One argument for a cascaded splitter approach has traditionally been that it makes more sense in a very high take rate situation Cable costs may be less since a 12-fiber cable used in the cascaded approach may substitute for the 72-fiber cable used in the centralized architecture However, since the price differential is probably not excessive (glass is fairly inexpensive today) and holes are being dug to bury the cable anyway, why not put the higher fiber count in case future upgrades or additions become possible? The economies of gaining simpler testing ability will almost always outweigh any cost savings realized in using smaller fiber counts

1x4 or 1x8 Splitter

Central Office

OSP Enclosure

1x4 or 1x8 Splitters

1x4 or 1x8 Splitters

Central Office

up to 1xN Splitter (N up to 32)

FTTP Cascaded Optical Splitter Network Diagram

Connectors vs Splicing – A Common

Sense Approach Reaps Big Benefits

Another major consideration in building a cost efficient,

flexible, distribution network is deciding when to splice

and when to use connectors A simple rule of thumb

would be to splice connections that will remain

permanent, and use connectors wherever a need for

access may occur Still, there are other factors to consider

Splicing may be preferable for distribution cables to

achieve reasonable distances that can be easily and

efficiently managed Connectors, on the other hand,

provide easy access for testing and troubleshooting They

also provide the network with considerably more

flexibility in terms of making adjustments or changes

during services provisioning

Traditional OSP networks used splicing exclusively as a

means of interconnecting cables However, where a

distribution network is involved, splicing could be a very

expensive and time-consuming operation Since

distribution networks require numerous connections for

quickly turning up services to thousands of homes and

businesses, connectors offer more flexibility and less

personnel training to accomplish The number of

technicians and equipment required for multiple splicing

operations should be considered

Finally, connectors enable easier access for troubleshooting and maintenance operations They provide access at multiple points along the network and are certainly simpler than cutting into the cable to perform these same operations The mythical “seamless” network may have appeared as a good solution for transport and backhaul operations, but with an access network, the ability to easily test and monitor is essential Without seams provided by connectors, there is no access or ability to physically restore a network outside of cutting into the optical cable

The risk of inadvertent failure also increases when cutting and splicing cables, leaving a possibility of service interruption or failure to other customers while troubleshooting a problem in another area of the network To most service providers, this is an unacceptable risk

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Foreword Path 1xN Splitter

Bulkhead Plate

Drop Cable OSP

Cable From C/O

Return Path 1xN Splitter

Factory Terminated Connectors

Factory Terminated Connectors

Bulkhead Plate Splice

Enclosure

Bulkhead Plate

Cross Connect Patchcords

Enclosure

FTTP Splitter Connector Access (Input and Output Connected)

High Performance Components –

Rain or Shine They Always Work

The high-performance components used in ADC’s FTTP

solution offer a wealth of robust features for exceptional

reliability The arguments that weather or other

environmental conditions will weaken them is no longer

valid Components and connectors have evolved to the

point where signal loss is minimal and life expectancy is

at an all-time high, despite harsh environments and

temperatures

A number of Telcordia studies have shown that

connectors in the OSP performed quite well in a variety

of outside environments The bottom line is whether a

slight loss is acceptable when the benefits, such as easy

test access, faster turn up, and lower skill sets, are

enhanced

Cable and cable assembly component shrinkage at low

temperatures is a common cause of attenuation on OSP

cable assemblies If this shrinkage issue isn’t dealt with,

optical fibers can fail at extreme cold temperatures For

ADC systems, only low-shrink plastic components are

selected, and the fiber fanout and cable breakout

assemblies are designed to accommodate disparate

shrinkage rates between the different materials This

process enables the highest performance characteristics

in ADC’s manufactured components – even in extreme

temperatures

Picking Up the Slack in Cable Management

Storing excess fiber cable is another area where most existing OSP fiber solutions run into cable management problems Excess patch cord fiber is usually necessary for reconfiguring a fiber circuit, but the slack must be managed to prevent damage, yet remain accessible during day-to-day operations of the network

Accessibility and the amount of time required to reconfigure a network will be optimal in a system that maintains a continuous non-coiled or twisted routing of the fibers A successful slack storage system such as ADC’s will provide flexible storage capacities, permanent bend radius protection, and easy access to individual fibers

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Foreword Path 1xN Splitter

Bulkhead Plate

Drop Cable OSP

Cable From C/O

Return Path 1xN Splitter Splice

Enclosure

Splice

Enclosure

Don’t Forget the Central Office

Today’s FTTP networks will also

have implications for the

central office environment For

instance, where to place the

WDM? There are advantages

for placing the WDM inside the

fiber distribution frame lineup

as opposed to placing it beside

the OLT equipment There are

also new considerations for

fiber raceways and connector

performance within this

environment that will

revolutionize the central office

of tomorrow for FTTP The

same fiber management

principles ADC has honed in

the central office environment

can be found within the

cabinets – specifically, the Fiber Distribution Terminal

The Anatomy of a Revenue

Generating Fiber Distribution

Terminal

ADC’s Fiber Distribution Terminals incorporate four

time-tested elements that have already been demonstrated

within central offices worldwide Now ADC has evolved

these elements into the OSP cabinet environment

keeping the craft person in mind to ensure field products

will perform with equal efficiency

These four specific elements, directly impacting the

reliability, functionality, and operational cost of the

network, are: bend radius protection, intuitive cable

routing, easy fiber/connector access, and physical

protection

• Bend radius protection – Fibers bent beyond the

specified minimum bend diameters can fracture,

causing service failures and increasing network

operations costs Adding new fibers on top of

previously installed fibers can easily bend the bottom

fiber beyond its minimum bend radius and suddenly

cause an increased level of attenuation and a shorter

service life By emphasizing fiber cable management,

ADC provides bend radius protection at all points

where a fiber cable is making a bend This practice

increases long-term reliability of the network, reduces

network down time, and ultimately reduces the

operating cost of the network

• Intuitive cable routing – Intuitive cable routing provides

a very clear path for a craftsperson to route a particular cable, leaving fewer options and virtually eliminating the chance for human error In addition, having defined routing paths makes accessing individual fibers much easier, quicker, and safer – reducing the time required for reconfigurations

Intuitive cable routing paths also reduce the training time required for technicians and make patch cord routing and rerouting a simpler operation

OLT Voice/

Data

WDM

OSP Cable

To Network

1480nm 1550nm

Splice Panel Termination Panel

Cross-Connect Patch cord

Equipment Patch cord

OLT Video

FTTP Central Office Fiber Network Architecture

unmated connector pairs in a “parking lot.” This parking lot is a key factor in maintaining connector cleanliness The practice of scoping every single fiber as it is being cleaned can be both cumbersome and expensive Because ADC places individually accessible connectors on both front and rear without the need for removing an entire panel, technicians have much easier access for cleaning operations to ensure optimal connector performance From the time each unit is shipped from the factory, a dust cap protects every connector’s end face while it’s plugged into the parking lot Superior fiber cable accessibility ensures that any fiber can be installed or removed without inducing a macrobend or otherwise damaging an adjacent fiber

• Physical protection – Physically protecting every fiber and connector from inadvertent damage is a major concern in cable management ADC’s cabinet design ensures maximum protection for every optical cable and component Fibers that are routed between pieces of equipment without proper protection are very susceptible to damage A fiber cable management system should ensure the physical protection of every fiber

ADC is Answering the Tough FTTP Questions

ADC provides efficient and flexible solutions for FTTP architectures to enable the distribution of triple-play services to multiple end users Through innovative products and time-tested

techniques, ADC is a leader in pushing the benefits of optical technology to everyone – at work

or at home