Tài liệu Multi-dwelling unit (MDU) pdf

In every case, there are key building blocks that include indoor and outdoor fiber distribution hubs FDHs, fiber distribution terminals FDTs, riser cables, drop cables, raceway systems,

WHITE P

Multi-dwelling unit (MDU)

Applications for greenfield

and overbuild scenarios

Multi-dwelling unit (MDU)

Applications for greenfield and overbuild scenarios

Deploying fiber to MDUs, such as apartment complexes, condominiums, townhouses, and other multi-family locations, represents a lucrative market for broadband service providers At the same time, these applications present unique challenges in both greenfield and overbuild scenarios This paper addresses the key elements of MDU construction practices, including the physical plant from backbone to premise and the architectural decisions required for a successful MDU application It will also cover additional network considerations for equipment and connectivity techniques

MDU connection strategies for fiber-to-the-premise (FTTP) deployments will differ from site to site and the type of structure will often dictate the strategies for fiber cabling and connections within the structure In every case, there are key building blocks that include indoor and outdoor fiber distribution hubs (FDHs), fiber distribution terminals (FDTs), riser cables, drop cables, raceway systems, and wall plates MDU applications typically require additional drop cables, raceways, and outlets for completing the interconnection and extending fiber into every living unit

Multi-dwelling unit (MDU) Applications for greenfield and overbuild scenarios

Page 3

The MDU architecture

Every MDU is served by at least one telecommunications

room (TR) Ideally, there is one TR per floor that is

recognized as the connection point between the

backbone cabling connection to the central office (CO) or

head-end and the horizontal pathways and cabling to the

living units or office spaces (see Figure 1)

The “backbone” cable of an MDU architecture refers

to the fiber-optic riser cable in multi-floor buildings,

but generally refers to the pathway between entrance

facilities, equipment rooms, floor-serving terminals,

TRs, common equipment rooms, or common

telecommunications rooms TRs will typically house the

entrance facilities and the main cross-connect, horizontal

connect (floor distributor), and intermediate

cross-connect (building distributor)

Vertically-aligned TRs with connecting sleeves or slots are

the most common types of backbone pathways They

offer better flexibility by providing accessibility to the

backbone cable sheath on each floor and enable circuits

to be distributed as needed It should be noted that

proper fire-stopping techniques should

be maintained at all times

With TRs aligned in a vertical pathway, a means for cable

pulling should be provided in line with the sleeves or

slots at the uppermost room of each vertical stack,

such as a steel anchor pulling iron or an eye-bolt

embedded in the concrete Where pulling irons are

not available, the building steel may act as a sufficient

pulling mechanism location

A goal should be to position cable sleeves or slots adjacent to a wall that can support backbone cabling However, sleeves or slots cannot obstruct wall terminating space by placement above or below the wall space intended for termination fields Modifications or changes to any MDU structure must be approved by a structural engineer Further, all sleeves and slots must conform to all national and local building and fire codes The “backbone” or riser cable in a vertical riser shaft may be extremely heavy (high strand count) optical fiber cable There are several considerations for deciding the best method of installation The preferred practice is to place the fiber-optic riser cable into a vertical pathway from the top down There may also be tensile strength considerations in the cable’s manufacturing specifications The cable can be placed vertically in an open riser shaft; through cores, sleeves, or slots; or within a large conduit The cable installer should determine the size and type of reel for loading the cable, particularly in a high-rise MDU situation where the cable must be spooled to each floor’s

TR with enough slack for splicing to a terminal Cable lengths must be verified for end-to-end distance – do not rely on the manufacturer’s cable-run label The riser cable should be secured to a back board support by at least three cable clamps at the top and a single clamp at the bottom Slack storage is accomplished by single clamps above and below each storage spool, with the spool secured to the back board Plywood back boards should

be at least ¾” and painted with fire-retardant paint

Nth Floor

1st Floor 2nd Floor 3rd Floor 4th Floor 5th Floor 6th Floor 7th Floor

1 - 78 mm (3-in) Trade Size Conduit between TRs minimum Telecommunications Room (TR)

103 mm (4-in) Trade

Size Conduits

103 mm (4-in) Trade Size Sleeves

103 mm (4-in) Trade Size Conduits

Main Terminal/Equipment Room Entrance Room/Facilities 103 mm (4-in) Trade

Size Conduits

103 mm (4-in) Trade Size Conduits

TR

103 mm (4-in) Trade Size Sleeves

Figure 1 Telecommunications Room

FTTP network architectures for MDU applications consist

of four basic building types – high-rise (100 or more

living units on 10 or more floors) , medium rise (less than

100 living units on multiple floors), low rise or garden

style (single living units on each floor), and horizontals

(each unit resembling a single family unit) Each building

type presents its own set of unique challenges for the

network installer (see Figure 2)

High-rise and medium rise MDUs

The most difficult MDU applications are typically in

existing high-rise and medium-rise structures, since

the plan must adapt itself to each building’s unique

architectural design Therefore, there is never a right or

wrong way to install the network – the installer must

adapt to the building’s layout and design Although the

considerations are basically the same for any high-rise,

the techniques and strategies will be different, particularly

in existing structures

Typically, a feeder cable is routed from the serving

FTTP equipment to the structure and connected to

an indoor FDH located in the basement or other usable

ground-level location The placement of these cables

must be well thought out For instance, care must be

taken not to place cabling or electronics within the

elevator shafts Keep in mind, however, that the location

for the FDH must be secure from intruders and protected

from the elements

The optical splitting function and connection of the

network within the building is performed in the FDH

For most MDUs, a centralized splitter configuration

works best However, circumstances could also dictate

using either a distributed splitter configuration or a

combination of both types

Riser cables are distributed to the various floors through established pathways Because the floor-to-floor access and entrance to the living units may be limited, new conduits may be required Metal tracking systems may also be used within an existing system If allowable, using an existing cable TV infrastructure may be

a viable solution In any case, proper bend radius must be maintained throughout the placement

of the riser cabling

Each FDT is connected to the riser cabling – using connectorized interfaces is recommended for enabling easy technician access to each living unit for turning up services, maintenance, and troubleshooting Drop cables are installed into each living unit and routed to that floor’s FDT Final interconnections can then be made as each subscriber requests services Again, it’s important

to ensure proper bend radius when routing cables to and within each living unit

In a typical greenfield application, the common equipment room would be located in the basement, with a common telecom room for every three floors Using a centralized architecture, 1x32 splitters are located

at the indoor FDH with a high-count fiber riser cable extending through the building The riser cable would

be intercepted with 12-fiber and 24-fiber cables to each indoor FDT on each floor Additional drop cables, raceways and outlets complete the interconnection to the living units on each floor

Horizontal MDU

Central Office Headend

Residential

Businesses

Indoor Fiber Distribution Terminal (iFDT)

Indoor Fiber Distribution Hubs (iFDH)

High-Rise

MDU

Medium-Rise MDU

Low-Rise/Garden Style MDU

Drop Cable

Fiber Distribution Hub (FDH)

Indoor/Outdoor Drop Cables

Outdoor Fiber Distribution Terminal (oFDT)

Feeder Distribution Drop

Figure 2 Network Architecture with MDUs

Multi-dwelling unit (MDU) Applications for greenfield and overbuild scenarios

Page 5

Garden-style and horizontal MDUs

The garden-style and horizontal MDU configurations

are typically less complicated, since these structures are

usually just two or three stories with walk-up access

But because most have not been designed with

future-proofing in mind for adding new cabling networks, they

will usually offer significant challenges to installing an

FTTP architecture, particularly in existing structures

Depending on the number of living units involved, the

FDH is placed at a strategic location A feeder cable

from the street “right-of-way” and a distribution cable

feed the complex Once an order for service turn-up is

generated, the installer runs a fiber-optic jumper from

the feeder cable to a distribution cable assigned to the

specific living unit

Distribution cables can be terminated in pull boxes

throughout the property, replacing above-ground

pedestals to maintain aesthetics Larger capacity cables

are spliced into smaller cables that feed directly into

specific buildings

Network interfaces between the outside plant and

drop cables tend to be either on the exterior surface

or closeted just inside the building entrance, often

co-located with other utilities In new construction, drop

cables can easily be routed through the framing structure

in conduits or directly into the walls before they are

sealed A new build also presents the option of installing

micro-ducts during construction for blowing fiber into

living units once services are requested

An outside FDT can be mounted on the side of the

building and grounded Fiber drop cables from each

living unit can then be spliced into the FDT Outside

FDTs provide splicing and conectorization within the

same units and should be NEMA 4 rated to protect

against the elements and sprinkler systems If fiber

drops are routed through exterior molding, color

matching is also important

Since the construction is new, additional micro-ducts

and composite cables can be placed at various locations

within the MDU structure to ensure future-proofing

The entire infrastructure should always be planned in

a manner that will ease the installation of the FTTP

network For example, the optical network units (ONTs),

along with media facility boxes, can easily be placed into

each living space

The facility box can hold the micro-duct from the central

telecom room and the ONT, as well as a router for data

distribution, a battery back-up, and the power supply

There should be a conduit to the media distribution box where all the home cabling is terminated, as well

as the AC powering Both the ONT and the media facility boxes can be flush mounted within each living unit’s utility closet

In order to provide multiple services, each wall outlet should have, at a minimum, two category 5e cabling connections – one for voice and one for data – as well

as a single RG-6 coaxial cable connection for video

A wall outlet should reside within each room for every living unit

In all MDU designs, the drop cable installation will be the most time consuming process Careful planning is required when existing spaces require retrofitting Time and cost can quickly be added to the process as drop cables are routed through attics, basements, or around the exterior of a structure New MDU molding raceway systems are making it easier for technicians to install drop cables inside the structure

There are many possible options for placing the riser cable, depending on the characteristics of the structure One alternative is to use factory pre-connectorized cables and a connectorized FDT, enabling an easy plug-and-play solution However, although this is simpler in concept, it also requires very careful planning

There are really only a few options for placing the ONT – using a recessed cabinet style facility box or simply surface mounting An ONT may be placed in each unit

or, to save costs, several living units can be serviced by a single ONT

Careful consideration

To summarize, there are truly no “one size fits

all” solutions for building FTTP networks for MDU

applications The architectural and topological choices

must be considered carefully, but are always driven by

the type of MDU structure, the design of the common

equipment room/common telecom room, and logical

placement of the active electronics

The overall efficiency of these networks is determined by

proper riser cable placement and determining whether to

use a centralized splitter architecture, a distributed splitter architecture, or some combination of both While MDUs offer very lucrative opportunities for service providers, increased competition is demanding that they “get it right the first time.”

Understanding and effectively deploying the correct available solution for the job at hand is critical Once the plan is carefully laid out, system connectivity can be developed and optimized for any structure – securing future services for the MDU occupants and healthy returns on investment for service providers

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