FTTH Basics and Network Design

FTTH Design and Network Basics

Mark Boxer

Applications Engineering Manager, OFS

Jeff Bush

Professional Services Manager, OFS

PC-101-G

Agenda

• Drivers for FTTx

• Why fiber

• Fiber feeds everything

• Flavors of FTTX

• Nuts and bolts – the components

• Installation techniques

• Network design configurations

The world is changing

• In the past 15 years, we’ve seen…– The Internet

– iPods

– HDTVs

– DVRs

– Smartphones (Blackberry, iPhone, etc)

– Tablet computers• All of these revolutionary technologies require

more BANDWIDTH (telecommunications capacity)

We must expect and plan for more and faster changes in the future!

Video on all screens - HDTV

An image is built on a screen, pixel by pixel, One HDTV program = 8-12 Mbps

Pixel

1920 pixels

1080

pixels

1 house = 48 Mbps bandwidth, just for video, today…

How about tomorrow? TV + DVR 24 Mbps

TV 12 Mbps

TV 12 Mbps

H.262 or MPEG-

2

H.264 or

MPEG-4

Standard

Definition (SD)480p 249 7 2

High Definition

(HD) 1080i/720p 1,493 16 8

Growing FastVery High

Definition (VHD)1080p 2,986 32 16

Super HD 2160p 14,930 100 50

Ultra HD 4320p 59,720 400 200

Mature

New Standards

2D Video Format Mb/s Native

per stream

Mb/s (compressed)

Video Evolution over next 5 – 10 years

* ITU Recommendation J.601, Transport of Large Scale Digital Imagery (LSDI) applications

Source: OFS Estimates from Industry Data

T

o

d

a

y

Video Bandwidth Growth Driving Fiber To The Home (FTTH)

Source: Technology

futures and OFS

Text Pictures Video HD SHD 3D

0

0.001

0.01

1

10

100

1,000

1980 1990 2000 2010 2020

Year

Top

Tie

r D

ata

Rat

e (

Mb

/s)

Analog

Modems

Digital

42% annual growth Increasing 4 times

every 4 years

0.1

2012 Offers

20 - 1,000 Mbps

10,000

Copper SpeedLimit

Fiber:

No limit!!*

* Fiber limit is >50 Tbps

Data Rate to Each Home

Agenda


• Why fiber


• Flavors of FTTX




1 Fiber Cable

>50 Tbps

>5000 KM

Why Fiber?Greater bandwidth, longer distance, lowest cost per bit

Bandwidth Distance Cost per Bit

Copper

Bandwidth Distance Cost per Bit

Fiber

2400 Pair

Copper

Cable

100 Gbps

to 1 KM

Why fiber? Lower cost, higher performance

• Metallic cable technologies are approaching their useful limits

• Copper (telephone) and coaxial cables (Cable TV)

– More expensive, less reliable, less capacity

• Wireless systems have significant capacity limitations

• Fiber optic cable is less expensive than copper, more reliable and has more capacity

Feature Benefit

High bandwidth High information carrying capacity

Low attenuation Long distances without repeaters…less expensive

Light weight Small size

Easier installationsUnobtrusive

No metallic conductors

No grounding problemsNo “crosstalk”

Passive No power requirementsNo circuit protection needed

Difficult to tap Very secure

Inexpensive Widely deployable. Cost effective

Why fiber? FTTH lower operating expenses (OPEX) versus competing technologies

Why? Fewer truck rolls– Remote provisioning though software– Increased reliability vs copper/coax electronics in

field such DSL/HFC

Savings estimates vs DSL/Hybrid Fiber-Coax

– FTTH Opex saves $100 to $250 per subscriber vs DSL

or HFC

Agenda


• Why fiber


• Flavors of FTTX




Wireless Loves Fiber (and vice versa)

Flavors of FTTxFiber feeds the cell network

Mobile bandwidth demand, driven by smartphones and video, is growing rapidly

Fiber is needed to and up the tower for 4G networks and beyond

Fiber has many advantages for cell network operators, shown below:

13

Bandwidth

WeightTower loading/bracingGroundingInstallation timePower lossesSpaceCooling requirements

Flavors of FTTxFiber feeds the Telephone and Cable Networks

Telephone: FTTN – Fiber to the Curb/NodeCable: HFC – Hybrid Fiber Coax

12 - 24 fibers

Switch or Node

Central Office OLTTwisted Pair or coax

•Fiber to the Node, Copper/coax to the home•Potential 24-100+ Mbps per subscriber (variable based on distance and metal cable quality)•Asymmetric bandwidth (more downstream than upstream)

150-1500 m5 to 100 KMTypical distance range

Flavors of FTTxFiber feeds the Power Network

• Fiber is an integral part of the utility communications network– Substation to substation communications, broad deployment

– Equipment within substations, broad deployment

– FTTH in limited cases

– Smart grid initiatives are changing the nature of power delivery

Transmission Distribution

Nuclear

Renewable

Smart Meter

Micro Grid--:Information

--:Power

Agenda


• Why fiber


• Flavors of FTTX




FTTH Electronics

Unmanaged Switch

OLT

Encoder & DVD

Fiber Management

A typical FTTH network has an “Optical Line

Terminal” (OLT) or switch at the “Headend”

or “Central Office”

The OLT or switch converts incoming traffic into

laser pulses and sends them down the fiber.

…And an “Optical Network Terminal” (ONT), media

converter, or gateway in the home. The ONT

converts the signals from light to electrical signals.

The ONT contains ports to distribute signals on the

existing home wiring (or wirelessly).

The ONT may be either inside or outside the home.

Fiber ONU

Typical FTTH Architectures

• PON (Passive Optical Network)– Incorporates a signal divider, such as

an optical power splitter

– One fiber at the central office feeds many fibers in the field

– G-PON (Gigabit PON) and GE-PON (Gigabit Ethernet-PON) are the most common architectures

• Point-to-Point (“Active Ethernet”)– One fiber in the headend = one

fiber in the field

OLT

Optical power

splitter or wavelength filter

PON

Point to point

Switch

Some equipment will serve both architectures

Summary of today’s common FTTH architectures

GPON GE-PON Point to Point (Active Ethernet)

Current gen

Next gen

Current gen

Next gen

Downstream bandwidth

2.4 Gbpstotal

10 Gbpstotal

1.2 Gbps total

10 Gbpstotal

100 -1000 Mbps per sub

Upstream bandwidth

1.2 Gbpstotal

10Gbpstotal

1.2 Gbpstotal

10 Gbpstotal

100 -1000 Mbps per sub

Typicaldistance

20 km 20 km 20 km 20 km

20 km

Wavelengths (nm), Downstream/Upstream)

14901310

15771270

15501310

1577 1270

15501310

OLT

Optical power

splitter or wavelength filter

PON

Point to point

Switch

WDM Mux /DeMuxs

1 fiber per subscriber

975 13 151131

1086 14 161242

l1, l2

WDM Mux/DeMux

WDM Mux/DeMux

WDM Mux/DeMux

WDM Mux/DeMux

l3, l4

l15, l16

l1, 3 -15

l2, 4, -16

Typical 1 Gb/s up/down dedicated to each subscriber

Longer reach than GPON or GE-PON

Emerging technology

CO or Head End

WDM PON NetworksProvides a dedicated wavelength (light color) per customer

Single-mode Fiber

Central Office or Head End

•Fiber to a switch or node with many ports to feed multiple customers •Uses Cat 5 or higher copper wiring or coax to the unit•Typical up to 100 Mb/s connection, limited by copper/coax bandwidth•Can be either symmetric or asymmetric bandwidth•Sometimes includes “fiber to the floor”

5 to 80 KMTypical distance range

FTTB – Fiber to the Building (MDUs)

100 m max

in building

Switch or node

Unit

Copper or coax cables

Agenda


• Why fiber


• Flavors of FTTX




Light as a Communications MethodUsed for hundreds of years

Smoke Signals “One if by land, two if by sea”

John Tyndall and William Wheeler

• John Tyndall, 1854

• Demonstrated that light could be guided within a liquid “Light Guide”

• William Wheeler, 1880

• Invented “Light pipes” for home lighting using reflective pipes

• Similar to concept used today for interior car illumination

http://www.fiber-optics.info/history

Optical FiberFastest communications pipe available

Core

Cladding

Coating

Light travels in core and is constrained by the cladding

Acrylate coating protects pure silica (glass) cladding

Light ray

vvsv

Fiber Structure

• Core - The center of an optical fiber. Contains dopants to change speed of light.

• Cladding - Outer layer of glass to contain light. Different refractive index.

• Coating - Cushions and protects fibers.

125 microns

250 microns

8-62.5

microns

Core

Cladding

Coatings

Two main types of fibers - Single-mode and MultimodeSinglemode fiber – Carries only one mode of lightMultimode fiber – Carries multiple modes of light

Singlemode

Multimode

50-62.5

µm

corecladding

Index of refraction profiles

8-10 µm

125 µm

125 µm

High level picture of where things go

The FTTx Network – Macro View

Aerial cable

Underground cable

Central Office /Headend

Fiber to the Cell Site Drop closures

or terminal

Fiber Distribution and Splitter Cabinet

Drop cable

Splice closures

Typical Outside Plant Cable Types –Aerial and Underground

Ribbon Cables

Aerial Self-Supporting (ADSS),Duct and armored loose tube cables

Microcables

Blown Fiber Units

Drop Cables

Outside Plant Fiber Optic Cable

• Most often “loose tube” cable structure

–Fibers loose in buffer tubes

• Handles stress/strain and temperature fluctuations and climatic extremes

–Also available in ribbons

–Fibers and buffers are color coded

• Underground applications

– Direct Buried – typically armored

– Duct cable

• Aerial applications

– Lashed to a messenger

– Self-supporting (ADSS, All-Dielectric, Self-Supporting

Buffer tube

Fiber

Loose buffer tube structure

Ribbon fiber and cable structure

Inside Plant Cables

• Indoor cables are different than outdoor cables

• Most often “tight buffer” cable structure

–Provides additional protection for handling

–Facilitates connectorization

• Multiple types of cable structures

• Riser, plenum, low smoke/zero halogen products

–Designed to meet flame smoke ratings

• Yellow colored jacket indicates single-mode fiber

Fiber management devices and closures

• Used to route and connect fibers

• Fiber management devices are used in the central office or remote cabinets

• Closures are used in the field to connect cables together

• Multiple designs available for each component

Connectors

LC Connector

SC Connector

MPO Connector(12 fiber ribbon

connector)

• Fibers use special, precisely manufactured connectors

• Connector color indicates the polish of the connector

• Polish type indicates amount of back reflection

• Critical parameter to ensure proper transmission

Blue = “Ultra” polishGreen = “Angle” polish

Splitters

Splitters

Splitter Distribution Cabinets

• Used with Passive Optical Network (PON) systems

• Used to split one fiber into multiple fibers

– Decreases power

– Splits bandwidth

• Split ratios are factors of 2

– 1x2, 1x4, 1x8, 1x16, 1x32, 1x64, 1x32

• Different deployment methods

– Centralized splits

– Distributed splits

– Cascaded splits

MDU deployments

• MDU installations are different than single-family home installations

• Most MDU installations require tight bends and bend insensitive fibers

• Manufacturers have developed fibers and distribution products specifically for MDU applications

Agenda


• Why fiber


• Flavors of FTTX




OSP Cable Placement Options

• Aerial

• Fast, minimal restoration time

• Typical choice for overbuilding existing aerial plant

• Below Grade

• Required by regulations for most Greenfield installations

• Aesthetically pleasing!

OSP Cable Placement Options

Below Grade

• Direct Buried

• In conduit

• In gas Lines

• In sewers

OSP Buried Considerations

• Existing neighborhood, or a new development?

• Must call your local “One Call” to locate existing utilities.

• Expose these utilities wherever you will be crossing them.

• A vacuum excavator is normally used to expose utilities. This is called “soft” excavation.

Source: FTTH Council

Overbuilding with Buried PlantDirectional Drilling

• Bores under driveways, streets, landscape,

around existing utilities

• Least restoration of ground of buried solutions

• Ensures good aesthetics

• Higher skilled operation than other methods

• More expensive equipment

• Typically surface launched

• Pilot bore is followed by a pullback of the cable

Source: FTTH Council

Overbuilding with Buried PlantVibratory Plow

• Lower cost option where no surface obstacles exist

• Little damage to surface, normally just leaves a

narrow slot

• Typically requires minimal restoration to the

ground after installation

• Conduit/cable is installed behind the plow blade

• Less operator expertise needed

• Normally requires only one operatorSource: FTTH Council

Greenfield with Buried PlantOpen cut trenching

• Often lowest cost method

• Easiest to operate method, lower

skilled operator

• Requires the most restoration of the

ground of the 3 methods

• In new developments can lay

cable/conduit in common utilities

trenchSource: FTTH Council

Splicing

• Fusion

– Most common type of splice

– Fibers joined together and melted at approximately 1600 degrees C

• Mechanical

– Common overseas

– Less common in US FTTH installations

Splice sleeve to cover completed splice

Illustration of electrodes used to form fusion splicing arc

Optical Loss Budget

Unmanaged Switch

OLT

Encoder & DVD

Fiber Management

Designers must ensure enough light

can reach the home in both directions.

Component Typical loss values@ 1550 nm

Fiber 0.25-0.30 dB/km

Splices 0.05 dB

Connectors 0.25 dB

Splitters (1x32) 17-18 dB

Agenda


• Why fiber


• Flavors of FTTX




PON Design Considerations

CapEx/OpEx

• Cost per Household

• Cost per Subscriber

• Cost to Connect

Scalability

• Ease of in-network additions

• Ease of network extensions

Build ability

• Ability to construction within required timelines

• Ability to construction without damaging customer relations

5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100%

Hubbed Split $75 $81 $82 $88 $94 $95 $101 $101 $108 $114 $114 $121 $127 $127 $133 $134 $140 $146 $147 $153

Distributed Split $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99

$0

$20

$40

$60

$80

$100

$120

$140

$160

$180

Incre

men

tal

Co

st

Incremental Cost per HH Passed Relative to Take Rate

43%

17%

32%

8%Electronics: OLT and ONT

generations

Electronics: installation labor 4

generations

Construction, Pathways, Design

ODN: Optical Fiber, Cable,

Splitters, Connections

Approximate cost proportions

Fiber Materials are only ~8% of cost per home*

Fiber Materials must last decades and support multiple generations of

electronics

FTTH Installed cost per Home*

Proper Selection and Design of the Fiber Materials (the 8%) can help lower the cost of the other 92%

* 35% take rate, costs and proportions may vary from this typical example

Network Design Options

Home Run or “Active Ethernet”/”Point to Point Design”

CentralOffice

OLT or switch

SFU

SFU

SFU

• Fibers from the OLT/switch all the way to the home

• For PON, splitters placed in a central office• Minimizes OLT port usage

Splitter for PON systems

PON Design Options

Centralized Design

CentralOffice

OLT

Splitter

SFU

SFU

SFUF1 Fiber

Cabinet• Splitters placed in a

cabinet or hub• Reduces OLT port usage• Requires investment in

cabinet

PON Design Options

Distributed Design

CentralOffice

OLT Splitter

SFU SFU

F1 Fiber F1 Fiber

Splice Case

Splitter

SFU SFU

Splice Case

F1 Fiber

• Splitters placed in splice cases• Minimizes fiber sizes and splicing• Requires dedicated OLT ports

PON Design Options

Cascaded Design

CentralOffice

OLT Splitter

F1 Fiber F1.5 Fiber

Splice Caseor Cabinet

Splitter

SFU SFU

Splice Caseor Cabinet

• Multiple splits between OLT and ONT• Balance between fiber and OLT port usage• Increased loss

PON Design Examples

Typical Layout – Centralized Split

250 HHs

Splitter

Cabinet

Roadway

Ro

ad

wa

y

288 Fiber

F2,1-280

Dead,281-288

Feeder

Fiber

Households

Drop Pedestals

Drop Pedestal

Serving Area

288 Fiber

F2,1-288

288 Fiber

F2,1-272

Dead,273-288

288 Fiber

F2,1-264

Dead,265-288

288 Fiber

F2,1-256

Dead,257-288

PON Design Examples

Typical Layout – Distributed Split

250 HHs

Feeder

Pick-up

Point

Roadway

Ro

adw

ay

36 Fiber

F1,1-3 (spare)

F1,4-12

F2,1-16

Dead,29-36Feeder

Fiber

1x32 Splitter

& Drop Pedestal

IN: F1,12

OUT: F2,1-32

36 Fiber

F1,1-3 (spare)

F1,4-11

Dead,12-24

F2,25-32

Dead,33-36

36 Fiber

F1,1-3 (spare)

F1,4-12

F2,1-8

Dead,21-36

36 Fiber

F1,1-3 (spare)

F1,4-12

Dead,13-36

36 Fiber

F1,1-3 (spare)

F1,4-11

Dead,12-36

Households

Drop Pedestal

Serving Area

Drop Pedestals

Splitter

Serving Area


1. OLT Cost per Port– As the cost per port drops, designs that require a higher utilization of ports but less

fiber and splicing become more cost effective

2. Take Rates– As take rates increase, the impact of dedicating OLT ports to a greater number of

splitters is reduced

3. Assessing Cost Impacts– When conducting a cost analysis to determine the impact of different design

approaches, it is helpful to focus only on cost that vary between the designs• Eliminate costs that are common to the designs being assessed

4. Cost Assessment Focus– Cost effectiveness can be measured in multiple ways:

• Cost per household/living unit

• Cost per subscriber


Example Cost Assessment

5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100%

Hubbed Split $75 $81 $82 $88 $94 $95 $101 $101 $108 $114 $114 $121 $127 $127 $133 $134 $140 $146 $147 $153

Distributed Split $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99 $99

$0

$20

$40

$60

$80

$100

$120

$140

$160

$180

Incre

men

tal

Co

st

Incremental Cost per HH Passed Relative to Take Rate


Example Cost Assessment

5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100%

Hubbed Split $1,502 $813 $545 $440 $377 $316 $288 $254 $239 $228 $208 $201 $195 $182 $178 $167 $165 $163 $155 $153

Distributed Split $1,980 $990 $660 $495 $396 $330 $283 $247 $220 $198 $180 $165 $152 $141 $132 $124 $116 $110 $104 $99

$0

$500

$1,000

$1,500

$2,000

$2,500

Inc

rem

en

tal

Co

st

Incremental Cost per Subscriber Relative to Take Rate

MDU Design Approaches

1. MDU ONT

– ONT placed at existing demarcation point

– Utilize existing wiring (coax, cat 3/5) to the living units

2. Single Family ONT – Drop placed to each living unit

– ONT mounted within the living unit

3. Desktop ONT– Drop placed within living units (along molding, etc.)

MDU Design Pros and Cons

1. MDU ONT– Avoids challenges and costs associated with retrofitting buildings

– Dependent on type and condition of existing wiring

2. Single Family ONT– Eliminates usage of existing wiring (possibly substandard)

– Cost and labor intensive

3. Desktop ONT– Minimal space requirements

– Typically requires drop to be routed through the living units (aesthetics)

Summary

• Video, internet, and new applications are driving bandwidth increases that require fiber

• Fiber is the best method for providing low cost, high bandwidth services

– Lowest cost/bit

– Lowest OPEX

– More reliable than metallic technologies

– Lower attenuation, weight

• Fiber architectures include various versions of PON and Point to Point

• Multiple ways of deploying FTTH– Different design options for outside plant can significant impact costs and network

functionality

FTTH Basics and Network Design

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