Ftth Report

8/2/2019 Ftth Report

http://slidepdf.com/reader/full/ftth-report 1/83

FTTH (FIBER TO THE HOME)

Dept. Of ECE, College of Engg. Poonjar. 1

CHAPTER 1

INTRODUCTION

Growing demand for high speed internet is the primary driver for the new

access technologies which enable experiencing true broadband. Traditionally

telecom companies have been offering T1 lines and DSL to small businesses,

houses for applications such as voice services, high speed data, internet and video

services. T1 lines are often expensive and DSL‟s performance issues limit

availability of these services. DSL Copper networks do not allow sufficient data

rates due to signal distortion and cross talk. Cable modem is another competing

technology for broadband services. In cable modems only few RF channels are

assigned for data and most of the bandwidth is dedicated to video channels.

FTTH offers triple play services with data speeds ranging from 155 Mbps

to 2.5Gbps Downstream (Network to User) and 155 Mbps to 1Gbps Up stream

(User to Network) range of services due to high bandwidth and Though the field

trials and technology development for fiber in the access loop started in late

1980s, real deployments did not happen as the deployment costs were very high at

that time. In the last 20 years enormous progress is made in optical networking

equipment and production of high quality optical fibers associated with falling

prices are driving forces for fiber to the home(FTTH). The recent telecom bubble

burst also had hard hit on the big telecom players and the revenue generation from

the long haul core networks are falling. This lead to shift in the business strategy

for maximizing the revenue generation from access loop and wireless. While there

is no standard definition for broadband, definition of broadband has become

country specific. In Japan more than 1 Mbps is defined as broadband and in India

bandwidth more than 256kbps is specified as broadband.





1.1 WHY FTTH

FTTH is a true multi service communications access which simultaneously

handles several phone calls, TV/Video streams and Internet users in the

home/office. There are several advantages of deploying FTTH over other

traditional access technologies as given below:

· FTTH provides end-users with a broad range of communications and

entertainment services, and faster activation of new services.

· Competition is beginning to offer a “multi-play” (i.e. voice, video, data etc.)

bundle.

· FTTH provides service provider‟s with the ability to provide “cutting edge”

technology and “best-in-class” services.

· Deploying a fiber optic cable to each premise will provide an extraordinary

amount of bandwidth for future services.

· FTTH provides the community in which it‟s located with superior

communications which enhance the efficiency of local business and thus deliver

economic advantage for the community.

· Around the world FTTH is viewed as strategic national infrastructure similar to

roads, railways, and telephone networks.

· FTTH provides carriers with an opportunity to increase the Average Revenues

Per User (ARPU), to reduce the capital

1.2 FIBER IN THE LOOP

Fiber In The Loop (FITL) is a system implementing or upgrading portions of the

POTS local loop with fiber optic technology from the central office of a telephone

carrier to a remote Serving area interface (SAI) located in a neighborhood or to an

Optical Network Unit (ONU) located at the customer premises (residential and/or

business). Generally, fiber is used in either all or part of the local loop distribution





network. FITL includes various architectures, such as fiber to the curb (FTTC),

fiber to the home (FTTH) and fiber to the premises (FTTP).

Residential areas already served by balanced pair distribution plant call for a trade-off

between cost and capacity. The closer the fiber head, the higher the cost of

construction and the higher the channel capacity. In places not served by metallic

facilities, little cost is saved by not running fiber to the home.

Fiber to the x (FTTX) is a generic term for any network architecture that uses

optical fiber to replace all or part of the usual copper local loop used for

telecommunications.

The four technologies, in order of an decreasingly fiber loop length are:

Fiber to the node / neighborhood (FTTN) / Fiber to the cabinet (FTTCab)

Fiber to the curb (FTTC) / Fiber to the kerb (FTTK)

Fiber to the building (FTTB)

Fiber to the home (FTTH)





CHAPTER 2

BASICS OF OFC

2.1 OPTICAL FIBER COMMUNICATION

Optical fiber has a number of advantages over the copper wire used to make

connections electrically. For example, optical fiber, being made of glass or plastic,

is immune to electromagnetic interference which is caused by thunderstorms.

Also, because light has a much higher frequency than any radio signal we can

generate, fiber has a wider bandwidth and can therefore carry more information at

one time.

Most telephone company long-distance lines are now of optical fiber.

Transmission on optical fiber wire requires repeaters at distance intervals. The

glass fiber requires more protection within an outer cable than copper. For these

reasons and because the installation of any new wiring is labor-intensive, few

communities yet have optical fiber wires or cables from the phone company's

branch office to local customers.

FIG 1. Optical System

http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci212890,00.html

http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci212890,00.html





2.1.1 TRANSMITTERS

Fiber optic transmitters are devices that include an LED or laser source,

and signal conditioning electronics, to inject a signal into fiber. The modulated

light may be turned on or off, or may be linearly varied in intensity between two

predetermined levels. Light Emitting Diodes (LEDs) have relatively large

emitting areas and as a result are not as good light sources as laser diodes.

However, they are widely used for short to moderate transmission distances

because they are much more economical. Laser diodes can couple many times

more power to optical fiber than LEDs. They are primarily used for applications

that require the transmission of signals over long distances.

Important performance specifications to consider when searching for fiber

optic transmitters include data rate, transmitter rise time, wavelength, spectral

width, and maximum optical output power. Data rate is the number of data bits

transmitted in bits per second. Data rate is a way of expressing the speed of the

transceiver. In the approximation of a step function, the transmitter rise time is

the time required for a signal to change from a specified 10% to 90% of full

power. Rise time is a way of expressing the speed of the transmitter. Wavelength

refers to the output wavelength of the transceiver. The spectral width refers to the

spectral width of the output signal.

2.1.2 RECEIVERS

Fiber optic receivers are instruments that convert light into electrical

signals. They contain a photodiode semiconductor, signal conditioning circuitry,

and an amplifier. Fiber optic receivers use three types of photodiodes: positive-

negative (PN) junctions, positive-intrinsic-negative (PIN) photodiodes, and

avalanche photodiodes (APD). PIN photodiodes have a large, neutrally-doped

region between the p-doped and n-doped regions. APDs are PIN photodiodes that

operate with high reverse-bias voltages. In short wavelength fiber optic receivers

(400 nm to 1100 nm), the photodiode is made of silicon (Si).





In long wavelength systems (900 nm to 1700 nm), the photodiode is made

of indium gallium arsenide (InGaAs). With low-impedance amplifiers, bandwidth

and receiver noise decrease with resistance. With trans-impedance amplifiers, the

bandwidth of the receiver is affected by the gain of the amplifier. Typically, fiber

optic receivers include a removable adaptor for connections to other devices. Data

outputs include transistor-transistor logic (TTL), emitter-coupled logic (ECL),

video, radio frequency (RF), and complementary metal oxide semiconductor (CMOS)

signals. Also, it uses many types of connectors.

2.2 LITERATURE REVIEW.

Today‟s standard optical fiber is the product of precision manufacturing

techniques and exacting standards. Even though it is found in almost any data or

communications link, optical fiber is a finely tuned instrument requiring care in its

production, handling, and installation. As shown in Figure, a typical optical fiber

comprises three main components: the core, which carries the light; the cladding,

which surrounds the core with a lower refractive index and contains the light; and

the coating, which protects the fragile fiber within.

FIG 2.Crosssection Of OFC





2.2.1 CORE

The core, which carries the light, is the smallest and most fragile part of

the optical fiber. The optical fiber core is usually made of glass, although some

are made of plastic. The glass used in the core is extremely pure silicon dioxide

(SiO2). In the manufacturing process, the glass used in the core has impurities

such as germanium or phosphorous added to raise the refractive index under

controlled conditions. Optical fiber cores are manufactured in different diameters

for different applications. Typical glass cores range from as small as 3.7 µm up to

200µm. Core sizes commonly used in telecommunications are 9µm, 50µm and

62.5µm. Plastic optical fiber cores can be much larger than glass. A popular

plastic core size is about 1000µm.

2.2.2 CLADDING

Surrounding and protecting the core, and providing the lower refractive

index to make the optical fiber work, is the cladding. When glass cladding is used,

the cladding and the core are manufactured together from the same silicon

dioxide – based material in a permanently fused state. The manufacturing process

adds different amounts of impurities to the core and the cladding to maintain a

difference in refractive indices between them of about 1 percent. Typically, the

core will have a refractive index of 1.48, while the cladding will have a refractive

index of 1.46. Like the core, cladding is manufactured in standard diameters. The

two most commonly used diameters are 125 µm and 140 µm. The 125µm

cladding typically supports core sizes of 9µ, 50µ, 62.5µ, and 85µ. The

140cladding typically has a 100 µcore.





2.2.3 COATING

The coating is the true protective layer of the optical fiber. Generally made

of plastic or acrylate, the coating absorbs the shocks, nicks, scrapes, and even

moisture that could damage the cladding. Without the coating, the optical fiber is

very fragile. A single microscopic nick in the cladding could cause the optical

fiber to break when it‟s bent. Coating is essential for all-glass fibers, and they are

not sold without it. The coating is solely protective. It does not contribute to the

light-carrying ability of the optical fiber in any way. The outside diameter of thecoating is typically either 250µm or 500 µm. The coating is typically colorless. In

some communication applications, however, the coating is colored so that

individual optical fibers in a group of optical fibers can be identified.

2.3 FIBER

Fiber is the medium to guide the light form the transmitter to the receiver.

It is classified into two types depending on the way the light is transmitted:

multimode fiber and single-mode fiber.

2.3.1 MULTIMODE FIBER

Multimode fiber designed to transmit more than one light at a time. Fiber

diameter ranges from 50-to-100 micron. Multimode fibers can be divided in to

two categories Multimode Step-index Fiber and Multimode Graded-index FiberIn

Multimode Step-index Fiber the lights are sent at angles lower than the critical

angle or straight (or simply the angle is zero). Any light angle exceed the critical

angle will cause it to penetrate through cladding (refracted) and being lost as

shown in Figure 1.





Obviously light with lower angle which has less number of reflection,

reach the end faster than those with larger angle and this will result in unstable

wave light. To avoid this problem there should be spacing between the light

pulses, but this will limit the bandwidth and because of that it is used for very

short distance.

FIG 3.Multimode Step-index Fiber

The Multimode Graded-index Fiber designed to reduce the problem in

Multimode Step-Index fiber by making all the beams reaching the receiver at the

same time. This can be done by slowing down the ones with shorter distance and

increasing the speed for ones with longer distance, see Figure 2. This is done in

fiber implementation by increasing its refractive index at the center and gradually

decreases it toward the edges. In the Figure 2 we can see the light near the edges

is curved until it is reflected, this is due to the refraction caused by the change in

density.

FIG 4. Multimode Graded-Index Fiber





2.3.2 SINGLE-MODE FIBER

In single-mode, only one light is transmitted in the fiber which diameter

ranges from 8.3 to 10 microns, see Figure 3. Since there is only one light the

problem associated with the multimode fiber does not exist and by this we can

have a higher transmission rate and also it can be used for longer distance. To

utilize the fiber a Wave-Division-Multiplexing (WDM) is used as it will be

described later.

This type of fiber has been improved over years and that result in three

types of single-mode fiber. The first is Non Dispersion-Shifted Fiber (NDSF)

which was used to transmit light with wave length 1310 nm, but some systems use

it with a wave length of 1550 nm and this wave length causes dispersion (losing

pulse mode) with this type of fibers. The second type is Dispersion-Shifted Fiber

(DSF), in this type the dispersion is shifted so that the dispersion at the wave

length 1550 nm is zero and in this way we could solve the problem of the first.

But system with DWDM (Dense Wavelength Division Multiplexing) found to be

nonlinear with this type of fiber. The term Dense Wavelength Division

Multiplexing (DWDM) came from the tremendously increase in use of WDM.

The third type is Non Zero-Dispersion-Shifted Fibers (NZ-DSF) which is

designed to solve the problems with the previous two.

FIG 5. Single-Mode Fiber





CHAPTER 3

FTTH SYSTEM OVERVIEW

3.1 FTTH ARCHITECTURE

Active and passive are two commonly used FTTH architectures for FTTH

deployment. Active Architecture is also called as Point 2 Point(P2P) and Passive

Optical Network (PON) architecture is called Point to Multi Point(P2M). Choiceof active or passive architectures for deployment depends on the type of services

to be delivered, cost of the infrastructure, current infrastructure and future plans

for migrating to new technology. ACTIVE Technology Active Ethernet also

called Ethernet Switched Optical Network (ESON) or Point to Point(P2P)

Network architecture provides a dedicated fiber to the side from the central office

exchange shown in the figure 2.1. A P2P architecture is a very simple network

design. Since the fiber is dedicated, Operation, administration and maintenance of

the content and trouble shooting become easy. Active FTTH solutions are

implemented in many different ways, through both standard and proprietary

methods. Since the distances of the central node and remote sites are known,

estimation of power budget, trouble shooting the faults in the network would be

easier. Transmission in P2P configuration, is more secure, since all transmissions

are physically separated by fiber. Only the end points will transmit and receive

information, which is not mixed with that of any other customer.

3.1.1 ACTIVE NETWORK ARCHITECTURE

Core switch, Aggregation switch and Optical Network Terminal (ONT)

are main building blocks of an P2P network. The Core Switch is a high capacity

Ethernet switch that communicates to Aggregator Switches using standard GbE

optical signals. The Aggregator Switch interfaces this data stream to multiple

Premises Gateways called Optical Network Terminals(ONT).





FIG 6. Point to Point Network

The Core Switch interfaces multiple content and service providers over an

MPLS-based Metro or Regional network to deliver data, video, and voice services

to the users on the access network. Aggregator Switch resides in both standard CO

and in building entrance and in outside plant cabinets to meet the environmental

needs of the network provider. The Aggregator Switch delivers traffic to the

subscriber in accordance with the specific bandwidth requirements from 1 Mb/s to

100 Mb/s (symmetrical) per subscriber.

3.1.2 PASSIVE OPTICAL NETWORK (PON) TECHNOLOGY

PON is a point to multipoint (P2M) network . Each customer is connected

into the optical network via a passive optical splitter, therefore, no active

electronics in the distribution network and bandwidth is shared from the feeder to

the drop.





FIG 7. Point To Multipoint Network

The advantage of FTTH PON is the fact that they use purely optical

passive components that can withstand severe and demanding outside plant

environment conditions without the need to consumer energy between in the

central office exchange and the customer premises. The benefit to telecom

operators is that low maintenance requirements of these passive optical

components will significantly reduce of the cost of upgrades and operating

expenditures. Passive systems utilize a common shared connection with the

centralized electronics. PON architecture uses unidirectional splitters. PON FTTH

solutions are driven by two key standards: FSAN/ITU and EFMA/IEEE, and

solutions can be built with either standard. The PON architecture can reduce the

cable cost as it enables sharing of each fiber by many users. There are different

PON Technologies available today.

APON / BPON

ATM Passive Optical Network APON was initiated in 1995 by ITU/FSAN

and standardized as ITU-T G.983. In 1999, ITU adopted FSAN‟s APON standard.

APON was the first PON based technology developed for FTTH deployment as

most of the legacy network infrastructure was ATM based. There are different

PON Technologies available today. Since the services offered by this architecture

are not only the ATM based serviced but also video distribution, leased line





services and Ethernet access and to express the broadband capability of PON

systems APON is renamed as BPON. Broadband Passive Optical

Network(BPON) was standardized by ITU recommendations G.983.1, G.983.2,

G.983.2. BPON has two key advantages, first it provides 3rd

wavelength for video

services, second it is stable standard that re-uses ATM infrastructure. ITU-T

recommendation G.983.1 defines three clauses of performance namely Class A,

Class B, Class C.

GPON

The progress in the technology, the need for larger bandwidths and the

complexity of ATM forced the FSAN group to look for better technology. Gigabit

Passive Optical Network(GPON) standardization work was initiated by FSAN in

the year 2001 for designing networks over 1Gbps. GPON architecture offers

converged data and voice services at upto 2.5 Gbps. GPON enables transport of

multiple services in their native format, specifically TDM and data. In order to

enable easy transition from BPON to GPON, many function of BPON are reused

for GPON. In January 2003, the GPON standards were ratified by ITU-T and are

known as ITU-T Recommendations G.984.1, G.984.2 and G.984.3. The GPON‟s

uses Generic Framing Procedure (GFP) protocol to provide support for both voice

and data oriented services. A big advantage of GPON over other schemes is that

interfaces to all the main services are provided and in GFP enabled networks

packets belonging to different protocols can be transmitted in their native formats.

EPONEthernet equipment vendors formed Ethernet in the First Mile Alliance

(EFMA) to work on architecture for FTTH as Ethernet is a dominant protocol in

Local Area Network. EPON based FTTH was adopted by IEEE standard

IEEE802.3ah in September 2004.Adopting Ethernet technology in the access

network would make uniform protocol at the customer end simplifying the

network management. Single protocol in Local Area Network, Access Network

and Backbone network enables easy rollout of FTTH. EPON standards





networking community renamed the term „last mile‟to „first mile‟ to symbolize its

importance and significance access part of the network. EFMA introduced the

concept of Ethernet Passive Optical Networks (EPONs), in which a point to

multipoint (P2MP) network topology is implemented with passive optical

splitters. EPON, is largely vendor-driven standard and it is fundamentally similar

to ATM-PON but transports Ethernet frames/packets instead of ATM cells. It

specified minimum standardization and product differentiation, also it has decided

not to standardize the Bandwidth allocation algorithm, TDM and ATM support,

Security, Authentication, WDM Overlay Plan, support for Analog Video

Protection, Diagnostics, Monitoring etc.

3.2 PROPOSED SYSTEM

Figure 2.3 Block diagram of FTTH

FIG 8.Proposed System





3.3 BLOCK DIAGRAM DESCRIPTION

Here the network used is PON .It is the passive optical network and is

used in FTTX solutions. The most important characteristics of this network is that

only the end components are active and others are passive. The different types of

PON flavours are APON , EPON and GPON.

They are ATM cells(533 byte cells).A PON is also called as B

PON(broadband PON).Their speed is about 622Mbps.It is the Ethernet PON. It is

also known as GEPON (Gigabit Ethernet PON).Their speed is about

1.25Gbps.Here we are spending Ethernet packets. It is the gigabit PON. This

support TDM traffic as well as Ethernet packet. Their speed is about 2.5Gpbs.

In this system, we use GE PON and it uses CDMA (code division multiple

access) technology for processing the data. Here we are sending Ethernet packets.

The downstream wavelength is about 1310nm.PON consist of optical line

terminal (OLT),optical network unit(ONU) and optical distribution

network(ODN).

3.4 WAVELENGTH DIVISION MULTIPLEXING (WDM)

With WDM it is possible to send multiple optical signals from deferent

source at the same time on one optical fiber. The data stream from each Source is

assigned an optical wavelength. The multiplexer modulates each data stream from

each Source. After the modulation process the resulting optical signal generated

for each Source data stream is placed on its assigned wavelength. The resulted

signals are simultaneously sent through the fiber.

At the User end the multiplexer receives a composite signal. It separates

the signal into the original signals according to their different wavelengths by





using prisms. These signals are further demodulated. The resulting separated data

streams are then provided to the respective Users.

The difficult part of the multiplexing process is at the receiver side

(demultiplexing). The designers have to put into their considerations for the

crosstalk and channel separation in the demultiplexing. The crosstalk specification

expresses how well the demultiplexer maintains port-to-port separation. That is

each channel should appear only at its intended port. Channel separation describes

ability for the demultiplexer to distinguish different wavelengths. In most

demultiplexer, the wavelengths must be widely separated allowing light to travel

in either direction without the penalty found in splitters.





CHAPTER 4

COMPONENTS

4.1 OLT (OPTICAL LINE TERMINAL)

It is the central office equipment providing PON with the various network

interfaces , basically an Ethernet switch or media Controller .it is used in the

transmitter as well as in the receiver side. It convert the electrical signal into

optical signal in the transmitting side and at the receiver, this optical signal is

converted into corresponding electrical signal. The other uses of OLT are code

conversion and maintenance

OLT is a carrier class large capacity GEPON (Gega bit Ethernet passive

optical network) access device for installation in a standard chasis. Here we use

BBS4000. BBS4000 have 44 GEPON ports. Optical switch module is configured

to protect lines leading e up to optical splitters for up to 4 GEPON ports .

Table 2.1 Power Range for OLT

Range Worst

case

Receiver

saturation

OLT TX Power PX20-D +2.5 to +6.7

dBm

2.5 dBm

OLT RX Sensitivity PX20-U -29 to -30 dBm -29 dBm -

10dBm

ONU TX Power PX10-U 0 to +3.7 dBm 0 dBm

ONU RX Sensitivity PX10-D -25 to -25.7 dBm -25 dBm -5dBm





4.2 FDF (FRAME DISTRIBUTION FRAME)

Fiber Distribution Frame rear fiber storage panel provides cable

management and service loop storage for fiber optic patch cord that terminate in

modules located in the rear of the frame. The patch cord are typically routed

between an FDF and fiber optic terminal[FOT] equipment in cross connect

application

An Optical Fiber Distribution Frame is the interface between the

transmission equipment and the optical network. At the point in the network

where the fiber from the transmission equipment meets the fiber from the

subscriber/trunk network, there must be some type of cross-connection to

facilitate cable rearrangements, measurements and fault location of optical lines.

The main function of a FDF/ODF is to organize and terminate fiber at this point

FIG 9. Frame Distribution Frame





4.3 SINGLE MODE FIBER (G.652)

A single mode fiber is coated with dual layers of UV-cured Acrylate and the

diameter with coating is 245 μm. The effective group index of refraction is 1.465

at 1550 nm. Table 2.2 Parameters of G.652 fiber

Parameter Value

Mode field diameter (MFD) m 4.06.9 at 1550 nm

Cladding Diameter m 125

Outer coating diameter m 5245

Non circularity of the

cladding

Not more than 1%.

Mode field concentricity

error

Not more than m 6.0

Core Silica (SiO2) doped with Germanium

dioxide (GeO2).

Cladding Silica (SiO2)

Coating Dual layers of UV-cured Acrylate.

Chromatic dispersion 18 ps/nm*km (1530 nm to 1570nm)

Cut off wavelength <1480 nm.





Parameters and dimensions of the fiber

4.4 PON SPLITTER

Passive Optical Network (PON) splitters play an important role in Fiber to

the Home networks by allowing a single PON network interface to be shared

among many subscribers. Splitters contain no electronics and use no power. They

are the network elements that put the passive in Passive Optical Network and are

available in a variety of split ratios, including 1:8, 1:16, and 1:32.

Splitters are installed in each optical network between the PON Optical

Line Terminal (OLT) and the Optical Network Terminals (ONTs) that the OLT

serves. Networks implementing BPON,GPON, EPON,10G GPON, and 10G

GPON technologies all use these simple optical splitters. In place of an optical

splitter, a WDM PON network will use an Arrayed WaveGuide (AWG).

A PON network may be designed with a single optical splitter, or it can

have two or more splitters cascaded together. Since each optical connection adds

attenuation, a single splitter is superior to multiple cascaded splitters. One net

additional coupling (and source of attenuation) is introduced in connecting two

splitters together.

Item Description Attenuation Units

1.Fiber optic cable

{a}1310 nm

0.33 db/km

{b}1490

nm

0.21 db/km

{c}1550

nm

0.19 db/km

http://www.fttxtra.com/category/ftth/gpon/

http://www.fttxtra.com/category/ftth/gpon/





A single splitter is shown in the GPON network diagram below. Note that

the splitter can be deployed in the Central Office (CO) alongside the OLT, or it

may be deployed in an OutSidePlant (OSP) cabinet closer to the subscribers. A

splitter can also be deployed in the basement of a building for a Multiple Dwelling

Unit (MDU) installation.

Table 2.3 Splitter attenuation

FIG 10. PON Splitter

1*2splitter 3.5 db

1*4splitter 7.4 db

1*8splitter 11 db

1*16splitter 14.3 db






4.5 ONT (OPTICAL NETWORK TERMINAL)

An ONT is a media converter that is installed by Verizon either outside or

inside your premises. An ONT is a media converter that is installed by Verizon

either outside or inside your premises

The ONT converts fiber-optic light signals to copper/electric signals.

Three wavelengths of light are used between the ONT and the OLT:

• 1310 nm voice/data transmit

• 1490 nm voice/data r eceive

• 1550 nm video receive

Each ONT is capable of delivering:

Multiple POTS (plain old telephone service) lines

Internet data

Video





CHAPTER 5

EXPERIMENTS

5.1 VERIFICATION OF INSERTION LOSS CHECK OF

DIFFERENT TYPES OF SPLITTERS

TYPES OF SPLITTERS :

1. 1x4 Splitter

2. 2x4 Splitter

3. 1x32 Splitter

5.1.1 1X4SPLITTER

Downstream: Path loss

Sending level at +1.40 dBm for wavelength at 1490nm at Com Port 1

COM PORT 1

Measured at Port Rx Level (dBm) Insertion Loss(dB) Limit

(dB)

Theorectical

Value

(10 log 1/ N)

1 -5.25 6.65 7.4 6.02

2 -5.06 6.46 7.4 6.02

3 -5.65 7.05 7.4 6.02

4 -5.27 6.67 7.4 6.02





Upstream: Path loss

Sending level at -3.20 dBm for wavelength at 1310nm at individual ports

COM PORT 1

Feeding at Port Rx Level (dBm) Insertion Loss(dB) Limit

(dB)

Theorectical

Value

(10 log 1/ N)

1 -10.00 6.80 7.4 6.02

2 -10.10 6.90 7.4 6.02

3 -10.25 7.05 7.4 6.02

4 -10.05 6.85 7.4 6.02





5.1.2. 2X4SPLITTER

Downstream: Path loss (1490 nm)

Sending level at +1.40 dBm for wavelength at 1490 nm at Individual ports

COM PORT 1

Sending level: +1.40 dBm

COM PORT 2

Sending level: +1.40 dBm

Limit

(dB)

Measured at

Port

Rx Level

(dBm)

Insertion

Loss(dB)

Rx

Level(dBm)

Insertion

Loss(dB)

1 -5.40 6.80 -5.32 6.72 7.4

2 -5.41 6.81 -5.30 6.70 7.4

3 -5.72 7.12 -5.85 7.25 7.4

4 -5.52 6.92 -5.35 6.75 7.4





Upstream: Path loss (1310 nm)

Sending level at -3.20 dBm for wavelength at 1310nm at Individual ports

COM PORT 1 COM PORT 2 Limit

(dB)Feeding at Port Rx

Level(dBm)

Insertion

Loss(dB)

Rx

Level(dBm)

Insertion

Loss(dB)

1 -10.00 6.85 -10.10 6.90 7.4

2 -10.05 6.80 -10.00 6.80 7.4

3 -10.55 7.35 -10.50 7.30 7.4

4 -10.35 7.15 -10.50 7.30 7.4





5.1.3 1X32SPLITTER

Downstream: Path loss

Sending level at +3.70 dBm for wavelength at 1490nm at Com Port 1

COM PORT 1

Measured at Port Rx Level (dBm) Insertion

Loss(dB)

Limit

(dB)

Theorectical

Value

(10 log 1/ N)

1 -12.95 16.65 17.8 15.05

2 -12.55 16.25 17.8 15.05

3 -12.45 16.15 17.8 15.05





4 -12.50 16.20 17.8 15.05

5 -12.90 16.80 17.8 15.05

6 -12.60 16.30 17.8 15.05

7 -13.10 16.80 17.8 15.05

8 -13.35 17.05 17.8 15.05

9 -13.15 16.85 17.8 15.05

10 -13.25 16.95 17.8 15.05

11 -13.05 16.75 17.8 15.05

12 -12.85 16.55 17.8 15.05

13 -12.90 16.60 17.8 15.05

14 -13.30 17.00 17.8 15.05

15 -12.90 16.60 17.8 15.05

16 -13.15 16.85 17.8 15.05

17 -13.30 17.00 17.8 15.05

18 -13.15 16.85 17.8 15.05

19 -13.20 16.90 17.8 15.05

20 -12.90 16.60 17.8 15.05

21 -13.35 17.05 17.8 15.05

22 -12.80 16.50 17.8 15.05

23 -13.10 16.80 17.8 15.05

24 -12.90 16.60 17.8 15.05





25 -13.25 16.95 17.8 15.05

26 -13.05 16.75 17.8 15.05

27 -13.55 17.25 17.8 15.05

28 -12.85 16.55 17.8 15.05

29 -12.90 16.60 17.8 15.05

30 -13.00 16.70 17.8 15.05

31 -13.10 16.80 17.8 15.05

32 -13.05 16.75 17.8 15.05

Upstream: Path loss

Sending level at -3.20 dBm for wavelength at 1310nm at individual ports

COM PORT 1

Feeding at Port Rx Level(dBm) Insertion

Loss(dB)

Limit

(dB)

Theorectical

Value

(10 log 1/ N)

1 -20.05 16.85 17.8 15.05

2 -20.30 17.10 17.8 15.05

3 -20.15 16.95 17.8 15.05

4 -19.95 16.75 17.8 15.05

5 -19.95 16.75 17.8 15.05

6 -20.55 17.35 17.8 15.05





7 -19.80 16.60 17.8 15.05

8 -20.45 17.25 17.8 15.05

9 -20.10 16.90 17.8 15.05

10 -20.05 16.85 17.8 15.05

11 -20.00 16.80 17.8 15.05

12 -19.95 16.75 17.8 15.05

13 -20.10 16.90 17.8 15.05

14 -20.05 16.85 17.8 15.05

15 -20.45 17.25 17.8 15.05

16 -19.90 16.70 17.8 15.05

17 -20.55 17.35 17.8 15.05

18 -20.15 16.95 17.8 15.05

19 -20.30 17.10 17.8 15.05

20 -20.40 17.20 17.8 15.05

21 -20.15 16.95 17.8 15.05

22 -20.15 16.95 17.8 15.05

23 -20.25 17.05 17.8 15.05

24 -20.10 16.90 17.8 15.05

25 -20.25 17.05 17.8 15.05

26 -20.20 17.00 17.8 15.05

27 -20.25 17.05 17.8 15.05





28 -20.20 17.00 17.8 15.05

29 -20.10 16.90 17.8 15.05

30 -20.00 16.80 17.8 15.05

31 -20.15 16.95 17.8 15.05

32 -20.10 16.90 17.8 15.05





5.2 SPLITTER ANALYSIS

Splitter Analysis is carried out by varying the Variable Optical

Attenuator, which is placed before and after the splitter. By varying the

attenuation, link length can be varied.

5.2.1 1 X 4 SPLITTER

Case 1: Attenuator placed before Splitter

CONNECTION DIAGRAM:

2.5Gbps Tx Tx 2.5Gbps

Rx

PROCEDURE:

1. Power meter is set to 1550nm wavelength.

2. Attenuator is set to low value.

3. 2.5 Gbps input data stream is given to attenuator from STM-16 equipment.

4. The attenuator is connected to 1x4 splitter.

5. The output port of the splitter is connected back to the Rx of the STM-16

equipment.

6. Vary the attenuator value, until UAS (Unavailable Seconds) ≠ 0.

Attenuation (dB) Distance (Km) UAS BBER

1 4 0 0

5 20 0 0

10 40 0 0

11 44 0 0

11.4 45.6 0 7.13x10-7

STM-16+99

EQUIPMENT

VOA1X 4

SPLITTER





12.1 48.4 0 6.34x10-7

13.4 53.6 0 1.92x10-5

14 56 0 0.0002

14.1 56.4 11 0

Case 2: Attenuator placed after Splitter

CONNECTION DIAGRAM:

2.5Gbps Tx 2.5Gbps

Rx

PROCEDURE:



3. 2.5 Gbps input data stream is given to1x4 splitter from STM-16

equipment.

4. The splitter is connected to attenuator.


1 4 0 0

5 20 0 0

10 40 0 0

11.5 46 0 0

12 48 0 0

STM-16

EQUIPMENT

1X 4

SPLITTER

VOA





5. The output of the attenuator is connected back to the Rx of the STM-16

equipment.


CONCLUSION:

In case1, when attenuator is placed before splitter, error free transmission

distance limit is 44km and Maximum reachable distance is 56 km.

In case2, when attenuator is placed after splitter, error free transmission

distance limit is 48km and Maximum reachable distance is 66.8km.

From this, it is found that sending data to the fiber after splitting is better.

5.2.2 1X 8 SPLITTER

Case 1: Attenuator placed before Splitter

CONNECTION DIAGRAM:

2.5Gbps Tx 2.5Gbps

Rx

14.2 56.8 0 4.42X10-7

14.8 59.2 0 8.74X10-6

15.4 61.6 0 2.68X10-5

16.2 64.8 0 0.008

16.7 66.8 23 0

STM-16

EQUIPMENT

VOA 1X 8

SPLITTER





PROCEDURE:

1.

Power meter is set to 1550nm wavelength.2. Attenuator is set to low value.

3. 2.5 Gbps input data stream is given to attenuator from STM-16 equipment.


5. The output port of the splitter is connected back to the Rx of the STM-16

equipment.


Case 2: Attenuator placed after Splitter

CONNECTION DIAGRAM:

2.5Gbps Tx 2.5Gbps


1 4 0 0

5 20 0 0

10 40 0 0

10.2 40.8 0 0

10.4 41.6 0 9.05x10-7

10.6 42.4 0 1.58x10

-5

10.8 43.2 0 0.00015

11.2 44.8 0 0.0008

11.4 45.6 0 0.005

12 48 0 0.009

12.8 51.2 15 0

STM-16

EQUIPMENT

1X8

SPLITTER

VOA





PROCEDURE:



3. 2.5Gbps input data stream is given to1x8 splitter from STM-16 equipment.

4. The splitter is connected to attenuator.

5. The output of the attenuator is connected back to the Rx of the STM-16 equipment.


CONCLUSION:

In case1, when attenuator is placed before splitter, error free transmission distance

limit is 40.8km and Maximum reachable distance is 51.2km.

In case2, when attenuator is placed after splitter, error free transmission distance limit

is 44km and Maximum reachable distance is 56.8km.

From this, it is found that sending data to the fiber after splitting is better.


1 4 0 0

5 20 0 0

10 40 0 0

11 44 0 0

11.5 46 0 8.74X10

-6

12 48 0 2.68X10-5

12.5 50 0 0.0001

13 52 0 0.0003

14 56 0 0.013

14.2 56.8 10 0





5. 3 EFFECT OF DOUBLE SPLITTING

Case1:

CONNECTION DIAGRAM:

STM-16

EQUIPMENT

PROCEDURE:



3. 2.5Gbps input data stream is given to an attenuator from STM-16 equipment.


5. The output of the 1x4 splitter is connected to 1x8 splitter.

6. The output from 1x8 splitter is connected to the Rx of the STM-16 equipment.


STM-16

EQUIPMENT

VOA 1X4

SPLITTER

1X8

SPLITTER





Case 2

CONNECTION DIAGRAM:

STM-16

EQUIPMENT

PROCEDURE:



3. 2.5Gbps input data stream is given to 1x4 splitter from STM-16 equipment.


1 4 0 0

2 8 0 0

2.1 8.2 0 9.39x10-7

2.4 9.6 0 4.56x10-6

2.6 10.4 0 3.84x10-5

3 12 0 0.0003

3.4 13.6 0 0.0019

3.6 14.4 0 0.004

3.8 15.2 11 0

STM-16

EQUIPMENT

1X4

SPLITTERVOA

1X8

SPLITTER





4. The 1x4 splitter is connected to attenuator .

5. The output of the attenuator is connected to 1x8 splitter.

6. The output from 1x8 splitter is connected to the Rx of the STM-16

equipment.


Case 3:

CONNECTION DIAGRAM:

STM-16

EQUIPMENT


1 4 0 0

2 8 0 0

5 10 0 0

6.5 26 0 0

6.8 27.2 0 7.86x10-7

7.1 28.4 0 1.05x10-5

7.5 30 0 0.00012

7.8 31.2 0 0.0007

8.2 32.8 0 0.002

8.4 33.6 11 0

STM-16

EQUIPMENT

1X4

SPLITTER

1X8

SPLITTER

VOA





PROCEDURE:



3. 2.5Gbps input data stream is given to 1x4 splitter from STM-16 equipment.

4. The 1x4 splitter is connected to 1x8 splitter.

5. The output of the 1x8 splitter is connected to an attenuator.

6. The output from the attenuator is connected to the Rx of the STM-16

equipment.



1 4 0 0

5 20 0 0

6 24 0 0

6.3 25.2 0 1.53x10-6

6.8 27.2 0 8.5x10-6

7.4 29.6 0 0.0002

7.6 30.4 0 0.001

7.8 31.2 0 0.002

8 32 0 0.004

8.1 32.4 15 0





CONCLUSION:

Case 1: When attenuator is placed before two splitters, the distance limit for error

free transmission is 8km and maximum reachable distance is 15.2km.

Case 2: When attenuator is placed between two splitters, the distance limit for

error free transmission is 26km and maximum reachable distance is 33.6km.

Case 3: When attenuator is placed after two splitters, the distance limit for error

free transmission is 24km and maximum reachable distance is 32.4km.

In the above three cases, second case is better. Here first 1x4 splitting is done

and after a long distance, again each of them splitted into 8.





CHAPTER 6

LINK DESIGN AND OPTIMIZATION

6.1 FIBER OPTICAL LINK DESIGN

Basically a telecommunication system contains a transmitter, a receiver,

and an information channel (media). A laser source (infrared), which is modulated

by information signals acts as the transmitter. The modulated pulses from the

transmitter are launched into an optical fiber. The optical pulses will undergo total

internal reflection within the fiber and is detected at the receiving end. The

receiver (APD or PIN) converts back the optical pulses into electrical information

signal. The block diagram of a fiber optic link is shown in Figure.

Network-Medium

Fiber Links Fiber Links

FIG 11.Link Design Model

The satisfactoriness of the transmission in a fiber optic link can be defined

in terms of some characteristic parameters. The user generally specifies the

distance over which the information is to be sent and the data rate to betransmitted. The Designer has to find the specification of the system components.

The designer generally has to define some additional criteria either as per the

standards or as per the user specifications.The Design criteria are given in the

following:

TransmitterAmplifier Amplifier Receiver





1. Primary Design Criteria

Data Rate

Link Length

2. Additional Design Parameters

Modulation format

System fidelity

Cost involved in components, installation and maintenance

Upgradeability

Commercial availability

A SIMPLE POINT – TO – POINT OPTICAL LINK DESIGN

The link has primarily three components to design:

Optical Transmitter

Optical Fiber

Optical Receiver

Considering the cost, speed etc, first choose the laser and the detector.

Also the type of fiber is chosen. The design of an optical link involves many

interrelated variables among the fiber, source, and photodetector operating

characteristics, so that the actual link design and analysis may require several

iterations before they are completed satisfactorily. Since performance and cost

constraints are very important factors in fiber optic communication links, the

designer must carefully choose the components to ensure that the desired

performance level can be maintained over the expected system lifetime without

overspecifying the component characteristics.





The key system requirements needed in analyzing a link are:

1. The desired ( or possible ) transmission distance

2. The data rate or channel bandwidth

3. The bit error rate

To fulfill these requirements the designer has a choice of the following

components and their associated characteristics:

1. Multimode or single- mode optical fiber.

Core size

Core refractive-index profile

Bandwidth or dispersion

Attenuation

Numerical aperture or mode-field diameter

2. LED or laser diode optical source

Emission wavelength

Spectral line width

Output power

Effective radiating area

Emission pattern

Number of emitting modes

3. PIN or avalanche photodiode

Responsivity

Operating wavelength

Speed

Sensitivity





Two analysis are usually carried out to ensure that the desired system

performance can be met; these are the link power budget and the system rise-time

budget analysis. In the link power budget analysis, one first determines the power

margin between the optical transmitter output and the minimum receiver

sensitivity needed to establish a specified BER. This margin can then be allocated

to connector , splice, and fiber losses, plus any additional margins required for

expected component degradation or temperature effects. If the choice of

components did not allow the desired transmission distance to be achieved, the

components might have to be changed or repeaters might have to be incorporated

into the link.

Once the link power budget has been established, the designer can perform

a system rise-time analysis to ensure that the desired overall system performance

has been met.In carrying out a link power budget, we first decide at which

wavelength to transmit and then choose components operating in this region. If

the distance over which the data are to be transmitted is not too far, we may

decide to operate in the 800nm to 900nm region. On the other hand, if the

transmission distance is relatively long, we may want to take advantage of the

lower attenuation and dispersion that occurs at around 1310 or 1550nm.

Having decided on a wavelength, we next interrelate the system

performances of the three major optical link building blocks, that is , the receiver,

transmitter, and optical fiber. Normally the designer chooses the characteristics of

two of these elements and then computes those of the third to see if the system

performance requirements are met. We first select the photodetector and then an

optical source and see how far data can be transmitted over a particular fiber

before a repeater is needed in the line to boost up the power level of the optical

signal.

In choosing a particular photodetector, we mainly need to determine the

minimum optical power that must fall on the photodetector to satisfy the BER

requirement at the specified data rate. In making this choice, the designer also





needs to take into account any design cost and complexity constraints. A pin

photodiode receiver is simpler, more stable with changes in temperature, and less

expensive than an avalanche photodiode receiver. In addition, pin photodiode bias

voltages are normally less than 50V, whereas those of avalanche photodiode are

several hundred volts. However, the advantages of pin photodiodes may be

overruled by the increased sensitivity of the avalanche photodiode if very low

optical power levels are to be detected.

The system parameters involved in deciding between the use of an LED

and a laser diode are signal dispersion, data rate, transmission distance, and cost.The spectral width of the laser output is much narrower than that of an LED. This

is of importance in the 800nm to 900nm region, where the spectral width of an

LED and dispersion characteristics of silica fibers limit the data rate-distance

product to around 150(Mbps)km. For higher values(upto 2500(Mbps)km) a laser

must be used at these wavelengths. At wavelengths around 1.3um, where signal

dispersion is very low, bit-rate-distance products of atleast 1500(Mbps)km are

achievable with LEDs. Since laser diodes typically couple from 10 to 15dB more

optical power into a fiber than an LED, greater repeaterless transmission distances

are possible with laser. This advantage and the lower dispersion capability of laser

diodes may be offset by cost constraints. Not only is a laser diode itself more

expensive than an LED, but also the laser transmitter circuitry is much more

complex, since the lasing threshold has to be dynamically controlled as a function

of temperature and device aging.

For the optical fiber we have a choice between single-mode and multi-

mode fiber, either of which could have a step- or a graded – index core. This

choice depends on the type of light source used and on the amount of dispersion

that can be tolerated. LEDs tend to be used with multimode fibers, although edge-

emittihg LEDs can launch sufficient optical power into a single mode fiber for

transmission at data rates upto 560Mbps over several kilometers. Either a single

mode or multimode fiber can be used with a laser diode. A single mode fiber can





provide the ultimate bit-rate-distance product, with values of 30(Gbps)km being

achievable. A disadvantage of single mode fibers is that the small core size makes

fiber splicing more difficult and critical than for multimode fibers.

When choosing the attenuation characteristics of a cabled fiber, the excess

loss that results from the cabling process must also be considered in addition to

the attenuation of the fiber itself. This must also include connector and splice

losses as well as environmental-induced losses that could arise from temperature

variations, radiation effects, dust and moisture on the connectors.An optical power

loss model for a point-to-point link is shown in the Figure

FIG 12. Link Network

The optical power received at the photodetector depends on the amount of

light coupled into the fiber and the losses occurring in the fiber and at the

connectors and splices. The link loss budget is derived from the sequential loss

contributions of each element in the link. Each of these loss elements is expressedin decibels as

Where Pin and Pout are the optical powers emanating into and out of the

loss element, respectively.





In addition to the link loss contributors as in figure, a link power margin is

normally provided in the analysis to allow for component aging, temperature

fluctuations, and losses arising from components that might be added at future

dates. A link margin of 6 to 8dB is generally used for systems that are not

expected to have additional components incorporated into the link in the future.

The link loss budget simply considers the total optical power loss PT that is

allowed between the light source and the photodetector, and allocates this loss to

cable attenuation, connector loss, splice loss, and system margin. Thus if PS is the

optical power emerging from the end of a fiberflylead attached to the light source,and if PR is the receiver sensitivity, then

Here lc is the connector loss, L is the transmission distance, and the

system margin is nominally taken as 6dB. Here we assume that the cable of length

L has connectors only on the ends and none in between. The splice loss is

incorporated into the cable loss for simplicity.The fiber loss depends upon the

wavelength and also the physical conditions of the fiber. The fiber loss is

generally higher than that specified by the manufacturers. Typical loss at 1550nm

may lie in the range 0.2-0.5dB/km.





6.2 FTTH PON LINK ENGINEERING

Case1: Considering the below FTTH link with one 1x8 splitter and the design

procedure is as follows.

Figure 13.1x8 Double Splitter

Power Range for OLT:

Range Worst case Receiver

saturation

OLT TX Power PX20-D +2.5 to +6.7 dBm 2.5 dBm

OLT RX Sensitivity PX20-U -29 to -30 dBm -29 dBm -

10dBm

ONU TX Power PX10-U 0 to +3.7 dBm 0 dBm





ONU RX Sensitivity PX10-D -25 to -25.7 dBm -25 dBm -5dBm

Splitter losses

Downstream Power Budget = +2.5dbm-(-25dbm) = 27.5dB

Upstream Power Budget = 0 dbm-(-29dbm) = 29 dB

Downstream Design (10 Km)

Downstream is done in 1490nm wavelength.

The main equation is

Tx =Rx +CL +Ms +Pd

Item Description Attenuation Units

1.Fiber optic cable {a}1310 nm 0.33 db/km

{b}1490 nm 0.21 db/km

{c}1550 nm 0.19 db/km

1*2splitter 3.5 db

1*4splitter 7.4 db

1*8splitter 11 db







Tx= transmitted power

Rx=Receiver sensitivity

CL=Channel loss

Ms=System margin

Pd=Dispersion penalty

Tx =2.5dBm , Rx =-25dBm

CL=Spice loss+ fiber loss+ connector loss+ splitter loss

Splice loss

Splice loss= (L/2 +1)*0.1

Where 0.1dB is splice loss per splice ,L=Length of the fiber

Splice loss= (10/2 + 1) *0.1

=6*0.1=0.6 dBm

Fiber loss

Fiber loss= 0.21dB*L

(0.21 dB is fiber loss per kilometer)

=0.21*10

=2.1 dBm







Dispersion penalty

Extra power required by the system to compensate the dispersion.

Dispersion penalty, Pd = -10 log (1- ½(3.14B)^2 * dt^2)

Where B is the Band width

dt is the total dispersion

dt = spectral width * link length *Dc

where spectral width = .5 nm at 1490 nm

Dc = 18 ps/ nm* km (constant)

dt = .5 * 10 * 18

dt =90 ps

pd = -10 log (1-1/2 *(3.14 * 1.25 *10^9)^2 * (90 * 10^-12)^2)

= -10 log (1- 0.5 * ( 1.540 * 10^19) * 8.1 * 10 ^ -21

= -10 log ( 1- 0.06237)

= -10 log 0.93763

Dispersion penalty = 0.281 dB

Tx = -25 + 16.5 + 2 + 0.281

= -6.219 dB

Tx>= -6.219 dB

2.5 >= -6.219 dB





Transmitter power is greater than the power received at the receiver. so

transmitter power is enough for the working of system. so the downstream link

works.

UP Stream design (10 Km)

Upstream is done in the wave length 1330 nm.

Tx = Rx + CL + Ms + Pd

Tx = 0 dBm, Rx = -29dBm

CL = Splice loss + splitter loss + connector los + fiber loss

Splice loss = (10/2 + 1 ) * .1

=6 * 0.1 = 0.6

Splitter loss = 11 db

Connector loss = 0.4 * 7 = 2.8 dB

Fiber loss = .33 * 10 = 3.3 dB

Channel Loss = 0.6 + 11 + 2.8 + 3.3 = 17.7dBm

System margin

system margin =2 dB

Dispersion penalty

Dispersion penalty, Pd = 10log (1- ½(3.14*B)^2 * dt^2)

dt= spectral width * link length*Dc

Where spectral width =1 nm at 1330 nm, B is Bandwidth

dt = 1* 10 * 18





dt = 180 ps

Pd = -10 log (1-.5(1.540*10^9) (3.24*10^-20))

=-10 log (1-.24948)

= -10 log .7505

Dispersion penalty, Pd= 1.246 dB

Tx= -29+ 17.7+ 2 +1.246

= -8.054

0>=- 8.054

Transmitter power is greater than the power at the receiver.The transmitting

power is enough for the system to work.

Case2:Considering the below FTTH link with one 1x8 splitter and the output portfrom that is again fed to a 1x4 splitter and the design procedure is as follows.

Figure 14. 1x8 And 1x4 Splitters Using Double Splitting





Downstream Power Budget = +2.5dbm-(-25dbm) = 27.5dB

Upstream Power Budget = 0 dbm-(-29dbm) = 29 dB

Downstream Design (10 Km)

Downstream is done in 1490nm wavelength.

The main equation is

Tx =Rx +CL +Ms +Pd

Tx= transmitted power

Rx=Receiver sensitivity

CL=Channel loss

Ms=System margin

Pd=Dispersion penalty

Tx =2.5dBm , Rx =-25dBm

CL=Spice loss+ fiber loss+ connector loss+ splitter loss

Splice loss

Splice loss= (L/2 +1)*0.1

Where 0.1dB is splice loss per splice ,L=Length of the fiber

Splice loss= (10/2 + 1) *0.1

=6*0.1=0.6 dBm

Fiber loss

Fiber loss= 0.21dB*L





(0.21 dB is fiber loss per kilometer)

=0.21*10

=2.1 dBm

Connector loss

Connector loss = 0.4 dB * no of connectors

(0.4 dB is the connector loss in a SC connector)

=0.4 * 8

=3.2 dB

Splitter loss

Splitter loss =11 dB

= 11 +7.4

= 18.4 dB

(11dB for 1x8 splitter, 7.4dB for 1x4 splitter)

CL = splice loss + fiber loss + connector loss + splitter loss

= .6 + 2.1 + 2.8 + 11

Channel Loss =12.41 dB

System margin

Extra allowance given to the system for compensating channel loss.

System margin = 2 dB

Which is given in the system parameters





Dispersion penalty

Extra power required by the system to compensate the dispersion.

Dispersion penalty, Pd = -10 log (1- ½(3.14B)^2 * dt^2)

Where B is the Band width

dt is the total dispersion

dt = spectral width * link length *Dc

where spectral width = .5 nm at 1490 nm

Dc = 18 ps/ nm* km (constant)

dt = .5 * 10 * 18

dt =90 ps

pd = -10 log (1-1/2 *(3.14 * 1.25 *10^9)^2 * (90 * 10^-12)^2)

= -10 log (1- 0.5 * ( 1.540 * 10^19) * 8.1 * 10 ^ -21

= -10 log ( 1- 0.06237)

= -10 log 0.93763

Dispersion penalty = 0.281 dB

Tx = -25 + 12.41 + 2 + 0.281

= -10.309 dB

Tx>= -10.309 dB

2.5 >= -10.309 dB





Transmitter power is greater than the power received at the receiver. so

transmitter power is enough for the working of system. so the downstream link

works.

UP Stream design (10 Km)

Upstream is done in the wave length 1330 nm.

Tx = Rx + CL + Ms + Pd

Tx = 0 dBm, Rx = -29dBm

CL = Splice loss + splitter loss + connector los + fiber loss

Splice loss = (10/2 + 1 ) * .1

=6 * 0.1 = 0.6

Splitter loss = 18.4 db

Connector loss = 0.4 * 8 = 3.2 dB

Fiber loss = .33 * 10 = 3.3 dB

Channel Loss = 0.6 + 18.4 + 3.2 + 3.3 = 25.5 dBm

System margin

system margin =2 dB

Dispersion penalty

Dispersion penalty, Pd = 10log (1- ½(3.14*B)^2 * dt^2)

dt= spectral width * link length*Dc

Where spectral width =1 nm at 1330 nm, B is Bandwidth

dt = 1* 10 * 18





dt = 180 ps

Pd = -10 log (1-.5(1.540*10^9) (3.24*10^-20))

=-10 log (1-.24948)

= -10 log .7505

Dispersion penalty, Pd= 1.246 dB

Tx= -29+ 25.5+ 2 +1.246

= -0.254

0>=- 0.254

Transmitter power is greater than the power at the receiver.The transmitting

power is enough for the system to work.





CHAPTER 7

IMPLEMENTATION AND RESULT.

Figure 15(A). Implementation





Figure 15(B). Implementation

Figure 15(C). Implementation





CHAPTER 8

ADVANTAGES

Unlimited Band width

No consumption of energy

Low cost of upgrade and operating expenditures

Reduced cable cost, as it enables sharing of each fiber by many users

High quality of service





CHAPTER 9

APPLICATIONS

Distance Learning

Telemedicine

Tele working

Peer to peer file sharing

Distributed computing

Online Gaming

HDTV

Home Monitoring and home automation.





CHAPTER 10

CONCLUSION AND FUTURE SCOPE

One of the major hurdles for the mass deployment of FTTH

is the relatively high cost of ONT. Equipment vendors efforts to integrate various

functions into a single IC would bring down the cost of ONTs. Carriers have a

large installed base of TDM based legacy infrastructure. There is no right or

wrong FTTH technology, rather the technology choice primarily depends on the

existing network operator infrastructure. With ambitious plans of Govt. of India to

increase the broadband availability, making a parallel start of FTTH would only

make achieve the targets set by the Govt. Both the architectures of FTTH: P2P

and P2MP offer scalability and flexibility for FTTH, though ultimately, the choice

of network architecture is typically driven by the demand for that which offers the

greatest service capabilities at the lowest costs.

Future scope

Connectivity from the optical network unit to the computer can be

implemented through the fiber.

Number of service can be increased by virtual LAN network .

Along with the frame VLAN is send which will indicate the particular

service.





CHAPTER 11

REFERENCES

1. http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=6095214

2. http://ieeexplore.ieee.org/search/freesrchabstract.jsp?tp=&arnumber=6095214

3. http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5970861

4. http://ieeexplore.ieee.org/search/freesrchabstract.jsp?tp=&arnumber=5604408

5. http://en.wikipedia.org/wiki/Fiber_to_the_x

6. http://en.wikipedia.org/wiki/10G-PON

7. Physical Layer Monitoring in 8-branched PON-based i-FTTH - Ng Boon

Chuan, Aswir Premadi, Mohammad Syuhaimi Ab-Rahman, and Kasmiran

Jumari, IEEE 2010.

8. Simulation of 1.25 Gb/s Downstream Transmission Performance of

GPON-FTTx - Hesham A. Bakarman, Sahbudin Shaari, Member, IEEE,

and Mahamod Ismail, Member, IEEE 2010.

9. Fiber Optic Subscriber Systems - Kenji Okada and Hiromichi

Shinohara,IEEE LTS November 1998.

http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=6095214


http://ieeexplore.ieee.org/search/freesrchabstract.jsp?tp=&arnumber=6095214






http://en.wikipedia.org/wiki/Fiber_to_the_x


http://en.wikipedia.org/wiki/10G-PON












APPENDIX





































OPTIC FIBER CONNECTORS

SC Connectors





LC connector and Pig Tail




















ONT (OPTICAL NETWORK TERMINAL)

Date post:	06-Apr-2018
Category:	Documents
Upload:	anto-mathew
View:	243 times
Download:	1 times

Ftth Report

Documents