SREE DATTHA INSTITUTE OF ENGINEERING AND SCIENCES

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

PROJECT REPORT ON OFC LINK DESIGN FOR SDH SYSTEM OF STM -16

By:

B.SOURAV (09E41A0465) A.SAHITHI (09E41A0473)

S.PRATYUSHA (09E41A04A7) T.SNEHITHA (09E41A0486)

OUTLINE OF PROJECT

• OVERVIEW OF FIBRE OPTICS TRANSMISSION SYSTEM

• PLESIOCHRONOUS DIGITAL HIERARCHY(PDH) • SYNCHRONOUS DIGITAL HEIRARCHY (SDH)• STM-16 DESCRIPTION• E1 CONNECTION CONFIGURATION• OTDR TESTING

OVERVIEW OF FIBRE OPTICS TRANSMISSION SYSTEM

PRESENTATION OUTLINE• Introduction• Designing a Fiber Optic System • Principle of operation of OFC • Types of OF cables• Optical fiber parameters • Advantages of optical fiber • Applications of optical fiber

INTRODUCTION

• An optical fiber is a flexible, transparent fiber made of a pure glass (silica) not much thicker than a human hair. It functions as a waveguide, or “light pipe”, to transmit light between the two ends of the fiber.

• Optical fibers typically include a transparent core surrounded by a transparent cladding material with a lower index of refraction.Light is kept in the core by total internal reflection.

Fig 1: Basic structure of OFC

Fig 2: Cross Section details

Designing

Fig 3 : Design of optical fiber system

Fig 4: Major elements of an optical fiber link

Principle of operation of OFC

Total internal reflection: “If the angle of incidence increases amore than the critical angle, the light is totally reflected back into the first material so that it does not enter the second material. The angle of incidence and reflection are equal and it is called Total Internal Reflection.”

Fig 5: Total internal reflection in an OFC

Types of OF cables

• Single Mode Fibre

• Multi Mode Fibre

1. Step index

2. Graded index

Fig 6: Different types of Fibers.

OPTICAL FIBRE PARAMETERS

• Wavelength• Frequency • Window • Attenuation • Dispersion• Bandwidth • Numerical Aperture

ADVANTAGES OF OPTICAL FIBER

• Wide bandwidth• Low loss• Electromagnetic immunity• Small size• Light weight• Greater safety• Higher security

Fig 7: Loss vs frequency curve

APPLICATIONS OF OPTICAL FIBER • Local area networks operating at high speeds or over

large areas, and backbone systems connecting slower local area networks.

• Transmission of signals within the ships/aircraft/automobiles.

• Moderate speed transmission of computer data in places where fibers is most economical to install.

• Link among computers and high-resolution video terminals used for such as computer aided design.

• Connection between telephone network and antennas for mobile telephone service

• Long haul telecommunication systems on land and at sea to carry many simultaneous telephone calls over long distances

Plesiochronous Digital Hierarchy

PRESENTATION OUTLINE

• INTRODUCTION

• VERSIONS OF PDH

• LIMITATIONS OF PDH

INTRODUCTION

• The term “PLESIOCHRONOUS” is derived from Greek plesio which means near, and chronous, time.

• It means, networks works in different state but not perfectly within network.

• Transmission and reception are synchronized but timing is not• The channel clocks derived from diff master clock and range is

within limit . It called “PLESIOCHRONOUS” SIGNAL.• PDH signal are neither SYNCHRONOUS nor ASYNCHRONOUS

VERSIONS OF PDH

There are two version in PDH namely

• THE EUROPEAN.

• THE AMERICAN.

EUROPEAN = 30 CHANNELS.

AMERICAN = 24 CHANNELS.

Fig 8: Plesiochronous Digital Hierarchy

Fig 9: Plesiochronous Digital Hierarchy

LIMITATIONS OF PDH NETWORK

• Homogeneity of equipment

• Limited functionality

• The problem of channel segregation

• The problem of cross-connection of channels

• Incompatibility

SYNCHRONOUS DIGITAL HIERARCHY(SDH)

INTRODUCTION

• SONET (Synchronous Optical Network) or SDH (Synchronous Digital Hierarchy) as it's known in Europe, is a set of standards for interfacing Operating Telephone Company (OTC) optical networks.

• They are a set of global standards for interfacing equipment from different vendors (One of the few where telephony is concerned).

PDH PRINCIPLE

SDH PRINCIPLE

SDH Advantages versus PDH

The advantage of SDH over PDH are

• SDH is based on the principal of direct synchronous multiplexing.

• Essentially, separate, slower signals can be multiplexed directly onto higher speed SDH signals without intermediate stages of multiplexing.

• SDH is more flexible than PDH and provides advanced network management and maintenance features.

BIT RATES

Fig 10. International organization defined standardized bit rates

SDH FRAME REPRESENTATION

SDH FRAME REPRESENTATION

• Everywhere in the world, the standard SDH frame representation is a MATRIX with 9 rows and with variable columns.

SDH FRAME REPRESENTATION

SDH MULTIPLEXING

STM FRAMES

SDH EQUIPMENTS1. TERMINAL MULTIPLEXER

2. REGENERATOR

3. TRANSPONDER (LAMDA CONVERTER)

4. ADD/DROP MULTIPLEXER

5. DIGITAL CROSS CONNECT

NETWORK TOPOLOGIES

NETWORK PROTECTION

• Protection can be given in 2 ways

1. Ring protection

2. 1:1 protection

3. 1:N protection

Fig 11: Ring protection

Fig 12: 1:1 Protection

Fig 13: 1:N Protection

QUALITY PARAMETER

• Errored Seconds (ES) Seconds during which there is at least one error per block or frame

• Severely Errored Seconds (SES) Length of time during which a major alarm (LOS, LOF, AIS, Etc.) is recorded or when 30% of the frames received in one second contain errors

• Unavailability Length of time where SONET equipment is not available (beginning after 10 consecutive SES)

STM-16 DESCRIPTION

Fig 14: STM-16 Practical Equipment

Different slots of STM-16

• COM 01 CARD• AGG06 CARD• ELAN05D CARD• 2 XCC05 CARD• 2 XCEXT CARD• 2 A010000 CARD• FAN• MFC3 CARD• POWER DSITRIBUTION MODULE

E1 CONNECTION CONFIGURATION

STEPS TO BE FOLLOWED

1. Connect the PC to NMS interface of the network element.

2. Log in to an uncommissioned network element requisites.

Designing a Fiber Optic System The following step-by-step procedure should be followed when

designing any system.• Determine the correct optical transmitter and receiver

combination based upon the signal to be transmitted.• Determine the operating power available • Determine the special modifications (if any) necessary (such as

impedances, bandwidths, special connectors, special fiber size, etc.).

• Calculate the total optical loss (in dB) in the system by adding the cable loss, splice loss, and connector loss. These parameters should be available from the manufacturer of the electronics and fiber.

• Compare the loss figure obtained with the allowable optical loss budget of the receiver.

• Check that the fiber bandwidth is adequate to pass the signal desired.

Calculation of receiver sensitivity

• We make use of DTA for calculation.

• DTA has transmitter to send the signal to STM-16 and receiver the same.

• It compare both this signal and indicates if there is any errors.

S.No Tx power (dbm)

Rx power (dbm)

attenuation Error status

1 . -0.11 -7.88 -7.99 NO

2. -0.11 -12 -12.11 NO

3. -0.11 -15 -15.11 NO

4. -0.11 -20 -20.11 NO

5. -0.11 -24 -24.14 NO

6. -0.11 -29 -29.20 NO

7. -0.11 -33.8 -33.19 NO

8. -0.11 -34.7 -34.18 NO

9. -0.11 -99 -99.11 YES

Table 1: Receiver sensitivity of station A

Receiver sensitivity of station A

• Transmitted power = -0.11dbm

• Minimum receiver power = -34.7dbm

• Transmitted overload = -12dbm (from overload sheet).

• Hence dynamic range = 12>Rx>34.7

S.No Tx power Rx power attenuation Error status

1. -2.8 -4.19 -6.99 NO

2. -2.8 -10.2 -16 NO

3. -2.8 -19.9 -22 NO

4. -2.8 -22.7 -25.5 NO

5. -2.8 -23.2 -26 NO

6. -2.8 -99 -101.8 YES

Table 2: Receiver sensitivity of station A

• Transmitted power = -2.8dbm

• Minimum receiver power = -23.2dbm

• Transmitted overload = -4.10dbm (from overload sheet).

• Hence dynamic range = 4.10>Rx>23.2

Receiver sensitivity of station B

OTDR TESTING

INTRODUCTION

• Optical Time Domain Reflectometer (OTDR) is used for system troubleshooting, verification documentation has always been an important step of the system installation process.

REASONS TO USE OTDR :

1. Product acceptance.

2. Troubleshooting.

3. System verification.

4. Documentation.

OTDR PRINCIPLE

• An OTDR takes advantage of the backscattered light that occurs in all fibers as light travels down the core

Fig 15: Backscattered light (Rayleigh scattering)

CALCULATION OF CABLE LENGTH USING OTDR

Fig 16: Correction Factor Calculation

LINK BUDGET

• Definition: Computation of all losses that comes into account from source node to destination node is called “LINK BUDGET”.

• Lets see how to prepare link budget of 2 station (seperated by 100 Kms) connected through of cable.

Numeric values for the link: Tx power = 0.11dbm (calculated)

Rx sensitivity (stn A) = -34.07dbm (calculated)

Rx sensitivity (stn B) = -23.2dbm (calculated)

Source fiber coupling = 3db

Connector loss = 1db

Splice loss = 0.5db per slice

Fiber loss = 0.5db per km

Power margin = 0.11- (-23.2) = 23.31db

Calculation of various losses:

Splice loss (50 slices) = 0.1 x 50 = 5db

Fiber loss (100Km) = 0.25 x 100 = 25db

Total loss = 3+2+5+25 =35db

System loss margin = power margin – total loss

= -11.69

Maximum distance between 2 station

Dynamic range between stn A and stn B = Tx power of stn A – Rx sensitivity of stn B

= 0.11-(-23.2) = 23.31

Connector loss =1dbm

System loss margin = -11.69

Max loss b/w 2 station = 23.31+1-11.69

= 12.62

We know that there is a loss of 0.5 db per Km (1310 nm)

Hence max distance between 2 station = 12.62/0.5

= 25.24 Km

= 25 Km (approx)

CONCLUSION

• We have successfully created an link between two STM-16 systems.By this we can say that compared to other STM-N systems.

• STM-16 has very high speed 2.5 Gbps.

• By using OFC cables we have transmitted the frames between two STM-16 systems and calculated receiver sensitivity using analyzer practically.