optical fiber communications: optical network · 2021. 1. 24. · high fiber plant cost because of...

Optical Fiber Communications:

Optical Network

Prof. Dr. Monir Hossen

Dept. of ECE, KUET

Dept. of ECE, Khulna University of Engineering & Technology (KUET), Bangladesh

02Dept. of ECE, Khulna University of Engineering & Technology (KUET), Bangladesh

❖ Internet Reality

❖ Optical Fiber Network Evolution

❖ Network Terminology

❖ Optical Layer

❖ Network Topologies

❖ Synchronous Optical Network (SONET)

❖ Basic Design of WDM

❖ Wavelength Options in WDM

❖ Properties of PON System

Inside

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Feb. 5, 2002

SONET

Data

CenterSONET

SONET

SONET

DWD

M DWD

M

AccessLong HaulAccess MetroMetro

Internet Reality

Optical Fiber Network Evolution

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Network Terminology

Optical Layer

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Network Topologies

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Synchronous Optical Network (SONET)

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SONET Add Drop Multiplexers

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Generic SONET Structure

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Levels and Bit Rate for SDN and SONET

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• OC-1 is the base signal with bite rate of 51.840 Mbps

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Basic Design of WDM

Various types of WDM upon wavelength spacing– CWDM (Coarse WDM)

• Bidirectional• Triple play (1310, 1490, 1550 nm)

– DWDM (Dense WDM)

CWDM– Over than 20 nm spacing between adjacent

channels– No tight control of wavelength needed → no temp.

control– Less channel crosstalk – Known as 40% cheaper than DWDM – Limited number of wavelengths available– 18 CWDM channels can be obtained over

1271~1611 nm

Wavelength Options in WDM

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ITU G.694.2 - Nominal central wavelengths of CWDM

– 1270 1290 1310 1330 1350 1370 1390 1410 1430 1450 1470 1490 1510 1530 1550 1570 1590 1610

Why Wavelengths Spacing of 20nm?

– Uncooled lasers: wavelength change with temperature.

– Wide pass band filters : wavelength variation of ± 6-7 nm with current filter technologies.

– 1/3 of the channel spacing is needed for the guard-band.

DWDM

– Less spacing than CWDM, but, usually less than 3.2 nm spacing (3.2, 1.6, 0.8, 0.4 nm)

– Tight control of wavelength needed → DWDM LD

– Careful about the channel crosstalk → DWDM Filter

– Can provides a lot of wavelengths

Wavelength Options in WDM

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Point to Point

N fibers, 2N optical transceivers

High Bandwidth

High Fiber Plant cost because of PTP configuration of fiber pairs.

Active Star (Curve Switched)

1 fiber, 2N+2 optical transceivers

Minimum fiber/space in CO

Electrical power in the filed

High Operations & maintenance cost

PON (Passive Optical Network)

1 fiber, N+1 optical transceivers

Minimum fiber/space in CO/OLT (Optical Line Terminal)

No electrical power in the field

Low Operations cost

Properties of PON System

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PON

No Power between CO & ONU (Optical Network Unit)

No active processing (routing, switching)

Only signal power split

Tree Topology

Downstream: Broadcasting and Selection

Upstream: Multiplexing

TDM-PONEPON, BPON, GPON

Requires Control Protocol for Upstream

Requires Encryption for Downstream

WDM-PONDWDM-PON, CWDM-PON

Properties of PON System

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Thanks for Your Kind

Attention

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