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Access Networks. lectures 200 8/09 - winter term Part 3: Classification of Access Networks 3.3 Optical Access Networks (OAN). OAN = Optical Access Network

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Access networks

Access Networks

lectures 2008/09- winter term

Part 3: Classification of Access Networks

3.3 Optical Access Networks (OAN)


  • OAN = Optical Access Network

  • access system with optical fibres and others optical and optoelectrical (optoelectronic) components + transmission of opt. signal through free space (opt. relay link or FSO – Free Space Optics)

  • - FITL (Fibre in the Loop)

  • advantages: frequency broadband,high bit rate, ability to operate in large access area

  • Phys. architecture:

star

1xN

coupler

star coupler

tree (multiple star)

coupler

ring

bus

OLT-optical line termination

ONU – optical network unit

Fig.3.3.1

- Logical arch.: Tree


The main parts of OAN – OAN architecture:

ODN = Optical Distribution Network

NT = Network Terminal

ONU = Optical Network Unit – in the user end – local loop connection (sometimes also NTU)

OLT = Optical Line Termination – in the exchange end – connection to the exchange

OAN

upstream

ONU

NT

network side

ODN

OLT

user side

ONU

downstream

Fig.3.3.2 Function architecture of OAN


Architectures (variants) of FITL: pure optical (FTTT) + hybrid (optics + metallic lines - the others apart from FTTT):

FTTT (Fibre to the Terminal)

FTTP (...Premise)

FTTH (... Home)

FTTB (... Building)

FTTC (.... Curb – the edge of the footpath)

FTTO (...Office)

FTTCab (...Cabinet)

*************************************************

FTTE (... Exchange)

Exchange

Fig.3.3.3

- on the metalic part (original POTS) there mostly operates VDSLsystem


5


- sometimes the most common solution – however, it is not OAN in fact opt. cable ends in central office. whre is DSLAM, and from it the the connections go out.


FTTO and FTTH are signified as fair optical – because the opt. fibers are led as far as famale plug (user socket).


shared opt. fibers are led as far as famale plug (user socket).

source: http://access.feld.cvut.cz/view.php?nazevclanku=&cisloclanku=2006051702


Management of access network opt. fibers are led as far as famale plug (user socket).

Fig.3.3.4: Reference configuration of OAN

Fig.3.3.5Reference model of AN in the building

frequency splitters

STB-SetTopBox

CPN-Customer Premises Network

B...Broadband

NB...Narrow Band

NTE-Network Termination Equipment


Refe opt. fibers are led as far as famale plug (user socket).rence configuration of OAN – continue: functional blocks OLT and ONU:

  • system core

  • functions of access to services

  • common functions

Optical distr.network

Switching network

Legend:

DCCF…

TMF…

ODNIF…

TUIF…

SPF…

OAMF…

CaSMF…

SIF…

PSF…

Fig.3.3.6.OLT

Optical distr.network

User ports

Fig.3.3.7ONU


  • DCCF opt. fibers are led as far as famale plug (user socket). – Digital CrossConnect Function

  • TMF – Transport & Multiplexing Function

  • ODNIF – Opt. Distrib.Network Interface Function

  • TUIF – Tributary UNIT Interface Function

  • SPF – Signalling Processing Function

  • common functions

  • OAMF – operation, administration and maintenance Function

  • PSF - power supply function

  • C&SMF – Customer and Service Multiplex Functions

  • SIF – Service Interface Function

commutation and multiplex

- EOC function

- V5 interface

- conversion from signalling of switching system to signalling in AN

  • control functions with access to overall network management TMN, and power supply

- demultiplexing

- services streams distribution


passive DP opt. fibers are led as far as famale plug (user socket).

active DP

without EOC

with EOC

unique optical segment

several optical segments

ODN – Optical Distribution Network

  • active one (AON) - equipments with power supply

  • passiveone (PON) – only passive equipments, in the building, short distances

Fig.3.3.8ODN classification according to DP (Distribution Point) properties


Optical hardware opt. fibers are led as far as famale plug (user socket).

Multipoint (PMP)

networks OAN

Point-to-Point (P2P)

relay links -FSO

active - AON

passive - PON

fibers

TDM

FDM

CWDM

APON

GPON

EPON

Fig.3.3.9 Optical access equipment classification

PON technology

APON – transport based on ATM cells (ITU-T G.983 standard )

BPON – Broadband PON – symetr.transportson higher bit rates (622,04 Mbps; either 2 fibers, i.e.for each rout (direction) 1, orunique fiberwith WDM

EPON – with Ethernet (Ethernet in the first Mile)

GPON – gigabit version PON, 1,244 a 2,488 Gbps (ITU-T G.984)

CWDM – Coarse WDM (coarsewave multiplexing) –interstage between WDM and DWDM (Dense WDM) – for the sake of cheaper increasing of information capacity, up to 8 channels, 1550nm window, uncooled lasers

hybrid -


  • Standards opt. fibers are led as far as famale plug (user socket).

  • ITU-TG.983

    • APON (ATM Passive Optical Network)-the first Passive optical network standard - primarily for business applications, and was based on ATM.

    • BPON (Broadband PON) - standard based on APON. It adds support for WDM, dynamic and higher upstream bandwidth allocation, and survivability. It also created a standard management interface, called OMCI, between the OLT and ONU/ONT, enabling mixed-vendor networks.

  • ITU-TG.984

    • GPON (Gigabit PON) - an evolution of the BPON standard - supports higher rates, enhanced security, and choice of Layer 2 protocol (ATM, GEM, Ethernet). In early 2008, Verizon began installing GPON equipment, having installed over 800 thousand lines by mid year. British Telecom, and AT&T are in advanced trials.

  • IEEE802.3ah

    • EPON or GEPON (Ethernet PON) is an IEEE/EFM standard for using Ethernet for packet data -is now part of the IEEE 802.3 standard.

  • IEEE802.3av

    • 10G-EPON (10 Gigabit Ethernet PON) is an IEEE Task Force for 10Gbit/s backwards compatible with 802.3ah EPON. 10GigEPON will use separate wavelengths for 10G and 1G downstream. 802.3av will continue to use a single wavelength for both 10G and 1G upstream with ATDMA separation. It will also be WDM-PON compatible (depending on the definition of WDM-PON). It is capable of using multiple wavelengths in both directions.

  • SCTEIPS910

    • RFoG (RFoverGlass) is an SCTE Interface Practices Subcomittee standard in development for Point to Multipoint (P2MP) operations that MAY have a wavelength plan compatible with data PON solutions such as EPON,GEPON or 10GigEPON. RFoG offers an FTTH PON like architecture for MSOs without having to select or deploy a PON technology.


P opt. fibers are led as far as famale plug (user socket).assive and active components of OAN


Examples of fiber technology (by EMTELL) opt. fibers are led as far as famale plug (user socket).

18


Optic opt. fibers are led as far as famale plug (user socket).al fibers and their properties

-on the base of Si-glassor plastic

- number of modes: 1-mode fibers and multimodes f. (largerΦ the more number of modes), multimodes with step change of i, or with gradient change

- velocity of light propagation~ 2/3 of c (in vacuum)

cladding

i – diffraction index

core

Fig.3.3.10: Opt.fiber with both higher and lower order mode

- attenuation= {10log(P1/P2) } / length [dB/km]

-dispersion - (different velocity depending onλ, also differenti  limiting of λ band of fiber)

  • max. modulation frequence band

Fig.3.3.11

[1]


... opt. fibers are led as far as famale plug (user socket).from optoelectronics:

boundary

100% reflection

Obr.3.3.13 ...total reflection on the boundary line of fibre-cladding (coating)

[5]


Fig. opt. fibers are led as far as famale plug (user socket).Optical fibers types

source: http://en.wikipedia.org/wiki/Image:Optical_fiber_types.svg


... opt. fibers are led as far as famale plug (user socket).from optics / physics:

n (or i) – diffraction index, v – velocity of propagation in solid material:

  • the most simple e-m waves – sinus: E(x,t) = E0cos(ωt-kx+Φ) – also: plane wavepropagatingin the direction x.

k=2π/λ .... wave number, Φ .... phase constante (start phase)

- remember also:

- phase velocity

-the group of waves with closedλ – they are moving by ‘group velocity’:

- other terms: critical impact angle, totale reflection, law of reflection


The other properties of optical fibers: opt. fibers are led as far as famale plug (user socket).

2nd window

3rd window width

wave length

Fig.3.3.15Attenuation dependance on wavelength ane others factors

optical fibers ...

[1]

reason of attenuation: presence and generation of OH ions, Raileigh scatter („total“ border, edge)


Tab. opt. fibers are led as far as famale plug (user socket).3.3.1Propertiesof standard 1-mode fiber by G.652


POF opt. fibers are led as far as famale plug (user socket).s = Plastic Optical Fibres

  • traditionally PMMA (acrylic) or new perfluorinated polymer core in fluorinated polymer cladding

  • equivalent to multimode glass fibers - plastic core (Φ about 1 mm)with step index profile

  • cheaper, suitable for LAN – for data and signals transport – in FTTH technology

  • manipulation with them is more simple

  • their specific attenuation is higher then this one of glass fibers; but they are in development (!)

  • good properties in unfriendly conditions (near the high voltage transformer stations) – that means they are resistant to disturbance, they are elastic (flexible)

  • EoPOF – Ethernet over POF

info – e.g.: http://en.wikipedia.org/wiki/Plastic_optical_fiber


Other passive components of opt. fibers are led as far as famale plug (user socket).OAN:

Couplers – basic is so called “Y“ or“1 x 2“.

  • or splitters

2 x 2 - devides signalfrom A to C andD

but, there is possible also transmission of light into all 8 directions

Creation of couplers – by fusionor by „tapering“

Fig.3.3.16 -a,b,c,d

[1], [5]


Transmission Star Coupler opt. fibers are led as far as famale plug (user socket).

Reflection star coupler

- the light arrives for instance at port A and is split equally through ports from G to L.

-the light arrives for instance at port A and is reflected back to all ports

Fig..3.3.17 - a,b,c

- patch panel - demountable coupler

[1]


  • Pas opt. fibers are led as far as famale plug (user socket).sive DWDM module

  • 32, 16 passive channels DWDM Mux/Demux

  • 100GHz (0,8nm) ITU Grid, C Band

  • Transparent transmission (protocol independent)

  • secure physical isolating between channels

  • minimal insertion loss

  • fully passive component (without power supply)

  • High density of ports

  • (http://www.technicomms.sk/)

  • Wave multiplexors

  • Optical connectors

  • even there are switches - they operate as routers – they redirect opt. signal into choosed direction; their fundamental components are lens and optical prisms; there can be bypass switches and 2-state switches


Wavelength multiplexors opt. fibers are led as far as famale plug (user socket).

Couplers - simple, or demountable

Optical connectors

29


- opt. fibers are led as far as famale plug (user socket).patch panel -for connecting opticalfibers and for their cover and screening

sources: http://www.b2bfiberoptic.com/04-01002.htm

http://www.alibaba.com/product-gs/212149133/Patch_Panel_Fiber_Optic_Patch_Panel.html

- ODF – Optical Distribution Frame –for controled connecting of fibers

30

source: http://www.huihongfiber.com/fiber-test-equipment.html


Tab. opt. fibers are led as far as famale plug (user socket).3.3.2 Typical values of attenuation (insertion loss) of optical components in OAN (μ –mean value, σ-st. deviation) [3]


odbočka opt. fibers are led as far as famale plug (user socket).

32


  • A opt. fibers are led as far as famale plug (user socket).ctive optical components

  • Optical sources (tunable lasers, diodes)

  • Optical detectors

  • Optical amplifiers

  • WADM – Wavelength add/drop multiplexor- programable optical switching array – between 2 optical links with WDM support


  • Duplex in opt. fibers are led as far as famale plug (user socket).OAN:

  • 2 fibers Spice Division Multiplex (SDM) – 1 fiber for each direction

  • 1 fiber with time alternating of directions (ping-pong system) – TCM (Time Compression Multiplex)

  • - 1 fiber with 2 wave length in the optical windows 1310 a 1550 nm – WDM

Examples of professional optical access systems:

Alcatel 1570 – narrowband optical access system in PON

Alcatel 1575 (HYTAS – Hybrid Telecommunication Access System) – with AON, it allows incorporate metallic circuits

Siemens Fast Link – hybrid


OPTIC opt. fibers are led as far as famale plug (user socket).AL RELAY LINKS

  • FOS - Free Space Optics

  • transmission through free space, analogous to RRL (Radio Relay Links)

  • advantages ....., disadvantages if compared to radio links...,

  • - the parts of opt. relay systems ...

  • - applications: ...


Referencie: opt. fibers are led as far as famale plug (user socket).

[1] http://www.oftc.usyd.edu.au/edweb/devices/networks/coupler8.html

[2] V.Kapoun: Přístupové a transportní síte. VUT v Brně, 1999.

[3] Vaculík: Prístupové siete. ŽU v Žiline, 2000.

[4] J. Vodrážka: Přenosové systémy v přístupové síti. ČVUT, 2003.

[5] J. Turán: Optoelektronika, Harlequin (s podporou FEI_TU-KE), 2002.


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