OS3 Fiber Day Fiber to the Home technology. May 21, 2014 / Erik Radius GlasOperator / Vodafone

Transcription

1 OS3 Fiber Day Fiber to the Home technology May 21, 2014 / Erik Radius GlasOperator / Vodafone

2 Contents (more or less) Optical fiber Inner workings Fiber types Transmitter, receiver Transmission Link budget calculations Optical networks Core, Metro, Access Architectures Access network scenarios

3 Why do we use light signals in networking? let s explain this with some conductor physics 3

4 Electrons versus photons Electrons in metal wire Spin ½, obeys Fermi-Dirac statistics (Fermion) Collisions: resistance, restricted flow Suitable for lightbulbs & toasters Photons in glass Spin 1, obeys Bose-Einstein statistics (Boson) No collisions: zero resistance, no flow limit Superconductors for data transport 4

5 A closer look at an optical fiber Optical fiber is a compact, low-loss carrier for broadband signals Optical fiber consists of 3 main parts 1: glass core 2: glass cladding 3: plastic buffer coating 5

6 Optical fiber inner workings Optical signal is contained within the fiber Higher index of refraction in core than in cladding Total internal reflection at the core/cladding boundary 6

7 Multimode versus Singlemode (1) Multimode Bigger core: 50 / 62,5mm Multiple optical modes supported/transmitted Bandwidth*distance product is limited Only suitable for shorter distances (<1km) 7

8 Multimode versus Singlemode (2) Singlemode Small core: 9mm 1 optical mode is supported/transmitted Signal may be carried over very large distance More information online, e.g. 8

9 Transmitter & receiver Optical fiber is only a passive waveguide Active components at the end points: Signal source: laser diode or LED Receiver: photo diode (Amplitude)modulation of the data stream Light signal is the carrier wave Both digital and analog transmission possible 9

10 Signal loss in optical fiber is wavelength dependent

11 Power budget: how far can you go 11

12 Optical power budget Fiber link design: what is involved Fiber type (single mode? multi mode?) Fiber length (km) Licht source: output power (dbm) Detector: receiver sensitivity (dbm) Elements in the link that cause additional signal loss Fiber link budget or optical power budget The amount of light available to make a fiber optic connection Provides the maximum distance with the available optics Take a minimum of 3dB safety margin into account 13

13 Optical power budget: case #1 Transmitter fiber Receiver Laser power: -7 dbm Fiber attenuation: 0,4 db per kilometer Fiber length: 20 km Receiver sensitivity: -29 dbm Splice loss: 0,1 db (max.) Connector loss: 0,5 db (max.) # of connectors: 2 # of splices: 4 Calculate Link Budget: laser power receiver sensitivity Calculate Margin: laser power receiver sensitivity [link losses] 14

14 Optical power budget: case #2 Transmitter fiber Receiver Laser power: +1 dbm Fiber attenuation: 0,25 db per kilometer Fiber length: 40 km Receiver sensitivity: -12 dbm Splice loss: 0,1 db (max.) Connector loss: 0,5 db (max.) # of connectors: 4 # of splices: 8 Calculate Link Budget: laser power receiver sensitivity Calculate Margin: laser power receiver sensitivity [link losses] 15

15 Pros and cons of optical fiber Question for you all... Give me 3 advantages of optical fiber over metallic wiring... and... 3 disadvantages 16

16 Fiber networks Transport network layers Core (+ international) network Metro(politan) network Access network Access network for telecom/cabletv: partial fiber Telecom Optical fiber up to central office Copper connection into the home (xdsl) Cable TV Optical fiber up to street cabinet coax connection into the home 17

17 International networks (submarine cable systems)

18 National networks source: GIGAport website

19 City networks (metro rings) source: GIGAport website

20 Fiber penetration in the access network Fiber. to the Node Central office, >300m to the Curb/Cabinet Street cabinet, <300m to the Building/Basement Multi-storey buildings to the Home Into the utility closet (meterkast) 21

21 FTTH cabling concept Access network branches off multiple times between central office and the home Installed: underground or above ground (!) 22

22 Fiber installation FTTH in Romenia (Bucharest) 23

23 Underground installation Several underground deployment methods available 1: modular tubes; insert fiber as needed (blown fiber) 2: fiber inside rugged cable (buried fiber) 24

24 Miniduct system for access network 1, 7, 12, 24 thin tubes in a rugged outdoor cable Branching off one or multiple tubes is relatively simple 25

25 Fiber in mini duct Install thin cable into duct using airflow 26

26 Fiber connection in the home Example optical fiber network terminal Services for end user: Internet Television Telephony Most often installed in the utility cabinet ( meterkast ) 27

27 Bidirectional data transmission popular in FTTH A Single fiber may be used in two directions Different signal wavelengths for uplink vs downlink 1500nm downlink 1310nm uplink Reason? Less fiber needed in the field fiber management is expensive Space in the Central Office is scarce 28

28 Bidirectional fiber optic modules (tranceivers) 29

29 POP fiber management 30

30 Fiber architectures (1): Point-to-point point-to-point 1 on 1 fiber connection between Central office and Home Central Office 31

31 Fiber architectures (2): PON point-to-multipoint (PON: passive optical network) optical splitter in the link, to send same signal to multiple end points Central Office 32

32 Passive splitter/coupler

33 PON: shared medium system reach

34 PON reach calculation Laser power: +2 dbm Receiver sensitivity: -26 dbm Fiber attenuation: 0,4 db per 1310nm 0,25 db per 1550nm Splice loss: 0,1 db (max.) Connector loss: 0,5 db (max.) # of connectors: 4 # of splices: 6 Splitter loss (1:16) 14,0 db Splitter loss (1:32) 17,1 db Splitter loss (1:64) 21,2 db Calculate max. reach (in km) with 1:16 split or 1:64 split

35 PON versus Point-to-Point: who uses which? PON popular with telcos USA Japan Australia closed business/network model Point-to-point mostly popular in Europe Scandinavia Netherlands, France, etc open network model

36 Thank you More questions? Ask me!