The where, why and how of optical access Dr John Mitchell University College London, UK Tel: +44 (0)

ALL ABOUT UCL Times Higher Education – QS World University Rankings 2008

Brief Introduction UCL was founded in 1826 as an alternative to Oxford and Cambridge We have over 19,000 students – 48% male, 52% female and ⅓ of students are from overseas 74% of students achieve a 2.1 degree or higher UCL is consistently placed in the top 5 universities in the UK Recently rank 7 th in the World 60 departments are graded 5/5* UCL is located in Central London, Bloomsbury ALL ABOUT UCL

Overview Why Fibre? What do we do at the moment? What is Fibre to the Home (FTTH)? –Point to Point or Point to Multipoint What are people deploying? What might happen next?

UK Access Network The BT access network consists of: 34 million copper pairs, km of underground ducts primary connection points 3.7 million manholes and joint boxes, 3 million distribution points, 4 million poles about 23 million customers The existing access network is dominated by twisted copper pairs in most countries

A Legacy Network Copper lines provisioned for analogue voice Bandlimited to 4kHz Never intended to carry data High speed equipment in exchange and customer premises ISDN capable of 144kbit/s 144 kbit/s 56 kbit/s

Why Upgrade? Firewire IEEE 1394 Communication between devices at 400Mbit/s Max distance of 4.5m Download from video camera How to distribute to others?

Today’s Options 56kbit/s Modem 56kbit/s = 8 days 6 hours ADSL 512kbit/s = 21 hours Best Option? –4.8GB DVD + overnight post = 660kbit/s Soon? –50GB Blue Ray Disk + overnight post = 6.6Mbit/s 2Mbit/s = 5½ hours

Snails Pace TechnologyKbps V.34 modem28.8 ISDN128 ADSL1500 Pigeons2270 SNAP37,000 “Sluggish Data Transport is faster that ADSL” A, Ben-Bassat, R. Ben-David-Zaslow, S. Schocken, Y Vardi, Annals of Improbable Research, May-June 2005 pp 4-7 See: DVD 4.7GB Achatina Fulica (Giant African Land Snail) LGS (Lettuce-Based Guidance Sub-system) SNAil-Based data transfer protocol (SNAP)

Overview Why Fibre? What do we do at the moment? What is Fibre to the Home (FTTH)? –Point to Point or Point to Multipoint What are people deploying? What might happen next?

ADSL (Asynchronous Digital Subscriber Line) Telephone network Broadband network Telephone CPE Broadband CPE splitter Existing line Utilizes the legacy copper access network - a major benefit to incumbent telecoms operators No major upgrades required to the telephone switches Opens up new revenue streams Low fixed costs (ADSL rack in exchange etc) and acceptable marginal costs (ADSL modems can cost around $100/pair) Allows incremental deployment Very capital efficient in that service is only provided to those who need it

ADSL Reach Source: Analysys, IEEE

VDSL (Very high bit rateDigital Subscriber Line) Broadband services could do with a higher data transfer rate than ADSL can support The same principles as ADSL (clever Digital Signal Processing) can be applied to address this by limiting the reach of the system VDSL supports data rates to over 50 Mbit/s to the customer thereby enabling support of these very broadband services The shorter reach of VDSL though means that data must be carried from the exchange to a point close to the customer (see later) PCP Exchange Existing E-side Cables Existing D-side Cables VDSL Cabinet New Fibre Feed Bit rate (Mbit/s)ReachSuitability kmFTTCab kmFTTC/FTTB mFTTB

Subscriber Lengths - UK Bit rate (Mbit/s)ReachSuitability kmFTTCab kmFTTC/FTTB mFTTB

© UCL 2008 Cable TV Optical TX/RX Modem Coax for approx last 500m Upstream Downstream Spectrum MHz Noisy Spectrum Broadband Analogue TV Digital TV Digital VOD POTS Data Over Cable Service Interface Specification (DOCSIS 3.0) is currently rolling out 50Mbit/s although it is cable of 400Mbit/s (length dependent) using modulation schemes from QPSK to 128QAM and TDMA and S-CDMA modes.

Overview Why Fibre? What do we do at the moment? What is Fibre to the Home (FTTH)? –Point to Point or Point to Multipoint What are people deploying? What might happen next?

Different Flavours

© UCL 2008 FSAN PON System Service Node SNI (VB5) ONU FTTH FTTB FTTC FTTCab Optical Fiber PONxDSL OLT ONU CPE Passive Optical Splitter FTTx FTTC:Fiber To The Curb FTTCab :Fiber To The Cabinet FTTH :Fiber To The Home FTTB :Fiber To The Building Q3 Operation System Internet Leased Line Frame/Cell Relay Telephone Interactive Video Twisted Pair ONU OLT – Optical Line Termination ONU – Optical Network Unit CPE – Customer Premises Equipment

Fibre-to-the-curb: deployment issues The fibre end is in a cabinet or access point (AP) - serves customers – optical receiver and transmitter – demultiplexes TDM data to provide feeds to individual customers Cabinet engineering – 1 m 3 too small for a dedicated building – security and environmental control – primary and backup power

Fibre-to-the-home When residential demand for high rate services is sufficient a case can be made for taking fibre to the home The CPE then needs to be a powered optical interface with security features and backup power CPE will be expensive after allowing for mass volume reductions - service demand is therefore a must The optical network can be active or passive For cost reasons a passive optical network (PON) has for a long time been the preferred approach Single and distributed star network topologies are being considered – often called point to multi-point Point to point systems are currently gaining favour in some countries

© UCL 2008 EPON

Fast-Web Architecture

FTTH: Point to Point IP Services, TV and telephony traffic are combined at concentration point A single fibre per customer is connected from the exchange through a cabinet and drop point Method is simple but wasteful of equipment Attractive for high service demand customers Advantages –CPE only operate at the line rate provided to each customer –Use standard existing technologies – i.e. ethernet –Each Individual line upgradeable Disadvantages –To avoid huge fibre bundles at exchanges, concentration points move closer to the customer – require active electronics in the field. –Not optimised for broadcast services –2N Transceivers needed

© UCL 2008 PON vs E-P2P ONU PON OLT PON OLT PON OLT PON OLT PON OLT PON OLT PON OLT PON OLT 4x PON OLT 157 Fibres 157x 1:64 Splits ONU Exchange CabinetCustomer Switch 24 x Ethernet Switch 1 fibre per home ONU 1 fibre per home 10,000 Fibres Cost per connection (€) in urban context. Source: IDATE

© UCL 2008 Passive Optical Networks OLTOLT SPLITTERSPLITTER ONUONU ONUONU ONUONU Local Exchange PCP Cabinet Customer Premises Optical Line Termination Optical Network Unit

© UCL 2008 PON Downstream OLTOLT SPLITTERSPLITTER ONUONU ONUONU ONUONU 0dBm -3dBm 3dB

© UCL 2008 PON Upstream SPLITTERSPLITTER ONUONU ONUONU ONUONU OLTOLT 0 dBm 3 dB

© UCL PON Ranging ONUONU ONUONU ONUONU ONUONU ONUONU ONUONU OLTOLT SPLITTERSPLITTER Optical Network Units At different distances

PON Operation Downstream, time division multiplexing (TDM) Upstream, time division multiple access (TDMA) TDMA requires ONUs to be ranged OLT is the master, complete control over network ONUs are slaves, obeying OLT commands Dual or single fibre operation Single fibre uses coarse wavelength division multiplexing (CWDM) –1490 nm downstream (OLT to ONU) –1310 nm upstream (ONU to OLT) Dual fibre uses 1310 nm in both directions

PON Advantages Cost effective FTTH architecture Long reach between central office and customers Minimises fibre deployment and equipment Completely passive, no electrical power –Like current ADSL and PSTN systems Optically transparent, allowing future upgrades High bandwidth due to deeper fibre penetration Broadcast operation allows for video broadcast

Bandplan US nm (1310 ± 50) DS nm (1490 ± 10) enhancement bands: –video nm –digital nm 1300 nm1400 nm1500 nm1600 nm UpstreamDownstreamVideo Voice Data OLT EDFA WDM ONU Video Voice Data 1490nm 1310nm 1550nm Thin Filter Filters 1310nm Laser 1490nm Detector 1550nm Detector TriDi Design

© UCL 2008 Local Exchange, Hand over point Example Deployment ONU 32 way Ethernet Layer 2 Switch GPON OLT Local Exchange, Hand over point End Users 28dB Max Example for Openreach Deployment, Ebbsfleet Communication Provider (CP) Interfaces CP1 CP2 Ethernet Diversely Routed Redundant Path

Overview Why Fibre? What do we do at the moment? What is Fibre to the Home (FTTH)? –Point to Point or Point to Multipoint What are people deploying? What might happen next?

© UCL 2008 Broadband per Capita Usually Means Fibre

How much Fibre?

USA Homes passed with fibre in the USHomes Conneted with fibre in the US

Japan High profile government incentive to be the most advance IT nation by 2007 Benefit from short loop lengths and a large amount of dark fibre in the feeder network By end of 2003 new FTTH connections passed any other type of new connection Over 6M subscribers aim at have 30M by 2010! 75% residential – not just business and luxury See as a major selling point for Real Estate B-FLET 100Mbit/s (symmetrical) service is ¥ 4,725 per month (>£25) Installed by NTT-East

© UCL 2008 Japan Source: Japan Ministry of Internal Affairs and Communications, March 13, 2007

South Korea –Target 100Mb/s to 5M by 2007, to 10M by 2010 –14.7M Broadband Subscribers (76% of Households) –FTTB is the main fibre deployment –50 percent of the population lives in large apartment complexes (Multiple Dwelling Units) Subscribers per Household 0.93 Internet Users in Millions 34.9 Internet Users/100 Inhabitants72.75 Average Speed Mbit/s 49.5 Price Per Month of 1 Mbps USD 0.45 Percent of Urban Population 81 Population Density per sq. km 481 (the US is 31, UK 241)

France France Télécom, via Orange, its service provider, offers fibre-to-the-home (FTTH) in Paris and will expand its services to 1 million homes in 12 other cities by the end of 2 Moreover, since August 2007, France Télécom’s primary rival Illiad (via Free, its service provider) is offering 100 Mbps of service through its own fibre to the premises (FTTP) infrastructure but almost exclusively to apartment buildings.

Costs of FTTH SBC estimate that FTTP saves more than 50% of the operational cost of copper This may grow to 70% with FTTH SBC also estimate in greenfield sites it is around $1100 for each home passed (not including CPE) Estimates of £15-£25 Billion for the UK Very High CAPEX but much reduced OPEX!

Overview Why Fibre? What do we do at the moment? What is Fibre to the Home (FTTH)? –Point to Point or Point to Multipoint What are people deploying? What might happen next?

© UCL 2008 Bandwidth Comparison Dial Up PSTN 56kbit/s ADSL 2Mbit/s VDSL 14Mbit/s BPON 20Mbit/s SuperPON ? bit/s Always On Narrowband Internet Access Broadband Internet Access DVD Video Possibly Single HDTV HDTV plus Other Services Simultaneously Copper Fiber

Next Generation PON Wavelength Division Multiplexing will become involved sooner or later, but how? Most likely will be that it will allow operators to offer extra services to selected customers on the same PON G983.3 specified wavelengths bands to be used for ‘enhanced’ services

Wish List Increase in upstream and downstream bit-rate Increased reach Increased split size WDM but with Colourless ONUs

Conclusions A number of different solutions are available and a number of factors govern where each is deployed – Population Concentration – Number of multiple dwelling units – Average Loop Lengths – Incumbent or New Entrant Speed of roll-out is controlled by a set of factors including: –Level of Government activity –Regulatory Framework –Current Broadband/TV penetration –Demand for Services –Availability of Fibre/ Access to Ducts The Technology is not the issue only the enabler…..

Thanks to: Dr Darren Shea Dr Bob Sutherland Dr Joseph C Attard Dr Russell Davey Links FTTH Council Ethernet in the First Mile B-FLET Fast Web company.fastweb.it/ FSAN Point Topic