Transcript Fibre Access Systems

The where, why and
how of optical access
Dr John Mitchell
University College London, UK
Tel: +44 (0) 20 7679 3281
Email: [email protected]
ALL ABOUT UCL
Times Higher Education – QS World University Rankings 2008
ALL ABOUT UCL
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 7th in the World
• 60 departments are graded 5/5*
• UCL is located in Central London,
Bloomsbury
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 existing access network is dominated by
twisted copper pairs in most countries
• The BT access network
consists of:
•
34 million copper pairs,
•
250000 km of underground ducts
•
74000 primary connection points
•
3.7 million manholes and joint
boxes,
•
3 million distribution points,
•
4 million poles
•
about 23 million customers
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
56
kbit/s
144
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
– 5GB @ 56kbit/s
• ADSL
=
–5GB
– 5GB@
@2Mbit/s
512kbit/s =
8 days 6 hours
5½
hours
21 hours
• Best Option?
–4.8GB DVD + overnight post = 660kbit/s
• Soon?
–50GB Blue Ray Disk + overnight post = 6.6Mbit/s
Snails Pace
SNAil-Based data transfer protocol (SNAP)
DVD 4.7GB
Achatina Fulica (Giant African
Land Snail)
Technology
Kbps
V.34 modem
28.8
ISDN
128
ADSL
1500
Pigeons
2270
SNAP
37,000
LGS (Lettuce-Based Guidance
Sub-system)
“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: http://www.notes.co.il/benbasat/10991.asp
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)
•
•
•
•
•
•
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
Telephone
splitter
network
Broadband
network
splitter
Existing line
Telephone
CPE
Broadband
CPE
ADSL Reach
Exchange-Customer length distribtion
100
Population Cumulant (%)
90
Exchange-Customer length
distribtion
80
70
60
50
40
30
20
10
0
0
1
2
3
4
equivalent 0.5mm length (km)
Source: Analysys, IEEE
5
6
7
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)
VDSL Cabinet
PCP
New Fibre Feed
Exchange
Existing D-side Cables
Existing E-side Cables
Bit rate (Mbit/s)
Reach
Suitability
13
1.5 km
FTTCab
26
1.0 km
FTTC/FTTB
52
300 m
FTTB
Subscriber Lengths - UK
Cabinet-Customer length distribution
3.5
equivalent 0.5mm length (km)
3
Bit rate (Mbit/s)
Reach
Suitability
13
1.5 km
FTTCab
26
1.0 km
FTTC/FTTB
52
300 m
FTTB
2.5
2
1.5
1
0.5
0
0
10
20
30
40
50
60
Population Cumulant (%)
70
80
90
100
Cable TV
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.
Optical
TX/RX
Broadband
Noisy
Spectrum
Analogue
TV
Digital
TV
Digital
VOD
Upstream Downstream Spectrum
Optical
TX/RX
MHz
Modem
Coax for approx last 500m
Modem
© UCL 2008
Modem
POTS
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
FSAN PON System
Operation
System
Service Node
OLT – Optical Line Termination
ONU – Optical Network Unit
CPE – Customer Premises Equipment
Q3
FTTx
Passive Optical Splitter
Internet
ONU
FTTH
Optical Fiber
Leased Line
ONU
Frame/Cell
Relay
FTTB
OLT
ONU
CPE
FTTC
CPE
FTTCab
Telephone
Twisted Pair
Interactive
Video
ONU
SNI
(VB5)
PON
FTTH :Fiber To The Home
FTTB :Fiber To The Building
© UCL 2008
xDSL
FTTC:Fiber To The Curb
FTTCab :Fiber To The Cabinet
Fibre-to-the-curb: deployment issues
• The fibre end is in a cabinet or access point (AP)
- serves 200-500 customers
– optical receiver and transmitter
– demultiplexes TDM data to provide feeds to individual
customers
• Cabinet engineering
– 1 m3 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
EPON
© UCL 2008
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
PON vs E-P2P
ONU
ONU
PON
PON
OLT
PON
OLT
PON
OLT
OLT
157 Fibres
ONU
157x 1:64
Splits
1 fibre per
home
ONU
4x PON OLT
Exchange
Cabinet
1 fibre per
home
ONU
Switch
24 x Ethernet
Switch
Customer
ONU
10,000 Fibres
ONU
Cost per
connection (€) in
urban context.
Source: IDATE
© UCL 2008
Passive Optical Networks
O
N
U
Optical Network Unit
S
P
L
I
T
T
E
R
O
L
T
Local
Exchange
Optical Line Termination
© UCL 2008
PCP
Cabinet
O
N
U
Customer
Premises
O
N
U
PON Downstream
-3dBm
0dBm
3dB
O
N
U
-3dBm
O
L
T
© UCL 2008
1010101
S
P
L
I
T
T
E
R
O
N
U
O
N
U
PON Upstream
0 dBm
3 dB
0 dBm
O
N
U
0 dBm
O
L
T
333
222
111
S
P
L
I
T
T
E
R
222O
N
U
O
N
U
© UCL 2008
PON Ranging
O
N
U
O
L
T
S
P
L
I
T
T
E
R
O
N
U
O
N
U
222O
N
U
Optical Network Units
At different distances
O
N
U
© UCL 2008
333
O
N
U
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
Video
1550nm
EDFA
Video
Voice
Data
OLT
1490nm
ONU
WDM
1310nm
Upstream
1300 nm
Voice
Data
Downstream Video
1400 nm
• US 1260-1360 nm (1310 ± 50)
• DS 1480-1500 nm (1490 ± 10)
• enhancement bands:
– video 1550 - 1560 nm
– digital 1539-1565 nm
1500 nm
1600 nm
Thin Filter Filters
TriDi Design
1550nm
Detector
1310nm
Laser
1490nm
Detector
Example Deployment
End Users
Local Exchange, Hand
over point
ONU
CP1
Ethernet Layer
GPON
Local
Exchange, Hand
over
2 Switch
OLT
point
Communication
Provider (CP)
Interfaces
© UCL 2008
Diversely Routed
Redundant Path
32
way
Ethernet
CP2
ONU
28dB Max
Example for Openreach Deployment, Ebbsfleet
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?
Broadband per Capita
OECD Broadband subscribers per 100 inhabitants, by technology, June 2007
35
Other
Fibre/LAN
Cable
DSL
30
25
20
Usually Means
Fibre
OECD average
15
10
5
0
Source: OECD
© UCL 2008
How much Fibre?
OECD Broadband subscriptions, by technology,
Percentage of fibre connections in total broadband
subscribers, June 2007
Japan
Korea
Sweden
Slovak Republic
DSL
62%
Denmark
Cable Modem
29%
OECD
Norway
Italy
Fibre + LAN
8%
Other
1%
United States
Czech Republic
Netherlands
Total subscribers: 221 million
Source : OECD
Iceland
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
USA
Homes Conneted
passed with
with
fibre
fibre
in in
thethe
USUS
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
Japan
© UCL 2008
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 Inhabitants 72.75
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)
http://www.lineage.com/
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?
Bandwidth Comparison
Fiber
SuperPON
? bit/s
HDTV plus
DVD Video
Broadband
Narrowband
Other Services
Possibly
Internet
Internet
Simultaneously
Single HDTV
Access
Access
BPON
20Mbit/s
Always On
© UCL 2008
Copper
VDSL
ADSL
PSTN
14Mbit/s
2Mbit/s
56kbit/s
Dial Up
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:
•
•
•
•
Links
Dr Darren Shea
Dr Bob Sutherland
Dr Joseph C Attard
Dr Russell Davey
• FTTH Council
• Ethernet in the First Mile
•
•
•
•
B-FLET
Fast Web
FSAN
Point Topic
www.ftthcouncil.org
www.efmalliance.org/
www.ieee802.org/3/efm/
www.ntt-east.co.jp/product_e/05/
company.fastweb.it/
www.fsanweb.org/
www.point-topic.com