1. xDSL Access work in ITU-T Study Group 15
Presented by:
Paolo ROSA
Counsellor – ITU-T Study Group 15
Optical and other transport networks

2. Contents
About ITU-T SG 15
Access Scenarios
xDSL Access

3. About Study Group 15 (www.itu.int/ITU-T/studygroups/com15)

4. ITU-T Study Group 15 Responsible for studies relating to:
optical and other transport networks, systems and equipment including transmission layer related standards for access, metropolitan and long haul sections of communication networks and relevant G-series Recoimmendations.
Lead Study Group on
Access Network Transport (ANT)
Optical Technology

5. ITU-T SG 15 Access Network Transport - Targeted Work and Standardization Plans
Finalize a Standardization Plan for:
identify existing Recs and standards
identify areas of overlapping
identify any missing area
resolving standardization issues for ANT
investigate needs for new Recommendations (

6. Many a type of access SAT Broadcast Cable UNI Access Network
Home Network
Broadcast
Access Network
Distribution Network
Cable
Longhaul
Copper or F.O.
Copper
F.O.
UNI
SNI

7. ITU-T Study Group 15 Structure http://www. itu
Optical and other transport networks
Peter Wery
ITU-TSB
Counsellor
Paolo Rosa
Working Party 1
Network Access
Andrew Nunn
Working Party 2
Network Signal Proc.
Yushi Naito
Working Party 3
OTN Structure
Stephen Trowbridge
Working Party 4
OTN Technology
Gastone Bonaventura
Working Party 5
Projects and Promotion
Haruo Okamura

8. Access Scenarios

9. Typical Access Network Construction
Central Office
(Exchange)
Street Cabinet
Distribution Network
Feeder Network
Underground
Feed
Overhead
Feed

10. Access technological evolution
G-PON
2.5 Gbit/s
OPTICAL
ACCESS
622 Mbit/s
50 Mbit/s
VDSL
25 Mbit/s
8 Mbit/s
HDSL/
ADSL
2 Mbit/s
640 kbit/s
ISDN
128 kbit/s
Analog
modems
56.6 kbit/s
28.8 kbit/s
9.6 kbit/s
Year
1989
1997
2000
2003

11. Capacity, technologies & availability
ISDN
100 1k
10k
100k 1M
10M
100M 1G
1980
1990
2000
2010
2020
Year
Bit rate per user (
bit/s)
PSTN / Modem
ADSL
SDSL
FTTH
double in 18
mon .
double in 24
N.B. The technology bars show
the introduction, not the end of
the technology
VDSL,
FTTCab
There will never be enough! The bandwidth demand will continue to grow.
Fiber to the home will be necessary sooner or later.
Source Siemens

12. Optical access network architecture (G.983.1)
Optical Distribution Network
FTTH O N U O L T
Fibre
Copper
FTTB/C N T O N U
Fibre
SNI
HOME
Copper
Fibre N T O N U
FTTCab
Access network

13. Access Network Transport Reference Model
Customer Premise
Core Network
Wireless
Phone
Access
Unit
[X]
Service
Function TV PC
Core
Network
[Y] L
XNI
CP1 x
WI1
SNI S1 C1 yn
xxn Q
Access Network (AN)
Network (CPN)
(CN)
CX1

14. Access Network Scenarios – 1 - 2
Scenario 1
Services
a) Voice/Data over telecom network and Video over cable, radio&DSB
b) Voice/Data/Video over 2- way cable
Core Network
Existing Infrastructure (PSTN/N-ISDN)
Access network
1-way Cable Distribution Network
b) 2-way Cable Distribution Network
DSB/terrestrial broadcasting in 1 a)
CPN
Access Unit TV, PC, Phone
Information Flow
a) Video Distribution over 1-way cable network, return via PSTN/ISDN
a) Voice/Data over telecom network and Video over cable
b) Voice/Data/Video over 2-way cable
B-ISDN

15. Access Network scenarios – 3 - 4
Scenario 3
Scenario 4
Services
Voice/Data & Video over ADSL/VDSL
Voice/Data & Video over Fibre Network
Core Network
B-ISDN
Access network
ADSL/VDSL
Fibre (Fibre to the curb/home)
CPN
Access Unit TV, PC, Phone
Information Flow

16. The use of ADSL or VDSL for video bandwidth over copper pairs
Scenario 3
The use of ADSL or VDSL for video bandwidth over copper pairs
Service
Function
{Video}
Core
Network
(N-ISDN)
(B-ISDN)
Access
[ADSL]
[VDSL]
SNI S1 C3
XNI
CP3
CP2 C4
Unit
CPN TV PC
Phone

17. Fibre Access – FTTC - FTTH – FTTB
Scenario 4
Fibre Access – FTTC - FTTH – FTTB
Service
Function
{Video}
{Internet}
Core
Network (B -
ISDN)
Access
[FTTC]
[FTTB]
[FTTH]
SNI C 5 DI CP
3/4 OA 1 6
Unit
FTTH
CPN TV PC
Phone
FTTC
FTTB

18. ANT – Scenario 5 Scenario 5 Services
Scenario 5
Services
a) Wireless Phone Voice/Data over telecom network and Video over cable
b) Voice/Data/Video over Radio
Core Network
N-ISDN or B-ISDN
Access network
Radio/Wireless for Voice/Data - Cable for a) Video
CPN
Access Unit TV, PC, Phone, wireless Phone
Information Flow
2-way wireless

19. The use of Radio in the Local Loop
Scenario 5
The use of Radio in the Local Loop PC
CPN
Access
Unit TV
Wireline
Phone
[CATV]
Service
Function
{Video}
Core
Network
(N-ISDN)
[Wireless]
SNI S 1 C 2
XNI CX 7 CP WI [N -
ISDN]
Wireless

20. ANT Scenarios 6 - 7 Scenario 6 Scenario 7 Services
Scenario 6
Scenario 7
Services
B-ISDN, Internet and Mobile Phone via Satellite
a) Data over Internet
Voice/Video and/or Data over Internet
Core Network
B-ISDN or
Existing (N-ISDN)
a) POTS/FR/ATM
b) ATM Backbone
Access network
Satellite
a) ADSL/VDSL
b) PSTN/ISDN, HFC, PON
c) Fixed wireless Access
CPN
Access Unit: TV, PC, Phone
Information Flow
2-way satellite

21. Scenario 6 - Access using satellites
NT-
function X NI
WI3
XNI
WI4
SA1 L F
ISP port server B S A1
Access Unit
(Gateway
Earth
Station)
Access Network
PSTN or ISDN
Switch A
SNI C1
CP5
CP1
Physical
Presentation C8
Telecommunications
Network SA 1
Phone PC
Video
Access
Unit (s)
CPE
Mobile Satellite
BISDN Satellite

22. Example of Internet Access
Scenario 7
Example of Internet Access
Splitter
Edge
Switch
Service
Function {
Video,etc}
Core
Network (N -
ISDN)
Access
[ADSL]
{Internet}
SNI S 1 C 3 2
XNI CP
Unit
CPN TV PC
Phone

23. xDSL Access

24. xDSL Market & Business Drivers
xDSL technology allows the provision of high-speed Internet access and other broadband services over existing copper telephone lines
Incumbent operators need to exploit their large installed base of copper access lines for broadband deployment
Competing operators can exploit incumbent operators access lines via ‘unbundling’ agreements
Competition:
Digital Cable / Cable Modem
Bi-directional Satellite

25. Typical components of an xDSL system
ADSL2+
ADSL2
ADSL
ADSL lite
HDSL
SHDSL
VDSL
audio/video/data
CUSTOMER PREMISES
CENTRAL OFFICE
xDTU-R
xDTU-C T
SNI
• B-ISDN SN
xDT
xDT
• Non-ATM based SN
(e.g. - video server
- IP router)
U-R
U-C
POTS
POTS
• PSTN/ISDN
Splitter
Splitter
(Subscriber line) SN
xDT
xDSL
Transceiver
DTU-R =
Transceiver Unit- Remote
DTU-C =
Transceiver Unit- Central office =
SN = Service Node
xDSL

26. ITU-T Recommendations on ADSL (1)
G (G.hdsl) - High bit rate Digital Subscriber Line (HDSL) transmission system on metallic local lines.
G (G.dmt) - Asymmetrical Digital Subscriber Line (ADSL) Transceivers.
G (G.lite) - Splitterless Asymmetrical Digital Subscriber Line (ADSL) Transceivers.
G Asymmetric digital subscriber line transceivers - 2 (ADSL2.dmt)
G Splitterless asymmetric digital subscriber line transceivers - 2 (ADSL2.lite)

27. ITU-T Recommendations on ADSL (2)
G – Asymmetric Digital Subscriber Line (ADSL) Transceivers – Extended Bandwidth ADSL2 (ADSL2plus) (Jan ’03)
G Overview of Digital Subscriber Line (DSL Recommendations).
G (G.shdsl) - Single pair High bit rate speed Digital Subscriber Line
G (G.vdsl) - Very high bit-rate Digital Subscriber Line
G.994.1, G and G for tests, management and handshake

28. ADSL2+ ADSL2 ADSL VDSL SHDSL HDSL Video/ voice/ data/copper
G.992.5
Video/ voice/ data/copper
16 Mb/s Down
Up to 800 Kb up
Higher-optional
video capabilities.
Ext reach/BW
ADSL2
With and without splitter – G / 4
8 Mb/s down
800 Kb/s up
Ext reach
ADSL
With and without splitter – G / 2
Voice/data
/copper
Up to 8 Mb/s down
Up to 1.5 Mb/s up
Full use existing copper. Web brows/Voice
VDSL
Symmetric
Asymmetric G.993.1
Video/ voice/ data (V/V/D) over copper
Up to 52 Mb/s down asymm
Up to 26 Mb/s
Symm.
Broadcast video, VoD, internet TV, V/V/D serv
SHDSL
G.991.2
Voice/data/
Video
1/2 pairs
192 K to 4.6 M
Steps 8/16 Kb/s
Poss amplif.
V/V/D Services mainly for business appl.
HDSL
Symmetric G.991.1
Voice data and video
1/2/3 pairs
784 Kbit/s to
2320 Kbit/s

29. G.991.2 (SHDSL) transceivers
Multi-rate transmission technology
duplex operation over only two-wire twisted metallic pairs. (G is for 1-3 pairs).
Symmetric data rates (scalable):
One pair mode: 192 kbit/s to 2312 Kbit/s (single pair mode), in increments of 8 kbit/s, distance from 1.8 up to 6.5 km.
Two-pair mode: 384 kbps to Mbps
Many Manufacturer’s options
4-wire operation
Repeaters, etc.

30. Symmetric and asymmetric data rates
G (VDSL) transceivers
Symmetric and asymmetric data rates
Downstream as high as 5 to 20 Mbit/s
Upstream 1.6, 2.3, 19 Mbit/s or equal to downstream in case of symmetric tx.
American/Japanese/European (Annexes: spectrum bandplans for national regulators)
300 – m. reach

31. G.992.1 - Asymmetric Digital Subscriber Line transceivers
One twisted pair
Payload upstream up to 640 kbit/s
Downstream up to Mbit/s
Simultaneous Voiceband and N-ISDN possible
Line Code - DMT (Discrete MultiTone)

32. G.992.2 - Splitterless asymmetric digital subscriber line transceivers
One twisted pair
Payload downstream up to Mbit/s
Upstream up to 512 kbit/s
Line Code - DMT (Discrete MultiTone)

33. ADSL versus ADSL2 (G x G.992.3)
2nd generation of ADSL with improvements on:
Loop-reach increase for equivalent bit rates (300m)
Higher down/up bit rates
loop diagnostics
Adjustable spectrum shaping during operat/initializ
Power vs traffic control: L0(full),L1, L2
robustness against loop impairments and RFI
Improved multivendor interoperability
Improved application support for an all digital mode of operation and voice over ADSL operation;

34. ADSL 2 Performance Improved initialization Fast Start up : 3 seconds
Downstream: 8 Mbit/s to 15 Mbit/s
Upstream: 800 Kbit/s to 1.5 Mbit/s
Data rate on long distances
Improved initialization
Fast Start up : 3 seconds
Fast return to L0 status full operation (0.5 s)
Additional 256 Kbit/s upstream data rate
In-line filters for home installation
Backwards/Legacy compatibility

35. ADSL 2 plus - G.992.5 Performance
Increase downstream: to 16 Mbit/s
Maybe increase in upstream (Oct. 2003)
Increase reach ( Km)
ADSL + doubles the bandwidth (from 1.1 to 2.2 MHz) with a significant increase of data rates on short loops
Backwards compatibility (needs G.992.3)

36. Things in progress in SG15
Network access
Home networking (data on in-premises wiring)
Refinements & enhancements xDSL
Web-based ANT standardization plan
Optical Transport Network (OTN)
x-WDM and 40Gbit/s signal channels
Optical Cross-Connect and Switch
Fiber characteristics, more channels/fiber
Network Node Interface for OTN
Continue as Lead Study Group on
Access Network Transport
Optical Technology

37. Q.4/15 - Transceivers for customer access and in-premises phone line networking systems on metallic pairs
Current/future work
Revision of Single-pair High-speed DSL (SHDSL) - G.991.2
G Annex C : ADSL in same ISDN cable
G Annex L : reach extended ADSL over POTS
G Annex J : improved Spectral Compatibility with ADSL over ISDN improved Spectral Compatibility with ADSL over ISDN
G Annex L : extended upstream bandwidth
Very high bit rate DSL (VDSL) – G.vdsl.l

38. CONCLUSIONS
An overview on the standardizations activities in ITU-T SG 15 was presented
The most recent standards for access network approved and consented in October 2002 and January 2003 were shown
Access scenarios, current and future work provide information about the next future in the field of access copper network technologies

39. Thank you for your attention!
For further contact, please feel free to contact:
Counsellor for SG 15: Paolo Rosa
Tel: Fax: