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Very-high-bit-rate digital subscriber line
Very-high-bit-rate digital subscriber line
(VDSL)[1] and very-high-bit-rate digital subscriber line 2 (VDSL2)[2] are digital subscriber line (DSL) technologies providing data transmission faster than asymmetric digital subscriber line (ADSL). VDSL
VDSL
offers speeds of up to 52  Mbit/s downstream and 16  Mbit/s upstream,[3] over a single flat untwisted or twisted pair of copper wires using the frequency band from 25 kHz to 12 MHz.[4] These rates mean that VDSL
VDSL
is capable of supporting applications such as high-definition television, as well as telephone services (voice over IP) and general Internet access, over a single connection. VDSL
VDSL
is deployed over existing wiring used for analog telephone service and lower-speed DSL connections. This standard was approved by the International Telecommunication Union
International Telecommunication Union
(ITU) in November 2001. Second-generation systems (VDSL2; ITU-T G.993.2 approved in February 2006)[5] use frequencies of up to 30 MHz to provide data rates exceeding 100  Mbit/s simultaneously in both the upstream and downstream directions. The maximum available bit rate is achieved at a range of about 300 meters; performance degrades as the local loop attenuation increases.

Contents

1 Development 2 VDSL
VDSL
standards 3 VDSL2

3.1 Vplus

4 Profiles 5 VDSL2 vectoring 6 See also 7 References 8 External links

Development[edit] The concept of VDSL
VDSL
was first published in 1991 through a joint Bellcore- Stanford
Stanford
research study. The study searched for potential successors to the then-prevalent HDSL and relatively new ADSL, which were both 1.5 Mbit/s. Specifically, it explored the feasibility of symmetric and asymmetric data rates exceeding 10 Mbit/s on short phone lines. VDSL2 standard is an enhancement to ITU T G.993.1 that supports asymmetric and symmetric transmission at a bidirectional net data rate up to 400 Mbit/s on twisted pairs using a bandwidth up to 35 MHz. VDSL
VDSL
standards[edit]

DSL SoC

A VDSL
VDSL
connection uses up to seven frequency bands, so one can allocate the data rate between upstream and downstream differently depending on the service offering and spectrum regulations. First generation VDSL
VDSL
standard specified both quadrature amplitude modulation (QAM) and discrete multi-tone modulation (DMT). In 2006, ITU-T standardized VDSL
VDSL
in recommendation G.993.2 which specified only DMT modulation for VDSL2.

Version Standard name Common name Downstream rate Upstream rate Approved on

VDSL ITU G.993.1 VDSL 55 Mbit/s 3 Mbit/s 2001-11-29

VDSL2 ITU G.993.2 VDSL2 100 Mbit/s 100 Mbit/s 2006-02-17

VDSL2-Vplus ITU G.993.2 Amendment 1 (11/15) VDSL2 Annex Q VPlus/35b 300 Mbit/s 100 Mbit/s 2015-11-06

VDSL2[edit]

A VDSL2 cabinet on top of the copper cables cabinet in Italy.

VDSL2 is an enhancement to VDSL. Designed to support the wide deployment of triple play services such as voice, video, data and high-definition television (HDTV) VDSL2 is intended to enable operators and carriers to gradually, flexibly, and cost-efficiently upgrade existing xDSL infrastructure. The protocol is standardized in the International Telecommunication Union telecommunications sector (ITU-T) as Recommendation G.993.2. It was announced as finalized on 27 May 2005,[5] and first published on 17 February 2006. Several corrections and amendments were published from 2007 to 2011.[2] VDSL2 permits the transmission of asymmetric and symmetric aggregate data rates up to 300+  Mbit/s downstream and upstream on twisted pairs using a bandwidth up to 35 MHz. It deteriorates quickly from a theoretical maximum of 350  Mbit/s at source to 100  Mbit/s at 500 m (550 yd) and 50  Mbit/s at 1,000 m (1,100 yd), but degrades at a much slower rate from there, and outperforms VDSL. Starting from 1,600 m (1 mi) its performance is equal to ADSL2+.[6] ADSL-like long-reach performance is one of the key advantages of VDSL2. LR-VDSL2 enabled systems are capable of supporting speeds of around 1–4  Mbit/s (downstream) over distances of 4–5 km (2.5–3 miles), gradually increasing the bit rate up to symmetric 100  Mbit/s as loop-length shortens. This means that VDSL2-based systems, unlike VDSL
VDSL
systems, are not limited to short local loops or MTU/MDUs only, but can also be used for medium range applications. Bonding ( ITU-T G.998.x) may be used to combine multiple wire pairs to increase available capacity, or extend the copper network's reach. Vplus[edit] Vplus is a technology to achieve higher speeds over existing VDSL2 networks. It was developed by Alcatel-Lucent
Alcatel-Lucent
and standardised in November 2015 in ITU G.993.2
ITU G.993.2
Amendment 1 as VDSL2 profile 35b.[2] It promises to deliver speeds of up to 300  Mbit/s downstream and 100  Mbit/s upstream on loops shorter than 250 m. On longer loops, Vplus falls back to VDSL2 17a vectoring performance.[7] Vplus uses the same tone spacing as VDSL2 17a to allow vectoring across Vplus (35b) and 17a lines, and thus mixed deployments and a smooth introduction of Vplus.[7] Profiles[edit] The VDSL1 standard has three bandplans: Annex A (Asymmetric BandPlan), Annex B (Symmetric BandPlan) and Annex C (Fx BandPlan). Annex A and Annex B were formerly called Plan 998 and Plan 997 respectively. VDSL1 Annex C is intended for use in Sweden only and it uses a variable separating frequency between the second downstream band, and the second upstream band. All VDSL1 bandplans has spectrum up to 12 MHz, so the length of the copper loops must be shorter than ADSL.[8][9] The VDSL2 standard defines a wide range of profiles that can be used in different VDSL
VDSL
deployment architectures; in the central office, in the cabinet or in the building for example.[10]

Profile Bandwidth (MHz) Number of downstream carriers Carrier bandwidth (kHz) Maximum aggregate downstream transmit power (dBm) Max. downstream throughput (Mbit/s)

8a 8.832 2048 4.3125 +17.5 50

8b 8.832 2048 4.3125 +20.5 50

8c 8.5 1972 4.3125 +11.5 50

8d 8.832 2048 4.3125 +14.5 50

12a 12 2783 4.3125 +14.5 68

12b 12 2783 4.3125 +14.5 68

17a 17.664 4096 4.3125 +14.5 100

30a 30 3479 8.625 +14.5 200

35b 35.328 8192 4.3125 +17.0 300

VDSL2 vectoring[edit] Vectoring is a transmission method that employs the coordination of line signals for reduction of crosstalk levels and improvement of performance. It is based on the concept of noise cancellation, much like noise-cancelling headphones. The ITU-T G.993.5 standard, "Self-FEXT cancellation (vectoring) for use with VDSL2 transceivers" (2010), also known as G.vector, describes vectoring for VDSL2. The scope of Recommendation ITU-T G.993.5 is specifically limited to the self-FEXT (far-end crosstalk) cancellation in the downstream and upstream directions. The far end crosstalk (FEXT) generated by a group of near-end transceivers and interfering with the far-end transceivers of that same group is cancelled. This cancellation takes place between VDSL2 transceivers, not necessarily of the same profile.[11][12] The American company CenturyLink is currently undergoing an extensive vectoring project for the continental United States, a several-year project started in spring 2016.[13] Although technically feasible, at the moment vectoring is incompatible with local-loop unbundling, but future standard amendments could bring a solution. See also[edit]

FS-VDSL List of device bit rates List of VDSL
VDSL
and VDSL2 deployments

References[edit]

^ " ITU-T Recommendation G.993.1: Very high speed digital subscriber line transceivers (VDSL)". Retrieved 24 July 2016.  ^ a b c " ITU-T Recommendation G.993.2: Very high speed digital subscriber line transceivers 2 (VDSL2)". Retrieved 24 July 2016.  ^ " VDSL
VDSL
Speed". HowStuffWorks.  ^ "G.993.1 (06/04)". ITU.  ^ a b "New ITU Standard Delivers 10x ADSL
ADSL
Speeds: Vendors applaud landmark agreement on VDSL2". News release. International Telecommunication Union. 27 May 2005. Retrieved 22 September 2011.  ^ "Tyrone Fabrication Ltd, Eircom VDSL". Retrieved 8 March 2012.  ^ a b Keith Russell; Paul Spruyt; Stefaan Vanhastel (16 October 2014). "Vplus gets more out of VDSL2 vectoring". Alcatel-Lucent.  ^ https://www.itu.int/ITU-T/worksem/asna/presentations/Session_6/asna_0604_s6_p4_palm.pdf ^ https://www.itu.int/rec/dologin_pub.asp?lang=s&id=T-REC-G.993.1-200406-I!!PDF-E&type=items ^ http://www.itu.int/rec/T-REC-G.993.2-201112-I/en ^ tsbmail (2013-06-14). "G.993.5 : Self-FEXT cancellation (vectoring) for use with VDSL2 transceivers". Itu.int. Retrieved 2013-07-04.  ^ http://www.ericsson.com/res/thecompany/docs/journal_conference_papers/broadband_and_transport/itu-ts_new_g_vector_standard_proliferates_100mbs_dsl.pdf ^ "CenturyLink plans to reach 14M households with 100 Mbps over copper via vectoring FierceTelecom". www.fiercetelecom.com. Retrieved 2017-10-12. 

External links[edit]

InterOperability Laboratory: Knowledge Base InterOperability Laboratory: DSL Testing Services Equipment DSL at Curlie (based on DMOZ)

v t e

Digital subscriber line
Digital subscriber line
(DSL) technologies

Symmetric

ANSI / ETSI / ITU-T

HDSL HDSL2 and HDSL4 SHDSL

Proprietary

IDSL SDSL MSDSL Etherloop HVDL DSL Rings

Asymmetric

ANSI / ETSI / ITU-T

ADSL

ANSI T1.413 Issue 2 G.dmt G.lite

ADSL2

Annex J Annex L Annex M G.lite.bis

ADSL2+

Annex J Annex M

VDSL
VDSL
and VDSL2

deployment

G.fast

Proprietary

ADSL
ADSL
(early CAP variants) RADSL UDSL

Related

Ethernet in the first mile Long Reach Ethernet

v t e

ITU recommendations (standards)

Lists: List of ITU-T V-series recommendations List of ITU letter codes Categories: Category:ITU-R recommendations Category: ITU-T recommendations

G series (ITU-T)

G.114 G.165 G.703 G.704 G.706 G.707 G.709 G.711 G.718 G.719 G.722 G.722.1 G.722.2 G.729.1 G.723 G.723.1 G.726 G.728 G.729 G.783 G.798 G.806 G.811 G.983 G.984 G.987 G.988 G.991.1 G.991.2 G.992.1 G.992.2 G.992.3

Annex J Annex L

G.992.4 G.992.5

Annex M

G.993.1 G.993.2 G.7041 G.7042 G.7043 G.8262 G.9700 / G.9701 G.9960 G.9970 G.9972

H series (ITU-T)

H.222.0 H.225.0 H.235 H.239 H.241 H.245 H.248 H.261 H.262/MPEG-2 Part 2 H.263 H.264/MPEG-4 AVC H.265/MPEG-H HEVC H.320 H.323 H.323
H.323
Gatekeeper H.324 H.450

V series (ITU-T)

V.10 V.11 V.21 V.22 V.23 V.24 V.61 V.70 V.90 V.92

ITU-R

ITU-R 468 noise weighting ITU-R BS.1534-1 ITU-R BT.1304 ITU-R BT.470-6 ITU-R BT.470-7 ITU-R BT.601 ITU-R BT.709 ITU-R BT.2020

See also: All articles be

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