digital subscriber line

• digital subscriber line

https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html

Digital subscriber line

1 In telecommunications marketing, the term DSL is widely understood to mean asymmetric digital subscriber

line (ADSL), the most commonly installed DSL technology


Digital subscriber line

1 The bit rate of consumer DSL services typically ranges from 256 kbit/s to 40 Mbit/s in the direction to the customer (downstream),

depending on DSL technology, line conditions, and service-level implementation. In ADSL, the

data throughput in the upstream direction, (the direction to the service provider) is lower, hence the designation of asymmetric service.

In symmetric digital subscriber line (SDSL) services, the downstream and upstream data

rates are equal.


Digital subscriber line - History

1 The theoretical foundations of DSL, like many other forms of communication

technology, can be traced back to Claude Shannon's seminal 1948 paper: A

Mathematical Theory of Communication. An early patent was filed in 1979 for the use of existing telephone wires for both telephones and data terminals that were connected to a remote computer via a

digital data carrier system.



1 Engineers developed higher-speed DSL facilities such as High bit rate Digital Subscriber Line (HDSL) and Symmetric Digital Subscriber Line

(SDSL) to provision traditional Digital Signal 1 (DS1) services over standard

copper pair facilities.



1 A DSL circuit provides digital service



1 Early DSL service required a dedicated dry loop, but when the U.S



1 On the subscriber's end of the circuit, inline low-pass DSL filters (splitters) are installed on each telephone to filter the high-frequency "hiss" that would otherwise be heard, but pass voice (5 kHz and below) frequencies



1 Older ADSL standards delivered 8 Mbit/s to the customer over about 2 km (1.2 mi) of

unshielded twisted-pair copper wire. Newer variants improved these rates. Distances greater than 2 km (1.2 mi) significantly

reduce the bandwidth usable on the wires, thus reducing the data rate. But ADSL loop

extenders increase these distances by repeating the signal allowing the LEC to

deliver DSL speeds to any distance.



1 By 2012 some carriers reported steadily declining numbers of DSL

users.https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html

Digital subscriber line - Basic technology

1 Telephones are connected to the telephone exchange via a local loop,

which is a physical pair of wires



1 For a long time it was thought that it was not possible to operate a

conventional phone-line beyond low-speed limits (typically under 9600

bit/s)



1 The local loop connecting the telephone exchange to most

subscribers has the capability of carrying frequencies well beyond the

3.4 kHz upper limit of POTS



1 One of Lechleider's contributions to DSL was his insight that an

asymmetric arrangement offered more than double the bandwidth

capacity of symmetric DSL



1 Because DSL operates above the 3.4 kHz voice limit, it cannot pass through a load coil



1 The commercial success of DSL and similar technologies largely reflects the advances made in electronics over the

decades that have increased performance and reduced costs even

while digging trenches in the ground for new cables (copper or fiber optic)

remains expensive. Several factors contributed to the popularity of DSL

technology:https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html


1 The two main pieces of equipment are a Digital subscriber line access

multiplexer (DSLAM) at one end and a DSL modem at the other end.



1 A DSL connection can be deployed over existing cable. Such

deployment, even including equipment, is much cheaper than installing a new, high-bandwidth

fiber-optic cable over the same route and distance. This is true both for

ADSL and SDSL variations.



1 In the case of ADSL, competition in Internet access caused subscription fees to drop

significantly over the years, thus making ADSL more economical than dial up access. Telephone companies were pressured into moving to ADSL

largely due to competition from cable companies, which use DOCSIS cable modem

technology to achieve similar speeds. Demand for high bandwidth applications, such as video and file sharing, also contributed to popularize

ADSL technology.



1 Most residential and small-office DSL implementations reserve low

frequencies for POTS service, so that (with suitable filters and/or splitters) the existing voice service continues to operate independent of the DSL

service



1 Once upstream and downstream channels are established, a

subscriber can connect to a service such as an Internet service provider.


Digital subscriber line - Naked DSL

1 A naked DSL (a.k.a. standalone or dry loop DSL) is a way of providing DSL services without a PSTN (analogue

telephony) service. It is useful when the customer does not need the traditional telephony voice service because voice service is received either on top of the DSL services (usually Voice over IP) or

through another network (mobile telephony).



1 It is also commonly called a "UNE" for Unbundled Network Element in the USA and

known as a ULL service (Unconditioned Local Loop) in Australia. It has started

making a comeback in the US in 2004 when Qwest started offering it, closely followed by

Speakeasy. As a result of AT&T's merger with SBC, and Verizon's merger with MCI,

those telephone companies have an obligation to offer naked DSL to consumers.



1 Even without the regulatory mandate, however, many ILECs offer

naked DSL to consumers. The number of telephone landlines in the US dropped from 188 million in 2000

to 115 million in 2010, while the number of cellular subscribers has grown to 277 million (as of 2010). This lack of demand for landline voice service has resulted in the

expansion of naked DSL availability.https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html


1 Naked DSL products are also marketed in some other countries e.g. Australia, New Zealand and

Canada.


Digital subscriber line - Typical setup

1 On the customer side, the DSL Transceiver, or ATU-R, or more

commonly known as a DSL modem, is hooked up to a phone line



1 When the DSL modem powers up it goes through a sync procedure. The actual process varies from modem to

modem but generally involves the following steps:



1 The DSL transceiver checks the connection between the DSL

transceiver and the computer. For residential variations of DSL, this is

usually the Ethernet (RJ-45) port or a USB port; in rare models, a FireWire

port is used. Older DSL modems sported a native ATM interface

(usually, a 25 Mbit/s serial interface). Also, some variations of DSL (such as

SDSL) use synchronous serial connections.



1 The DSL transceiver then attempts to

synchronize with the DSLAM



1 Modern DSL gateways have more functionality and usually go through an

initialization procedure very similar to a PC boot up. The system image is loaded from

the flash memory; the system boots, synchronizes the DSL connection and

establishes the IP connection between the local network and the service provider, using protocols such as DHCP or PPPoE. The system

image can usually be updated to correct bugs, or to add new functionality.



1 The accompanying figure is a schematic of a simple DSL connection (in blue). The right side

shows a DSLAM residing in the telephone company's central office. The left side shows the customer premises equipment with an optional

router. This router manages a local area network (LAN) off of which are connected some number

of PCs. With many service providers, the customer may opt for a modem which contains a wireless router. This option (within the dashed

bubble) often simplifies the connection.


Digital subscriber line - Exchange equipment

1 At the exchange, a digital subscriber line access multiplexer (DSLAM) terminates the DSL circuits and aggregates them, where they are handed off to other networking

transports. In the case of ADSL, the voice component is also separated at this step,

either by a filter integrated in the DSLAM or by a specialized filtering equipment installed

before it. The DSLAM terminates all connections and recovers the original digital

information.


Digital subscriber line - Customer equipment

1 The customer end of the connection consists of a terminal adaptor or "DSL modem". This converts data

between the digital signals used by computers and the voltage signal of a suitable frequency range which is

then applied to the phone line.



1 In some DSL variations (for example, HDSL), the terminal adapter connects directly to the computer via a serial interface, using

protocols such as ethernet or V.35. In other cases (particularly ADSL), it is common for the customer equipment to be integrated

with higher level functionality, such as routing, firewalling, or other application-

specific hardware and software. In this case, the equipment is referred to as a gateway.



1 Most DSL technologies require installation of appropriate filters to separate, or "split", the DSL signal

from the low frequency voice signal. The separation can take place either

at the demarcation point, or with filters installed at the telephone

outlets inside the customer premises. Either way has its practical and

economical limitations.https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html

Digital subscriber line - Protocols and configurations

1 Many DSL technologies implement an Asynchronous Transfer Mode (ATM) layer over the low-level bitstream layer to enable the

adaptation of a number of different technologies over the same link.


Digital subscriber line - Protocols and configurations

1 DSL implementations may create bridged or

routed networks


Digital subscriber line - Transmission methods

1 Transmission methods vary by market, region,

carrier, and equipment.



1 2B1Q: Two-binary, one-quaternary,

used for IDSL and HDSL



1 CAP: Carrierless Amplitude Phase Modulation - deprecated in 1996 for ADSL, used for HDSL



1 TC-PAM: Trellis Coded Pulse Amplitude

Modulation, used for HDSL2 and SHDSL



1 DMT: Discrete multitone modulation, the most common kind, also known

as OFDM (Orthogonal frequency-division multiplexing)


Digital subscriber line - DSL technologies

1 The line-length limitations from telephone exchange to subscriber impose more restrictions on higher data-transmission rates. Technologies such as VDSL provide very high-speed, short-range links as a method of delivering "triple

play" services (typically implemented in fiber to the curb network architectures). Technologies like GDSL can further increase the data rate of DSL. Fiber Optic technologies exist today that allow the conversion of copper based ISDN,

ADSL and DSL over fiber optics.



1 DSL technologies (sometimes summarized

as xDSL) include:



1 ISDN digital subscriber line (IDSL), uses ISDN based technology to provide data flow that is slightly higher than dual channel ISDN.



1 High-bit-rate digital subscriber line (HDSL / HDSL2), was the first DSL

technology that used a higher frequency spectrum of copper,

twisted pair cables.



1 Symmetric digital subscriber line (SDSL / SHDSL), the volume of data

flow is equal in both directions.



1 Single-pair high-speed digital subscriber line (G.SHDSL), a

standardized replacement for early proprietary SDSL.



1 Asymmetric digital subscriber line (ADSL), the volume of data flow is greater in one direction than the

other.



1 Asymmetric digital subscriber line 2

(ADSL2), an improved version of

ADSLhttps://store.theartofservice.com/the-digital-subscriber-line-toolkit.html


1 Asymmetric digital subscriber line 2 plus (ADSL2+), A version of ADSL2

that doubles the data rates by using twice the spectrum.



1 Asymmetric digital subscriber line plus plus (ADSL++), technology

developed by Centillium Communications (Centillium has

been acquired by TranSwitch Corp.) for the Japanese market that extends

downstream rates to 50 Mbit/s by using spectrum up to 3.75 MHz.



1 Rate-adaptive digital subscriber line (RADSL), designed to increase range and noise tolerance by sacrificing up

stream speed



1 Very-high-bit-rate digital subscriber line 2 (VDSL2), an improved version of VDSL



1 Uni-DSL (Uni digital subscriber line or UDSL), technology developed by Texas Instruments, backwards

compatible with all DMT standards



1 Gigabit digital subscriber line

(GDSL), based on binder MIMO technologies.



1 Universal high-bit-rate digital subscriber line (UHDSL) using fiber optics. Developed in 2005 by RLH

Industries, Inc. Converts HDSL-1, 2 or 4 copper service into fiber optic

HDSL service.



1 Internet Protocol subscriber line (IPSL), developed by Rim

Semiconductor in 2007, allowed for 40 Mbit/s using 26 AWG copper

telephone wire at a 5,500 ft (1,700 m) radius, 26 Mbit/s at a 6,000 ft (1,800 m) radius. The company

operated until 2008.


Digital subscriber line - Further reading

1 Dave Burstein (2002). DSL. John Wiley and Sons.

ISBN 0-471-08390-9. pp 53–86


Digital subscriber line - Further reading

1 Digital Subscriber Line. International Engineering Consortium. 2001. ISBN 978-0-

933217-95-9.


Internet access - Digital subscriber line (DSL, ADSL, SDSL, and VDSL)

1 Digital Subscriber Line (DSL) service provides a connection to the Internet

through the telephone network. Unlike dial-up, DSL can operate using

a single phone line without preventing normal use of the

telephone line for voice phone calls. DSL uses the high frequencies, while the low (audible) frequencies of the

line are left free for regular telephone communication. These frequency

bands are subsequently separated by filters installed at the customer's

premises.



1 With a symmetric digital subscriber line (SDSL), the downstream and upstream data

rates are equal.



1 Very-high-bit-rate digital subscriber line (VDSL or VHDSL, ITU G.993.1) is

a digital subscriber line (DSL) standard approved in 2001 that

provides data rates up to 52 Mbit/s downstream and 16 Mbit/s upstream

over copper wires and up to 85 Mbit/s down- and upstream on

coaxial cable. 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 physical connection.



1 VDSL2 (ITU-T G.993.2) is a second-generation version and an

enhancement of VDSL. Approved in February 2006, it is able to provide

data rates exceeding 100 Mbit/s simultaneously in both the upstream

and downstream directions. However, the maximum data rate is

achieved at a range of about 300 meters and performance degrades as

distance and loop attenuation increases.


Broadband Internet access - Digital subscriber line (DSL, ADSL, SDSL, and VDSL)

1 to the customer), hence the designation of asymmetric.[http://whirlpool.net.au/wiki/?

tag=ADSL_Theory ADSL Theory], Australian broadband news and information, Whirlpool,

accessed 3 May 2012 With a symmetric digital subscriber line (SDSL), the

downstream and upstream data rates are equal.[http://docwiki.cisco.com/wiki/Digital_Subscriber_Line#SDSL SDSL], Internetworking

Technology Handbook, Cisco DocWiki, 17 December 2009, accessed 3 May 2012


Bell Sympatico - Digital Subscriber Line (DSL)

1 Bell's digital subscriber line (DSL) services are based on ADSL, ADSL2+ and VDSL2

technology



1 On May 8, 2012, Bell has simplified its FTTN DSL lineup to offer only

three plans. The service offerings are as follows:



1 In regions where FTTN is unavailable, a plan called Bell Internet 5 is

available. It is similar to the Fibe 5/1 plan, but uses traditional DSL instead

of FTTN DSL. Upload speeds are limited to 800 kbit/s.


Rate-Adaptive Digital Subscriber Line

1 'Rate-adaptive digital subscriber line' ('RADSL') is a variation of

asymmetric digital subscriber line (ADSL) technology. In RADSL the DSL

modem adjusts the upstream (networking)|upstream Bandwidth (signal processing)|bandwidth to

create a wider frequency band for the downstream traffic. Using this

technique the line is more tolerant of errors caused by Noise (physics)|

noise and signal loss.


Rate-Adaptive Digital Subscriber Line

1 As the frequency is adjusted, the upstream bandwidth may be

markedly decreased if there is a large amount of line noise or signal degradation - this may reduce the upstream bit rate to as little as 64 kbit/s - the same speed as a single

ISDN B channel.


Very high speed digital subscriber line 2

1 'Very-high-bit-rate digital subscriber line 2' ('VDSL2') is an access

technology that exploits the existing infrastructure of copper wires that

were originally deployed for plain old telephone service|traditional telephone service as a way of

delivering very high speed internet access


Very high speed digital subscriber line 2 - Description

1 VDSL2 is the newest and most advanced standard of digital

subscriber line (DSL) broadband wireline communications. Designed to support the wide deployment of triple play (telecommunications)|triple play services such as voice,

video, data, high-definition television (HDTV) and interactive gaming,

VDSL2 is intended to enable operators and carriers to gradually, flexibly, and cost-efficiently upgrade

existing xDSL infrastructure.



1 The protocol is standardized in the International Telecommunication Union telecommunications sector

(ITU-T) as Recommendation G.993.2. It has been announced as finalized on 27 May 2005, and first published

on 17 February 2006. Several corrections and amendments have

been published in 2007 through 2011.



1 VDSL2 is an enhancement to very-high-bit-rate digital subscriber line

(VDSL), Recommendation G.993.1. It permits the transmission of asymmetric and symmetric

aggregate data rates up to 200Mbit/s downstream (networking)|downstream and upstream

(networking)|upstream on twisted pairs using a bandwidth up to

30MHz.https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html


1 VDSL2 deteriorates quickly from a theoretical maximum of 250Mbit/s at source to 100Mbit/s at and 50Mbit/s at , but degrades at a much slower rate from there, and outperforms

VDSL. Starting from its performance is equal to ADSL2+.



1 Asymmetric digital subscriber line|ADSL-like long reach performance is one of the key advantages of VDSL2.

LR-VDSL2 enabled systems are capable of supporting speeds of

around 1–4Mbit/s (downstream) over distances of 4–5km (2.5–3miles),

gradually increasing the bit rate up to symmetric 100Mbit/s as loop-length shortens. This means that

VDSL2-based systems, unlike VDSL1 systems, are not limited to short

local loops or MTU/MDUs only, but can also be used for medium range

applications.



1 Channel bonding|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.


Very high speed digital subscriber line 2 - Profiles

1 The standard defines a wide range of profiles that can be used in different VDSL deployment architectures; in

the central office, in the cabinet or in the building for example.


Very high speed digital subscriber line 2 - Vectoring

1 Vectoring is a transmission method that employs the coordination of line

signals for reduction of Crosstalk (electronics)|crosstalk levels and

improvement of performance


Very high speed digital subscriber line 2 - Vectoring

1 Although technically feasible at the moment vectoring is incompatible

with local-loop unbundling but future standard amendments could bring a

solution.


Asymmetric digital subscriber line

1 It does this by utilizing frequencies that are not used by a voice

telephone call.ANSI T1.413-1998 Network and Customer Installation

Interfaces – Asymmetric Digital Subscriber Line (ADSL) Metallic

Interface


Asymmetric digital subscriber line

1 At the telephone exchange the line generally terminates at a digital

subscriber line access multiplexer (DSLAM) where another frequency splitter separates the voice band Signal (electronics)|signal for the conventional Telecommunications

network|phone network. Data carried by the ADSL are typically routed over

the telephone company's data network and eventually reach a conventional Internet Protocol

network.


Asymmetric digital subscriber line - Overview

1 ADSL differs from the less common symmetric digital subscriber line (SDSL). Bandwidth (computing)|

Bandwidth (and bit rate) is greater toward the customer premises

(known as downstream (networking)|downstream) than the reverse

(known as upstream (networking)|upstream).



1 This is why it is called asymmetric. Providers usually market ADSL as a

service for consumers to provide Internet access in a relatively passive mode: able to use the higher speed direction for the download from the

Internet but not needing to run servers that would require high

speed in the other direction.



1 There are both technical and marketing reasons why ADSL is in

many places the most common type offered to home users



1 The marketing reasons for an asymmetric connection are that,

firstly, most uses of internet traffic will require less data to be uploaded

than downloaded


Asymmetric digital subscriber line - Operation

1 Currently, most ADSL communication is Duplex (telecommunications)|full-duplex



1 With commonly deployed ADSL over Plain old telephone service|POTS

(Annex A), the band from 26.075kHz to 137.825kHz is used for upstream

communication, while 138kHz – 1104kHz is used for downstream

communication



1 The total maximum capacity derived from summing the bits-per-bins is reported by DSL modems and is

sometimes termed sync rate



1 The choices the DSL modem make can also be either conservative, where the modem chooses to

allocate fewer bits per bin than it possibly could, a choice which makes

for a slower connection, or less conservative in which more bits per bin are chosen in which case there is

a greater risk case of error should future signal-to-noise ratios

deteriorate to the point where the bits-per-bin allocations chosen are too high to cope with the greater

noise present



1 Vendors may support usage of higher frequencies as a proprietary

extension to the standard. However, this requires matching vendor-

supplied equipment on both ends of the line, and will likely result in

crosstalk problems that affect other lines in the same bundle.



1 There is a direct relationship between the number of channels available

and the throughput capacity of the ADSL connection. The exact data

capacity per channel depends on the modulation method used.



1 ADSL initially existed in two versions (similar to VDSL), namely Carrierless Amplitude Phase Modulation|CAP and

Orthogonal frequency-division multiplexing|DMT. CAP was the de

facto standard for ADSL deployments up until 1996, deployed in 90 percent

of ADSL installations at the time. However, DMT was chosen for the first ITU-T ADSL standards, G.992.1 and G.992.2 (also called G.dmt and

G.lite respectively). Therefore all modern installations of ADSL are

based on the DMT modulation scheme.


Asymmetric digital subscriber line - Interleaving and fastpath

1 ISPs (rarely, users) have the option to use Bit-interleaving|interleaving of packets to counter the effects of burst noise on the telephone line


Asymmetric digital subscriber line - Interleaving and fastpath

1 Fastpath connections have an interleaving depth of 1, that is one packet is sent at a time


Asymmetric digital subscriber line - Installation problems

1 ADSL deployment on an existing plain old telephone service (POTS)

telephone line presents some problems because the DSL is within a frequency band that might interact

unfavourably with existing equipment connected to the line



1 In the early days of DSL, installation required a technician to visit the premises



1 Commonly, microfilters are only low-pass filters, so beyond them only low frequencies (voice signals) can pass



1 A side effect of the move to the self-install model is that the DSL signal can be degraded, especially if more

than 5 voiceband (that is, POTS telephone-like) devices are

connected to the line



1 DSL signals may be degraded by older telephone lines, surge protectors, poorly-designed

microfilters, Repetitive Electrical Impulse Noise, and by long telephone

extension cords


Asymmetric digital subscriber line - Transport protocols

1 * STM-1|Synchronous Transport Module (STM), which allows the transmission of frames of the

Synchronous Digital Hierarchy (SDH)


Asymmetric digital subscriber line - Transport protocols

1 In home installation, the prevalent transport protocol is ATM. On top of ATM, there are multiple possibilities of additional layers of protocols (two

of them are abbreviated in a simplified manner as PPPoA or PPPoE), with the all-important

Transmission Control Protocol|TCP/Internet Protocol|IP at

layers 4 and 3 respectively of the OSI model providing the connection to

the Internet.


High bit rate digital subscriber line 2

1 'High bit rate digital subscriber line 2' ('HDSL2') is a standard developed by

the American National Standards Institute (ANSI) Committee T1E1.4

and published in 2000 as 'ANSI T1.418-2000'


Symmetric digital subscriber line

1 'Symmetric digital subscriber line' ('SDSL') can have two

meanings:



1 * In the wider sense it is a collection of Internet access technologies

based on Digital subscriber line|DSL that offer symmetric Bandwidth

(computing)|bandwidth Upstream (networking)|upstream and

downstream (computer science)|downstream, including IDSL, HDSL,

HDSL2, G.SHDSL, and the SDSL variant below. It is considered the

opposite of asymmetric digital subscriber line (ADSL) technologies where the upstream bandwidth is

lower than the downstream bandwidth.



1 * In the narrow sense SDSL is a particular proprietary and non-standardized DSL variant that

supports data only on a single line and does not support analog calls,

see below.


Symmetric digital subscriber line - Proprietary SDSL technology

1 SDSL is a rate-adaptive digital subscriber line (DSL) variant with T-

carrier|T1/E-carrier|E1-like data rates (T1: 1.544 Data rate units#Megabit per second|Mbit/s, E1: 2.048 Mbit/s). It runs over one pair of copper wires, with a maximum range of . It cannot

co-exist with a conventional voice service on the same pair as it takes

over the entire bandwidth.https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html

Symmetric digital subscriber line - Standardization efforts

1 SDSL is a Proprietary protocol|proprietary technology that was never standardized. As such it usually only interoperates with

devices from the same vendor. It is the predecessor of single-pair high-

speed digital subscriber line|G.SHDSL which was standardized in February

2001 by International Telecommunication Union|ITU-T with

recommendation G.991.2.https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html


1 SDSL is often confused with G.SHDSL and High bit rate Digital Subscriber Line|HDSL;



1 in Europe, G.SHDSL was standardized by ETSI using the name

'SDSL'. This ETSI variant is compatible with the ITU-T G.SHDSL standardized regional variant for

Europe.



1 As there is a standardised successor available, SDSL installations today

are considered Legacy system|legacy. Most new installations use

G.SHDSL equipment instead of SDSL.


Symmetric digital subscriber line - Target audience

1 SDSL typically falls between ADSL and T1/E1 in price and was mainly

targeted at small and medium businesses who don't need the

service guarantees of Frame Relay or the higher performance of a leased

line.


Multi-rate symmetric digital subscriber line

1 'Multi-rate symmetric DSL' ('MSDSL') is a Proprietary protocol|proprietary, non-standardized digital subscriber

line technology with a maximum distance of 8,800m (29,000ft). It is

capable of multiple transfer rates, as set by the Internet service provider, typically based on the service and/or price. The maximum speed in both

directions is about 2 Mbit/s.https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html

Multi-rate symmetric digital subscriber line - Technology

1 MSDSL is based on 2B1Q transmission with a capacity of

2.32 Mbit/s


High-bit-rate digital subscriber line

1 Successor technology to HDSL includes HDSL2|HDSL2 and HDSL4,

proprietary Symmetric digital subscriber line|SDSL, and G.SHDSL.


High-bit-rate digital subscriber line - Standardization

1 HDSL was developed for T1 service at 1.544 Mbit/s by the American

National Standards Institute (ANSI) Committee T1E1.4 and published in

February 1994 as 'ANSI Technical Report TR-28'


High-bit-rate digital subscriber line - Comparison to legacy T1

1 Legacy T-carrier|T1 carriers use the line codes alternate mark inversion

(AMI) and more recently B8ZS


High-bit-rate digital subscriber line - Comparison to legacy T1

1 Legacy T1 required repeaters every 35dB of attenuation, equivalent to , depending on conductor gauge and

other circumstances. Originally marketed as non-repeated T1, HDSL

increased the reach to on a American Wire Gauge|AWG24 local

loop. To enable longer HDSL lines, up to four repeaters can be used for a

reach of .https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html

High-bit-rate digital subscriber line - Comparison to other DSL variants

1 Unlike ADSL, HDSL operates in the baseband and does not allow plain old telephone service|POTS or ISDN to coexist on the wire same pairs. Unlike ADSL, the proprietary SDSL,

and G.SHDSL, HDSL is not rate adaptive: the line rate is always

1.544Mbit/s or 2.048Mbit/s. Lower rates at multiples of 64kbit/s are

offered to customers by using only a portion of the DS0 channels in the

DS1 signal, referred to as channelized T1/E1.


High-bit-rate digital subscriber line - Comparison to other DSL variants

1 HDSL gave way to new symmetric DSL technologies, HDSL2|HDSL2 and

HDSL4, the proprietary SDSL, and G.SHDSL. HDSL2 offers the same

data rate over a single pair of copper; it also offers longer reach, and can work over copper of lower

gauge or quality. SDSL is a multi-rate technology, offering speeds ranging from 192kbit/s to 2.3Mbit/s, using a

single pair of copper.https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html

Single-pair high-speed digital subscriber line

1 'Symmetrical high-speed digital subscriber line' ('SHDSL') is a form of digital subscriber line (DSL), a data communications technology that enables faster data transmission

over copper telephone lines than a conventional voiceband modem can

provide



1 SHDSL features symmetrical data rates in both the upstream (networking)|upstream and downstream (networking)|

downstream directions, from 192 kbit/s to 2,312 kbit/s of payload (computing)|payload in 8 kbit/s increments for one pair and 384 kbit/s to 4,624 kbit/s in 16 kbit/s increments for two pairs of wires



1 An optional extended SHDSL mode allows symmetric data rates up to 5,696 kbit/s on one pair, using the

32-TC-PAM modulation scheme specified in Annexes F and G. Using M-pair bonding, up to four pairs of wires may be bonded to yield data rates up to M×5,696 kbit/s. In this

way, a single SHDSL interface using four bonded wire pairs can carry up

to 22,784 kbit/s.https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html


1 The SHDSL payload may be either 'clear channel' (unstructured), T-

carrier|T1 or E-carrier|E1 (full rate or fractional), multiple ISDN Basic Rate

Interface (BRI), Asynchronous Transfer Mode (ATM) cells or Ethernet packets. A 'dual bearer' mode allows

a mixture of two separate streams (e.g. T1 and ATM) to share the SHDSL

bandwidth.https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html

Single-pair high-speed digital subscriber line - SHDSL standards

1 The industry standard for SHDSL is defined by ITU-T recommendation G.991.2. This was first published in February 2001. SHDSL equipment is also known by the standard's draft name of G.SHDSL. Major updates to G.991.2 were released in December 2003. Equipment conforming to the

2003 version of G.991.2 is often referred to by the standard's draft

name of G.SHDSL.bis or just SHDSL.bis. The updated G.991.2

features:



1 * Optional support for up to four copper pair connections

(M-pair)



1 * Optional extensions to allow user data rates up to 5696 kbit/s per pair,

described in Annexes F and G



1 * Optional support for dynamic rate repartitioning, allowing flexible change of the SHDSL data rate

without service interruption, described in Annex E.10.3



1 * New payload definitions including Ethernet packet transfer mode (PTM), described in

Annex E.11



1 SHDSL supersedes the older HDSL symmetric DSL technology defined in

ITU-T G.991.1. SHDSL is largely replaced by VDSL2 because of

greater bandwidth, less interference and greater utilization.



1 In Communications in Europe|Europe, a variant of SHDSL was standardized by the European Telecommunications Standards Institute (ETSI) using the

name 'SDSL'. This ETSI variant is compatible with the ITU-T SHDSL standardized regional variant for Europe and must not be confused with the usage of the term SDSL in

North America to refer to symmetric digital subscriber line.


Very-high-bit-rate digital subscriber line

1 'Very-high-bit-rate digital subscriber line' ('VDSL' or 'VHDSL') is a digital subscriber line (DSL) technology

providing data transmission faster than ADSL over a single flat

untwisted or twisted pair of copper wires (up to 52Mbit/s Downstream

(networking)|downstream and 16Mbit/s Upstream (networking)|

upstream), and on coaxial cable (up to 85Mbit/s down- and upstream)

using the frequency band from 25kHz to 12MHz


Very-high-bit-rate digital subscriber line

1 Second-generation systems (very high speed digital subscriber line 2|VDSL2; ITU-T G.993.2 approved in

February 2006) use frequencies of up to 30MHz to provide data rates

exceeding 100Mbit/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 loop attenuation increases.


Very-high-bit-rate digital subscriber line - Development

1 The concept of VDSL was first published in 1991 through a joint

Bellcore-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.https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html

Very-high-bit-rate digital subscriber line - VDSL standards

1 VDSL uses up to 7 different frequency bands, which enables

customization of data rate between upstream and downstream

depending on the service offering and spectrum regulations. First

generation VDSL standard specified both quadrature amplitude

modulation (QAM) and discrete multi-tone modulation (DMT). In 2006, ITU-

T standardized VDSL in recommendation G.993.2 which

specified only DMT modulation for VDSL2.


ISDN digital subscriber line

1 'ISDN Digital Subscriber Line' ('IDSL') uses Integrated Services Digital

Network|ISDN-based digital subscriber line technology to provide

a data communication channel across existing copper telephone

lines at a rate of 144 kbit/s, slightly higher than a bonded dual channel

ISDN connection at 128kbit/s



1 IDSL is not available in all countries.



1 ISDN digital subscriber line (IDSL) is a cross between ISDN and xDSL. It is

like ISDN in that it uses a single-wire pair to transmit full-duplex data at 128 kbit/s and at distances of up to RRD range. Like ISDN, IDSL uses a

2B1Q line code to enable transparent operation through the ISDN U

interface. Finally, the user continues to use existing Customer-premises equipment|CPE (ISDN BRI terminal adapters, bridges, and routers) to

make the CO connections.



1 The big difference is from the carrier's point-of-view. Unlike ISDN, IDSL does not connect through the voice switch. A new piece of data

communications equipment terminates the IDSL connection and

shunts it off to a router or data switch. This is a key feature because

the overloading of central office voice switches by data users is a

growing problem for telcos. https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html


1 The limitation of IDSL is that the customer no longer has access to

ISDN signaling or voice services. But for Internet service providers, who do

not provide a public voice service, IDSL is an interesting way of using

Plain old telephone service|POTS dial service to offer higher-speed Internet access, targeting the embedded base of more than five million ISDN users

as an initial market.https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html

Asymmetric Digital Subscriber Line 2 Plus

1 'ITU G.992.5' (also referred to as 'ADSL2+' and 'G.DMT.bis+') is an International Telecommunication Union standard for asymmetric digital subscriber line (ADSL)

broadband Internet access. The standard has a maximum theoretical

download speed of '24 Data rate units|Mbit/s'. Utilizing

ITU_G.992.5_Annex_M upload speeds of 3.3 Data rate units|Mbit/s can be

achieved.


Asymmetric Digital Subscriber Line 2 Plus - Technical information

1 ADSL2+ extends the capability of basic Asymmetric digital subscriber line|ADSL by doubling the number of

downstream (computer science)|downstream Channel

(communications)|channels. The data rates can be as high as 24Data rate units|Mbit/s downstream and up to

1.4Mbit/s upstream depending on the distance from the digital subscriber

line access multiplexer|DSLAM to the customer's premises.



1 ADSL2+ is capable of doubling the frequency band of typical ADSL

connections from 1.1MHz to 2.2MHz. This doubles the downstream data

rates of the previous G.992.3|ADSL2 standard (which was up to 12Mbit/s), and like the previous standards will

degrade from its peak bitrate after a certain distance.



1 Also ADSL2+ allows port bonding. This is where multiple ports are physically

provisioned to the end user and the total bandwidth is equal to the sum of all

provisioned ports. So if 2 lines capable of 24Mbit/s were bonded the end result would be a connection capable of 48

Mbit/s download and twice the original upload speed. Not all DSLAM vendors have implemented this functionality.


Asymmetric Digital Subscriber Line 2 Plus - Finland

1 ADSL2+ and triple play solutions are offered by the major DSL providers

(including Elisa Oyj and TeliaSonera) in certain areas. Usually maximum

download speed when using ADSL2+ is 24Mbit/s and upload speed

1Mbit/s. Also Nebula, SuomiCom, DNA, KPO, Finnet and many other ISPs provide ADSL2+ connections.


Asymmetric Digital Subscriber Line 2 Plus - Greece

1 As of January 2007, most DSL Internet service provider|providers started offering ADSL2+ from their

proprietary network.



1 * [http://www.algonet.gr/ Algonet] (Website in Greek language|Greek only) – Offers double play services

([http://www.algonet.gr/site/main.php?mode=home.pagemid=9pid=1

algonet DualPlay]) – Up to 24Data rate units|Mbit/s downstream

(computer science)|downstream, 1Data rate units|Mbit/s upstream

(networking)|upstream.https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html


1 * [http://www.cyta.gr CYTA Hellas] – Double Play Services (2play) – Up to

24Mbit/s downstream, 1Mbit/s upstream.



1 * Forthnet [http://www.forthnet.gr/templates/por

talHomeEn.aspx?c=10002035] – Offers Double Play services

([http://www.forthnet.gr/templates./corporateProductsDetails2.aspx?

c=10009640 Forthnet ADSL Economy] and

[http://www.forthnet.gr/templates/corporateProductsDetails2.aspx?

c=10009586 Forthnet 2play]) – Up to 24Mbit/s downstream, 1Mbit/s

upstream.



1 * Hellas On-Line|Hellas Online (http://www.hol.gr) – Offers double

play services ([http://www.hol.gr/default.asp?

pID=23ct=3itmID=50 hol double-play]) – Up to 24Mbit/s downstream,

1Mbit/s upstream.



1 * [http://www.netone.gr/ Net One] – Offers double play services

([http://www.netone.gr/index.php?option=com_contenttask=viewid=26Itemid=68lang=iso-8859-7 Net One

Για το Σπίτι]) – Up to 24Mbit/s downstream, 1Mbit/s upstream.



1 * On Telecoms [http://www.ontelecoms.com/on/chan

geLanguageAction.do?tab=nulllanguage=enlastPath=/main.jsp?null ] – Offers triple play

services ([http://www.ontelecoms.com/on/residential/index.jsp?category=allinone

Όλα σε Ένα – All in One]) – Up to 24Mbit/s downstream.



1 * OTE [http://www.ote.gr/] – Offers Double play

([http://oteshop.ote.gr/storefront/en/for-the-home/conn-x-adsl/conn-x-talk/prodconn_x_talk.html conn-x

TALK]) – Up to 24Mbit/s downstream, 1Mbit/s upstream.



1 * [http://www.tellas.gr/default.asp?langid=2 Tellas] (a subsidiary of Wind Hellas) – Offers double play services ([http://www.tellas.gr/default.asp?siteID=1pageid=5langid=2 Tellas

Double Play Best Price, Tellas Double Play No Limit] and

[http://www.tellas.gr/default.asp?siteID=1pageID=4langID=2 Tellas

Double Play Unlimited]) – Up to 24Mbit/s downstream, 1Mbit/s

upstream.



1 * Vivodi [http://www.vivodi.gr/] – Offers triple play services

(Vivodi#Triple Play|cableTV [http://www.cabletv.gr/]) – Up to 24Mbit/s downstream, 1Mbit/s

upstream.



1 * Vodafone Greece|Vodafone – Offers double play services

([http://www.vodafone.gr/portal/client/cms/viewCmsPage.action?

pageId=2453request_locale=en Vodafone Double Play Plus]) – Up to

24Mbit/s downstream, 1Mbit/s upstream.


Asymmetric Digital Subscriber Line 2 Plus - Hungary

1 In Hungary, since mid-2006, multiple telecom companies have started

offering ADSL2+ services. As of July 2007, T-Com, the biggest Hungarian

ISP, is silently upgrading its customers' ADSL connections to ADSL2+, although with no speed

changes.


Asymmetric Digital Subscriber Line 2 Plus - Guatemala

1 Telgua in Guatemala has deployed services across Guatemala City and nearby zones, its deploying ADSL2+ in other cities and now operates the

largest ADSL2+ network in the country. Deliver speeds capacity up

to 5Mbit/s downstream and 1024kbit/s upstream and increasing.


Asymmetric Digital Subscriber Line 2 Plus - Bangladesh

1 BTCL – Bangladesh Telecommunications Company

Limited Provides Up to 2 Mbit/sdownstream with its ADSL2+

Broadband Internet connection. Although there are new internet

service providers such as qubee and banglalion who are also offering up

to 2 M/bits/p/s. Other than that several other network providers such

as Grameenphone, Aktel, Airtel, Citycell (zoom) and Banglalink.


Asymmetric Digital Subscriber Line 2 Plus - India

1 [http://www.bsnl.co.in BSNL] offers ADSL2+ Broadband under the

DataOne brand name, with advertised speeds up to 24Mbit/s

(download)


Asymmetric Digital Subscriber Line 2 Plus - Turkey

1 *ADSL2+ ([http://www.turktelekom.com.tr Türk Telekom]): Download speed up to 16

Mbit/s and upload 1 Mbit/s for unlimited connection.



1 *ADSL2+ ([http://www.smileadsl.com Smile adsl]): Download speed up to

16Mbit/s and upload 1Mbit/s for unlimited connection.



1 *ADSL2+ ([http://www.biriadsl.com Biri adsl]): Download speed up to 10Mbit/s and upload 1Mbit/s for

unlimited connection.



1 *ADSL2+ ([http://www.doping.com.tr Doping adsl]): Download speed up to

16Mbit/s and upload 1Mbit/s for unlimited connection.



1 *ADSL2+ ([http://www.superonline.net Turkcell Superonline]): Download speed up to

8Mbit/s and upload 1Mbit/s for unlimited connections.



1 *ADSL2+ ([http://www.turk.net TurkNet]): Download speed up to 8Mbit/s and upload 1Mbit/s for

unlimited connection.


Powerline Digital Subscriber Line

1 'Power-line communication' ('PLC') carries data on a conductor that is also used simultaneously for AC electric power transmission or

electric power distribution to consumers. It is also known as

'power-line carrier', 'power-line digital subscriber line' (PDSL), 'mains communication', 'power-line

telecommunications', or 'power-line networking' (PLN).



1 A wide range of power-line communication technologies are needed for different applications, ranging from home automation to

Internet access which is often called broadband over power lines (BPL)



1 A number of difficult technical problems are common between

wireless and power-line communication, notably those of

spread spectrum radio signals operating in a crowded environment. Radio interference, for example, has

long been a concern of amateur radio groups.


Powerline Digital Subscriber Line - Basics

1 Power-line communications systems operate by adding a modulated

carrier signal to the wiring system. Different types of power-line

communications use different frequency bands. Since the power distribution system was originally intended for transmission of AC

power at typical frequencies of 50 or 60 Hertz|Hz, power wire circuits have only a limited ability to carry higher

frequencies. The propagation problem is a limiting factor for each type of power-line communications.



1 The main issue determining the frequencies of power-line

communication is laws to limit interference with radio services



1 Data signaling rate|Data rates and distance limits vary widely over many power-line communication

standards


Powerline Digital Subscriber Line - Long haul, low frequency

1 Utility companies use special coupling capacitors to connect radio transmitters to the power-frequency

AC conductors



1 On some powerlines in the former Soviet Union, PLC-signals are not fed into the high voltage line, but in the

ground conductors, which are mounted on insulators at the pylons.



1 While utility companies use microwave and now, increasingly, fiber optic cables for their primary system communication needs, the

power-line carrier apparatus may still be useful as a backup channel or for

very simple low-cost installations that do not warrant installing fiber

optic lines.



1 power-line carrier communication (PLCC) is mainly used for

telecommunication, tele-protection and tele-monitoring between

electrical substations through power lines at high voltages, such as 110

kV, 220 kV, 400 kV. The major benefit is the union of two

applications in a single system, which is particularly useful for

monitoring electric equipment and advanced energy demand

management|energy management techniques (such as OpenADR and

OpenHAN).



1 The modulation generally used in these system is amplitude

modulation. The carrier frequency range is used for audio signals,

protection and a pilot frequency. The pilot frequency is a signal in the audio range that is transmitted

continuously for failure detection.



1 The voice signal is compressed and filtered into the 300Hz to 4000Hz range, and this audio frequency is

mixed with the carrier frequency. The carrier frequency is again filtered,

amplified and transmitted. The transmission power of these HF carrier frequencies will be in the

range of 0 to +32 Decibel|dbW. This range is set according to the distance

between substations.https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html


1 PLCC can be used for interconnecting private

branch exchanges (PBXs).



1 To sectionalize the transmission network and protect against failures,

a wave trap is connected in series with the power (transmission) line



1 A coupling capacitor is used to connect the transmitters and

receivers to the high voltage line. This provides low impedance path for carrier energy to HV line but blocks

the power frequency circuit by being a high impedance path. The coupling capacitor may be part of a capacitor voltage transformer used for voltage

measurement.https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html


1 power-line carriers may change its transmission system from analog to digital to enable Internet Protocol devices. Digital power-line carrier (DPLC) was developed for digital

transmission via power lines. DPLC has the required quality of bit error

rate characteristics and transmission ability such as transmitting

information from monitored electric-supply stations and images.



1 power-line carrier systems have long been a favorite at many utilities

because it allows them to reliably move data over an infrastructure

that they control. Many technologies have multiple applications. For

example, a communication system bought initially for automatic meter reading can sometimes also be used

for load control or for demand response applications.



1 A PLC carrier repeating station is a facility, at which a power-line

communication (PLC) signal on a Electric power transmission|

powerline is refreshed. Therefore



1 the signal is filtered out from the powerline, Demodulation|

demodulated and Modulation|modulated on a new Carrier wave|

carrier frequency, and then reinjected onto the powerline again.

As PLC signals can carry long distances (several 100 kilometres),

such facilities only exist on very long power lines using PLC equipment.



1 PLC is one of the technologies used for

automatic meter reading



1 In a one-way (inbound only) system, readings bubble up from end devices

(such as meters), through the communication infrastructure, to a master station which publishes the

readings. A one-way system might be lower-cost than a two-way system, but also is difficult to reconfigure should the operating environment

change.https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html


1 In a two-way system (supporting both outbound and inbound),

commands can be broadcast out from the master station to end devices (meters) – allowing for

reconfiguration of the network, or to obtain readings, or to convey

messages, etc


Powerline Digital Subscriber Line - Home control (narrowband)

1 Power-line communications technology can use the electrical power wiring within a home for home automation: for example, remote control of lighting and

appliances without installation of additional control wiring.



1 Typically home-control power-line communication devices operate by

modulating in a carrier wave of between 20 and 200 Hertz|kHz into

the household wiring at the transmitter



1 The universal powerline bus, introduced in 1999, uses pulse-position modulation (PPM). The physical layer method is a very different scheme than the X10.

LonTalk, part of the LonWorks home automation product line, was

accepted as part of some automation standards.


Powerline Digital Subscriber Line - Low-speed narrow-band

1 Narrowband power-line communications began soon after electrical power supply became

widespread. Around the year 1922 the first carrier frequency systems began to operate over high-tension

lines with frequencies of 15 to 500kHz for telemetry purposes, and this continues. Consumer products

such as baby alarms have been available at least since 1940.



1 In the 1930s, ripple carrier signalling was introduced on the medium (10–20 kV) and low voltage (240/415V)

distribution systems.



1 For many years the search continued for a cheap bi-directional technology

suitable for applications such as remote meter reading



1 Since the mid-1980s, there has been a surge of interest in using the

potential of digital communications techniques and digital signal

processing. The drive is to produce a reliable system which is cheap

enough to be widely installed and able to compete cost effectively with

wireless solutions. But the narrowband powerline

communications channel presents many technical challenges, a

mathematical channel model and a survey of work is available.



1 Applications of mains communications vary enormously, as would be expected of such a widely

available medium



1 Control and telemetry applications include both 'utility side'

applications, which involves equipment belonging to the utility

company up to the domestic meter, and 'consumer-side' applications which involves equipment in the

consumer's premises



1 A project of EDF, France includes demand management, street lighting control, remote metering and billing, customer specific tariff optimisation,

contract management, expense estimation and gas applications

safety.



1 There are also many specialised niche applications which use the

mains supply within the home as a convenient data link for telemetry.

For example, in the UK and Europe a TV audience monitoring system uses

powerline communications as a convenient data path between

devices that monitor TV viewing activity in different rooms in a home

and a data concentrator which is connected to a telephone modem.


Powerline Digital Subscriber Line - Medium-speed narrow-band

1 The Distribution Line Carrier (DLC) System technology used a frequency range of 9 to 500kHz with data rate

up to 576 kbit/s.



1 A project called Real-time Energy Management via Powerlines and

Internet (REMPLI) was funded from 2003 to 2006 by the European

Commission.



1 In 2009, a group of vendors formed the PoweRline Intelligent Metering

Evolution (PRIME) alliance. As delivered, the physical layer is OFDM,

sampled at 250kHz, with 512 differential phase shift keying

channels from 42–89kHz. Its fastest transmission rate is 128.6

kilobits/second, while its most robust is 21.4 kbit/s. It uses a convolutional

code for error detection and correction. The upper layer is usually

IPv4.



1 In 2011, several companies including distribution network operators

(Électricité de France#Distribution network .28RTE and ErDF.29|ERDF,

Enexis), meter vendors (Sagemcom, LandisGyr) and chip vendors (Maxim

Integrated, Texas Instruments, STMicroelectronics) founded the G3-

PLC Alliance to promote G3-PLC technology


Powerline Digital Subscriber Line - Transmitting radio programs

1 Sometimes PLC was used for transmitting radio programs over

powerlines. When operated in the AM radio band, it is known as a carrier

current system.


Powerline Digital Subscriber Line - High-frequency (≥ 1 MHz)

1 High frequency communication may (re)use large portions of the radio

spectrum for communication, or may use select (narrow) band(s),

depending on the technology.


Powerline Digital Subscriber Line - Home networking (LAN)

1 Power line communications can also be used in a home to interconnect home computers and peripherals, and home entertainment devices

that have an Ethernet port. Powerline adapter sets plug into power outlets and establish an Ethernet connection using the existing electrical wiring in the home. (Power strips with filtering may absorb the power line signal.) This allows devices to share data

without the inconvenience of running dedicated network cables.


Powerline Digital Subscriber Line - Home networking (LAN)

1 The most widely deployed powerline networking standard is from the HomePlug

Powerline Alliance


Powerline Digital Subscriber Line - Broadband over power line

1 Broadband over power line (BPL) is a system to transmit two-way data over existing AC MV (medium voltage) electrical distribution wiring, between transformers, and AC LV (low voltage)

wiring between transformer and customer outlets (typically 110 to 240V). This avoids the expense of a dedicated network of wires for data communication, and the expense of

maintaining a dedicated network of antennas, radios and routers in wireless network.



1 BPL uses some of the same radio frequencies used for over-the-air

radio systems. Modern BPL employs frequency-hopping spread spectrum

to avoid using those frequencies actually in use, though early pre-2010 BPL standards did not. The

criticisms of BPL from this perspective are of pre-OPERA, pre-

1905 standards.https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html


1 The BPL OPERA standard is used primarily in Europe by ISPs. In North

America it is used in some places (Washington Island, WI, for instance)

but is more generally used by electric distribution utilities for smart

meters and load management.



1 Since the ratification of the IEEE 1901 LAN standard and its

widespread implementation in mainstream router chipsets, the

older BPL standards are not competitive for communication

between AC outlets within a building, nor between the building and the transformer where MV meets LV

lines.https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html

Powerline Digital Subscriber Line - Automotive uses

1 Power-line technology enables in-vehicle network communication of

data, voice, music and video signals by digital means over direct current

(DC) battery power-line



1 Prototypes are successfully operational in vehicles, using

automotive compatible protocols such as CAN-bus, Local Interconnect Network|LIN-bus over power line (DC-

LIN) and [DC-bus].[http://www.yamar.com/DC-

LIN.html DC-LIN Over Power line]



1 LonWorks power line based control has been used for an HVAC system in a production

model bus.



1 The SAE J1772 committee developing standard connectors for plug-in electric

vehicles proposes to use power line communication between the vehicle, off-

board charging station, and the smart grid, without requiring an additional pin;

SAE International|SAE and the IEEE Standards Association are sharing their draft standards related to the smart grid

and vehicle electrification.


Powerline Digital Subscriber Line - Standards

1 Within homes, the HomePlug AV and IEEE 1901 standards specify how, globally,

existing AC wires should be employed for data purposes. The IEEE 1901 includes

HomePlug AV as a baseline technology, so any IEEE 1901 products are fully

interoperable with HomePlug AV, HomePlug GreenPHY or the forthcoming HomePlug

AV2 specification (under development now and expected to be approved in Q1 2011).


Powerline Digital Subscriber Line - Standards organizations

1 Several competing organizations have developed specifications,

including the HomePlug Powerline Alliance, Universal Powerline

Association (defunct) and HD-PLC Alliance. On December 2008, the ITU-

T adopted Recommendation G.hn/G.9960 as a standard for high-

speed powerline, coax and phoneline communications. The National

Energy Marketers Association was also involved in advocating for

standards.


Powerline Digital Subscriber Line - Standards organizations

1 In July 2009, the IEEE P1901 working group approved its draft standard for

broadband over power lines


Internet in the United Kingdom - Digital subscriber line (DSL)

1 Asymmetric digital subscriber line (ADSL) was introduced to the UK in

trial stages in 1998 and a commercial product was launched in 2000. In the United Kingdom, most

telephone exchange|exchanges, local loops and backhaul

(telecommunications)|backhauls are owned and managed by BT

Wholesale, who then wholesale connectivity via Internet service

providers, who generally provide the connectivity to the Internet, support,

billing and value added services (such as web hosting and email).


Internet in the United Kingdom - Digital subscriber line (DSL)

1 Some exchanges, numbering under 1000, have been upgraded to

support Symmetric Digital Subscriber Line|SDSL products


Very-high-bitrate digital subscriber line - VDSL standards

1 A 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 standard specified both quadrature amplitude modulation

(QAM) and discrete multi-tone modulation (DMT). In 2006, ITU-T standardized VDSL in recommendation G.993.2 which specified

only DMT modulation for VDSL2.


TekSavvy - Digital subscriber line (DSL) Internet

1 TekSavvy offers DSL service using Bell lines in Ontario and Quebec, Telus lines in Alberta and British Columbia, and Bell Aliant lines in

New Brunswick, Newfoundland and Labrador|Newfoundland, Nova Scotia

and Prince Edward Island.



1 Before the summer of 2011, TekSavvy could only access Bell's

Performance speed tier, with maximum speeds of 5Mb/s



1 On March 20, 2013, TekSavvy added a 50 Mbit/s tier, the fastest FTTN tier that Bell

started offering a month earlier. TekSavvy offers the same FTTN DSL speeds available from Bell. The only exceptions are that for

the slowest plans, 6 Mbit/s regular DSL and 7 Mbit/s FTTN DSL is sold by TekSavvy instead

of Bell's 5 Mbit/s plans. All plans offer a choice between 300 GB or unlimited Internet access, while the 6 and 7 Mbit/s plans offer a

lower-priced 75 GB option.


Internet in Bulgaria - Digital subscriber lines (DSL)

1 Asymmetric digital subscriber line (ADSL) technology was introduced in Bulgaria after the privatization of the

state monopoly Bulgarian Telecommunications Company (BTC)

in 2004


Internet in Croatia - Digital Subscriber Line (DSL)

1 In Croatia ADSL was introduced in 2000 by the German owned operator

T-Com, formerly HT (Hrvatski telekom, meaning Croatian telecom)



1 * Iskon Internet (owned by T-HT) - part of the network is locally based (in major urban areas), and partly

services are run by local loop over T-Com copper lines, TriplePlay plan

Iskon.TV, but only on the local part of the network for now.



1 * Optima Telekom d.d. - part of the network is locally based (in major

urban areas), and partly services are run by local loop over T-Com copper lines, TriplePlay plan is called OptiTV. The reach for TriplePlay is extended

gradually.



1 * Metronet telekomunikacije d.d. - has TriplePlay


Digital subscriber line access multiplexer

1 A 'digital subscriber line access multiplexer' ('DSLAM', often

pronounced dee-slam) is a network device, often located in telephone exchanges, that connects multiple

customer digital subscriber line (DSL) interfaces to a high-speed digital communications channel using

multiplexing techniques.


Digital subscriber line access multiplexer - Path taken by data to DSLAM

1 # Customer premises: DSL modem terminating the ADSL, SHDSL or VDSL circuit and providing LAN

interface to a single computer or LAN segment.



1 # Local loop: the telephone company wires from a customer to the

telephone exchange or to a serving area interface, often called the last

mile (LM).



1 #* Main distribution frame (MDF): a wiring rack that connects outside

subscriber lines with internal lines. It is used to connect public or private

lines coming into the building to internal networks. At the telco, the MDF is generally in proximity to the Utility tunnel|cable vault and not far

from the telephone switch.



1 #* DSL filter|xDSL filters: DSL filters are used in the telephone exchange to split voice from data signals. The voice signal can be routed to a Plain old telephone service|POTS provider or left unused whilst the data signal is routed to the ISP DSLAM via the

HDF (see next entry).



1 #* Handover distribution frame (HDF): a distribution frame that

connects the last mile provider with the service provider's DSLAM



1 #* DSLAM: a device for DSL service. The DSLAM port where the

subscriber local loop is connected converts analog electrical signals to data traffic (Upstream (networking)|

upstream traffic for data upload) and data traffic to analog electrical

signals (Downstream (networking)|downstream for data download).


Digital subscriber line access multiplexer - Role of the DSLAM

1 The DSLAM equipment collects the data from its many modem ports and

aggregates their voice and data traffic into one complex composite

signal via multiplexing. Depending on its device architecture and setup, a

DSLAM aggregates the DSL lines over its Asynchronous Transfer Mode (ATM), frame relay, and/or Internet Protocol network (i.e., an IP-DSLAM

using PTM-TC [Packet Transfer Mode - Transmission Convergence])

protocol(s) stack.



1 The aggregated traffic is then directed to a telco's Backbone

network|backbone switch, via an access network (AN), also called a Network service provider|Network Service Provider (NSP), at up to 10

Gbit/s data rates.



1 The DSLAM acts like a network switch since its functionality is at Data link layer|Layer 2 of the OSI

model



1 A DSLAM may or may not be located in the telephone exchange, and may also serve multiple data and voice customers within a neighborhood

serving area interface, sometimes in conjunction with a digital loop carrier.

DSLAMs are also used by hotels, lodges, residential neighborhoods,

and other businesses operating their own private telephone exchange.



1 In addition to being a data switch and multiplexer, a DSLAM is also a large collection of modems. Each modem on the aggregation card

communicates with a single subscriber's DSL modem. This

modem functionality is integrated into the DSLAM itself instead of being

done via an external device like a 20th-century voiceband modem.



1 Like traditional voice-band modems, a DSLAM's integrated DSL modems

are usually able to probe the line and to adjust themselves to electronically or digitally compensate for forward

echoes and other bandwidth-limiting factors in order to move data at the maximum possible connection rate.



1 This compensation capability also takes advantage of the better

performance of balanced line DSL connections, providing capabilities

for LAN segments longer than physically similar unshielded twisted

pair (UTP) Ethernet connections, since the balanced line type is

generally required for its hardware to function correctly


Digital subscriber line access multiplexer - Bandwidth versus distance

1 The following is a rough guide to the relation between wire distance (based on 0.40 mm copper and

Asymmetric Digital Subscriber Line 2 Plus|ADSL2+ technology) and

maximum data rate


Digital subscriber line access multiplexer - Hardware details

1 Customers connect to the DSLAM through ADSL modems or DSL Router

(computing)|routers, which are connected to the Public switched

telephone network|PSTN network via typical unshielded twisted pair

telephone lines. Each DSLAM has multiple aggregation cards, and each

such card can have multiple Computer port (hardware)|ports to

which the customers' lines are connected. Typically a single DSLAM aggregation card has 24 ports, but

this number can vary with each manufacturer.



1 The most common DSLAMs are housed in a telephone company|telco-grade chassis, which are

supplied with (nominal) 48 volts direct current|DC. Hence a typical DSLAM setup may contain power

converters, DSLAM chassis, aggregation cards, cabling, and

upstream links.



1 On the upstream trunk (ISP) side many early DSLAMs used

Asynchronous Transfer Mode|ATM—and this approach was standardized

by the DSL Forum—with Gigabit Ethernet support appearing

sometime later. Today, the most common upstream links in these DSLAMs use Gigabit Ethernet or

multi-gigabit Optical fiber|fiber optic links.


Digital subscriber line access multiplexer - IP-DSLAM

1 Internet Protocol|IP-DSLAM stands for Internet Protocol Digital Subscriber

Line Access Multiplexer. User traffic is mostly IP based.


Digital subscriber line access multiplexer - IP-DSLAM

1 Traditional 20th century DSLAMs used Asynchronous Transfer Mode

(ATM) technology to connect to upstream ATM routers/switches


For More Information, Visit:

• https://store.theartofservice.com/the-digital-subscriber-line-toolkit.html

The Art of Servicehttps://store.theartofservice.com






digital subscriber line

Documents

digital subscriber line

linetoolk slide

digital service https

line conditions

traditional digital

digital data carrier

dsl circuit

installed dsl technology