New ADSL standards: ADSL2 and ADSL2 plus. ADSL - what is it? Operating principle, maximum speed, advantages and disadvantages of ADSL technology ADSL connection speed

New ADSL standards - ADSL2 and ADSL2 plus (Rebuild)

In July 2002, the International Telecommunications Union (ITU) finalized the development of two new ADSL standards (G.992.3 and G.992.4), collectively referred to as "ADSL2". In January 2003, at the same time that the number of users of the first generation ADSL chipsets exceeded 30 million, G.992.5 officially joined the ADSL2 family under the name ADSL2plus (or ADSL2+).
Providers and users played a key role in the development of the ADSL2 standard, as their feedback led the ITU to include new standard many different add-ons that increase performance and functionality. As a result, ADSL2 will be more user-friendly and more profitable for providers, and promises to replicate the success of ADSL for the rest of the decade.
ADSL2 (ITU G.992.3 and G.992.4) contains many innovations aimed at improving network performance and interoperability and supporting new applications, services and installation options. Changes include performance improvements, speed adaptation, diagnostics, and more.
ADSL2plus (ITU G.992.5) doubles data reception capacity, reaching speeds of 20 Mbit/s on telephone lines 1500 meters long. Solutions based on ADSL2plus will mainly be multimodal, allowing interaction with both ADSL2 chipsets and ADSL and ADSL2plus.
ADSL2plus will allow providers to configure their networks to support advanced services such as flexible video with a single solution for both short and long distances. It includes all ADSL2 capabilities while maintaining interoperability with existing equipment. This way, providers can upgrade their equipment gradually rather than changing the whole thing all at once.

Speed ​​and range improvements

ADSL2 was specifically designed to improve ADSL speed and range, mainly to achieve better performance on long, noisy lines. ADSL2 can achieve downstream and downstream speeds of up to 12 Mbps and 1 Mbps, respectively, depending on range and other factors. This was made possible by using more effective methods modulation, reducing the amount of overhead information, increasing coding efficiency, and the use of advanced signal processing algorithms.
Modulation efficiency in ADSL2 is enhanced by the combined use of 4D, 16-phase trellis and 1-bit quadrature modulation. This allows you to achieve higher speeds on long lines with a low signal-to-noise ratio.
ADSL2 systems use less overhead thanks to a frame with a programmable number of overhead bits. Therefore, unlike the first generation ADSL, where the service bits in the frame were fixed and consumed 32 kbit/s from useful information, the number of service bits in a frame can vary from 4 to 32 kbit/s. In first-generation ADSL systems on long lines, where the information transmission speed is already low (for example, 128 kbit/s), 32 kbit/s (or more than 25% of the total speed) is fixedly allocated for service information. On ADSL2 systems, this value can be reduced to 4 kbit/s, which will add an additional useful 28 kbit/s to the throughput.
On long lines, where transmission rates are typically low, ADSL2 allows for greater Reed Solomon coding efficiency. This is possible thanks to improvements in frames that increase flexibility and programmability when creating codewords.
In addition, the initialization mechanism contains many improvements that increase the transmission speed of ADSL2 systems:

1. power reduction on both sides, allowing to reduce crosstalk;
2. detecting the placement of a pilot signal by the receiver, eliminating interference from AM radio;
3. carrier detection, used by the receiver for initialization messages to eliminate AM radio interference and other nuisances;
4. improvements in channel identification for receiver and transmitter configuration;
5. muting the signal during initialization to enable RF interference suppression circuitry.

Figure 1 shows the speed and range of ADSL2 compared to first generation ADSL. On long lines, ADSL2 will give a speed increase of 50 kbit/s for incoming and outgoing streams. This speed increase is achieved on 180m longer lines, equivalent to a 6% increase in coverage area.

Diagnostics

The difficulty of identifying the source of problems has often been a barrier to using ADSL. To facilitate troubleshooting, advanced diagnostic capabilities have been added to ADSL2 transceivers. They are designed to identify faults during and after installation, monitor performance during operation and to facilitate upgrades.
To identify and troubleshoot problems, ADSL2 transceivers can measure line noise, attenuation, and signal-to-noise ratio at both ends of the line. The results of these measurements can be collected using a special diagnostic mode, even if the line quality is not sufficient to establish a normal ADSL connection.
In addition, ADSL2 can provide real-time performance monitoring, showing line quality and noise levels at both ends of the line. This information is converted software and can then be used by the provider to monitor the quality of the ADSL connection and prevent failures. It can also be used to determine opportunities to provide the user with a faster connection.

Energy Improvements

First generation ADSL transceivers were active 24/7, whether they were in use or not. Considering that the number of installed ADSL modems can reach several millions, a huge amount of energy could be saved if the modems could enter sleep mode. This would also save energy for ADSL transceivers operating in small control rooms where heating is a problem. To address these issues, ADSL2 power management includes two modes designed to reduce overall power consumption when servicing a user's "always on" connection. These modes include:

L2 low consumption mode. This mode performs statistical energy conservation on the ADSL transceiver from the central station (ATU-C) by quick login and entering a low power mode based on Internet traffic going through the ADSL connection.
L3 low consumption mode. This mode implements overall power saving for both the ATU-C and the remote ADSL transceiver (ATU-R) by entering sleep mode while the connection is not in use for an extended period of time.
L2 mode is one of the most important innovations of the ADSL2 standard. ADSL2 transceivers can enter and exit L2 mode based on the Internet traffic carried over the connection. When the user downloads large files, the transceiver operates at full power (also called L0 mode) to provide maximum download speed. When Internet traffic decreases, for example when a user is reading a long text, ADSL2 systems can enter L2 low-power mode, in which the transmission speed is greatly reduced and, accordingly, the overall power consumption is reduced.
While in L2 mode, the ADSL2 system can instantly return to L0 mode and increase data transfer speed as soon as the user initiates file downloads. The L2 input/output mechanisms and the resulting data rate adaptations operate without any service interrupts or even a single bit error and are thus invisible to the user.
L3 power mode is a sleep mode and is used when the user is not using the network. When switched, no traffic is transferred to it. When the user needs the network again, ADSL transceivers only need about three seconds to reinitialize and establish communication.

Speed ​​adaptation

Telephone wires are bundled together into multi-pair cables containing 25 or more twisted pairs. As a result, electrical signals from one pair can be coupled to adjacent pairs in the cable (Figure 3). This phenomenon is called "crosstalk" and can interfere with ADSL data transmission. Moreover, changes in the level of crosstalk in the cable can lead to a break in the ADSL connection.

To solve these problems, ADSL2 adapts data rates in real time. This innovation, called Seamless Rate Adaption (SRA), allows ADSL2 systems to change the data rate of the connection on the fly without service interruptions or bit errors. To do this, ADSL2 detects changes in the communication channel - for example, when a local AM radio station turns off its transmitter at night - and changes the transmission speed transparently to the user.
SRA is based on the separation of modulation layer and frame layer in ADSL2 systems. Thanks to this, the modulation layer can change the data rate parameters without modifying the parameters at the frame level, which would cause the modems to lose frame synchronization and, therefore, uncorrectable bit errors or restart the system. SRA uses advanced ADSL2 sophisticated online reconfiguration (OLR) procedures to seamlessly change the data transfer rate of a connection.
The protocol used for SRA works as follows:
1. The receiver monitors the signal-to-noise ratio for the channel and determines that it needs to adapt the data rate for the prevailing conditions.
2. The receiver sends a message to the transmitter to initiate a change in baud rate. This message contains all the necessary transmission parameters for the new speed. These parameters include the number of modulated bits and the transmit power for each subchannel of a multi-carrier ADSL system.
3. The transmitter sends a "Sync Flag" signal, which is used as a marker to determine the exact time that the new transmit parameters will be used.
4. The "Sync Flag" signal is detected by the receiver, and now the receiver and transmitter are switched to a different speed mode without any system interruption.

Combining to achieve higher speeds

A common requirement for providers is the ability to provide different quality of services to different users. Data transfer speeds can be significantly increased by simultaneous use of several telephone lines. To support this capability, ADSL2 supports the af-phy-0086.001 “Inverse Multiplixing for ATM (IMA)” standard, designed for traditional ATM architectures. Using IMA, ADSL2 chipsets can combine two or more copper pairs into a single ADSL connection. The result is much greater flexibility in incoming data flow rates (Figure 4).

IMA defines new level, which lies between the physical layer and the ATM layer. On the transmitter side, this sublayer, called the IMA sublayer, receives a single ATM stream from the ATM layer and distributes it among multiple physical sublayers. On the receiver side, the IMA sublayer receives ATM parts from multiple physical sublayers, assembles them into a single ATM stream, and sends them to the ATM layer.
The IMA sublayer defines IMA framing, protocols, and control functions that are used to perform the above operations when the physical sublayers are bit-errored, asynchronous, or have varying latency. To work under these conditions, the IMA standard also requires modifications to some standard ADSL physical layer features, such as the receiver discarding empty or corrupted packets. ADSL2 supports a special IMA mode designed for compatibility with ADSL.

Channelization and Multichannel Voice over DSL (CVoDSL)

ADSL2 supports the ability to split the bandwidth into multiple channels with different characteristics for various applications. For example, ADSL2 can simultaneously support voice applications that require low latency, but can high frequency errors and information applications for which latency is not so important, but the lowest possible error rate is important. Channelization also provides support for CVoDSL, a method of transparently transporting derived lines of TDM voice traffic over DSL. CVoDSL reserves 64 kbps channels from DSL bandwidth (Figure 5) to deliver PCM DS0 from the DSL modem to a remote central office terminal, similar to a conventional telephone system. Next, the access equipment transmits voice DS0 via PCM directly to the circuit switch.

Some additional benefits

ADSL2 also supports some other important features listed below.
Improved compatibility. Microcircuits from different manufacturers are compatible and can easily work together.
Quick start. ADSL2 supports quick start, which reduces initialization time from more than 10 seconds (required for ADSL) to less than 3 seconds.
Fully digital mode. ADSL2 also allows you to use the voice range for data transmission, adding another 256 kbit/s to the outgoing channel. This is a rather attractive opportunity for office use, since, as a rule, in offices, voice and data lines are separated and large outgoing channel bandwidth is required.
Support for package-based services. ADSL2 includes a PTM-TC layer (Packet Mode Transmission TransConvergence layer) allowing packet-based services (such as Ethernet) to be transmitted over ADSL2

DSL2plus

ADSL2plus was developed by the ITU in January 2003 and is included in the ADSL standards as G.992.5. The ADSL2plus recommendation doubles the downstream speed on lines shorter than 1500 meters.
While the first two members of the ADSL2 family of standards set downlink bandwidths to 1.1 MHz and 552 kHz respectively, ADSL2plus sets upstream bandwidth to 2.2 MHz. The result is a significant increase in incoming channel speed on shorter lines (see Figure 8). The speed of the outgoing ADSL2plus channel depends on the quality of the connection and is around 1 Mbit/s.

ADSL2plus can also be used to reduce crosstalk. To do this, it can use tones between 1.1 MHz and 2.2 MHz, masking the incoming channel frequencies around 1.1 MHz. This can be useful when ADSL terminals are connected to a central location via the same cable in the same order as the connections to customers' homes (Fig. 9). Crosstalk from remote terminal lines on a line from a central location can significantly reduce data rates on a line from a central location.

ADSL2plus can solve this problem by using frequencies below 1.1 MHz from the central location to the remote terminal and frequencies between 1.1 MHz and 2.2 MHz from the remote terminal to the user's home. This will eliminate most crosstalk between services and protect the line speed from the central office.

ADSL is a data transmission technology based on the asymmetric distribution of bandwidth between incoming and outgoing traffic. It is implemented using citywide analogue telephone communication, which includes a subscriber terminal (ADSL modem) and a multiplexer installed on the service provider's PBX.

The principle of operation of the technology is as follows. A standard telephony line for voice transmission uses a frequency range from 0.3 to 3.4 kHz. In order to avoid any interference when operating the telephone line for its intended purpose in ADSL technology, the lower bandwidth threshold is set at 26 kHz, and the upper, in accordance with communication capacities and data transfer speed requirements, is set at 1.1 MHz. In this case, the entire band is divided into two sectors. The first is intended for downward flow of information and works in frequency range 26-138 kHz. The second sector is intended for the incoming stream and operates in the range from 138 kHz to 1.1 MHz. This frequency division allows voice calls to be made without interrupting data exchange over the same line. In some cases, it becomes necessary to install an additional frequency filter, the so-called splitter, on the subscriber side. This is due to the possibility of extraneous noise in the telephone line and, as a result, leads to incorrect operation of this or that equipment.

Equipment required for ADSL networks

In order to access the World Wide Web using telephone communications, you need three types of equipment:

• Required for installation:
• ASAM. ATM subscriber access multiplexer, which is installed on the side of the Internet access service provider.
• ADSL modem. It is installed at the premises of an MGTS subscriber and is the end point of access to the network.
• Filter low frequencies. It is an optional equipment and is installed at the subscriber’s premises only in cases where the line is planned to be used not only for Internet access, but also for making voice calls at the same time.

ADSL and ADSL2+ structure

ADSL network construction technology involves data transmission via an existing city telephone line. The implementation goes as follows:

• At the telephone exchange of the Internet access service provider, in parallel with its equipment, an Internet access switch is installed.
• These two installations are then combined into one line using a frequency divider.
• After this, the signal is transmitted via one carrier directly to the subscriber’s premises.
• On the subscriber side, another frequency divider is installed (necessary if access to the Internet will be used in parallel with the direct assignment of the line).
• The last devices in this scheme are telephones and an access point (modem from manufacturers such as D-link, ASUS, ZTE, ZyXEL and others).

Connecting a subscriber using ADSL2+ technology is slightly different. The first point is the ability to transmit a signal using a coaxial cable, which allows the provision of services using networks designed to connect subscribers to television broadcasting services. The second difference is the data transfer speed. It differs on the downlink and is up to 20-25 Mbit/s.

Already created recently ADSL modems, which, despite everything, are designed for connection to a telephone line and support ADSL2+ communication standards and now the data transfer speed depends only on the capabilities of the service provider’s equipment.

ADSL option, which has both an asymmetric transmission mode with a throughput of up to 1.536 Mbit/s from the network to the user and up to 384 kbit/s from the user to the network, and symmetrical - with a speed of up to 384 kbit/s in both directions. The ITU-T has introduced the designation ADSL G.Lite for this version of ADSL. Uses the same modulation scheme as ADSL, but without a crossover filter on the subscriber side, which leads to a decrease in the capacity of the ADSL G.Lite line due to increased noise levels. ADSL G.Lite technology allows data transmission over longer lines than ADSL, is easier to install and has a lower cost, which makes it attractive to the mass user.

ADSL2

ADSL2 technology appeared in 2002, and ADSL2+ in 2003. The ADSL2 standard was specifically developed to increase the bit speed and range of ADSL. ADSL2 downstream and upstream bit rates can reach 12 and 1 Mbps, respectively, by increasing modulation efficiency, reducing framing congestion, and providing advanced signal processing algorithms.

ADSL2+ technology doubles (compared to ADSL2) the bandwidth from 1.1 to 2.2 MHz. The maximum bit rates over the telephone line increase to 20 Mbit/s over a distance of up to 1500 m. The “upstream” bit rate of ADSL2+ is approximately 1 Mbit/s depending on the line condition. ADSL2+ chipsets are compatible with ADSL and ADSL2.

ADSL2+ allows operators to upgrade their networks to support an expanded range of services, such as flexible video delivery in a single solution for short and long haul lines. All the features and performance benefits of the ADSL2 specification will be retained while ensuring interoperability with legacy (legacy) equipment. ADSL2+ technology can be used to reduce crosstalk as it allows only tones between 1.1 and 2.2 MHz to be used by masking downstream frequencies below 1.1 MHz.

ADSL2 and ADSL2+ technologies are modifications of the “classic” ADSL technology. They were developed taking into account the increased requirements of providers and end users. In ADSL2 and ADSL 2+, with almost the same transmission range as in ADSL, speeds are increased to 12 and 25 Mbit/s, respectively. In addition, an adaptive speed change function has been implemented. Thanks to these changes, it became possible to support a large number of new applications and additional services (video, multimedia, etc.).

Despite the maximum speed limit of 24 Mbit/s, a number of providers continue to use ADSL technology. The editors of WiNetwork have prepared their rating of routers operating according to this standard. The presented models are reliable and relatively easy to set up, so they are suitable for home use.

5th place in the ranking: NETGEAR DGN2200

Not very popular, but a productive ADSL router with wide functionality. The device comes with a stand that allows you to install it not only horizontally, but also vertically. The NETGEAR web interface has convenient system configurations and built-in help system. It allows you to figure out the connection even when the Internet is still configured, and the user does not have the opportunity to clarify information about the meaning of the parameters.

The setup wizard will help you set the necessary parameters step by step, without the need to understand advanced parameters. The disadvantages of the DGN2200 model, which worsen its place in the ranking, include the inability to limit the speed of certain network clients by MAC address. The router heats up quite strongly, but it does not affect the operation of the device. The body of this model is made of glossy plastic, which retains fingerprints.

Among the built-in utilities, it is worth noting a convenient traffic counter with the ability to display warnings. In addition to the main WiFi, a guest network is also supported. Its clients work with access point isolation (AP isolation), so they cannot exchange data with each other, but have unrestricted access to the Internet. The guest password is set separately from the main WiFi password.

Note! The router is also suitable for horizontal or vertical wall installation. In this case, the stand must be removed, since the fastenings are on the underside of the case.

4th place in the ranking: D-Link DSL-2650U/RA

Standards Compliant ADSL Router wireless network 802.11 bgn. It does not have external antennas, but is equipped with a powerful built-in antenna. The vertical placement of the board in this ADSL router reduces its heating. This allows you to extend the service life and increase the reliability of the device. On the left side of the case there is a USB port, on the back there is an RJ-11 input and four WAN connectors. There are 10 indicators on the front panel:

• Power — power supply (lit when the router is connected to the electrical network);
• DSL — DSL synchronization status;
• Internet—availability of WAN connection;
• WLAN — WiFi network status;
• LAN 1-LAN 4 - activity indicators for home Ethernet network devices;
• WPS - the LED blinks when the “WiFi Protected Setup” mode is activated;
• USB - lights up when devices are connected via a USB port.

Unlike many other models, any of the WAN ports in the DSL-2650U/RA is available for connecting to the Internet via an Ethernet cable. This feature makes the router universal, since in addition to ADSL, communication can be established via 3G/LTE (using a modem connected via USB) and a regular twisted pair cable.

Important! Another hardware version of the router is also available for sale - DSL-2650U. Its functionality is almost no different from the DSL-2650U/RA model described in the rating. The main differences are horizontal installation and external antenna instead of internal.

3rd place in the ranking: TP-Link TD-W8961ND

This inexpensive router has proven itself to be easy to set up and stable in operation. The device is equipped with two powerful removable antennas with gains of 5 dBi. In addition to the router itself, the package includes an SP-201 splitter (or a similar model) and two RJ-11 cables. On the reverse side are:

• Connector for power plug;
• ADSL router power button;
• Hidden “Reset” button, allowing you to restore factory settings;
• WiFi on/off button;
• Four LAN ports;
• RJ-11 port for connecting ADSL cable.

One of the features of the TP-Link ADSL router is the ability quick connection via the Easy Setup Assistant utility. It is a step-by-step wizard for specifying basic parameters. Additional settings can be specified in sections of the main web interface, typical for TP-Link devices.

As for the hardware of this model, the manufacturer has added surge protection. According to TP-Link, the device can withstand an increase in network voltage up to 4000 V as a result of a lightning strike. A large number of holes on the case provide good ventilation and prevent increased heating of the router.

2nd place in the ranking: ASUS DSL-N14U

The device has attractive design and good technical characteristics. The maximum data transfer speed via WiFi for the DSL-N14U model is 300 Mbit/s. However, such a high speed value is only relevant for receiving and sending information between computers local network. It does not affect Internet speed, since this parameter depends on the provider.

USB port version 2.0, located near the LAN connectors, allows you to organize autonomous file server or print server. When you connect a flash drive or external hard drive, all devices on your home network can access the stored data. Synchronization is carried out via ASUS AiCloud, for mobile devices developed special applications. If you connect a printer to this port, printing files will be available from any computer connected to the Internet.

Another advantage of having a USB port on ASUS router is the ability to connect to an alternative provider. If your ADSL provider has temporary difficulties and the main communication channel is unavailable, you can connect a 3G modem to the router. After quick setup the router will establish a connection with the 3G provider and continue to provide Internet access via WiFi and LAN cable.

Advice! When installing ASUS DSL-N14U or any other router with movable antennas, position them perpendicular to the desired WiFi coverage plane. When using the antenna in an apartment, it is better to point it vertically. In a private house on several floors, rotate one antenna horizontally so that the signal extends to other floors.

1st place in the ranking: Zyxel Keenetic DSL

High-performance ADSL router with two USB ports and non-removable 5 dBi antennas. Provides high-quality WiFi coverage in a private house or large apartment. This model is suitable for the most demanding users, as its NDMS 2 operating system has a number of additional functions and advanced settings. The disadvantage of the router is significant heating caused by powerful hardware components.

The standard Keenetic DSL firmware has a built-in torrent client. You don't need your computer to be turned on to download and share files. Instead of a PC, this work will be performed by the router; you just need to configure the Transmission client and connect to USB port external storage device (flash drive or HDD). To quickly enable traffic filtering, use installed applications Yandex.DNS and SkyDNS. In the service settings, you can specify the categories of sites that need to be blocked, for example, malicious sites, adult sites, or low-rated resources.

A convenient way to manage your Zyxel router is the My.Keenetic application for smartphones on Android and iOS. It is compatible with all Keenetic routers with firmware version 2.05 or higher. Through your phone you can set up a connection, manage network security, a torrent client, or DLNA server. However, it is not necessary that the smartphone be connected to home WiFi. Configuration can be done remotely via the Internet.

Let's sum it up

Thus, WiNetwork's Editors' Choice is Wireless ADSL Zyxel router Keenetic DSL. This advanced router topped the rating due to its good balance between price, quality and functionality. It is a universal device and is suitable for connecting to the Internet using backup communication channels.

ADSL stands for Asymmetric Digital Subscriber Line in English. There are several types of DSL connections: ADSL, HDSL and VDSL. All three options are based there is a telephone line.

What is ADSL

DSL technology was developed at a time when telephone lines became popular and became available to every citizen of the country. In the late 80s and early 90s, the first version of the ADSL protocol appeared. She supported incoming traffic speed up to 1 Mbit/s, and outgoing – up to 8 Mbit/s.

ADSL was born thanks to the company Bellcore, which in the mid-eighties was looking for methods to create interactive TV. Next, the technology was adopted by providers of access services to the World Wide Web. Thus, the first devices that transmitted and received signals appeared - ADSL modems.

Today asymmetrical line used in remote settlements, where it is impossible to use other wired technology or wireless communication via 3/4G USB modems

ADSL technology - operating principle

The first word in the name - asymmetrical - implies that it is used uneven distribution telephone line between receiving and sending data.

In this case, incoming traffic has a wider bandwidth compared to outgoing traffic. Earlier we mentioned approximate figures - the difference in speed can reach eight times.

The use of a telephone line as a means of data transmission implies that ADSL uses different frequency in cables. This fact allows you to use the phone and the Internet simultaneously without interfering with each other.

Sometimes situations arise in which the use of a telephone core for two directions leads to certain interference, but such cases are rare and are associated with improper cable shielding.

The signal comes from the provider and reaches the end user on special equipment - a modem. It translates the incoming data stream into a digital value.

Equipment used

As with any technology, ADSL also uses special equipment and components. Let's take a closer look at the example diagram below.

Signal coming from telephone socket, initially arrives at a special device – splitter. He divides it into telephone and high frequency. The first goes directly to the communication device, and the second to the translator. In its turn network device processes the incoming analog stream into a digital one. After this operation the data can be processed operating system end user device: for example, a workstation or tablet.

ADSL modem

The network device is the entry point for the analog data stream. He can convert the signal in both directions simultaneously, allowing you to use bandwidth more efficiently.

Pure ADSL modems are almost no longer produced, since there is a more modern network hardware– routers. They will be discussed below.

ADSL cable

The cable is a wire with an RJ-12 connector. It is used to connect the telephone line to the modem.

Contains four cores, through which it is transmitted analog signal for entry and exit.

Routers

Improved version of the modem. It is equipment capable of not only receive and transmit signal to the end user, but also route traffic within the local network.

Using an ADSL router, the user can connect several devices to gain access to the World Wide Web.

Today, most ADSL routers have built-in WiFi module, which allows you to connect mobile devices to the Internet.

Splitters and microfilters

To separate the signal coming through the telephone line for the modem and telephone, a special filter is used - a splitter.

The operating principle is as follows. One incoming signal – several outgoing ones. The simplest example splitter is shown in the screenshot above. It can split a maximum of 16 signals.

Microfilters needed to create two parallel signals. This allows you to use ADSL Internet and telephone simultaneously, without creating interference on the line.

Other equipment

There are other devices used to create a connection to the World Wide Web based on ADSL technology.

For example, a user only has an ADSL modem, but wants to use wireless communication at home. He will have to purchase additional router withWi— Fimodule. It connects via an Ethernet port to the modem.

The second common option. There is an office space in which access to the global network is organized using ADSL technology. To provide Internet in each room you must purchase switches and router. The first ones are installed separately in each office, and the router will carry out the correct routing of data within the local network.

Basic connection steps

First thing we connect telephone cable, going into the room, through a splitter. Next from connector Phone we bring out the wire to the phone, and from ADSL– to network equipment.

The next step is to connect the ADSL device to the power supply network and connect it to workstation via Ethernet cable.

At the last stage, the user conducts setting up network equipment in accordance with the instructions provided by the provider.

Maximum ADSL speed

The data transfer speed when using ADSL depends on the standard used by the provider. The last option is ADSL2++. The data can be summarized in one table.

The information presented above is theoretical, i.e. specified values are achieved under ideal conditions. In fact, 13-15% of the speed is lost when the signal passes from the provider to the endpoint. This fact is due technical characteristics equipment used.

Also, do not forget about other subscribers. The signal comes from a single point of exit from the service provider. Many other clients are connected to it, so the total speed value begins to be divided into equal parts.

Advantages and disadvantages of technology

Advantages of using ADSL technology:

1. Subscribers receive high frequency access service to the World Wide Web without laying additional cables indoors.
2. Organize a global network it is possible almost anywhere where there is a telephone line.
3. Initial financial expenses to connect below some other methods.
4. High download speed files for the end client.
5. Using modern network equipment, the client can organize a wireless network.

Flaws:

1. Exists more modern solutions Internet connections that provide high download speeds.
2. Technology gives away most of the channel for incoming traffic, and outgoing is several times lower. Accordingly, sending larger files to another subscriber will take a long time.
3. Signal quality and stability depends on the telephone line, which is not designed for high-frequency signals.