ADSL Internet connection technology. ADSL - what is it? Principle of operation, maximum speed, advantages and disadvantages of ADSL technology

ADSL is understood as an asymmetric method of access to the global information network Internet. This is the so-called asymmetric system, which allows you to work with connections at speeds up to eight Mbps. So, ADSL, through which the data transfer rate is calculated up to one Mbit per second, operates at a distance of more than five kilometers.

So let's look at what kind of connection it is and how it actually works.
So, before touching on the very concept of ADSL, let's plunge into history a little. It is today that high-speed connections are not surprising, but are perceived as something ordinary and supposed to be a privileged property of modernity. But in order for the end user to be able to use this resource, the developers had to work hard and create the perfect version.

For the first time, the idea of ​​creating high-speed connections, as such, appeared precisely in the eighties, when no one even thought about the Internet. A high-speed connection was required to improve and speed up data transmission over copper wires in telephony.

After some time, the people were faced with familiarity with computer technology, the concept of the Internet. This is where the development of a resource was required for the rapid transfer of information electronic units between various interactive services, video game products, as well as for access to other network local systems.

Modern ADSL technology is a network that is based on a digital subscriber line, through which a connection to an Internet resource is made through telephone channels. Since these telephone lines use an analog signal in their work to be able to transmit voice messages, ADSL transforms it into a digital format and transfers it directly to a computer.

If the previously used Dial-up modems blocked the telephone line, then it is timely ADSL that allows you to simultaneously use both an analog signal and a digital signal at the same time.

So, the whole point of the new generation of ADSL lies in the fact that the user of computer technology has the ability to download a very large amount of information and save it on a hard disk, or simply view it and transmit a minimum of information in the form of requests. In other words, maximum traffic - minimum downstream traffic - this is the principle of modern ADSL technology.

Naturally, incoming traffic is video files, media products, software applications, and graphic elements. Downstream traffic includes only technically important information at the level of commands and various requests, emails, and some other minor components of working with the Internet.

So, the asymmetry in question implies the connection speed of the subscriber is much higher than the speed of traffic from the user himself. The asymmetric high-speed connection system is by far the most budgetary and economical. In operation, this system uses the same copper telephone wires. The only thing that has changed compared to the first samples is the number of twisted pairs in them, this fact did not require any actions in the direction of upgrading the switches and measures for their reconstruction.

Modern ADLS-ka connects very quickly, it is perceived by all types of modern modems. But still, for the optimal connection of this system, special types of modem devices are used. This list includes modems connected via USB ports, devices similar to the Ethernet interface, as well as routers and routers with the Ethernet scheme itself, profile modems and Wi-Fi routers are also suitable.

Often additional elements are also used in the form of splitters and microfilters, they are selected for the type of telephone cable. Splitters are used when a cable outlet is made in order to separate the modem channel and the phone itself. In other cases, microfilters are suitable for installation; one such element is installed on each telephone in the room.

The use of splitters allows you to prevent interference in the operation of the phone and modem, which seem to work in the same bundle, but one device receives voice calls, the other makes it possible to connect to the Internet.

Splitter devices are compact and do not interfere with their presence at all. This is a miniature box with three light weight connectors.
ADLS technology in modern times is recommended to be used by every second Internet provider. Naturally, the types and tariffs of connection to the global information network are classified depending on the regional predisposition of PC users. Yes, coverage is important.

When building a network, it is inappropriate to buy everything today - a modem, a router, a router, and splitters. The network provider offers to rent all the necessary equipment today, this list also includes an ADSL modem. If the contract for the services provided is terminated, then all equipment is returned to the provider intact and safe.

This is the cheapest way to use the Internet as such. The user pays only for the connection itself, without incurring the cost of purchasing all the necessary equipment for connection.

So, we are convinced that ADLS is nothing but the fastest, highest quality and cheapest method of connecting to the Internet. Each user using this type of connection must have his own account, which is assigned to him by the provider himself. It is activated within twelve days after registration. If the region has normal uninterrupted coverage, then this procedure does not exceed two hours.
Before using DDLS technology, the provider must check the phone for the presence of already used elements of the same DDLS. If the coverage is not effective, then it is unlikely that you will ever need to use a high-speed network connection at all.

To use this very ADLS connection, you must first connect and configure all the elements correctly. So, a modem, splitters, microfilters are connected to the phone, drivers are installed on a computer storage medium, the network parameters of the modem are set in the browser used to use browsing sites located in the Internet environment.

Now let's touch on the advantages of modern high-speed technology for connecting to the global information network, which makes using the Internet many times effective and elementary simple.

So, the most important advantages of ADLS-ki include the high speed of information electronic data transfer. In order to send or receive the necessary file, you do not need to wait a long time for the connection, it happens instantly.

This type of technology is constantly evolving and more and more connection speeds are offered to the consumer.
The second advantage of modern ADLS-ki is the fact that the phone works as a phone, and the modem as a modem, the work of these devices is not interrupted by each other. The use of ADLS-ki does not require installation of overall equipment, cable laying to the subscriber. Interference on the telephone line is absent in principle.

ADLS is a reliable stable system that does not fail, which does not require reconnection, the user with such a connection can sit in the Internet space around the clock. This is the most efficient method of connecting to the Internet, which has no alternatives.
The minimum prices for connecting ADLS-ki, installing a modem with a router spare the family budget. Despite these advantages, this technology still has its modern disadvantages.

None of the users of such a connection is protected from cross connections to the network and other Internet users. If dozens and hundreds of subscribers are connected to such a network, there is no need to talk about high speed. Naturally, the more consumers eat, the lower.
The disadvantages can also be attributed to the low speed of file transfer. Receiving and quickly viewing information is good, but sending is not very convenient. So keep in mind, if you want to use the high-speed connection model, that it is not aimed at sending data, but at constantly receiving it in large volume.

The speed of such a perfect system as ADLS depends in most cases not on its perfection, but on many side factors. And this is the main prerequisite for the network to be laid by a specialist who will evaluate the effectiveness of the coverage, correctly connect all the elements and achieve a high-quality result.

The quality of communication is affected by the condition of the subscriber line. That is, we are talking about the presence of cable outlets, their serviceability, wire diameter and length, which can reach several kilometers. If the signal goes astray, this indicates that the subscriber line is too long, this defect can be eliminated with a large wire diameter.

A well-functioning ADLS-ka has a length of five kilometers. This is the fastest system, as mentioned above. It allows you to transfer data at a speed of 2048 Mbps.

If the length of the wire does not go off scale, then the user is practically not limited in anything - neither in speed, nor in the number of other connected subscribers, as well as mobile phones, tablets and other modern gadgets.

Developers say that ADLS has not yet fully exhausted its resource and there are long-term plans for its development in the future.
So we figured out what modern Internet connection technology is - ADLS, what are its advantages and disadvantages, why many today focus on this type of network creation.

If you decide to connect your computer device to the network, do not look for a better way, it does not exist today. A lot of personal computer users are convinced of this. This method is used not only by individuals, but also by large companies that have to work daily with a large amount of information flow.

Trust the suggestions of specialists, try this method in practice, and you will see that today this is the limit of perfection in terms of achieving connection speed and connecting subscribers to the virtual space.

We hope that the information presented in this article was clear to you, and you have drawn the right conclusions for yourself. In modern times, you need to use the most advanced high-quality communication systems, one of which, just the same, is the above-considered ADLS technology.

ADSL(Asymmetric Digital Subscriber Line - Asymmetric Digital Subscriber Line) is one of the high-speed data transmission technologies known as DSL technologies (Digital Subscriber Line - Digital Subscriber Line) and collectively referred to as xDSL. Other DSL technologies include HDSL (High data rate Digital Subscriber Line), VDSL (Very high data rate Digital Subscriber Line), and others.

The common name of DSL technologies originated in 1989, when the idea first appeared to use analog-to-digital conversion at the subscriber's end of the line, which would improve the technology of data transmission over twisted-pair copper telephone wires. ADSL technology was developed to provide high-speed (one might even say megabit) access to interactive video services (video on demand, video games, etc.) and equally fast data transfer (Internet access, dial-up LAN and other networks).

ADSL technology - so what is it?

First of all, ADSL is a technology that allows you to turn a twisted pair of telephone wires into a high-speed data transmission path. ADSL line connects two ADSL modem that are connected to each end of the twisted-pair telephone cable (see Figure 1). In this case, three information channels are organized - a “downstream” data transfer stream, an “upstream” data transfer stream and a conventional telephone communication channel (POTS) (see Figure 2). The telephone communication channel is allocated with the help of filters, which guarantees the operation of your phone even if the ADSL connection fails.

Picture 1

Figure 2

ADSL is an asymmetric technology - the speed of the "downstream" data stream (that is, the data that is transmitted towards the end user) is higher than the rate of the "upstream" data stream (in turn transmitted from the user to the network). It should immediately be said that one should not look for a cause for concern here. The data transfer rate from the user (the "slower" data transfer direction) is still significantly higher than when using an analog modem. In fact, it is also significantly higher than ISDN (Integrated Services Digital Network - Integrated Digital Communications Network).

ADSL technology uses digital signal processing and specially designed algorithms, advanced analog filters and analog-to-digital converters to compress the large amount of information transmitted over twisted-pair telephone wires. Long distance telephone lines can attenuate a transmitted high frequency signal (for example, at 1 MHz, which is the normal transmission rate for ADSL) by up to 90 dB. This forces the analog ADSL modem systems to work with a large enough load to allow high dynamic range and low noise. At first glance, the ADSL system is quite simple - high-speed data transmission channels are created over a regular telephone cable. But, if you understand in detail the work of ADSL, you can understand that this system belongs to the achievements of modern technology.

ADSL technology uses a method of dividing the bandwidth of a copper telephone line into multiple frequency bands (also called carriers). This allows multiple signals to be transmitted simultaneously on a single line. Exactly the same principle underlies cable television, when each user has a special converter that decodes the signal and allows you to see a football match or an exciting movie on the TV screen. With ADSL, different carriers simultaneously carry different parts of the transmitted data. This process is known as Frequency Division Multiplexing (FDM) (see Figure 3). With FDM, one band is allocated for the transmission of the "upstream" data stream, and the other band for the "downstream" data stream. The downstream range is in turn divided into one or more high speed channels and one or more low speed data channels. The upstream range is also divided into one or more low-speed data channels. In addition, Echo Cancellation technology can be used, in which the upstream and downstream ranges overlap (see Figure 3) and are separated by local echo cancellation.

Figure 3

This is how ADSL can provide, for example, simultaneous high-speed data transmission, video signal transmission and fax transmission. And all this without interrupting the normal telephone connection, which uses the same telephone line. The technology provides for the reservation of a certain frequency band for conventional telephone communication (or POTS - Plain Old Telephone Service). It is amazing how quickly telephone communication has become not only "simple" (Plain), but also "old" (Old); it turned out something like "the good old telephone connection." However, one should pay tribute to the developers of new technologies, who still left telephone subscribers with a narrow band of frequencies for live communication. In this case, a telephone conversation can be carried out simultaneously with high-speed data transmission, and not choose one of the two. Moreover, even if your electricity is turned off, the usual “good old” telephone service will still work and you will not have any problems calling an electrician. Making this possible was part of the original ADSL development plan. Even this capability alone gives the ADSL system a significant advantage over ISDN.

One of the main advantages of ADSL over other high-speed data transmission technologies is the use of the most common twisted-pair copper wire telephone cables. It is quite obvious that there are much more such pairs of wires (and this is still an understatement) than, for example, cables laid specifically for cable modems. ADSL forms, so to speak, an "overlay network". At the same time, costly and time-consuming upgrades of switching equipment (as is necessary for ISDN) are not required.

ADSL connection speed

ADSL is a high speed data transfer technology, but how fast? Considering that the letter "A" in the ADSL name means "asymmetric" (asymmetric), we can conclude that data transfer in one direction is faster than in the other. Therefore, there are two data rates to consider: "downstream" (transferring data from the network to your computer) and "upstream" (transferring data from your computer to the network).

Factors affecting the data transfer rate are the condition of the subscriber line (ie, the diameter of the wires, the presence of cable outlets, etc.) and its length. The signal attenuation in the line increases with increasing line length and signal frequency, and decreases with increasing wire diameter. In fact, the functional limit for ADSL is a subscriber line 3.5 - 5.5 km long with a wire thickness of 0.5 mm. ADSL currently provides downstream data rates ranging from 1.5 Mbps to 8 Mbps and upstream data rates from 640 Kbps to 1.5 Mbps. The general trend in the development of this technology promises to increase the data transfer rate in the future, especially in the "downstream" direction.

In order to evaluate the data transfer speed provided by ADSL technology, it is necessary to compare it with the speed that may be available to users using other technologies. Analog modems allow you to transfer data at speeds from 14.4 to 56 Kbps. ISDN provides a data rate of 64 Kbps per channel (typically a user has access to two channels, for a total of 128 Kbps). Various DSL technologies allow the user to transfer data at speeds of 144 Kbps (IDSL), 1.544 and 2.048 Mbps (HDSL), "downstream" 1.5 - 8 Mbps and "upstream" 640 - 1500 Kbps s (ADSL), downstream 13 - 52 Mbps and upstream 1.5 - 2.3 Mbps (VDSL). Cable modems have a data transfer rate from 500 Kbps to 10 Mbps (it should be taken into account that the bandwidth of cable modems is divided between all users who simultaneously have access to this line, so the number of simultaneously working users has a significant impact on the actual speed data transmission of each of them). Digital lines E1 and E3 have data rates of 2.048 Mbps and 34 Mbps, respectively.

When using ADSL technology, the bandwidth of the line through which the end user is connected to the backbone network belongs to this user always and entirely. Do you need an ADSL line? It's up to you, but in order for you to make the right decision, let's look at some of the benefits of ADSL.

First of all, the data transfer speed. The numbers were given two paragraphs above. And these figures are not the limit. The new ADSL 2 standard implements 10 Mbps downstream and 1 Mbps upstream speeds at a range of up to 3 km, and the ADSL 2+ technology, the standard of which is due to be approved in 2003, features downstream speeds streams of 20, 30 and 40 Mbps (respectively for 2.3 and 4 pairs).

Internet via ADSL

In order to connect to Internet via ADSL, no need to dial a phone number. ADSL creates a broadband data link using an already existing telephone line. After installing ADSL modems, you get a permanently established connection. The high-speed data link is always ready to go - whenever you need it.

The bandwidth of the line belongs entirely to the user. Unlike cable modems, which allow bandwidth sharing between all users (which has a significant impact on data transfer speed), ADSL technology allows only one user to use the line.

ADSL connection technology allows full use of line resources. Conventional telephony uses about one hundredth of the capacity of a telephone line. ADSL technology eliminates this "flaw" and uses the remaining 99% for high-speed data transmission. In this case, different frequency bands are used for different functions. For telephone (voice) communication, the lowest frequency region of the entire line bandwidth (up to approximately 4 kHz) is used, and the rest of the band is used for high-speed data transmission.

The versatility of this system is not the last argument in its favor. Because different subscriber line bandwidth channels are dedicated to different functions, ADSL allows simultaneous data transmission and telephone conversations. You can make and receive phone calls, send and receive faxes, while being on the Internet or receiving data from a corporate LAN. All this on the same telephone line.

ADSL opens up completely new possibilities in those areas in which it is necessary to transmit a high-quality video signal in real time. These include, for example, videoconferencing, distance learning and video-on-demand. ADSL technology allows service providers to provide their users with services that are more than 100 times faster than the fastest analog modem (56 Kbps) and more than 70 times faster than ISDN (128 Kbps) ).

ADSL technology allows telecommunications companies to provide a private secure channel for the exchange of information between the user and the provider.

Internet connection via ADSL

We should not forget about the costs. The technology of connecting to the Internet via ADSL is effective from an economic point of view, if only because it does not require the laying of special cables, but uses existing two-wire copper telephone lines. That is, if you have a connected telephone at your home or office, you do not need to lay additional wires to use ADSL. (Though there is a fly in the ointment. The company that gives you regular phone service must also provide ADSL service.)

Not much equipment is needed to make an ADSL line work. ADSL modems are installed at both ends of the line: one on the user's side (at home or in the office), and the other on the network side (at the Internet provider or at the telephone exchange). Moreover, the user does not have to buy his own modem at all, but it is enough to rent it from the provider. In addition, in order for the ADSL modem to work, the user must have a computer and an interface card, such as Ethernet 10baseT.

As telcos step into the untapped field of end-user video and multimedia data transfer, ADSL technology continues to play a big role. Of course, after some time, the broadband cable network will cover all potential users. But the success of these new systems will depend on how many users will be involved in the process of using new technologies now. By bringing movies and television, video catalogs and the Internet to homes and offices, ADSL makes this market viable and profitable for both telephone companies and other service providers in various fields.