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Digital Subscriber Line (DSL)

Internet connectivity has greatly evolved with the introduction of advanced technologies that promises much faster and secured access. This has benefited homes and businesses largely, as it offered them the right communications means through a high-speed internet service. Several new internet technologies have come up in the last few years, which have offered ultra fast connectivity speeds and covers a vast area than was previously possible. This has resulted in a democratization of the internet, which has much relevance now considering the fierce debates for net neutrality around the world.

These networking technologies have essentially made our lives better by enabling us to become connected and allowed us to gain access to all kinds of services and other requirements. All this has been possible only because of the introduction of high-speed internet, which in itself has evolved from other networking technologies chiefly DSL. It has served as the backbone of the internet technologies used nowadays and is still the base for high-speed internet connectivity.

What is DSL?

DSL or Digital Subscriber Line is a networking technology that provides high-speed broadband internet connectivity to residences and businesses via regular copper telephone lines. DSL is one of the first technologies that enabled the birth of high-speed internet. Its infrastructure and methods are still the basis of all internet connection options available today. The technology used in DSL ensures that customers get access to both Internet and telephone services through the same copper line without disconnecting either one of them.

This is a critical advantage over other types of internet connections such as dial up, which only allows single mode of communication at a time (data or voice). Customers can access DSL internet with a broadband modem and a few other equipments. The use of simple networking equipments to access the internet has led to its popularity among users upon introduction.

A Brief History of DSL

The origin of DSL internet technology can be traced back to the developments made by several telecommunications companies such as Bell Communications Research Inc. in the 1980s. They envisioned a technology that enabled home and business users to access internet via their telephone lines, which is exactly what DSL does. This idea of sending broadband signals also led to the development of the asymmetry technique called as ADSL (Asymmetric DSL) that allows the transmission of high data rates across one direction. This has in turn led to the first transition of the networks from analog to digital and hence ISDN (Integrated Services Digital Network) was born.

These developments were further encouraged as internet advanced into more interactive forms extensively reliant on graphics. This advancement in internet required an internet connection that was much faster in order to offer a full experience of using the World Wide Web to users. It was in the beginnings of 1990 that DSL was first launched with the sole objective of connecting on-demand television. However, this was abandoned quickly due to the large-scale growth of cable TV channels that diminished the role of on-demand television. This resulted in the repurposing of DSL to connect computers to the Internet.

How DSL Works?

DSL works on the basic principle of sending data over a telephone line by modulating the data signal to higher frequencies. This ensures that the signal does not mix with the voice signals used in telephone transmission and reception. The two signals are of different frequencies, which enable them to be sent across one line without interlinking with each other. The following illustrations will help you to better explain the transmission and reception methods used in DSL

In order to understand DSL networking, we must first have a clear understanding regarding the working of conventional telephone service, which is also known as, POTS (Plain Old Telephone System). This technology uses copper wires to connect homes and business to the telecom company and its numerous exchanges boxes distributed throughout the area. Twisted pair cables were the primary channels of facilitating these telecommunications due to their advantage of cancelling out any electromagnetic interference.

Plain Old Telephone System

This communication method relied on analog signals for the transmission and reception of voice signals. By installing a modem, the analog imformation can be easily converted into binary digital information such as 0 and 1 that can be read by a computer. This analog transmission method can only carry a limited amount of information via the copper wires and hence is limited in its speeds to a maximun of 56 Kbps.

ISDN (Integrated Services Digital Network), the forerunner of DSL technology has a much better speed of 128 Kbps. ISDN was a network of digital phone conections that allowed simultaneous transmission and reception of voice and data across the world. However, this method was constrained as it required the conversion of data into analaog and digital each time when passed between the telephone company and the home or business computer.

The advent of DSL resolved all these issues as it eliminated the need for conversion of the data into analog and digital back and forth. DSL transmits digital data directly through the line without converting it into analog signals. This digital data can be directly received by your computer, which eliminates the need of demodulating the signal back again.

Moreover, DSL connections can enable the simulataneous transmission and reception of both analog and digital signals using the same line, which allows you to use your telephone systems along with the computer at the same time.

Types of DSL

Many types of DSL network are used to connect homes and businesses. Most of the internet connection in homes and offices will most likely fall under any one of the two categories of DSL internet that are listed below.

Asymmetric DSL

Asymmetric DSL connections are the most popular and have more network bandwidth. This allows increased bandwidth when users are downloading a file to their computer. However, the uploading speed will not be as fast as the downloading speed. More bandwidth is possible during download because internet providers usually reduce the upload traffic. This attribute of DSL internet makes it an ideal choice for users who download plenty of video contents and other files. Most common asymmetric DSL internet types are as follows.

  • ADSL – ADSL provides downstream speeds of up to 8 Mbps and upstream speeds of 384 Kbps. It is popularly used in residences due to sufficient downstream speeds. ADSL allows both voice and data communication simultaneously.
  • ADSL 2+ - ADSL 2+ is a new version of ADSL and provides 20 Mbps download speed and 850 Kbps upload speed
  • VDSL – VDSL or Very High Bit-Rate Digital Subscriber Line is currently the fastest service and it offers 52 Mbps downstream and 2.3 Mbps upstream speeds.
  • R-ADSL – A-ADSL or Rate-Adaptive Digital Subscriber Line provides the same data speeds as a conventional ADSL network. However, users can adjust the data transmission modem using the modem.

Symmetric DSL

Symmetrical DSL differs from asymmetrical DSL in the fact that it offers the same bandwidth for uploads and downloads. It is most popularly used in businesses due to the comparatively equal upload speed with download, which is helpful in transferring data. Some types of Symmetric DSL are:

  • SDSL (Symmetric Digital Subscriber Line) – SDLS provides the users with the same upload and download speed of 1.54 Mbps.
  • SHDLS (Symmetrical High-Speed Digital Subscriber Line) - SHDSL uses the same technology of SDSL. The standards of approval are different as the International Telecommunications Union certifies it.
  • HSDL (High Bit-Rate Digital Subscriber Line) - HSDL provides data speeds of about 2.048 Mbps and is one of the earliest versions of DSL technology.

How DSL Benefits You?

Many of the major telecom companies operating in the country provide DSL internet services. If you are looking for a high-speed internet connectivity option, DSL is one of the best options available to you. DSL has been around since the 1980s and is therefore a time-tested internet connectivity mode. Utilizing DSL will certainly benefit your home or business and allow you to get connected to a high-speed internet service. DSL internet is also highly reliable and thus is not prone to congestions that happen on the network, thereby allowing you to enjoy uninterrupted internet access.

Additionally, DSL internet guarantees a steady speed even in cases of high network traffic, which is another useful aspect of the service. Moreover, the availability of different types of DSL connections allows you to enjoy the luxury of choosing a certain internet service that truly caters to your demands. It is also easy to connect as most part of the country are covered under the landline network and all it takes is connecting your computer via a DSL modem into the telephone line.

Most DSL internet providers offer home phone service along with internet service, which is highly beneficial as it allows customers access to both the services at the same time. DSL internet is also provided independently and all you need to do is to conduct an adequate research on the different providers that offers the best plans and tariffs. Since DSL allows both voice and data services, you can actually save more by bundling them together.


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