Asymmetric Digital Subscriber Line

Description

ADSL: The Revolutionizing Internet

The technology that enabled the provision of internet connectivity to the masses, through ADSL, was unassumingly potent in millions of homes even before smartphones, fiber optics, and even widely Wi-Fi. It may be humble not flashy but it changes the interplay with the outside world.

What is ADSL or Asymmetric Digital Subscriber Line?

What was all of this such a breakthrough? Let’s see how this holds up in the modern, fast-evolving digital world.

ADSL: Asymmetric Digital Subscriber Line – a relative of DSL technology that provides fast internet access over ordinary phone lines. ADSL was able to integrate both phone services and the internet at the same time; a capability the dial-up could not.

This is known as “asymmetric” because typically, the broadband communication system is designed so that download speed is much higher than the upload speed. This makes sense to most home users since, on average, they download more content (music, videos, web pages) than they upload (e.g., file transfer or video calling to the Internet).

It’s perhaps almost a miracle that both internet data and voice calls can use exactly that same copper telephone wire, but it’s all to do with frequency. During a conventional voice call, only a small fraction of the line's capacity is used, typically up to 4 kHz. The higher frequency bands unused by voice are used by ADSL for data. It chops up the line into different channels, some for voice calls, others for uploading, others for downloading. A DSL filter/splitter keeps the signals from interfering with each other.

A clever utilization of already installed telecommunication infrastructure enabled telecom companies to provide Internet services without the necessity of installing new cables. This was one of the major contributing factors in the fast spread of ADSL during the early 2000s.

Important ADSL Features

The major contribution of ADSL has been categorized under the following headings, which were the first to offer high data rate services over existing copper loop telephone networks:

• Always-On Connection: There’s no need to dial and wait; it provides constant availability with an always-on connection.
• Symmetrical vs Asymmetrical: While data rate of symmetric DSL is characterized by equivalent rates in both directions, the data rate of asymmetric DSL is chiefly characterized by highly different rates in both directions.
• Uninterrupted Phone and Data Usage: Any standard telephone model can be used on any split outlet to make or receive calls while information is being transmitted.
• Initial Capital: This technology was much cheaper to implement at that time when compared to laying down fiber optics or coaxial cables as it utilized the already existing copper network.

Its asymmetrical speeds is one of the features that make ADSL what it is, e.g. it’s common that an ADSL line provides 1 Mbps upload and 8 Mbps download.

It was like moving from a bicycle to a motorcycle when ADSL came. It made achievable:

• Web surfing that is more fluid
• Downloading of music and movies
• Online gaming
• Email and video conferencing
• Telecommuting

Further, it set the foundation for what’s now known as the Internet economy, i.e., streaming services and e-commerce. Online sites that have found early success, such as YouTube, Skype, and even Facebook, may not have been able to take off that quickly without ADSL.

ADSL v/s Today’s Internet Options

Today, ADSL is much slower than fiber optic, cable broadband, 4G/5G, and even satellite; yet – it still remains one of the few reliable and accessible cost modes in many rural or isolated locations where fiber hasn’t reached and installed. Here is how ADSL shapes up:

Download speed: Fiber Optic - 100 to 1000+ Mbps | ADSL - 1 to 24 Mbps

Upload speed: Fiber Optic - Comparable or nearly identical to download | ADSL - 0.5 to 3 Mbps

Infrastructure: Fiber Optic - Fibre optic cables | ADSL - Copper lines

Dependability: Fiber Optic - Good but distance limited | ADSL - Great, very reliable albeit

Price: Fiber Optic - Reasonable generally | ADSL - Getting cheaper but then increasing

There’s little that’s perfect, of course:

• Upload Speeds: Generally, this low upload speed doesn’t support uploading live to streaming services or even cloud storage, nor video calling.
• Distance and Speed: Decreases as the distance from the phone exchange increases.
• Infrastructure: Over time, copper lines degrade.

What does the future look like for ADSL?

ADSL is being phased out with fiber broadband in all cities; it’s not yet old, though. This helps give millions of people internet access, in countries and regions where high-speed options are still developing—not available.

Though it may not be the fastest service out right now, ADSL keeps the legacy of starting the broadband revolution. It allowed for regular homes to get high speed internet without needing very expensive installations or having to manage something so complex. It helped people to connect and share in ways dial-up never could; and therefore, to learn and develop.

While it’s true that fiber and wireless will probably be the future, any history of the Internet would be incomplete without giving some props to the silent workhorse known as ADSL, which one copper line at a time hooked the planet.