Digital Subscriber Line (DSL) brings broadband information to homes and businesses over ordinary copper telephone lines. DSL provides a high-speed broadband conduit for instant transmission of data for information, entertainment, and much more.
Symmetric (SDSL) vs. Asymmetric (ADSL)
There are two main types of DSL. Symmetric DSL refers to DSL technologies that provide the same bandwidth upstream (sending) and downstream (receiving). Symmetric DSL services provide identical data rates whether you are sending information, like an email, or receiving information, downloading a file or accessing a web site. Asymmetric DSL provides relatively lower rates upstream but higher rates downstream. When considering your broadband needs, the choice between ADSL and SDSL largely hinges on price. SDSL is more expensive.
Asymmetric Digital Subscriber Line
ADSL is ideal for most homes and small businesses. Most of its two-way or duplex bandwidth is devoted to the downstream direction, sending data to the user. Only a small portion of bandwidth is available for upstream or user-interaction messages. Most broadband data (graphics and multi-media, for example) need lots of downstream bandwidth. At the same time, the average homes or small business DSL generally requires little upstream bandwidth. Using ADSL, up to 6.1 megabits per second of data can be sent downstream and up to 640 Kbps upstream. The high downstream bandwidth means that your telephone line will be able to bring motion video, audio, and 3-D images to your computer or hooked-in TV set. In addition, a small portion of the downstream bandwidth can be devoted to voice rather data, and you can hold phone conversations without requiring a separate line.
Unlike a similar broadband service over your cable TV line, ADSL won't compete for bandwidth with neighbors. Although existing telephone lines will probably work with ADSL, in some areas, they may need upgrading to support broadband communication.
ADSL Varieties
There are several sub-categories of ADSL. RADSL (Rate-Adaptive DSL) is an ADSL technology in which software is able to determine the rate at which signals can be transmitted on a given customer phone line and adjust the delivery rate accordingly.
G.lite (also known as DSL Lite, splitterless ADSL, and Universal ADSL) is essentially a slower ADSL that provides a data rate from 1.544 Mbps to 6 Mpbs downstream and from 128 Kbps to 384 Kbps upstream. G.Lite is expected to become the most widely installed form of DSL.
Symmetric Digital Subscriber Line
SDSL is generally used for wideband digital transmission within a corporate site and between the telephone company and a customer. The main characteristic of SDSL is that it is balanced: an equal amount of bandwidth is available in both directions and the data rate is the same in both directions. SDSL can carry as much on a single wire of twisted-pair cable as a T1 line (up to 1.544 Mbps) but over a somewhat longer range.
In the final analysis, for the broadband needs of the average home or small business, the cheaper ADSL is probably the smarter choice.
DSL Related Articles:
- DSL vs Cable – What’s the Best Broadband Connection?
- How Does DSL work?
- What Is the Difference Between ADSL And SDSL?
- DSL Availability – How to Find DSL Availability in my Area?
- What is VDSL?
- Compare DSL and T1 Lines
- DSL, T1 and T3 Internet Connections
- Bridged Vs. Routed DSL Connections
- Compare DSL Prices from Top DSL Broadband Internet Providers
- A Guide to Comcast Broadband Services
- Benefits of a Business DSL High Speed Internet Service
