Digital Subscriber Line (DSL) is the technology that provides digital data transmission through local telephone network. Now the term digital subscriber line has been widely adopted by IT professionals as a more marketing-friendly term for Asymmetric Digital Subscriber Line (ADSL). Usually the download speed of consumer DSL services ranges from 256Kbps to 20Mbps depending on DSL technology, line conditions, and services. Typically download speed is much higher than download speed for ADSL, and for Symmetric Digital Subscriber Line (SDSL) upload and download speed remains the same.
Data-transmission rate differ depending on the line-length from telephone exchange to subscriber. Many technologies are implemented globally to provide maximum internet speed to subscriber, here are brief introduction of advanced DSL technologies:
ISDN Digital Subscriber Line (IDSL) – ISDN based technology is being used to provide higher data flow as compared to dual channel ISDN.
High Data Rate Digital Subscriber Line (HDSL / HDSL2) – known as the first DSL technology that uses a higher frequency spectrum of copper and twister pair cables.
Symmetric Digital Subscriber Line (SHDSL / SDSL) – data transfer volume for download and upload remains the same by using this technology.
Asymmetric Digital Subscriber Line (ADSL) – by using this technology the volume of data flow is greater in one direction than the other.
Asymmetric Digital Subscriber Line 2 (ADSL2) – it is the improved version of ADSL
Asymmetric Digital Subscriber Line 2 Plus (ADSL2+) – it is the next version of ADSL2 that doubles the data rates by using twice the spectrum.
Asymmetric Digital Subscriber Line Plus Plus (ADSL++) – an advanced technology developed by Centillium Communications. This technology was adopted for the Japanese market that extends downstream rates to 50 Mbit/s by using spectrum up to 3.75 MHz.
Rate-Adaptive Digital Subscriber Line (RADSL) – technology was designed to increase range and noise tolerance by sacrificing up stream speed.
Very High Speed Digital Subscriber Line (VDSL)
Very High Speed Digital Subscriber Line 2 (VDSL2), an improved version of VDSL
Uni-DSL (UDSL or Uni Digital Subscriber Line), Texas Instruments developed this technology
Gigabit Digital Subscriber Line (GDSL) – based on binder MIMO technologies.
Universal High bit rate Digital Subscriber Line (UHDSL) – use fiber optics, in 2005 RLH Industries, Inc. developed this technology.
Cable vs DSL: A Broadband Comparison
Computer Basics : What Is a DSL Modem?