DSL Technologies:
– DSL transmits digital data over telephone lines.
– ADSL is the most common DSL technology for Internet access.
– SDSL offers equal data rates in both directions.
– VDSL+ technology provides higher data rates than ADSL.
– Different modes of transport in ADSL cater to different needs.
– ADSL standards have evolved to improve data rates and distances.
DSL Speeds:
– Consumer ADSL speeds range from 256kbit/s to 25Mbit/s.
– VDSL+ delivers between 16Mbit/s and 250Mbit/s downstream.
– SDSL speeds have reached over 1Gbit/s in research settings.
– Performance depends on technology, line conditions, and implementation.
– DSL filters prevent interference between DSL and telephone service.
History and Deployment of DSL:
– In the 1950s, twisted-pair cables showed potential for high-speed data transmission.
– ISDN specifications in the 1980s influenced DSL development.
– Cost of DSL equipment reduced significantly due to VLSI technology.
– DSL deployment over existing cables is cost-effective.
– DSL became popular due to advantages over dial-up and competition from cable companies.
Future and Limitations of DSL:
– Microfilters were introduced to simplify self-installation of DSL service.
– DSL technology continues to evolve to meet increasing bandwidth demands.
– Advances in electronics have improved DSL performance and reduced costs.
– DSL remains a viable option for high-speed Internet access alongside fiber optics.
– DSL cannot pass through loading coils, affecting service eligibility.
DSL Implementation and Variants:
– Low frequencies reserved for POTS in DSL.
– DSL and POTS can share wires with filters.
– Only one DSL modem can use line at a time.
– Naked DSL provides only DSL services over the local loop.
– Various DSL technologies like IDSL, HDSL, ADSL, VDSL, and their high-speed variants offer different speeds and bitrates.
Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric digital subscriber line (ADSL), the most commonly installed DSL technology, for Internet access.
In ADSL, the data throughput in the upstream direction (the direction to the service provider) is lower, hence the designation of asymmetric service. In symmetric digital subscriber line (SDSL) services, the downstream and upstream data rates are equal.
DSL service can be delivered simultaneously with wired telephone service on the same telephone line since DSL uses higher frequency bands for data transmission. On the customer premises, a DSL filter is installed on each telephone to prevent undesirable interaction between DSL and telephone service.
The bit rate of consumer ADSL services typically ranges from 256 kbit/s up to 25 Mbit/s, while the later VDSL+ technology delivers between 16 Mbit/s and 250 Mbit/s in the direction to the customer (downstream), with up to 40 Mbit/s upstream. The exact performance is depending on technology, line conditions, and service-level implementation. Researchers at Bell Labs have reached SDSL speeds over 1 Gbit/s using traditional copper telephone lines, though such speeds have not been made available for the end customers yet.
English
Noun
digital subscriber line (plural digital subscriber lines)
- A family of technologies that provides digital data transmission over the wires of a local telephone network.
