A Copper Alliance Member
xDSL Glossary
Copper Applications in Electronic & Communications
April 1998
When one dabbles in the alphabet-soup world of telecommunications, one is instantly inundated by acronyms. This article is no exception. Following is a small sampling of the acronyms one might run across in reading about xDSL technology. All the acronyms used in this article are included, but there are hundreds more in the industry.
| xDSL | Digital Subscriber Line technologies, with x denoting any of the various varieties, as follows: | ||
|---|---|---|---|
| ADSL | Asymmetric Digital Subscriber Line, with a larger portion of the capacity devoted to downstream communications, less to upstream. Typically thought of as a residential service. | ||
| DSL | Digital Subscriber Line technology, on which all the variations in this listing are based. Sometimes used to refer only to the earliest forms of the technology. | ||
| HDSL | High-bit-rate Digital Subscriber Line, a technology for the business market in commercial operation several years, and using two wire pairs with 1.5 Mbps each way. | ||
| IDSL | ISDN-based Digital Subscriber Line | ||
| RADSL | Rate-Adaptive Digital Subscriber Line, where the DSL equipment senses the speed limitations of the customer's phone line and adjusts the rate downward accordingly from some maximum. | ||
| RDSL | same as RADSL. | ||
| SDSL | Symmetric Digital Subscriber Line using one pair, typically with about half the speed each way when compared to HDSL. | ||
| VDSL | Very-high-bit-rate Digital Subscriber Line, with speeds up to 50 Mbps, but for only short distances, perhaps 1000 or 2000 feet at the highest rates of transmission. | ||
| ADSLF | ADSL Forum, a group of several hundred companies involved in some way in DSL technology, formed to identify and solve technical and market problems and issues and to encourage standards, using a generic approach. |
|---|---|
| CAP | means one of two things:
|
| CLEC | Competitive Local Exchange Carrier, company that typically leases capacity from the local telephone company and resells it. In some cases these companies have networks of their own, such as in large cities. |
| DMT | Discrete Multi-Tone, one of the line codes, or modulation systems, in which incoming data are spread over a number of channels of the available spectrum in an efficient way. |
| DSLAM | Digital Subscriber Line Access Multiplexer, the piece of DSL equipment at the telephone company end of the phone line, usually in a central office. |
| ILEC | Incumbent Local Exchange Carrier, such as any of the regional Bell operating companies or GTE. |
| ISDN | Integrated Services Digital Network, an alternative method to simultaneously carry voice, data and other traffic, using the switched telephone network. |
| ISP | Internet Service Provider, company which provides connection to the Internet, typically piggybacking on the local telephone company's wires. |
| IXC | Inter-Exchange Carrier, typically a long-distance telephone company. |
| LAN | Local Area Network, a wiring system to connect computers together within a company, a building or other local area. |
| LEC | Local Exchange Carrier of whatever variety. It should be noted that there are more than 1000 such carriers in the USA in addition to the five RBOCs and GTE. |
| PSTN | Public Switched Telephone Network, over which voice traffic moves. |
| RBOC | Regional Bell Operating Company, of which there are five: Ameritech, Bell Atlantic, BellSouth, SBC Communications and U S West. |
| STP | Shielded Twisted Pair copper wires, more common in Europe. Each pair may be separately shielded, or the entire cable or sections of the cable may be shielded to protect against outside interference. |
| TP | Twisted Pair copper wires, where the twist provides protection against crosstalk or other interference. |
| UAWG | Universal ADSL Working Group, a group formed in late 1997, and made up of Intel, Compaq, Microsoft, the five RBOCs and others, to move a specific version of xDSL technology to market quickly. |
| UTP | Unshielded Twisted Pair copper wires, typically used in the USA. |
| VLSI | Very Large Scale Integration, a high-speed chip technology. |
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