ADSL Essay Research Paper Overview

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ADSL Essay, Research Paper Overview Asymmetrical Digital Subscriber Line (ADSL) uses the plain twisted pair wiring already carrying phone service to subscribers’ homes to transmit video signals and high-speed data to the home. ADSL uses adaptive digital filtering to overcome noise and other problems on the line. Initially, the telephone companies hoped to use ADSL to provide Video on Demand service in competition with cable pay-per-view and neighborhood video rental stores. But ADSL can also offer a wide range of other applications, including Internet service, work-at-home access to corporations, and interactive services, such as home shopping and home banking. In addition, ADSL could make at-home educational access affordable for consumers. Early Development As early as

1991, Bellcore, the research company associated with the seven regional Bell operating companies, began touting ADSL to expand the transmission capacity of the copper-based telephone networks. This was originally seen as the telephone companies’ answer to CATV’s encroachment into telephone service and their entree into providing video on demand to telephone customers. Both the cable companies and the telephone companies were itching to get into each other’s businesses, but their networks were totally different, each with its own strong points and shortcomings. The telephone companies had greater access to homes in the United States (more than 90 percent), but the cable companies had more bandwidth capacity going into homes. The telephone companies were set up for two-way

communication, but lost video quality over distance. The cable companies had better quality but limited upstream capacity. Both industries knew that their ultimate solution would be fiber-optic networks connecting everyone, but realistically this was not possible. Although fiber has been run by both cable companies and telcos over the vast majority of their network, taking it from the curb to the customer’s residence or business was the problem. The cost alone would run into the billions, and nobody could afford to keep laying fiber in hopes that the home they went to would use all of the capabilities fiber had to offer. Enter ADSL. ADSL allows a standard copper telephone line to carry a high-speed digital signal while simultaneously transmitting a voice conversation. The

asymmetrical part of the service refers to the fact that the high-speed transmission of data is one-way, from the central office to the home or business. Since most homes or small businesses only need the speed to receive information, not transmit it, this works very well. And, initially, ADSL permitted transmission at 1.5 megabits per second (Mbps) over copper wire for up to 18,000 feet. The vast majority of small businesses and residences easily fell within 18,000 feet of a telephone switching office. Because of the poor initial success of the last great plan to use the telephone companies’ copper wire, Integrated Services Digital Networks (ISDN), ADSL was met with skepticism. Many telcos, as well as manufacturers, originally developed a wait-and-see attitude before investing

in the new service. But, in 1993, a tiny California company called Amati teamed up with Northern Telecom to prove that ADSL could be used to send 6 Mbps of full-motion video down a conventional telephone line. Suddenly the telephone companies had a weapon, albeit an interim one, that could be used against the cable companies. Big companies, like Bell Atlantic, realized that ADSL could be used immediately to stay in the game, removing the pressure to replace the copper wire with fiber. Instead of spending time and money to bring hybrid fiber/coax (HFC) or fiber-to-the-curb (FTTC) into a large area for an unknown number of users, the telcos could now target specific users who were willing to pay for the equipment necessary to make the service work. ADSL Today By 1994, ADSL