Реферат: ADSL Essay Research Paper Overview

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.

--> ЧИТАТЬ ПОЛНОСТЬЮ <--