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TEL 355: Communication and Information Systems in Organizations. Extending ADSL Services to Remote Digital Loop Carrier (DLC) Locations Professor John F. Clark. Definitions.
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TEL 355: Communication and Information Systems in Organizations Extending ADSL Services to Remote Digital Loop Carrier (DLC) Locations Professor John F. Clark
Definitions • Digital Loop Carriers (DLCs) consolidate the voice traffic of remotely located customers onto a few lines running to a CO. • Asymmetric Digital Subscriber Line (ADSL) will transport large amounts of data traffic at high speeds over existing copper twisted pairs while simultaneously supporting Plain Old Telephone Service (POTS)
The Problem • Suburban and rural areas are experiencing rapid residential and business growth. • Demand for ADSL in these areas is growing. • Delivering ADSL to DLC customers is difficult for a number of technical reasons. • Solutions are being developed – each has its advantages and disadvantages, depending on the individual situations.
Market Demand for ADSL • In general, demand for data-intensive network-based applications is rising. • DLC (suburban) customers are prime candidates for ADSL and represent a lucrative source of revenue for service providers. • The number of ADSL lines nationally was expected to grow over 6,000% over four years (1999). • End of 2006 – the rate of subscriber growth of DSL was one and a half times cable broadband. • DSL subscribers are expected to exceed cable subscribers by early 2008.
The Challenge, Part I • Legacy DLC systems were built to provide high-quality voice service. • They can’t support the amount of bandwidth required by ADSL • Newer DLC systems can support the bandwidth, but at the cost of seriously constraining the capacity for phone service. • Plus, newer DLC systems are not engineered for data transmission, anyway.
The Challenge, Part II • The incidence of legacy DLC systems (pre-1990) outnumbers new DLC systems 4:1. • Legacy DLCs can supply only 64 kbps per subscriber line because of their sample rate. • Plus, the basic structure does not allow the entire DLC to support more bandwidth than a single T1 line.
The Challenge, Part III • ADSL is designed to use existing copper pairs to deliver both ADSL and POTS. • But legacy DLC systems will not support the data-intensive bandwidth. • The solution has been the installation of a completely separate system – the Digital Subscriber Line Access Multiplexer (DSLAM) – no connection to the DLC.
Solution Options • There are three primary solutions to ADSL/DLC problem: • Remote DSLAM solutions • Highly scalable but very costly • ADSL line-card solutions • Cost-effective but causes technical problems • Remote-Access Multiplexer (RAM) solutions • Combines the strengths of the first two and minimizes the drawbacks