06-12-2012, 05:35 PM
Powerline communications
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Introduction
Connecting to the Internet is a fact of life for business, government, and most households. The lure of e-commerce, video on demand, and e-mail has brought 60 million people to the Internet. Once they get to the Internet, they find out what it’s really like. That includes long waits for popular sites, substantial waits for secure sites, and horrible video quality over the web.
Telephone companies have offered high bandwidth lines for many years. For the most part, the cost of these lines and the equipment needed to access them has limited their usefulness to large businesses. The lone exception has been ISDN (Integrated Services Digital Network) which has won over some residential customers. ISDN offers fast Internet access (128k) at a relatively low cost.
Here the solution is Powerline communications (or PLC). Powerline communications is a rapidly evolving market that utilizes electricity power lines for the high-speed transmission of data and voice services.
None of the available Internet access services offer the right balance of cost, convenience, and speed. Digital Powerline technology could change all that. It gives customers high speed Internet access through electrical networks. Lower costs are achieved because the service is implemented on standard electrical lines.
History
The technology has roots going back to the 1940s.It has been used by power utilities for simple telemetering and control of electrical equipment in their networks.
What is new is the integration of activities outside the building with those inside the building at a much higher bandwidth, 2.5 mbps or higher.
Overview of Technology
PLC works by transmitting high frequency data signals through the same power cable network used for carrying electricity power to household users. Such signal cannot pass through a transformer. This requires devices that combine the voice and data signals with the low-voltage supply current in the local transformer stations. The signal makes its way to neighborhoods and customers who could access either it wirelessly, through utility poles.
The Server
The Digital Powerline base station is a standard rack mountable system designed specifically for current street electricity cabinets. Typically, one street cabinet contains twelve base station units, each capable of communicating over 1 of 40 possible radio channels. These units connect to the public telecommunications network at E1 or T1 (*see appendix D) speeds over some broadband service.
The HFCPN Conditioning Unit
The conditioning Unit (CU) for the Digital Powerline Network is placed near the electric meter at each customer’s home. The CU uses band pass filters to segregate the electricity and data signals, which facilitate the link between a customer’s premise and an electricity substation.