30-11-2012, 12:36 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. The service is also convenient because it’s already in your home. Internet access through Digital Powerline would be at (at least) 1Mbps, 20 times faster than a standard phone/modem connection.
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.
Digital Powerline use a network, known as a High Frequency Conditioned Power Network (HFCPN), to transmit data and electrical signals. A HFCPN uses a series of Conditioning Units (CU) to filter those separate signals. The CU sends electricity to the outlets in the home and data signals to a communication module or "service unit". The service unit provides multiple channels for data, voice, etc. Base station servers at local electricity substations connect to the Internet via fiber or broadband coaxial cable. The end result is similar to a neighborhood local area network.
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.
Several options, with different costs, can provide broadband Internet service to each base station. The simplest solution is connecting leased lines to each substation. This solution is potentially quite costly because of the number of lines involved. A wireless system has also been suggested to connect base stations to the Internet. This option reduces local loop fees, but increases hardware costs. Another alternative involves running high bandwidth lines, along side electric lines, to substations. These lines could be fiber (*See appendix C), ATM, or broadband coaxial cable. This option avoids local loop fees, but is beset by equipment fees. The actual deployment of Digital Powerline will probably involve a mix of these alternatives, optimized for cost efficiency in different areas and with different service providers.
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.
The CU contains three coupling ports. The device receives aggregate input from its Network Port (NP). This aggregate input passes through a high pass filter. Filtering allows data signals to pass to a Communications Distribution Port (CDP) and a low pass filter sends electric signals to the Electricity Distribution Port (EDP).
The 50 Hz signal flows from the low pass filter, out of the EDP and to the electricity meter. The low pass filter also serves to attenuate extraneous noise generated by electrical appliances at the customer premises. Left unconditioned, the aggregation of this extraneous noise from multiple homes would cause significant distortion in the network.
Powerline telecommunication
Powerline telecommunications is a rapidly evolving market that utilises electricity power lines for the high speed transmission of data and voice services. The especially exciting thing about the potential for PLT is that it holds the promise of solving the underlying structural problem confronting the local access market today. PLT can provide the holy-grail of a much needed, highly elusive, alternative source of ubiquitous local loops other than the incumbent telco operator, something we sadly have yet to see happen on a sufficient scale and scope. Indeed, what make PLT so attractive from a public policy point of view are the facts that:
• The power grid is ubiquitous; it constitutes an existing network infrastructure to billions of private consumers and businesses
• The power grid offers last-mile conductivity
• The power grid supports information based services with strong growth potential.
Home Automation
The Home Plug Powerline Alliance (HPA), a U.S. consortium of 90 members, including such high-tech giants as Cisco, Intel, Motorola, and Hewlett-Packard is working on technology to link appliances such as TVs, computers and cookers via the home electrical system.
Appliance makers like Samsung Electronics Co. have been solidifying cooperation with their technology partners to enable them to market Internet-controllable home appliances this year. Samsung plans to set up a “Dream LG” site on its homepage to advertise its Internet-enabled products to potential customers.
Internet access
Last December Intellon announced its PowerPacketTM Powerline networking chipset, the first product certified as compliant with the HPA’s 1.0 Specification introduced earlier that year. The chipset allows users to access the Internet and connect computers and other devices at speeds up to 14 mbps by simply plugging into power outlets throughout a home or small office.