Power Line communication

Tracy Pettigrue
Tracy Pettigrue
Oct 15, 2009
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Powerline Communications, is a breakthrough communications technology for high-speed data, voice and media transfer over existing power lines. PLC provides home networking and broadband internet access using existing electric infrastructures without the need to install new networks. PLC is a cost effective wide broad band telecommunication system offering high speed, opening a wide range of new business opportunities and improving the operations of the electric system.

Power lines, unlike fiber-optic lines, are already installed in U.S. homes. Current power line speeds are 3-4 megabits per second, but a new generation of modem chips has opened the door to in-home access at about 10Mbps. The average U.S. broadband connection speed obtained through cable or DSL now stands at about 2Mbps.

36 million U.S. homes are connected to the Web through broadband. By next year, the number of broadband subscribers in the U.S. will surpass the number of Dial-up users and comprise more than half of the nation’s 83 million Internet households. Fees for broadband access, meanwhile, are dropping by double-digit percentage points annually.

South Korea, with a population about one-sixth that of U.S., has 17 million broadband users, an 80% percent penetration rate. More importantly, those users pay no more than American broadband subscribers and get access speeds at least four times those of the U.S. broadband; and often as fast as 20Mbps. Japan has 25 million subscribers who receive such super-fast services. In both markets, access fees average about $20 a month, significantly less than what Americans pay.

There are about 140 million broadband subscribers worldwide and this number is expected to become more than double by the year 2008.

For utilities, existing power lines are capable of delivering the radio frequencies that carry broadband data. What they need to install are fiber lines that carry bits of data from a central distribution office and “inject” them onto localized power grids. From there the data can be distributed to individual homes. A bonus for consumers is that once a home is subscribed, any power outlet can be used to link all components capable of networking, eliminating the need to invest in Ethernet cabling or a wireless system.

PLC promises high-speed data transmission with higher data rate than ADSL without adding new wiring, and it enables broadband services like internet and VoIP easily through existing power lines.

As there remain technical problems on distance and quality of telephone lines, broadband Internet service has not been expanded in Russia. The 200Mbps PLC modems shipped to Russia promise high speed communication services over access networks. They consist of a head end, which receives high-speed communication signals, a repeater, which amplifies the signals, and customer premises equipment (CPE). That is installed at the subscriber house. The modems employ the orthogonal frequency division multiplexing (OFDM) modulation scheme, and achieve low-noise communications by superimposing many sub-carriers. PLC chips by DS2, a Spanish chip vendor, are adopted in the modems.

Communication deployment of PLC has been accelerated in Europe and USA. In Korea, regulations on PLC will be eased in this month to promote PLC deployment. Only experiments are allowed in Japan due to concerns that the PLC radiation could cause interference to other radio receivers. Deregulation of PLC services in Japan is expected after the influence of PLC on radio receivers is evaluated.

Broadband over Power Lines (BPL), is also known as power-line internet or Powerband is the use of PLC technology to provide broadband Internet access through ordinary power lines. A computer (or any other device) would need only to plug a BPL “modem” into any outlet in an equipped building to have high-speed Internet access.

BPL offers obvious benefits over regular cable or DSL connections: the extensive infrastructure already available would appear to allow more people in more locations to have access to the internet. Also such ubiquitous availability would make it much easier for other electronics, such as televisions or sound systems to hook up. However, variations in the physical characteristics of the electricity network and the current lack of IEEE standards mean that provisioning of the service is far from being a standard, repeatable process and the amount of bandwidth a BPL system can provide compared to cable and wireless is in question. High-speed data transmission or broadband over the Power Line uses the electric circuit between the electric substations and home networks. A standard used for this is ETSI PLT.

PLC modems transmit in medium and high frequency (1.6 to 30 MHz electric carrier). The asymmetric speed in the modem is generally from 256kbit/s to 2.7 Mbit/s. In the repeater suited in the meter room the speed is up to 45 Mbit/s and can be connected to 256 PLC modems. In the medium voltage stations, the speed from the head ends to the internet is up to 135Mbit/s. To connect to the internet, utilities can use optical fiber backbone or wireless link.

The functionality of the system is very simple. An MV Node injects data coming from the Network Operator into the medium voltage power line. Data flows over the electric grid from the substations to the final users’ socket. This data is sent using different frequency bands through the low voltage lines, where repeaters are installed. A repeater regenerates the PLC signal on the low voltage lines between home units, including an MV Node, an LV Head End, another Repeater and CPEs. Finally, the end user connects the CPE, design for quick and easy installation, to one standard electric socket to receive the data signals.

PLC allows access to new territories in developing countries, remote rural areas, and residence buildings. This technology is generally applicable to all types of network specifications, topologies, frequencies, and voltages. Large- scale projects can be implemented and economically attractive. It provides new sources of revenue for companies. It uses existing power lines so there is no need for additional cable connections. It offers point-point multipoint access via distribution lines for multiple users with only one master modem. It provides fast data access rate in the high frequency band. Helps in improving the use of existing fixed assets, and enables energy efficiencies, cost savings and operational improvements.

Keywords: PLC, Power, Line , Communication, data access, modems , Communication , Ethernet , South Korea, speed

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