Power line communication: Encyclopedia II - Power line communication - Broadband over power lines

Power line communication - Broadband over power lines

Broadband over Power Lines (BPL) aka 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 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 256 kbit/s to 2.7 Mbit/s. In the repeater situated 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 135 Mbit/s. To connect to the Internet, utilities can use optical fiber backbone or wireless link.

Much higher speed transmissions using microwave frequencies transmitted via a newly discovered surface wave propagation mechanism have been demonstrated using only a single power line conductor. These systems have shown the potential for symmetric and full duplex communication in excess of 1 Gbit/s in each direction. Multiple WiFi channels as well as simultaneous analog television in the 2.4 and 5.3 GHz unlicensed bands have been demonstrated operating over medium voltage lines.

Differences in the electrical distribution systems in North America and Europe affect the implementation of BPL. In North America relatively few homes are connected to each distribution transformer, whereas European practice may have hundreds of homes connected to each substation. Since the BPL signals do not propagate through the distribution transformers, extra equipment is needed in the North American case.

Adapted from the Wikipedia article "Broadband over power lines", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki