Broadband Over Power Line
After years of development, technology to deliver high-speed data over the existing electric power delivery network has emerged in the marketplace. Called broadband over power line (BPL), this technology offers an alternative means of providing high-speed internet access, Voice over Internet Protocol (VoIP), and other broadband services, using medium- and low- voltage lines to reach customers’ homes and businesses.
Broadband over Power Line (BPL), also known as Power Line Communications (PLC) is a disruptive communications technology that enables power line infrastructure landlords (electric utilities & property owners) and their system operator partners to deliver a suite of Internet Protocol (IP) based services using their existing power distribution infrastructure.
BPL transmits high frequency data signals through the same power cable network used in carrying electrical power to household/or business subscribers. In order to make use of BPL, subscribers install a modem that plugs into an ordinary electrical wall outlet and pay a subscription fee similar to those paid for other types of Internet service.
Evolution of BPL
BPL is based on PLC technology developed in 1928 by AT&T Bell Telephone Laboratories, and which has been used for internal and low-speed data communication applications since that time by the electric power utilities. Based on PLC technology, some customer premises equipment (CPE) such as intercom systems, have used the embedded electrical wire to avoid the cost of special wiring. In Europe and most of the rest of the world, PLC standards allow for communications over the 220-240 volt power grid at frequencies of 30 KHz to 150 KHz. In the United States, the standards for the 120 volt power grid allow the use of frequencies above 150 KHz as well. Power utilities use the frequencies below 490 KHz for internal applications such as telemetry and monitoring and control of equipment at remote sub-stations. In the 1990s, development began on broadband over power line (BPL), which has since then been regionally standardized.
Despite the spread of broadband technology in the last few years, there are significant areas of the world that don't have access to high-speed Internet. When weighed against the relatively small number of customers Internet providers would gain, the incremental expenditures of laying cable and building the necessary infrastructure to provide DSL or cable in many areas, especially rural, is too great. But if broadband could be served through power lines, there would be no need to build a new infrastructure. Anywhere there is electricity there could be broadband. Technology to deliver high-speed data over the existing electric power delivery network is closer to reality in the marketplace. By combining the technological principles of radio, wireless networking, and modems, developers have created a way to send data over power lines and into homes at speeds between 500 kilobits and 3 megabits per second (equivalent to DSL and cable). The technology evolution in the next few years is important from a perspective of future competitive position of BPL as new networks are built and alternative technologies emerge.
Broadband access and services are delivered using a variety of technologies, network architectures and transmission methods. The most significant broadband technologies include:
•Digital Subscriber Line (DSL)
DSL is a very high-speed connection to Internet that uses the same wires as a regular telephone line. A standard telephone installation in the United States consists of a pair of copper wires. This pair of copper wires has sufficient bandwidth for carrying both data and voice. Voice signals use only a fraction of the available capacity on the wires. DSL exploits this remaining capacity to carry information on the wire without affecting the line’s ability to carry voice conversations.
But there are several limitations of DSL describe below :
•The quality of connection depends upon the proximity to the provider’s central
office, closer the better
•Receiving data is faster than sending data over the internet
•DSL is not available everywhere
For millions of people, television brings news, entertainment and educational programs into their homes. Many people get their TV signal from cable television (CATV) because cable TV provides better reception and more channels.
Many people who have cable TV can now get a high-speed connection to the Internet from their cable provider. Cable modems allow subscribers to access high-speed data services over cable systems that are generally designed with hybrid fiber-coaxial (HFC) architecture. Cable modem service is primarily residential, but may also include some small business service.
The disadvantage of coaxial cable is that when there are heavy-access users, are
connected to the channel, you will have to share the entire bandwidth, and may see your performance degrade as a result. It is possible that, in times of heavy usage with many connected users, performance will be far below the theoretical maximums.
Satellite Internet access is ideal for rural Internet users who want broadband access. Satellite Internet does not use telephone lines or cable systems, but instead uses a satellite dish for two-way (upload and download) data communications. Upload speed is about one-tenth of the 500 kbps download speed. Cable and DSL have higher download speeds, but satellite systems are about 10 times faster than a normal modem. Two-way satellite Internet consists of approximately a two-foot by three-foot dish, two modems (uplink and downlink), and coaxial cables between dish and modem. The key installation planning requirement is a clear view to the south, since the orbiting satellites are over the equator area. And, like satellite TV, trees and heavy rains can affect reception of the Internet signals.
Architecture of BPL
Broadband over Power Lines network is overlaid on the medium-voltage and low-voltage segments of the power distribution system. High-speed backhaul connections can be brought to the BPL network at substations or elsewhere along the medium voltage circuit. An Ambient node provides connectivity between the backhaul connection and the medium voltage segment of the BPL network. High speed data travels over this medium-voltage segment to remote locations where is it transferred to the low-voltage segment or to a wireless interface for the final leg to the end user or network element being managed. A simplified view is shown is Figure
The diagram below (Inductive Coupling Injection Technique) shows how the BPL injector converts the IP data traffic into an RF signal in a signal cable. The signal is then injected into the MV or LV cable by induction using ferrite cores. This is known as “inductive coupling” and can be done without switching off power. An alternative injection technique, known as “conductive coupling” connects the signal cable directly to the electricity cables but requires the power to be switched off during connection for safety reasons.