03-01-2013, 11:47 AM
BROADBAND OVER POWERLINE (BPL)
BROADBAND.docx (Size: 803.51 KB / Downloads: 39)
INTRODUCTION
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.
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 1.2.
Working of BPL
In order to provide data communication, the initial BPL systems coupled radio frequency (RF) data signals into the existing electric power lines. The high frequency data signals are transmitted through the same power lines that carry low frequency electricity to the household or business. This enables both signals to coexist on the same wire.
From the specific technological perspective, the basic idea of BPL technology is to modulate a radio signal with data and send it through power lines in a band of frequencies which are not used for supplying electricity. The frequencies used and the encoding scheme have a significant influence on the efficiency and the speed of BPL service. The encoding scheme which is used by most of the BPL providers is Orthogonal Frequency Division Multiplexing (OFDM). OFDM is a technique used for transmitting large amounts of digital data over a radio wave. OFDM splits the radio signals into multiple smaller sub-signals that are then transmitted at different frequencies to the receiver. The transmission of data by OFDM along several of the carrier frequencies simultaneously increases speed and reliability. Data loss occurs when electrical distribution is interrupted by electrical devices turned on and off. OFDM uses small packets to deliver data within the home, losing only small amounts of data rather than the whole signal.
End to End Access BPL
End-to-end Access BPL systems use either a combination of MV and LV power lines or LV power lines only. These systems represent the classical architectures for Access BPL. In this case the BPL signal is injected onto and carried by the MV power line. The BPL signal is then transferred to the LV power line via couplers or through the LV transformer and delivered directly to the end-user. In the case of LV only BPL systems, the BPL signal is injected onto the LV power line at the transformer or the utility meter.
Hybrid Access BPL
Hybrid systems use a combination of power lines and wireless transmission. For example, a hybrid system may inject a BPL signal onto an MV power line and use a special extractor to translate the signal into a wireless channel which is delivered to the end-user.
IN-HOUSE BPL
In-house BPL systems utilize electric power lines not owned, operated or controlled by an electricity service provider, such as the electric wiring in a privately owned building. Broadband devices are connected to the in-building wiring and use electrical sockets as access points
The only thing that the user has to do is plug the modem into the socket and connect it to the computer.
In-House BPL makes use of indoor adapters to transmit data signals over existing interior electric wires within a home, and to connect the data signals to various appliances.
TECHNOLOGICAL DEVELOPEMENTS
Because of low speed, low functionality and high development cost, BPL technology was never seriously considered as a communication medium, even though it has been operational since the 1930s. Historically, BPL was not only a control mechanism for electrical utilities, but also was originally designed to send simple commands over power lines at such low frequencies as 100-180 kHz. Such a mechanism makes both remote monitoring and diagnostics possible even over long distances. More recently, BPL has been used in “smart homes”. Smart homes can provide such automated applications as entry, entertainment, and comfort systems, and can be networked and controlled from a central location. A simple form of BPL also provides the basis for intercom systems.
In the mid 1980s, experiments on higher frequencies were carried out to analyze the technological characteristics of the electric power grid as a medium for data transfer. Frequencies especially in the range of 5-500 kHz were tested. In these tests, both the signal to noise levels and the attenuation of the signal by the power grid were important topics for measurements. These tests were undertaken both in Europe and in the United States.
Technological complexity and its challenges
The introduction of BPL technologies around the world has not been received with universal, unbridled enthusiasm due largely to interference concerns. The interference characteristics associated with BPL can be divided into two broad categories: (1) conducted and (2) radiated. In the FCC Report & Order 04-245, Access BPL systems are exempted from the conducted emissions limits in FCC Part 15 rules because measuring the conducted emissions presents a safety hazard due to the 1-40 kilovolt energy on the power lines. Instead, the FCC has focused on compliance with established radiated emission requirements.
Technological Issue
Power lines were not designed for data transmission, but were originally created to deliver power at 50 to 60 Hz. Broadband data can be transmitted at different frequencies, over the same wires, however, in order to enable high-speed and long-distance transmission of data on power lines several technological obstacles have to be overcome. These include data interference or electrical signal interference, the distance over which data can travel while still providing good quality, and the lack of international standards and specifications. The technological issues of BPL in this section deal with how BPL should be implemented to minimize interference with other services such as amateur radio frequencies and international standardization efforts for BPL technology to increase reliability, interoperability, and security of broadband transmission over power lines.
CONCLUSION
As it is emerging technology, the next few years will decide whether BPL can compete in the broadband market.
BPL offers a method of broadband access for those living in isolated areas, who have no other viable means of broadband access. Therefore, it seems plausible that when BPL will become available in rural areas, it will be a moderate success. However, this success is unlikely to be long-term, since telecommunications companies are already contemplating rolling out FTTH (Fiber to the Home) connections to all of their customers sometime in the future. Therefore, it appears that BPL will be little more than a stopgap solution.
BROADBAND.docx (Size: 803.51 KB / Downloads: 39)
INTRODUCTION
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.
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 1.2.
Working of BPL
In order to provide data communication, the initial BPL systems coupled radio frequency (RF) data signals into the existing electric power lines. The high frequency data signals are transmitted through the same power lines that carry low frequency electricity to the household or business. This enables both signals to coexist on the same wire.
From the specific technological perspective, the basic idea of BPL technology is to modulate a radio signal with data and send it through power lines in a band of frequencies which are not used for supplying electricity. The frequencies used and the encoding scheme have a significant influence on the efficiency and the speed of BPL service. The encoding scheme which is used by most of the BPL providers is Orthogonal Frequency Division Multiplexing (OFDM). OFDM is a technique used for transmitting large amounts of digital data over a radio wave. OFDM splits the radio signals into multiple smaller sub-signals that are then transmitted at different frequencies to the receiver. The transmission of data by OFDM along several of the carrier frequencies simultaneously increases speed and reliability. Data loss occurs when electrical distribution is interrupted by electrical devices turned on and off. OFDM uses small packets to deliver data within the home, losing only small amounts of data rather than the whole signal.
End to End Access BPL
End-to-end Access BPL systems use either a combination of MV and LV power lines or LV power lines only. These systems represent the classical architectures for Access BPL. In this case the BPL signal is injected onto and carried by the MV power line. The BPL signal is then transferred to the LV power line via couplers or through the LV transformer and delivered directly to the end-user. In the case of LV only BPL systems, the BPL signal is injected onto the LV power line at the transformer or the utility meter.
Hybrid Access BPL
Hybrid systems use a combination of power lines and wireless transmission. For example, a hybrid system may inject a BPL signal onto an MV power line and use a special extractor to translate the signal into a wireless channel which is delivered to the end-user.
IN-HOUSE BPL
In-house BPL systems utilize electric power lines not owned, operated or controlled by an electricity service provider, such as the electric wiring in a privately owned building. Broadband devices are connected to the in-building wiring and use electrical sockets as access points
The only thing that the user has to do is plug the modem into the socket and connect it to the computer.
In-House BPL makes use of indoor adapters to transmit data signals over existing interior electric wires within a home, and to connect the data signals to various appliances.
TECHNOLOGICAL DEVELOPEMENTS
Because of low speed, low functionality and high development cost, BPL technology was never seriously considered as a communication medium, even though it has been operational since the 1930s. Historically, BPL was not only a control mechanism for electrical utilities, but also was originally designed to send simple commands over power lines at such low frequencies as 100-180 kHz. Such a mechanism makes both remote monitoring and diagnostics possible even over long distances. More recently, BPL has been used in “smart homes”. Smart homes can provide such automated applications as entry, entertainment, and comfort systems, and can be networked and controlled from a central location. A simple form of BPL also provides the basis for intercom systems.
In the mid 1980s, experiments on higher frequencies were carried out to analyze the technological characteristics of the electric power grid as a medium for data transfer. Frequencies especially in the range of 5-500 kHz were tested. In these tests, both the signal to noise levels and the attenuation of the signal by the power grid were important topics for measurements. These tests were undertaken both in Europe and in the United States.
Technological complexity and its challenges
The introduction of BPL technologies around the world has not been received with universal, unbridled enthusiasm due largely to interference concerns. The interference characteristics associated with BPL can be divided into two broad categories: (1) conducted and (2) radiated. In the FCC Report & Order 04-245, Access BPL systems are exempted from the conducted emissions limits in FCC Part 15 rules because measuring the conducted emissions presents a safety hazard due to the 1-40 kilovolt energy on the power lines. Instead, the FCC has focused on compliance with established radiated emission requirements.
Technological Issue
Power lines were not designed for data transmission, but were originally created to deliver power at 50 to 60 Hz. Broadband data can be transmitted at different frequencies, over the same wires, however, in order to enable high-speed and long-distance transmission of data on power lines several technological obstacles have to be overcome. These include data interference or electrical signal interference, the distance over which data can travel while still providing good quality, and the lack of international standards and specifications. The technological issues of BPL in this section deal with how BPL should be implemented to minimize interference with other services such as amateur radio frequencies and international standardization efforts for BPL technology to increase reliability, interoperability, and security of broadband transmission over power lines.
CONCLUSION
As it is emerging technology, the next few years will decide whether BPL can compete in the broadband market.
BPL offers a method of broadband access for those living in isolated areas, who have no other viable means of broadband access. Therefore, it seems plausible that when BPL will become available in rural areas, it will be a moderate success. However, this success is unlikely to be long-term, since telecommunications companies are already contemplating rolling out FTTH (Fiber to the Home) connections to all of their customers sometime in the future. Therefore, it appears that BPL will be little more than a stopgap solution.