A SEMINAR REPORT ON
BROADBAND OVER POWERLINE
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
SREE CHITRA THIRUNAL COLLEGE OF ENGINEERING, THIRUVANANTHAPURAM
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. Broadband OverPowerline, is positioned to offer 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. 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). By modifying the current power grids with specialized equipment, the BPL developers could partner with power companies and Internet service providers to bring broadband to everyone with access to electricity
1.1.WHAT IS BPL
Broadband over Power Line (BPL) is a technology that allows voice and Internet data to be transmitted over utility power lines. BPL is also sometimes called Power-line Communications or PLC. Many people use the terms PLC and BPL interchangeably. We chose to use the term “broadband over power line” for consumer applications. In order to make use of BPL, subscribers use neither a phone, cable nor a satellite connection. Instead, a subscriber installs a modem that plugs into an ordinary wall outlet and pays a subscription fee similar to those paid for other types of Internet service .Here wediscusses two types of BPL: 1) Access BPL, and 2) In-house BPL. Access BPL is a technology that provides broadband access over medium voltage power lines.voltage power lines are the electric lines that you see at the top of electric utility poles beside the roadways in areas that do not have underground electric service. Typically there are three electric lines (called phases A, B and C), each carrying several thousand volts. One phase is usually enough to power the houses on a residential street, two or even three phases can be joined together to power the big electric motors in an industrial or commercial area. In-house BPL is a home networking technology that uses the transmission standards developed by the Home Plug Alliance.
1.2 MAIN COMPONENTS OF BPL SYSYTEM
The Last Mile is the portion of the network that connects end users, such as homes and business, to high-speed services and the Internet. For residential broadband service customers who get cable modem service, for example, the drop wire connecting the interface on a house to cable
company’s network and the wire from the interface connecting to the wall plates in the home would all be part of the last mile.
BPL modems use silicon chips designed to send signals over electric power lines, much like cable and DSL modems use silicon chips designed to send signals over cable and telephone lines. Advances in processing power have enabled new BPL modem chips to overcome difficulties in sending communications signals over the electric power lines.
Inductive couplers are used to connect BPL modems to the medium voltage power lines. An inductive coupler transfers the communications signal onto the power line by wrapping around the line, without directly connecting to the line. A major challenge is how to deliver the signal from the medium voltage line to the low voltage line that enters your house, because the transformer that lowers the electric power from several thousands volts down to 220/110 is a potential barrier to the broadband signal.
Router is a device that acts as an interface between two networks and provides network management functions.
Repeater is a physical-layer hardware device used on a network to extend the length, topology or interconnectivity of the physical medium beyond that imposed by a single segment.
Concentrator/Injector is a device that aggregates the end-user CPE data onto the MV (medium voltage) grid. Injectors are tied to the Internet backbone via fiber of T1 lines and interface to the MV power lines feeding the BPL service area.
Carrier-Current System: There are a number of types of BPL systems, using different approaches and architecture. All are “Carrier-Current” systems, a term used to describe systems that intentionally conduct signals over electrical wiring or power lines.
1.3AN OVERVIEW OF HOW BPL WORKS
At a high-level, a Powerline Telecom network consists of three key segments, the backbone, themiddle mile, and the last mile as shown . The BPL vendors are primarilyseeking to address the “last mile” segment all the way into “the home” market.From the end user’s perspective, BPL technology works by sending high-speed data alongmedium or low voltage power lines into the customer’s home. The signal traverses the networkover medium and low voltage lines either through the transformers or by-passes the transformerusing bridges or couplers. The technology transports data, voice and video at broadband speeds tothe end-user’s connection. The user only needs to plug an electrical cord from the “BPL modem”into any electrical outlet then plug an Ethernet or USB cable into the Ethernet card or USBinterface on their PC. Any Internet Service Provider (ISP) can interface with the BPL networkand provide high speed Internet access. The data signal can also interconnect with wireless, fiberor other media for backhaul and last mile completion. The actual hardware used for thedeployment varies by manufacturer but typically feature some common characteristics.
Fig1.an overview of bpl system
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 equivalent to those of DSL and cable. By modifying the current power grids with specialized equipment, the BPL developers could partner with power companies and Internet service providers (ISPs) to bring broadband to everyone with access to electricity.The Internet is a huge network of networks that are connected through cables, computers, and wired and wireless devices worldwide. Typically, large ISPs lease fiber-optic lines from the phone company to carry the data around the Internet and eventually to another medium (phone, DSL or cable line) and into the homes. Trillions of bytes of data a day are transferred on fiber optic lines because they are a stable way to transmit data without interfering with other types of transmissions. The idea of using AC (alternating current) power to transfer data is not new. By bundling radiofrequency (RF) energy on the same line with an electric current, data can be transmitted without the need for a separate data line. Because the electric current and RF vibrate at different frequencies, the two don’t interfere with each other. Electric companies have used this technology for years to monitor the performance of power grids. There are even networking solutions available today that transfer data using the electrical wiring in a home or business. But this data is fairly simple and the transmission speed is relatively slow. There are several different approaches to overcoming the hurdles presented when transmitting data through power lines. The power lines are just one component of electric companies' power grids. In addition to lines, power grids use generators, substations, transformers and other distributors that carry electricity from the power plant all the way to a plug in the wall. When power leaves the power plant, it hits a transmission substation and is then distributed to high voltage transmission lines. When transmitting broadband, these high-voltage lines represent thefirst hurdle. The power flowing down high-voltage lines is between 155,000 to 765,000 volts. That amount of power is unsuitable for data transmission. It's too "noisy." Both electricity and the RF used to transmit data vibrate at certain frequencies. In order for data to transmit cleanly from point to point, it must have a dedicated band of the radio spectrum at which to vibrate without interference from other sources. Hundreds of thousands of volts of electricity don't vibrate at a consistent frequency. That amount of power jumps all over the spectrum. As it spikes and hums along, it creates all kinds of interference. If it spikes at a frequency that is the same as the RF used to transmit data, then it will cancel out that signal and the data transmission will be dropped or damaged en rout.
An overview of power line system
Fig 1.1 power line system
BPL bypasses this problem by avoiding high-voltage power lines all together. The system drops the data off of traditional fiber-optic lines downstream, onto the much more manageable 7,200 volts of medium-voltage power lines. Once dropped onto the medium-voltage lines, the data can only travel so far before it degrades .To counter this, special devices are installed on the lines to act as repeaters. The repeaters take in the data and repeat it in a new transmission, amplifying it for the next leg of the journey. In one model of BPL, two other devices ride power poles to distribute Internet traffic. The Coupler allows the data on the line to bypass transformers, and the Bridge , a device that facilitates carrying the signal into the homes. The transformer's job is to reduce the 7,200 volts down to the 240-volt standard that makes up normal household electrical service. There is no way for low-power data signals to pass through atransformer, so you need a coupler to provide a data path around the transformer. With thecoupler, data can move easily from the 7,200-volt line to the 240-volt line and into the housewithout any degradation.
The last mile is the final step that carries Internet into the subscriber's home or office. In the various approaches to last-mile solutions for BPL, some companies carry the signal in with the electricity on the power line, while others put wireless links on the poles and send the data wirelessly into homes. The Bridge facilitates both. The signal is received by a powerline modem that plugs into the wall. The modem sends the signal to your computer. BPL modems use silicon chipsets specially designed to handle the work load of pulling data out of an electric current. Using specially developed modulation techniques and adaptive algorithms, BPL modems are capable of handling power line noise on a wide spectrum.
A BPL modem is plug and play and is roughly the size of a common power adapter. It plugs into a common wall socket, and an Ethernet cable running to your computer finishes the connection. Wireless versions are also available.
Fig 1.2 a bpl modem
Electric utilities may not necessarily want to enter the communications business. In fact ,they may want to leave that part of BPL to a partner, perhaps an ISP, a Competitive Local ExchangeCarrier (CLEC), or a long distance company looking for an alternative last mile path to their customers. Current focus of most electric utilities is using BPL for an intelligent electric distribution grid. Power companies have often employed low-speed power line communication for their own internal use—to monitor and control equipment in the power grid. This could result in lower electric power costs, less pollution and greater reliability and security, essentially, more intelligent electric power grid.
The Broadband services enabling partners may be in one or more of the delivery segment or role.
:The last mile: This is the portion of the network that connects end users, such as homes and business, to high-speed services and the Internet. For residential broadband service customers who get cable modem service, for example, the drop wire connecting the interface on a house tocable company’s network and the wire from the interface connecting to the wall plates in thehome would all be part of the last mile.
The middle mile : This portion of the network consists of high-speed fiber backbones and other“middle-mile pipes” that connect computers to networks, connect those networks into thecomplex that constitutes the Internet, and deliver traffic among ISPs, content providers, onlineservice companies, and other customers.
Internet service providers (ISPs): These are companies that receive and translate internetbounddata and help customers obtain online information from the Internet.
Content providers : This part of broadband consists of companies that provide information,goods, and services available to consumers through the Internet.These characteristics and distinctions are based on network functionality and the fact that each ofthese categories has its own economic properties with distinct regulatory issues. Currently there isa dearth of competition in the provision of middle -mile services, which means existing providerscan discriminate against their customers. Content providers, on the other hand, raise competitiveissues in terms of their ability or willingness to engage in exclusive contracts for the carrying oftheir content, as well as posing challenges in the area of consumer protection and free speech
The following Figure shows key players interested in BPL, affording utilities theopportunity to structure partnerships to push the technology forward
Fig.2 key players in bpl
3.ADVANTAGES FOR BPL AS AN ACESS TECHNOLOGY
Most stakeholders in BPL industry suggest that BPL could offer a number of significant benefits in the delivery of broadband services to homes and businesses. A number of BPL proponents submit that this technology could increase the availability of broadband and improve the competitiveness of the broadband services market. Many players believe that Access BPL could facilitate the ubiquitous availability of broadband services and bring valuable new services to consumers, stimulate economic activity, improve national productivity, and advance economic opportunity for the American public. The ubiquitous nature of BPL is expected to create theopportunity for providing new and innovative services to virtually any location serviced with electric outlets. The National Telecommunications and Information Administration (NTIA) states that BPL holds great promise as a new source of innovation and competition in the broadbandmarketplace. It believes that BPL has the potential to open new avenues of Internet access, to enable new and expanded services for utility companies, and to create a new platform for furtheradvances in communications technology.
3.1HOMELAND SECURITY AND NETWORK BENEFITS
The benefit is the ability of BPL technology to improve the provision of electric power service and therefore advance homeland security. The BPL technology could also be used toassist the utility companies by adding intelligent capabilities to the electric grid, thereby improving efficiency in activities such as energy management, power outage notification and automated meter reading. As per United Power Line Council (UPLC), Access BPL would allow electric utilities to better monitor and control electric system operations and thereby improve thereliability of their service and reduce costs to consumers. Under the Mission Essential VoluntaryAssets (MEVA) guidelines, utilities are responsible for ensuring secure infrastructure power forfederal facilities, including military bases, and state, city and local government. BPL will alsoenhance security and enable other security applications such as video surveillance consistent with the MEVA guidelines.
3.2 CONSUMER BENEFITS
The supporters of BPL expect it to improve the competitiveness of the market for broadband services. It offers the long sought third wire (other two being telephone and cable) for last-mile delivery of broadband communication services to residences and small businesses. The United
Power Line Council (UPLC) believes that BPL offers a unique opportunity in the broadband marketplace and that there is widespread interest in BPL among utilities. In the areas already served by other broadband providers, BPL will increase competition, which in turn will bring better service and lower prices for consumers.
3.2.1 GEOGRAPHICAL COVERAGE AND AVAILABILITY
It is forecasted that the ubiquitous nature of electric power grid will make it possible for Access BPL systems to bring broadband services to rural and other underserved locations. The American Public Power Association (APPA), for example, states that seventy five percent of its members serve communities with populations less than 10,000, many of which do not have access to broadband. 10 Current Technologies states that technical and economic considerations limit the deployment of cable and DSL. It submits that Access BPL is not constrained by these considerations and can deliver “broadband to many of those unserved by other broadband technologies” and “ bring the advantages of the Internet to the people who need them most.” Itis also expected that the availability of Access BPL will make it possible for those persons whocurrently do not have access to broadband to better participate and compete in the informationage. The Office of the People’s Counsel, District of Columbia (OPC DC) supports the efforts tofacilitate deployment of BPL because it has the potential to improve the District of Columbia’stelecommunications landscape for consumers by providing a solution to the “digital divide” thatcurrently exists in the District of Columbia and to increase the number of broadband service
providers in the District.
3.2.2 A BETTER CONNECTED APPLIANCE
An interesting aspect of BPL is that every electric device is connected to the electric distribution network. Potentially, BPL could let chips in every electric device talk to each other. Of course, a Wi-Fi, Blue Tooth or other wireless chip could be placed in every appliance. But BPL may be a better solution. Those who had PC’s before the Internet exploded remember the difference in functionality between a standalone PC and a networked PC. Networking every electric device together over the power lines might result in a similar growth in productivity and convenience for the home and office.
Advances in BPL communications over medium technology now allow for high-speed, broadband and low voltage lines yielding potential market opportunities. Using BPL technology theutilities can now offer new facilities-based competition for broadband services and provide high speedaccess to qualified urban, suburban, and rural areas of the country.
BPL can help utilities maximize the value of their existing assets by leveraging the transmission and distribution network infrastructures. The business development managers in utilities, atpresent, are focused on more traditional transition into the market via energy related applicationssuch as Automatic Meter Reading (AMR), demand side management, outage notification,distribution transformer overload analysis, phase loss monitoring, fault characterization, andseveral others.There are a number of applications BPL architecture can help deliver. These applications are shown below
Table no.1 Applications
5 FEASIBILTY ASSESMENT
Several utilities, particularly municipally owned ones, have been running pilots of broadbandservices over fiber to the home (FTTH), and some have moved to full deployment. While BPLhas come a long way in the past two years, some issues, especially the lack of standards for“Access BPL”, remain unresolved. However, the technologies appear to work well enough toprovide commercial service. In fact, the state of BPL today strikes in many ways resemblances towhat cable modem service was like in 1997. There are several proprietary technologies that work,standards are not yet there, and a pretty significant culture change will have to occur in utilitypersonnel, just as it did for cable.Willingness of utilities to invest in new technologies and take risks, is to some extent, determinedby what constituencies they serve. Historically, it appears that “Munis” have been quicker toembrace new technology, since they do not have to produce results for shareholders.
Access BPL equipment consists of injectors (also known as concentrators), repeaters, andextractors. BPL injectors are tied to the Internet backbone via fiber of T1 lines and interface to the Medium Voltage (MV) power lines feeding the BPL service area. MV lines, typically carrying 1,000 to 40,000 volts, bring power from an electrical substation to a residential neighbourhood. Low Voltage distribution transformers step down the line voltage to 220/110 volts for residential use. MV power lines may be overhead on utility poles that are typically 10 meters above the ground. Three-phase wiring generally comprises an MV distribution circuit running from a substation, and these wires may be physically oriented on the utility pole in a number of configurations (e.g. horizontal, vertical, or triangular). This physical orientation may change from one pole to the next. One or more phase lines may branch out from the three phase lines to serve a number of customers. A grounded neutral conductor is generally located below the phase conductors and runs between distribution transformers that provide Low Voltage (LV) electric power for customer use. In theory, BPL signals may be injected onto MV power lines between two-phase conductors, between a phase conductor and the neutral conductor, or onto a single phase or neutral conductor .Extractors provide the interface between the MV power lines carrying BPL signals and the households within the service area. BPL extractors are usually located at each LV distribution transformer feeding a group of homes. Some extractors boost BPL signal strength sufficiently allow transmission through LV transformers and others relay the BPL signal around thetransformers via couplers on the proximate MV and LV power lines. Other kinds of extractorsinterface with non-BPL devices (e.g. WiFi, WiMax) that extend the BPL network to the customers’ premises. For long runs of MV power lines, signal attenuation or distortion through the power line may lead BPL service providers to employ repeaters to maintain the required BPL signal strength and fidelity. Figure illustrates the basic BPL system, which can be deployed in cell-like fashion over a large area served by existing MV power lines.
fig 5.1bpl system in a large area
6 REGULATORY ISSUES AND CHALLENGES
The FCC has implemented new rules after obtaining comments from proponents of the new BPLservice, i.e., electric utilities and BPL vendors, as well as those who might be impacted by theBPL signals. On most electric utility poles below the four electric utility lines there is a lowersegment of the pole where telephone and cable television wires are attached (referred to as thecommunications space). One of the questions the FCC has addressed is whether radiated signalsfrom access BPL systems on the electric power lines would interfere with signals on the cable and telephone lines, and vice versa.Regulations in the BPL arena can broadly be grouped into three categories of issues as shown in the figure. Even though the Telecommunications Act of 1996 mandated that broadband service be widelyavailable in the United States, the actual market for that service today is a duopoly—with customers in most jurisdictions connecting to the internet through either their incumbent local exchange carrier (ILEC), which provides broadband service through digital subscriber lines (DSL), or their local cable operator, which provides the service through cable modem. Duopoly does not necessarily provide consumers the opportunity to get the best combination of rates and services, and many now are looking to electric companies as a third competitive provider of broadband.
fig 5.2 regulatory issues
BPL technology provides the opportunity to have true competition for broadband service. Giventhe applications and services it can offer, it is incumbent upon regulators to adopt a uniform set ofrules and regulations that will facilitate the provision of BPL service in the United States whileensuring that public interest concerns are protected . In order to provide broadband access to allAmericans, the FCC and the states are defining and adopting a regulatory scheme that removesunnecessary barriers to market entry and permits electric companies to be competitive in themarketplace.
6.1 INTERFERENCE AND RADIOSTATIC
Powerline system is a type of carrier current system that electric utility companies have traditionally used for protective relaying and telemetry. They operate between 10 kilohertz (KHZ) and 490 KHZ, although today many utilities rely on the 1-30 megahertz (MHZ) bandwidth forBPL transmission. A carrier current system transmits radio frequency energy to a receiver by conduction over the electric power line.
Under Part 15 of the FCC’s current rules, which regulate carrier current systems and powerline carrier systems, each is subject to different emission limits. The FCC also limits the amount ofconducted radio frequency (RF) energy that may be injected into a building’s wiring by an RF device that receives power from the commercial power source, including carrier current systems that couple RF energy onto the AC wiring for communications purposes. This conducted energy can cause interference to radio communications by two possible paths.
First, the RF energy may be carried through electrical wiring to other devices also connected to the electrical wiring. Second, at frequencies below 30 MHZ, where wavelengths exceed 10 meters, long stretches of electrical wiring can act as an antenna, permitting the RF energy to be radiated over the airwaves. Due to low propagation loss at these frequencies, such radiated energy can cause interference to other services at considerable distances.
6.2 UNIVERSAL SERVICE AND POLE ATTACHMENTS
Currently, all interstate telecommunications, wireless phone, and paging service providers must contribute 6.8 percent of their long distance and international calling revenue to a universal service fund. The fund is designed to provide rural, low income, and other consumers access toadvanced and inter-exchange telecommunications services at reasonably comparable rates charged for similar services in urban areas. The obligation to contribute to the universal fund, if applied to BPL providers, would add to the costs of providing such service.Pole attachments have been an issue since before BPL technology arrived on the scene. Pursuant to the adoption of the Telecom Act, an electric utility had to provide access to its poles—if the utility used its poles for any type of communications, including its own—to any company requesting access. Under the FCC’s rules, where access is mandated, the rates, terms, and conditions of access must be uniformly applied to all telecommunications carriers and cable operators that have or seek access. Utilities may deny access for reasons related to insufficient capacity, safety, reliability and other engineering purposes.
Cross-subsidization is a particularly significant concern when a company provides one service in a competitive market, but is a monopoly provider of another service, as is the case with many electric companies. As for BPL technology, the concern is whether electric companies will use earnings or resources from the provision of electric service to subsidize their BPL businesses. Regulators will focus on this issue for two reasons—first, such subsidies could provide electric companies with an unfair advantage in the broadband market and, second, needed resources that are diverted away from the provision of electric service could hurt quality of service.
7. FUTURE OF BPL
While in-home BPL is already on the scene with commercial products readily available, proliferation of Access BPL faces a more formidable challenge. RFI concerns are legitimate and specific cases have been documented. Standardization by the IEEE for device compliance is critical to avoiding the proliferation of proprietary solutions. Companies manufacturing BPL devices will have to ensure their products meet the revised standards set forth by the FCC, which will increase the cost of the deployment. The electric companies are eager to pursue BPL, envisioning increased services and reduced operating costs as a result of the deployment (Forbes, 2005). Cable and DSL providers will be watching the emerging competition closely and, along with the ARRL, will be eager to ensure the BPL installations are meeting the requirements of the FCC.BPL companies such as Current Technologies Group will continue working with the electricity providers in more trials around the country while continuing to work through issues with RFI. At the same time, the ARRL will continue to monitor and report occurrences of RFI to defend licensed service
This paper presents “BROADBAND OVER POWER LINE”,that is broadband connection through power line,ie the same power line which brings the electricity to our home.This can be a boon for the people in remote areas and especially to our country where ther are a lot f villages because electric line covers over 95% of the land. For that proper awareness must be done and people must be equipped with basic knowledge about computer.This technology is in its budding state and many countries have employed research teams to have a better understanding of this technology. This technology has greater advantages which makes it a blessing for developing countries like ours.
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