Electronic Bulletin / Number 15 - September, 2005

Versión Español

Access Broadband over Power Line

During the VII meeting of the Permanent Consultative Committee I, Telecommunication Standardization, it will be possible to have on September 22 from 9:00 am to 12:30 pm, within the work of the Working Group on Eonomic Aspects and Tariff Principles,an Expert Panel on Broadband over Power Lines Communications (BPL/PLC) that will analyze economic, regulatory and commercial aspects on BPL/PLC.

You can download the draft agenda.

Below for information purposes we include part of the information included in Amendment of Part 15 which establishes rules for Access Broadband over Power Lines. FCC Report and Order released:  October 28, 2004

"Access Broadband over Power Line (Access BPL) systems is a new type of carrier current technology that provides access to high speed broadband services using electric utility companies’ power lines.  This new broadband delivery medium could also serve to introduce additional competition to existing cable, DSL, and other broadband services.

Carrier current systems use alternating current (AC) electric power lines to carry communications by coupling very low power RF signals onto the AC electric wiring.[1]  Traditionally, these systems have included amplitude modulated (AM) radio systems on school campuses and devices intended for the home, such as intercom systems and remote controls for electrical appliances and lamps.[2]

Until recently, carrier current devices generally operated on frequencies below 2 MHz and with relatively limited communications capabilities.  In the last few years, the availability of faster digital processing capabilities and the development of sophisticated modulation schemes have allowed the development of new designs for carrier current devices that are capable of overcoming earlier technical obstacles caused by the inherent noise and impedance mismatch of power lines.  These new designs have led to the development of BPL systems that use spread spectrum or multiple carrier techniques with highly adaptive algorithms to effectively counter the noise in the line.

The new low-power, unlicensed BPL systems provide high speed digital communications capabilities by coupling RF energy onto either the power lines inside a building (“In-House BPL”) or onto the medium voltage power delivery lines (“Access BPL”).[3]  In-House BPL systems use the electrical outlets available within a building to transfer information between computers and between other home electronic devices, eliminating the need to install new wires between devices, and hence facilitating the implementation of home networks.[4]  Access BPL systems deliver high speed Internet and other broadband services to homes and businesses.  In addition, electric utility companies can use Access BPL systems to monitor, and thereby more effectively manage, their electric power distribution operations.  Because Access BPL capability can be made available in conjunction with the delivery of electric power, it may provide an effective means for “last-mile” delivery of broadband services and may offer a competitive alternative to digital subscriber line (DSL), cable modem services and other high speed Internet access technologies.

Access BPL systems carry high speed data signals to neighborhoods from a point where there is a connection to a telecommunications network.  The point of network connection may be at a power substation or at an intermediate point between a substation and network terminations, depending on the network topology.  Within a residential neighborhood, some system implementations complete the connection between the medium voltage lines and subscriber homes or businesses by using wireless links.[5]  Other implementations employ a coupler or bridge circuit module at the low-voltage distribution transformers to transfer the Access BPL signals across (thereby bypassing) these devices.[6]  In such systems, the BPL signals are brought into homes or businesses over the exterior power supply cable from the coupler/bridges, either directly, or via Access BPL adaptor modules.[7]  Typically, the medium voltage lines are carried overhead on transmission poles or tower mountings; however, in a large number of locations, and in newer subdivisions and neighborhoods, these lines are enclosed in underground conduits and the distribution transformers are mounted above ground on a pad, inside a metal housing.

The interference concern regarding BPL operation arises from the fact that electric power lines are not shielded and therefore portions of any RF energy they may carry can be radiated.  While the power distribution management devices, such as transformers, and sometimes underground placement of lines that are characteristic of many electric utility systems tend to substantially diminish the effectiveness of these systems as radiators of RF energy, the potential for significant radiation of RF energy from utility systems that carry RF signals nonetheless remains.  This “signal leakage,” which has for years made possible the reception of carrier current radio stations at colleges, universities and other institutions without a connection to the power line, can become harmful interference if not carefully managed.  That is, radio systems using the same frequency bands as those on which local Access BPL signals are transmitted could possibly receive harmful interference from such signal leakage if adequate safeguards are not in place.

Most Access BPL systems that are currently deployed [in USA] operate in the range from 2 MHz to 50 MHz, with very low-power signals that are spread over a broad range of frequencies.  These frequencies are also used by licensed radio services that must be protected from harmful interference."

 

[1]     A carrier current system is defined as a system, or part of a system, that transmits radio frequency energy by conduction over an electric power line to a receiver also connected to the same power line.  See 47 C.F.R. § 15.3(f).

[2]      Campus radio systems have been operating for over fifty years in the United States at many universities as unlicensed broadcast radio stations in the AM Broadcast band, see 47 C.F.R. § 15.221.  Initially, the receiver and signal source were attached to the same electric power line.  After the advent of the transistor radio, receivers are sensitive enough to be able to pick up enough radiated signal for adequate reception when placed next to the electric power line in a dormitory or other locations on a campus’ electric power lines.  See also, e.g., X-10 products for home automation at http://www.X10.com, and products conforming to ANSI/EIA-600.31-97 Power Line Physical Layer and Medium Specification (CEBus Standard).

[3]      In-House BPL uses the 110 volt power wiring inside a residence or business to carry information within a structure.  Access BPL typically uses the medium voltage exterior power distribution network lines (carrying between 1,000 to 40,000 volts) as a transmission medium to bring high-speed communications services, e.g., the Internet and other broadband services, to neighborhoods from where they are delivered to users.

[4]    Home networks allow information to be transferred among computers, set-top boxes, information appliances and consumer electronics devices.  Applications of home networking include, for example, shared Internet access, shared printing, file sharing between personal computers, and device control.

[5]    See e.g., http://www.amperion.com/products.asp.

[6]   Low voltage transformers are poor conduits for high-frequency digital signals, as they are intended to conduct 60 Hz electric power. 

[7]    See e.g., http://www.currenttechnologies.com/products.asp; http://www.mainnet-plc.com.

 

 


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