Consultation Paper on Broadband over Power Line (BPL) Communication Systems

SMSE-005-05
July 2005

Note: 
October 7, 2005: In Section 6.2 Prospective Technical Requirements, the consultation intended to reflect the technical limits established in the United States. The measurement distance for Access BPL system above 30 MHz was incorrectly reproduced. The consultation paper states a measurement distance of 3 metres for these systems. The distance should have been 10 metres. This has been corrected in the consultation paper.

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Table of Contents

• 1.0 Intent
  
  
• 2.0 Background
  
  
• 3.0 General Description of BPL System
  • 3.1 The Power Distribution Grid
  • 3.2 BPL Systems
  • 3.3 In-house BPL
    
    
• 4.0 Benefits and Deployment Issues of Access BPL
  • 4.1 Benefits
  • 4.2 Deployment Issues
    
    
• 5.0 Current Status of BPL
  • 5.1 International Activities
  • 5.2 United States Activities
  • 5.3 Industry Canada Activities
    
    
• 6.0 Discussion and Proposals
  • 6.1 Equipment Standard and Approval Process
  • 6.2 Prospective Technical Requirements
  • 6.3 Operational Requirements
    
    
• 7.0 Next Steps

1.0 Intent

As announced in Gazette Notice SMSE-005-05, Industry Canada is releasing this consultation paper to seek public and industry views on systems that deliver high-speed Internet and broadband services over power lines. These systems are often referred to as Broadband over Power Line (BPL) communication systems.

BPL communication systems function by coupling radio frequency (RF) energy to existing electrical power lines. These systems can be used to deliver high-speed voice and data communications to customers, or improve the management of the power distribution grid by facilitating monitoring and automated meter reading activities. Since power lines reach virtually every household in Canada, BPL could bring broadband services to rural and urban areas and improve competition where similar services are already provided by other technologies, such as digital subscriber line (DSL), cable modem and wireless access.

The intent of this consultation paper is to seek comment on the deployment and regulation of BPL systems in general, including the specific equipment standards and operational requirements that would be required if BPL systems were deployed. Moreover, the Department intends to take steps to facilitate the deployment of BPL technology in Canada while ensuring the protection of authorized radiocommunication services.

Gazette Notice SMSE-005-05 invites interested parties to submit their comments by November 28, 2005 to the Director General, Spectrum Engineering Branch.

2.0 Background

Historically, power utilities have used alternating current (AC) power line distribution facilities to carry information by coupling radio frequency (RF) energy to AC electrical wiring in houses or buildings. In the past, these devices have operated on frequencies below 2 MHz with limited communications capabilities. [Footnote 1] Due to power line characteristics it has been difficult to achieve dependable high-speed communications. However, technological advancements have resulted in the development of new systems [Footnote 2] which have overcome these technical obstacles. Trials have demonstrated that high-speed communication voice and data services can be achieved using the existing medium-voltage (MV) and low-voltage ( LV ) power distribution grid.

BPL technology has evo LV ed rapidly over the past two years. While the technology appears promising, there are a number of issues with respect to its operation as well as the possibility of it interfering into radio services in the 2-80 MHz range.

The Department has received numerous enquiries from power companies, manufacturers and other organizations regarding BPL technology. We are working with the industry to understand the compatibility of BPL technologies and applications with other radio services. There have been a limited number of BPL trials in Canada where the Department has performed preliminary analyses on BPL emissions.

Since power lines reach virtually every home in Canada, BPL may provide an additional option to delivering broadband services to rural and urban areas. Furthermore, the introduction of BPL fits within the Government of Canada's Federal Broadband project, which was developed to narrow the "digital divide" between Canadians living in urban, rural and remote communities.

Since BPL systems can transmit and receive intelligence by wire, they may be considered as transmission facilities under the Telecommunications Act. Therefore, BPL operators may ultimately be subject to the regulatory requirements of the Act and to the oversight of the Canadian Radio-television and Telecommunications Commission (CRTC).

In considering BPL under the Radiocommunication Act, the Department can give regard to the policies outlined in section 7 of the Telecommunications Act, which includes: 

(a) to facilitate the orderly development throughout Canada of a telecommunications system that serves to safeguard, enrich and strengthen the social and economic fabric ofCanada and its regions;

(f) to foster increased reliance on market forces for the provision of telecommunications services and to ensure that regulation, where required, is efficient and effective; and,

(g) to stimulate research and development in Canada in the field of telecommunications and to encourage innovation in the provision of telecommunications services.

The United States (U.S.) Federal Communications Commission (FCC) has carried out a consultation to implement BPL and recently established technical and operational rules for BPL systems. [Footnote 3] Considering the similarities between the U.S. and Canadian power distribution grids BPL manufacturers will view Canada and the U.S. as a common marketplace.

The Department is seeking comments on the technical and operational criteria which will facilitate the deployment of BPL systems in Canada with minimal impact on radiocommunication services.

3.0 General Description of BPL Systems

BPL systems are comprised of different components which function together to deliver broadband services to customers. Briefly, data is carried by fibre optic or telephone lines to avoid high-voltage (HV - greater than 69 kV) transmission power lines. The data is injected onto the MV power distribution grid and special electronic devices, known as repeaters, re-amplify and re-package the signal because the signal loses strength as it travels along the MV power line. Other technologies are used to detour the signal around transformers. The signal is delivered directly into homes via their regular electric current.

3.1 The Power Distribution Grid

The power distribution grid is made up of a number of components aimed at delivering electricity to customers, and includes overhead and underground MV and LV power lines and associated transformers. MV power lines carry electricity in the range of 12.5-36 kV and the voltage is decreased by step-down transformers to provide LV power to houses and buildings. In general, the LV power lines carry electricity at 120/240 volts or 347/600 volts.

3.2 BPL Systems

Historically, power utilities have coupled RF energy to AC electrical wiring in houses or buildings to carry information. Although simple communication was possible, these systems were not capable of delivering dependable broadband services. Recent technological advancements have resulted in the development of new systems that promise to deliver broadband services over the existing power distribution grid. These systems are comprised of Access BPL, In-house BPL, or a combination of both technologies.

3.2.1 Access BPL

Access BPL systems utilize the power distribution network, owned, operated and controlled by an electricity service provider, as the means of broadband delivery to and from premises such as the home or office. Access BPL systems use injectors, repeaters, and extractors to deliver high-speed broadband services to the end-user.

Injectors provide the interface between the Internet backbone and the MV power lines. Once the signal has been injected onto the MV power line, it is extracted to deliver the information to the end-user. Extractors provide the interface between the MV power lines which carry the signals to the customers in the service area. Extractors are generally installed at LV distribution transformers that service groups of homes. Since the BPL signal loses strength as it passes through the LV transformer, extractors are required to retransmit the signal. In other cases, couplers on the MV and LV lines are used to bypass the LV transformers and relay the signal to the end-user. At least one company has designed a third type of extractor which transmits a wireless signal directly from the MV power line to end-users.

To transmit signals over long distances, repeaters are employed to overcome losses resulting from physical characteristics of the power line.

At this time, the Department is proposing to adopt the following definition [Footnote 4] for Access BPL systems:

Access Broadband over Power Line (Access BPL):  A carrier current system installed and operated on an electric utility service as an unintentional radiator that sends radio frequency energy on frequencies between 1.705 MHz and 80 MHz over medium-voltage lines or over low-voltage lines to provide broadband communications and is located on the supply side of the utility service’s points of interconnection with customer premises.

3.2.2 Multiple Formats of Access BPL

The Department is aware of various implementation/deployment architectures of Access BPL systems. However, the Department believes that Access BPL systems can be generally classified as either: (1) an end-to-end system, or (2) a hybrid system.

3.2.3 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.

Figure 1: Overview of End-to-End Access BPL System [Footnote 5]

3.2.4 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.

More recently, a second hybrid system has been developed. These systems capture wireless signals and inject them directly onto the LV power line. The signal is distributed using the LV power line and in‑house wiring to the end-user.

Figure 2: Overview of Hybrid Access BPL System [Footnote 5]

As shown in Figure 2, the hybrid Access BPL system uses repeaters and extractors which are capable of transmitting and receiving wireless signals to and from end-users.

3.3 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 (see Figure 1).

In-house BPL technologies are largely designed to provide short-distance communication solutions which compete with other in-home interconnection technologies. Product applications include networking and sharing common resources such as printers.

In Canada, In-house BPL equipment is regulated under Interference Causing Equipment Standard 006, AC Wire Carrier Current Devices (Unintentional Radiators) (ICES-006). [Footnote 6] Since there are established regulations for In-house BPL systems in Canada, the intention of this consultation paper is not to address these systems.

Although the main focus of this consultation is to address Access BPL systems, after reviewing the FCC’s final rules in the context of the Canadian regulatory environment, the Department believes that separate definitions are required to differentiate between the two forms of BPL to prevent confusion. ICES-006 will be modified accordingly to reflect the adopted definitions for in-house systems.

At this time, the Department is proposing to adopt the following definition [Footnote 7] for In-house BPL systems:

In-house broadband over power line (In-house BPL): A carrier current system, operating as an unintentional radiator, which sends radio frequency energy by conduction over electric power lines that are not owned, operated or controlled by an electric service provider. The electric power lines may be aerial (overhead), underground, or inside the walls, floors or ceilings of user premises. In-house BPL devices may establish closed networks within a user’s premises or provide connections to Access BPL networks, or both.

4. Benefits and Deployment Issues of Access BPL

4.1 Benefits

Access BPL systems have the potential to offer a number of benefits including: (1) increasing the availability of broadband services to homes and businesses; (2) improving the competitiveness of the broadband services market; and, (3) improving the quality and reliability of electric power delivery.

With regard to increasing broadband services to Canadian homes and businesses, Access BPL systems can potentially provide high-speed data access and other broadband services to areas that do not currently have access to these services. Furthermore, Access BPL systems could potentially improve the competition for broadband services in Canada by providing another option for high-speed Internet access.

Access BPL systems have also been identified as a means of improving the quality and reliability of electric power delivery and creating a more intelligent power grid. BPL technology could allow utilities to more effectively manage power, perform automated metering and monitor the existing power grid for potential failures. [Footnote 8]

4.2 Deployment Issues

International and Canadian activities have established that the deployment of Access BPL systems could potentially impact the current radiocommunication environment by creating interference to existing services. Moreover, some authorized radiocommunication service users have expressed concern about the potential interference to their respective services from Access BPL systems.

In Canada, there are a number of authorized radio services in the 2-80 MHz frequency range. These services include amateur radio, fixed mobile, maritime mobile, aeronautical mobile, fixed broadcasting, space research, radio astronomy and aeronautical radio navigation. They are used by public safety organizations, Federal government agencies, aeronautical navigation licensees, amateur radio operators, international broadcasting stations, and General Radio Service (i.e. citizens band or CB radio) operators (see Canadian Table of Frequency Allocations [Footnote 9] ).

Access BPL systems are designed to send information within parts of the 2-80 MHz frequency range along unshielded power lines, which results in the unintended emission of RF energy. This unintentional radiation can create interference to the radiocommunication services mentioned above.

The Department continues to assess Access BPL systems to understand the technology and the interference mechanisms.

Footnotes

[1] The original power line communication (PLC) systems operated on 135 kHz and were used for internal communications by power utilities. These systems were not capable of high-speed voice or data transmission.

[2] These new systems use spread spectrum or multiple carrier techniques with built-in algorithms to circumvent the noise in the power line. For example, orthogonal frequency division multiplexing (OFDM) is used to distribute the BPL signal over a wide bandwidth using many narrowband sub-carriers.

[3] FCC. In the Matter of Amendment of Part 15 regarding new requirements and measurement guidelines for Access Broadband over Power Line Systems (ET Docket No. 04-37) and Carrier Current Systems, including Broadband over Power Line Systems (ET Docket No. 03-104). Report and Order. October 2004.

[4] This definition is used in the FCC BPL rules.

[5] The diagram is based on the National Telecommunications and Information Administration's (NTIA) Report 04‑413: Potential Interference from Broadband over Power Line (BPL) Systems to Federal Government Radiocommunications at 1.7-80 MHz Phase 1 Study.

[6] ICES-006 can be found on the Spectrum Management and Telecommunications Web site at:  http://strategis.ic.gc.ca/epic/internet/insmt-gst.nsf/en/sf02134e.html.

[7] This definition is used in the FCC BPL rules.

[8] National Association of Regulatory Utility Commissioners (NARUC). Report of the Broadband Over Power Lines Task Force. February 2005.

[9] http://strategis.ic.gc.ca/epic/internet/insmt-gst.nsf/en/h_sf01678e.h tml