Overview

Broadband over Power Line (BPL) is the transmission of high-speed communications services over the existing electric network using adaptive technologies.  It is a maturing technology that is developing as a viable third alternative to DSL and cable modems to provide high-speed Internet access and offer ISPs an alternative way into homes and businesses. BPL may be suitable in areas where there is a latent demand for broadband, regulatory clarity, demand stimulation is in place, and the financial barriers to entry are still too high.  Broadband over Power Line (BPL) makes it possible for the distribution of high-speed Internet service, by leveraging pre-existing electric distribution systems and thereby avoiding the need to build a new infrastructure.

BPL technology enables radio-frequency energy to be transmitted on the same medium voltage power lines that carry the electric current from the electric sub-stations to transformers outside the customer’s premises and then into the home or business. BPL does not require the installation of a separate data line, as there is no interference between the electric current and the radio-frequency energy because they operate at different frequencies. 

The BPL system operates at the electric sub-station level where there is a network connection to the Internet backbone and distribution switches that inject digitised data into the medium voltage lines. The signal quality of the data tends to degrade with distance travelled, which is solved with the installation of repeaters along the electric line used to regenerate and retransmit the data stream to or near the transformer outside the customer’s premises.   The real technical challenge with BPL technology has been to transmit the signal from the distribution transformer to the Customer Premises Equipment without attenuation or reduction in the signal strength. The approach has been to either bypass it or send the signals through it.[xi]

There are three methods that are used. Option (1) is to send the signal through the transformer but this approach with the present equipment limits the bandwidth available to the consumer; (2) the second option is to ‘bypass’ the transformer where a coupler and a router or a bridging device is co-located near the transformer that re-routes broadband signals around the transformer; (3) the third option is the ‘wireless step-off’ that creates a wireless hotspot around each transformer. [xii]

 
Improvements in the BPL technology over the past few years, such as development of the point-to-point protocol over Ethernet (PPPOE), have resulted in its movement beyond laboratory and technical trials to actual commercial provision.  Also, two specific problems that were cited as drawbacks to the technology; (1) radio frequency interference to wireless and ham radios and emergency radios (2) difficulties with attenuation and scaling up solutions, have been addressed.

The deployment of BPL networks has, in the last few years, received increased attention internationally.  In 2004, the European Union established OPERA (Open PLC European Research Alliance) with an initial budget of 20 million euros to foster the development of BPL technology to address the broadband market in Europe.  The technology is also being piloted in South Africa, as one of the City of Tshwane Digital Hub pilot projects in the town of Rooiwal, located north of the City.  Rooiwal was chosen as a pilot project because the City owns it with most residents employed by the power station and there is no access to high-speed Internet service. The BPL network will connect all the businesses, public buildings and 130 households in Rooiwal.[xiii]

Advantages and Limitations

What are the capabilities and advantages of using BPL technologies?

• BPL technology has many of the same advantages as DSL and cable modem services in that it is always on and has speeds that are relatively comparable to many residential service offerings. BPL technology has an advantage in that it is a symmetrical service providing download and upload of data at the same speed.  A BPL modem can be plugged into any electric outlet in the house or business giving more flexibility to the user,
  
• BPL technology can be used by the electric utility to more effectively manage the entire electric system.  Current Communications Group, LLC, has entered into a contract with Texas-based utility TXU Electric Delivery, the sixth largest electric transmission and distribution Company in the U.S., to provide a BPL network that will provide a broadband enabled ‘smart’ electric grid.[xiv]  This will provide the utility with the following capabilities

1. Monitoring of its electric distribution network remotely and in real time
   
2. Automated outage and restoration detection as well as outage prevention
   
3. Automated meter reading of state-of-the-art BPL-enabled electricity meters

• One of the basic issues related to the economics of deploying BPL networks for the provision of consumer high-speed Internet access is that this one service may not be sufficient to justify the expenditure, particularly in a competitive market where it is competing with DSL and cable modem providers.  In a 2005 report on BPL produced by the Millennium Research Council, it noted:
  
  “An important element in further deployment of BPL is the development of the so-called “triple play’- voice, video, and data – capability in order for the industry to be competitive with cable and DSL/fibre networks. VoIP, when digitised correctly, is possible over BPL networks. Video services, however, remain problematic since they require higher speeds than the approximately 1-4 Mbps services currently available to the home with BPL. This issue also affects DSL and is one of the driving forces behind the move to fibre networks.” [xv]

As part of its service offering, Current Communications announced that it would provide TXU customers with a triple play package of voice, television and high-speed access delivered across the existing electric infrastructure. If it can provide these services, it will significantly enhance the competitive advantage of BPL.

What are the constraints and disadvantages of using BPL technologies?

• Two of the main technology issues associated with BPL are attenuation or reduction in signal strength and potential radio frequency interference.[xvi] On the typical U.S. electric distribution line, a BPL signal may travel less than a mile before it needs to be amplified requiring the installation of repeaters at possibly intervals of 1000 feet, which can be a significant cost in network construction.  There is also the problem of attenuation at the distribution transformer, which can affect the available bandwidth.  The potential of radio frequency interference has been one of the major obstacles to the introduction of BPL and although the industry believes they have solved the problem, it remains an outstanding issue with amateur radio groups and some national spectrum authorities.
• Although BPL experts expect that the next generation of BPL technology could deliver speeds of between 10 and 30 Mbps[xvii], the current generation of BPL installations in the U.S. are currently delivering between 280-800 kbps in Manassas, Virginia and Current Communications provides1-3 Mbps in Cincinnati, Ohio.[xviii]  The ability of BPL technology to compete with other types of technology like DSL and cable modem will depend in part on the ability to provide greater bandwidth, particularly for video applications.
• The economics of deploying BPL systems appears to be more favourable in countries that use a 240-volt standard and typically serve 200 – 250 households per transformer than in the U.S. where the average number of households per transformer is 7.5.[xix]

BPL Technology and Local Open Access Networks

Although BPL technology is being rolled out on a commercial basis, it is still in an early development phase and its future as a potential alternative to DSL and cable modem technologies is unclear.  BPL technology may represent a potential solution to many communities that do not have access to high-speed Internet services, however a key determinant will be the cost. 

In a presentation[xx] made by COMTek Technologies on its BPL deployment in Manassas, it noted that the cost to pass each building or home was $75 with an additional $40 - $150 for Customer Premise Equipment.  Other studies from the U.S. have indicated a possible range of between $50 and $200 per residence passed.[xxi]  Although BPL may represent a cost effective solution for some rural communities, it is unlikely to provide a viable commercial proposition to ensure universal access in rural areas.  A major cost in deploying BPL systems is the repeaters that are required to amplify the signal making it extremely expensive to serve individual households that may be located miles from the utility pole.

None of the commercial deployments in the U.S. can be characterised as Local Open Access Networks in that access is restricted to one ISP that operates and is the sole provider of services on the network.  Although this may be explained by the start-up nature and financing of these operations, there is no clear evidence that there is likely to be any shift towards a LOAN model at least in the United States.  Although BPL technology may be suitable for open access networks, the ownership of the underlying infrastructure and the business model used by most utilities may limit its deployment on that basis. 

 <- previous chaper | next chaper ->