May 17, 2005

Flawed BPL is no broadband panacea

Author: Joe Barr

Broadband over power lines has been in the news again recently. At one time BPL was seen as the best way to bring affordable Internet access to poor and rural America: an answer to the technology gap between the haves and the have-nots. Now, thanks primarily to boosters like Michael Powell and Kevin Martin, Powell's successor at the FCC, it's back for another go at the broadband access market. But BPL remains a flawed and controversial technology. Proponents in Texas are pushing a pro-BPL bill past confused legislators in Austin at the same time their counterparts in Washington, D.C., are considering a measure to rescind "BPL-friendly" rule changes made at the FCC last fall.If you listen to the marketing that surrounds BPL, you can understand why it has supporters. Proponents say that BPL will finally bring broadband access to the poor, the underserved, and to rural areas. They also suggest that BPL will enhance the coming "smart grid" technology which someday will replace our antiquated power systems. The third BPL talking point is that once the technology is flourishing, consumers will benefit from increased competition in the marketplace. Lastly, BPL proponents admit that there is a possibility of interference being generated, but that it will be minor and mainly affect only amateur radio operators who live within close proximity to a BPL-equipped power line. Unfortunately, three of the four talking points are untrue, and the fourth is far from certain.

The reality behind the talking points

There are two basic types of BPL: Access BPL and In-house BPL. Access BPL carries broadband traffic into homes or buildings over existing power lines. In-house BPL -- like the popular X10 home automation product line -- works entirely within the framework of the home or building's internal electrical system. All the buzz in the news these days is about Access BPL.

Access BPL is a "last mile" technology. That means that broadband traffic is carried by other means -- optical fiber, for example -- all the way from the ISP to the neighborhood being served. At that point, broadband traffic is "injected" into the power lines that serve the neighborhood.

Once the broadband traffic has been injected into a power line, all that a customer needs to access the Internet is a BPL modem connected to any available electrical outlet served by that power line. From the ISP to the injection point, there is nothing new or unique. From the modem to the routers, computers, and LANs in the house or business connected to BPL, there is nothing new. BPL only exists on that "last mile" of the power line, between the injection point and the BPL modem. (Mostly -- one BPL provider is working on a hybrid solution, using BPL on medium voltage lines, then using wireless 802.11 communications between the power lines and consumers.)

For a more detailed technical explanation, see the paper entitled "Technical Considerations for Broadband Powerline (BPL) Communication," by Robert G. Olsen.

Remember the first of the three BPL talking points, the one about bringing affordable Internet access to America's poor and rural areas? It's not true. Perhaps it was at one time, during its infancy, while BPL was still on the drawing board. That was before experimenters learned that transformers can eat the broadband traffic at points between the power plant and its final destination. Now that we know the signal has to carried by other means in order to get it into the neighborhoods being served, a large chunk of the original cost savings have disappeared, and it's clear that the BPL is no panacea for the digital divide.

That conclusion doesn't come just from those opposing BPL, but from within the industry as well. Karen George, market research director for Primen, a Colorado subsidiary of the utility industry's Electric Power Research Institute, told the San Diego Union-Tribune last December that while the actual costs for adding BPL to existing power grids are still unknown, rural deployments will cost more than urban. That means the same demographics that drive the existing broadband delivery systems apply to BPL as well: optimal profits will come from operations in the areas with the highest population density, and lower profits -- or losses -- will come from operations outside those areas.

Smart grid technology? Nobody even knows for sure just what that phrase means just yet, other than that our existing power infrastructure is not it. Simple meter reading and control communications are handled by BPL on frequencies where it doesn't cause interference with the HF or VHF bands, so if that's your definition of a smart grid, relax. It's here today, and Access BPL for the Internet is not required for its operation. But visionary smart grid technology is a phenomenon whose birth date still lies on the far side of the event horizon. Driven by the catastrophic Blackout of 2003, "smart grid" has emerged as a collective, curative buzzword.

But even if it were real and available today, there is nothing intrinsic to Access BPL that would allow it to carry data any faster or more reliably between different points of the grid than existing broadband carriers.

There is some merit to the BPL lobby's third talking point: increased competition among broadband providers would be good for consumers. The only catch to this one is that BPL must first prove to be at least as fast, at least as reliable, and at least as cost-efficient as existing broadband carriers. If and when that happens, we can all celebrate, because everyone except monopolies know that competition is a good thing for consumers. The problem is that BPL is a long way from being faster, more reliable, or cheaper than conventional broadband access.

But the real killer in BPL -- its fatal flaw -- is the interference it causes. This interference is not, as former FCC chairman Michael Powell and other BPL cheerleaders have claimed, minor. Nor is it just a "possible risk." It is a certainty.

When a signal is injected onto a long, unshielded wire at radio frequencies, that wire becomes an antenna, and it radiates the signal. A power line is a long, unshielded wire. When broadband traffic is injected onto a power line, that signal is broadcast. It interferes directly with radio communications operating at or near the same frequencies the power company uses. I say frequencies, because BPL today uses multiple carrier frequencies to try to raise its level of reliability.

The HF frequency spectrum -- from 3MHz to 30MHz -- and the VHF spectrum - 30MHz to 80MHz -- are the two that would suffer the most interference from Access BPL. These spectrums are used by thousands of public safety agencies: police departments, fire departments, and emergency medical services. They are also used by the military, by government entities at all levels, by ships and planes, and by many other licensed users. The communications of all of these critical functions would be subjected to the interference generated by Access BPL.

BPL performance

There are three problems with Access BPL from a technical perspective: harmful interference, slow speed, and poor reliability. Vendors have tried BPL pilots all over the country -- unsuccessfully. Companies like AT&T and Nortel Networks tried BPL and gave up on it for one reason or another. Other pilots have shut down in the face of complaints of interference. In Texas, TXU shut down its pilot near DFW following complaints from the American Radio Relay League (ARRL). Similar complaints were filed in Iowa, leading Alliant Energy to end its pilot months ahead of its announced schedule. Both firms say there were reasons for the shutdowns other than the issue of interference.

When a power line becomes a radio antenna, it does more than just broadcast the broadband traffic; it also receives radio transmissions. The internal "noise" from those signals appears to cause additional problems for BPL's performance. Tests conducted by amateur radio operators, voluntarily working with customers at BPL pilot sites, have shown that mobile radio transmissions made while parked in the street near a BPL power line -- and using as little as 5 watts of power -- impede the flow of data from the Internet to the home.

According to Ed Hare, the ARRL Laboratory Manager, "The testing of susceptibility done by amateurs did show that as little as 5 watts of power had an impact on the systems tested, but there is no way of knowing whether this would occur on all BPL systems. ARRL has offered to BPL manufacturers and electric utilities to do more thorough testing of this problem, but so far, this is not something that they want to look at closely. Until that more thorough testing happens, the unencouraging results seen so far will have to serve as the red flag that BPL may not work well near licensed radio transmitters."

Carol Arneson and Robert Herbst, both senior managers at business consulting firm Virchow, Krause & Company, LLP, recently wrote a study on BPL entitled "Broadband Over Powerline: A midterm grade." The grades they awarded are as follows:

  • A in Politics
  • B in Self-Promotion
  • D in Technical Performance
  • D in Business Model Demonstration
  • D in Market Identification
  • F in Pilot to Implementation Transition

Giving equal weight to each category, BPL earned a D+ overall. The study notes that the interference issue has largely been ignored in pilots, and that data rates have slipped from early projections of 100Mbps to as low as 10Mbps. They stop short of declaring the technology dead, saying "there is interest and potential niche applications." But they also warn that BPL technologies today are not investment-grade.

Next: BPL legislation stumbles in Texas

It appears that at least one large power conglomerate in Texas agrees with the Broadband over Powerline report's assessment. It's sometimes difficult to follow the BPL action in Texas, even if you have a program. Public committee hearings on SB 1748 were reportedly orchestrated in such a way that concerned citizens who came to Austin from around the state were not able to testify. Even if you did manage to testify, it appears that the committee misrepresented who was for or against the bill. One person who testified on behalf of EFF-Austin claims that her position was misrepresented in the committee's final report. Stranger still, TXU -- the firm reported to have been cozying up to the committee chairman and at least one other member of the committee -- was listed as having testified against it.

Senator Troy Fraser is chairman of the Texas Senate's Business and Commerce committee. He is also the author of SB 1748, "An act entitled relating to the development and provision of broadband over electric delivery systems and the development of enhanced electric delivery systems." Senator Ken Armbrister is also a member of that committee. TXU is conglomerate of electric power related holdings.

TXU recently made it possible for Fraser and Armbrister to attend the Masters golf tournament in Augusta, Ga., by providing them with passes to the event. Since that coziness was made public, Fraser has said he wrote a check to TXU to cover the face value of the passes, which was $300 per day. Of course, street prices for the tickets were much higher, with two-day badges reportedly going for $1,750. And dinner for all his guests the night before the opening day of the tournament was picked up by TXU lobbyist Mark Malone, as was a meeting at the sponsor's tent the next day.

Something happened to the bill along the way, and it didn't make it out of committee without two significant changes. Originally, it allowed electric companies to charge existing customers for their investment in BPL, relieving the companies of shouldering any risk in their venture. That wording was removed from the bill. The second change was the addition of the following section: "Sec. 43.152. COMPLIANCE WITH FEDERAL LAW. BPL operators are required to comply with all applicable federal laws, including laws protecting licensed spectrum users from interference by BPL systems."

Those changes are why TXU ended up speaking against it. TXU has since assured me that it is still behind BPL in general, just not the version of the bill that came out of committee. Apparently either TXU doesn't have enough confidence in BPL to risk investing its own money in it, or else it feels there is no cure for those interference blues -- or both.

When I noticed that EFF-Austin's Adina Levin on the final committee report as speaking in favor of the bill, I queried her as to why EFF-Austin was supporting Access BPL. She replied:

I didn't sign the testimony card FOR the bill -- if the record says so, they misread the card. I did not get a chance to see the committee substitute before testifying.

EFF-Austin and SaveMuniWireless aren't in favor of BPL or any specific broadband technology. We're in favor of multiple options to increase access to broadband. We're in favor of enabling cities and towns to make choices that are right for the area. And we're against a state ban on the ability of cities and towns to support broadband access.

At the hearing, a representative of a power company testified to the problems in a recent pilot that did not deliver commercial-quality results because broadband performance was inconsistent. If this pilot and other pilots continue not to deliver good results, then BPL won't gain traction in the market.

Next: Clearly interference

In order to learn more about the interference generated by Access BPL, and the techniques being used to try to mitigate that interference, I spoke with Ed Hare, the ARRL Laboratory Manager. Hare has visited 10 different BPL pilot installations to gain firsthand experience with issues of interference. I wanted to learn how BPL providers could tune their systems in order to avoid interfering with critical communications. Hare began by giving a little background information on how most BPL systems work:

The exact mechanism can vary from system to system, but for the most part what they are doing with these systems is some form of multiple-carrier transmission, where they are sending information on a power line on multiple carriers spread across the frequency range, with the expectation that at least some of them will get to the other end in reasonably strong signal levels, so they can properly demodulate the signal and get all of the digital data that's been sent.

Then Hare proceeded to describe the most commonly used method of mitigation of the resulting interference, called "notching."

To protect licensed users, what they usually do is to turn off the carriers in the spectrum they are trying to protect. So, for example, they didn't have carriers operating in any of the amateur bands, then in theory, if those signals were protected enough, they could operate without interfering with that particular part of the spectrum.

In our experience in a number of different BPL systems, BPL that starts off at the FCC limits, with a typical 30db of notching, has not done enough to fully protect that spectrum. In the notched spectrum, we can still hear BPL signals at levels that might be 10, 20, or more times stronger than other signals that are on the band. In the amateur radio service, for example, if we're trying to communicate with a station that is not extremely strong, those BPL signals would cover up many of the signals on the band.

Hare's description of the cause of the interference -- using the same frequencies for carriers to transmit BPL data that others are using -- and the apparently ineffectual job at undoing that interference using the notching technique, paints a far different picture of BPL interference than the one provided by the BPL lobby, or by the FCC, for that matter. I asked Hare about that disparity. He said, "The FCC has stated that the likelihood of interference from BPL is very low, or words to that effect. We've looked at their own test data, and the ARRL does not believe that their own test data supports that statement."

The raw data from those test results (available as a large PDF file on the ARRL site) -- as measured by the FCC itself -- clearly shows levels of harmful interference in the HF band generated by BPL pilot tests. When the FCC was asked to comment on the apparent discrepancy between its own tests and its Rule and Order, spokesperson Bruce Romano said, "Those issues are under reconsideration."

On the same day that I spoke with Ed Hare, the U.K.'s Office of Communications (OFCOM) telecommunications regulatory agency released the results of a recently completed study it did on a BPL pilot in Scotland. According to the ARRL's BPL news page, OFCOM:

... concluded that Amperion BPL equipment deployed in a field trial in Scotland "as tested is not and cannot be FCC Part 15 compliant above 30 MHz." Ofcom today released a study, "Amperion PLT Measurements in Crieff," which summarizes measurements it took at the site in Scotland. PLT is another term for BPL. Ofcom's investigation also demonstrated the limitations of Amperion's "notching" capabilities to mitigate interference to radio reception. ARRL CEO Dave Sumner, K1ZZ, says Ofcom's study reflects what the League and others have known all along about BPL.

To date, the only real success that BPL has achieved in mitigating interference has come in getting the FCC to relax its rules on the harmful interference it does generate. And now that relaxation of the rules is coming under close scrutiny. Michael Ross, a Representative from Arkansas, has introduced a resolution in the U.S. House of Representatives calling for a "full and complete analysis" of the radio interference created by Access BPL with an eye towards undoing last October's rule changes.


After having spent some considerable time researching this story, I'm left primarily with a sense of deja vu. BPL today is like the very worst of the dot com era: mythological, deliberately misstated, and majorly overhyped technology that is being used in ways it was never designed to be in the first place.

The FCC's role in the BPL soap opera has been less than stellar. I asked Dave Sumner, ARRL's CEO and Secretary, if the FCC stance on BPL seemed out of the ordinary, based on his dealings with them over the years. He replied:

Yes, it does. Historically the FCC has a reasonably good record of basing its decisions on sound technical analysis. However, Chairman Powell was cheerleading for BPL before the facts were in and continued to do so even after there was clear evidence that radio interference would be a major problem. Now that he has left the FCC we're hopeful that more sober leadership will recognize the need for reconsideration.

If you find it hard to believe that Michael Powell, the FCC, and the BPL lobby have been less than honest about the amount and severity of radio interference generated by BPL, all you have to do is to look and listen: here, here, or here.

In the interest of full disclosure, I am both a newly licensed amateur radio operator and a member of the ARRL.

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