BPL - Broadband over Powerlines

[Kevster]

In another forum, some people here are excited about BPL. I am not one of those people. I am a communications engineer by profession and I am seriously concerned about the power company's efforts to get FCC restrictions relaxed so that they can deploy BPL technology and transform the HF radio band (2 to 80Mhz) from a relatively quiet radio spectrum into a noisy wasteland.

Want to see how the 2nd Generation PLC (the technology that is supposed to have the interference problems fixed) trial areas in MD, NY, PA and VA test out in the short-wave and ham radio frequencies?

High-speed video results (http://216.167.96.120/BPL_Trial-web.mpg)

Low-speed video results (http://216.167.96.120/BPL_Trial-small.mpg)

What are they measuring? The frequencies being measured in this video are in a BPL trial area in July, 2003. They are measuring what should be reletively quiet licensed public/maritime shortwave communication frequencies and what are they getting? Lots and Lots of EM noise thanks to BPL. This is just at the low end of the frequency spectrum they plan to use. At higher frequencies, you get the licensed 30-40Mhz range that has Highway Patrol, rural Fire/Emergency and utility on it.

Here's a link to FEMA's complaints about BPL deployment on December 4, 2003 (http://gullfoss2.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6515292045). According to FEMA, BPL could "severely impair FEMA's mission-essential HF radio operations in areas serviced by BPL technology."

PLease post your comments so we can discuss this.

EDIT: Fixed Typo

[Jeffbx]

Geez, I remeber about 5 years ago that some company was selling a 'do it yourself' powerline networking kit. Just plug it into an outlet & you can share your connection with any outlet in your house. The thing that intrigued me about it was that the signal was supposedly strong enough that you could even share it with your neighbors (i.e., you would be broadcasting your network on the power lines going out of your house).

Never tried it, but I thought it was a pretty novel idea. Never even thought about the noise it might generate.

Maybe we should re-think the barbed wire network... (http://www.cawnet.org/pipermail/rfmon/2002-May/000900.html)

[johnnymk]

If the security issues can be resolved, Intel's plan seem to make more sense: (BTW, I could care less about FEMA's concerns)
The following is from Business Week:

Barrett fully intends to upend the status quo in communications and consumer-electronics markets. Think of Intel as a silicon arms dealer. By hawking cutting-edge digital technologies, the chipmaker will offer weapons that upstart companies can use to knock existing players for a loop, while forcing entrenched companies to consider buying the same weapons. This fall, for instance, Intel plans to roll out a chip based on a technology called WiMax that could be used to deliver high-speed wireless Internet access throughout a small city for about $100,000, one-tenth the cost of rolling out fiber-optic lines today. Either cable and phone companies buy into Barrett's vision, or their near-monopoly on broadband could be cracked by upstarts using WiMax. That's just the tactic that led to the dizzying popularity of Wi-Fi, a similar wireless technology, after Intel got behind it last year.

[ski]

I work for a communications company that specializes in Public Safety radio (700 and 800 Mhz), and though with that being one of the higher priorities in the radio frequency band, maybe the power companies think it's okay to step on the public's toes for shortwave radios? I don't like it either.

[Kevster]

Originally posted by skiAtomic
I work for a communications company that specializes in Public Safety radio (700 and 800 Mhz), and though with that being one of the higher priorities in the radio frequency band, maybe the power companies think it's okay to step on the public's toes for shortwave radios? I don't like it either.

:stupid:

They want to walk all over the HF public licensed frequencies with their current technology that doesn't work and a lot of people and organizations are pissed off. I only put in the FEMA comments because they are one of the latest to join the long list of organizations against BPL in its current form.

They are ignoring simple physics here - energy in the 2 to 80 MHz frequency range, imposed on the power lines as they exist today will radiate. Period.

Someone (who doesn't know cable systems) in another comm forum I look at questioned how it was different from other installed cable plants (coax, unshielded twisted pair, heliax, etc). Cable plants such as those are specifically designed to avoid leakage of signal passing through the cables (there are even FCC signal leakage standards that all but the smallest cable systems must meet.) Telephony generally uses twisted pair cables, which help cancel out stray signals. How in the world can one stop signal leakage on open wire, short of lowering transmit power?

Noisy power lines alone are a big problem in the AM, FM and HF frequency ranges. An example of this is when you cross a power line and hear a burst of noise on your AM radio. If you think that is legally acceptable, you're wrong. The FCC has written advisory notices to over 30 power companies to date, requiring that they correct the harmful radio interference from their power lines.

To give people here a couple real examples of how BPL can completely ruin frequencies, consider these:

A few years back, an early version of wireless modem jacks operated on 3.53 MHz. Like BPL, they were carrier current devices that operated at the FCC limits. They were purchased in volume by TCI Cablevision to use with their digital cable TV installations. Very soon the FCC started getting hundreds of reports of harmful interference. In some areas, the lower portion of the 3.5 MHz amateur allocation was blanketed with dozens of signals. Ultimately, AT&T Broadband (who had purchased TCI), did a system-wide recall of these devices. The manufacturer acted responsibly and redesigned the product to use a different frequency, but someone's license was getting gored.

Phase II of that problem represents a different frequency hijacking. Aeronautical, Inc (AIRINC - a customer of my company) operates aeronautical HF communications centers around the globe. In their California facility, they were getting interference on 3.013 MHz. They contacted the FCC, who tracked it down to a number of devices in a nearby neighborhood, but they were unable to pinpoint the exact source because the power lines were radiating the signal everywhere. AIRINC had to abandon the use of that frequency at that facility.

These are some pretty serious problems from carrier-current devices that operate at the FCC limits. Both operated on a single frequency and were intended to be used on residential and business electrical wiring (ostensibly a localized interference potential), but both caused some pretty serious problems.

Now, take that same "legal" level and operate it on entire swaths of spectrum. Operate it 24 hours a day and build it as big as an entire community. That's BPL.

EDIT: Fixed some typos

[LPMiller]

wouldn't you also get interference on various monitors at the frequency? I get it on and off NOW because I'm pretty close to transmission lines. I can't imagine what would happen if those lines were radiating broadband.

[JackHammer]

Let me try and understand your view point. You're saying that the biggest problem you see with BPL is signal leakage and interference from noise?

[Kevster]

Originally posted by JackHammer
Let me try and understand your view point. You're saying that the biggest problem you see with BPL is signal leakage and interference from noise?

Simply stated, yes.

The problem with interference is multi-faceted and to some extent difficult to fully comprehend. The HF radio spectrum is a different animal, different than all other radio spectrum. A very low powered signal can propagate hundreds or thousands of miles. This is why, if the conditions are right, you can talk to someone on the other side of the world using a shortwave radio.

The BPL trial areas are a bit misleading as some of the problems we see won't fully manifest themselves until full scale rollouts occur. BPL providers are basically hedging their bets that they can coexist in HF spectrum by tweaking their systems to not use frequencies that aren't in use locally. The assumption is that they won't interfere locally with anyone and should be fine. Due to the propagation characteristics of HF, it's likely long distance interference or an increased noise floor across the HF bands will occur. Such problems are hard to track down to a particular system and hundreds of these systems operating across the country could have a cumulative effect.

The other misnomer with the trials is scalability. As the subscribers are added, more bandwidth is needed, so more network segmentation needs to occur. This means that more chunks of HF spectrum will be needed in a given area. At some point, it will be impossible for a BPL provider to not avoid local interference as they will need all of the HF spectrum to operate their system.

Most of these trial areas have claimed no interference issues due to lack of complaints. This is analogous to saying you don't smell anything, meanwhile your furnace is malfunctioning and filling your house with carbon monoxide. BPL proponents have provided only anecdotal evidence to the FCC while those opposing BPL due to interference issues and potential have filed computer models and field measurements.

BPL also has issues with ingress interference, or interference into the system from outside sources. BPL from a regulatory standpoint has no protection from such interference.

Other countries have tried BPL over the past five or six years and have met with failure. These coutries include the Netherlands, England, Germany and Japan to name a few. This is being presented as a new high technology item in the US by many, but the reality is that it's not.

While we're at it, let's talk about the BPL technology itself.

First of all, there are two versions of it. There is the older HF version and a newer 5GHz version being developed by a company called Corridor. This new version is an interference free 802.11 based BPL. The system will have much more bandwidth than this lower frequency BPL that is plagued with interference and other issues. For some reason this high speed BPL isn't taking off and the various utilities don't seem to be noticing that there is a technology that will leapfrog what they're testing.

When you look at the "rural" business model for HF BPL, things start to get a little screwy. BPL has less of a range than cable and DSL, so that means the costs to backhaul the network are significant. Also, repeaters cost anywhere from $2k to $5k. If you need a repeater just under every 100 yards or so, and there's only one or two subscribers every quarter mile, it's tough to have this system pay itself off anytime soon. It's very likely if you don't have cable passing your house, you'll never see BPL. If BPL was a long haul technology such that it could transport data tens of miles (as many people erroneously perceive), it might have a chance in rural deployments, however it's far from being able to do that. That is why the best chance for it to somehow succeed is in an urban environment, and that is where the interference problems with HF-based BPL become intolerable.

Unfortunately, the FCC hasn't grasped the technical realities surrounding HF-based BPL and they have praised it in their rhetoric. Instead of encouraging telecommunications providers to deploy real future proof solutions like fiber, the FCC encourages electric utility companies with little or no data experience to deploy Dark Ages technology.

I have tried to make this as simple to understand for non-engineers. I hope this answers your question.

[hapoo]

I remember when they were doing trials of this in england a couple years ago. Apparently you could see the data transfer from the flickering of street lights.

[johnnymk]

I sent this link to a friend of mine who believes that this is the greatest thing since sliced bread was invented.