Broadband Fool's Gold
Editorial: 'Great broadband hope' it's not...
by Karl Bode 02:16PM Tuesday Mar 30 2004 Tipped by rf_engineer
Broadband over power-lines (BPL) has been hailed as the "great broadband hope" by FCC commissioner Powell, who believes it will usher in a new age of competition. Others lean on world-wide trial failures as evidence the technology is doomed-for-obsolescence; during its run bringing plenty of trouble (and interference) to areas contemplating the option.
BPL is a system that is being tested to provide broadband Internet service via powerlines to power outlets in homes and is a last mile technology. The system uses radio frequencies that will radiate into the air and cause interference to several licensed communications services including Amateur Radio. The frequencies BPL uses in general is 1 to 80 megahertz (MHz). Of particular interest is the band of frequencies known as HF, which is 1 to 30 MHz . This part of the radio spectrum has very special properties not found elsewhere. With this band, one can communicate around the world with very minute power levels. This is due to the fact that radio waves in this band can bounce off the ionosphere multiple times to get to a faraway destination. Other portions of the radio spectrum, like that used by 802.11 wireless LANs, are essentially line-of-sight. This means that the signals cannot bend or bounce off the ionosphere, but they can only propagate like light – in a straight line and shorter distances.
The medium of BPL, the powerline cable, unlike other broadband mediums such as copper twisted pair, fiber, and coaxial cable, is inherently unsuited for carrying the frequencies BPL uses. Power lines, twisted pair, and coaxial cable all act like natural low pass filters, meaning higher frequencies are attenuated more than lower frequencies when attempting to transmit them through the medium. The exact slope of the graph of attenuation depends on the specific construction of the material, but in general, twisted pair is suitable up to 100 MHz and coaxial cable can go up to about 3 GHz. Power lines are suitable for up to perhaps 350 kHz or so. The exact figure will vary and is unimportant for this discussion, but note that this is kilohertz, not megahertz or gigahertz. The medium of BPL is simply not suited for broadband data.
The other property of the medium chosen for BPL is its radiating capability. Unlike all other broadband mediums, power lines are excellent radiators of the frequencies BPL uses. Copper twisted pair, coaxial cable, and fiber are all inherently non-radiating self-shielded mediums. Powerlines act like a natural antenna and “lose” the BPL signal out into the air. The resulting interference can vary from a noticeable noise to a “deafening roar” on radio equipment which drowns out all communications.
BPL has been tested and deployed on a limited basis in other countries and was rejected in some places due to interference issues. BPL vendors may claim “new technology” and advances have now made it possible, but the fact is they can’t change the laws of physics. High speed data must occupy a certain amount of “bandwidth” and power lines which were designed to operate at 60 hertz will radiate radio frequency energy that is applied to them. Only changing power line construction (i.e. coaxial cable) would eliminate this radiation. BPL proponents reject this as being too costly, but that would be the cost to make this a real viable technology.
Users of the affected radio spectrum cannot be relocated, or at least not economically or in a timely manner. All of the services that use HF bands require the characteristics that only HF spectrum exhibits. There would also be huge international treaty implications with any relocation. Relocating government and military services alone would take years as the FCC would have to structure a migration plan. Chances are it would be ten years before this could be completed and it’s likely that power companies will have run fiber to the home or DSL and cable will finally be ubiquitous. Perhaps the largest issue to tackle though is where to move these services in what is an already overcrowded spectrum.
If it was determined that relocation was the way to go, this would be very irresponsible as HF radio bands are a unique natural resource. No other radio spectrum can provide worldwide communications without any supporting infrastructure. The military (and Amateurs for that matter) have had satellites at their disposal for years, but HF is still in use as it provides unique capabilities that satellites just can't. Internet technologies such as email, streaming media, and instant messaging, or cell phones simply cannot take the place of the wireless infrastructure-free communications capabilities that HF provides.
Destroying a large portion of wireless spectrum is not justifiable because it benefits more people. There are many examples of this in society where reallocation of a resource would benefit more people, but it would be detrimental long term to the people and the resource itself. Right now, Amateur frequency allocations belong to the people internationally and can be enjoyed in nearly every country by simply passing a test and getting licensed. Once they are given to a business interest, they cease to be the public's and can only be used as a customer of that business. BPL impacts other groups including government, military, shortwave, aviation, maritime communications, and CBers, so this would have national security and international implications as well. BPL has been linked in some rhetoric with increasing “homeland security”. BPL in fact takes spectrum away from government agencies directly tasked with protecting the country.
To deploy BPL an up front investment must be made in BPL headend / injection point equipment and repeaters -- it's not as simple as FCC Commissioner Powell makes it sound, as if all powerlines can immediately be easily lit up. There's going to be significant recurring costs in backhauling the IP traffic from the numerous BPL injection points serving an area. Neither DSL or Cable has this recurring cost or need for multiple network origination points. These costs unique to BPL make it even less attractive for deployment in rural areas that Cable or DSL as customer densities and revenue potential is lower.
The scalability of BPL is questionable. Chunks of HF spectrum must be reused between repeater/injection point segments. With customer bandwidth requirements going up, over subscription ratios going down, systems will need to be segmented in a cellular fashion. This exacerbates the interference issue as more frequency chunks are in use in a given area. More avoidance of frequencies will be needed, making less spectrum available for use by BPL. The frequency chunks in use will need to be smaller to enable tighter frequency reuse, and the available bandwidth per injection point will get to a point where it won't be sufficient.
BPL is also lacking on the regulatory front. It has no protection from interference from licensed wireless services. This means your BPL provider has no recourse if a licensed wireless station knocks out your BPL service regularly. If BPL interferes with a licensed wireless station, the BPL provider must cease to operate the system if the interference problem cannot be solved. While on the surface one would think that this would inherently protect wireless communications, it places a huge burden on such services to expend time and money identifying and seeking resolution to interference issues. With such a weak regulatory basis and a system that is immediately at odds with incumbent services, why would anyone want to depend on BPL to provide reliable broadband?
The FCC recently released Notice of Proposed Rulemaking (NPRM) 04-29 which attempts to both encourage BPL deployment and address interference concerns. The NPRM basically proposes a national database of BPL systems and some interference mitigation techniques. Neither solve the interference problem. The database hopefully will aid in identifying BPL systems operating in a given area so that interference complaints can be filed more quickly with BPL carriers. While in general this is a good idea, it does little for mobile operations as it's impractical for such operators to research ahead of time before travelling into an area to determine if interference-free operation is possible. The interference mitigation techniques the FCC is proposing comes down to moving interference around in the HF spectrum until no one complains. The problem with this is that it's very difficult to find “open space” in this spectrum that won't affect anyone. The NTIA alone has over 18,000 frequencies in use. BPL carriers will receive an interference complaint, reconfigure their system to use other frequencies, only to interfere with another service. As BPL systems need more spectrum to feed a growing number of customers, more cells, and an increased demand for bandwidth, this interference avoidance juggling act will become impossible.
Radio Amateurs have been the most vocal in defending the radio spectrum, especially in Internet forums. Amateurs do not oppose broadband deployment, and in fact welcome it as most are born techies and use the Internet extensively. Some Amateur applications such as VHF repeater linking systems and position reporting systems actually use the Internet for connectivity and messaging. It is the ill effects of BPL on wireless spectrum which Amateurs vehemently oppose.
In summary, power companies should be building for broadband dominance in the coming decades with viable technology such as fiber, not for the next year or two with doomed-for-obsolescence technology. Wireless spectrum should be used for wireless applications, not to accommodate a wired network that pollutes the spectrum. The risk to critical licensed communications services is too great, the technological and regulatory foundation of BPL is too weak, and when compared head-to-head with other technologies, BPL loses on both the business model and technical capability sides. BPL appears glittery, but in reality it's Broadband Fool's Gold.
Anthony Good (RF_Engineer
) is Director of Systems Engineering at a regional ISP and CLEC and is experienced in RF Engineering in Wireless ISPs (ISM/UNII), Cellular, MMDS/ITFS, licensed point-to-point microwave, and LPTV. He is an Amateur Radio operator and holds an FCC General Radiotelephone Operator License.
Good idea but... From an engineering standpoint, BPL is not a very good idea just for the reasons stated in the article. I know that many people here could care less about the airwaves, but many people depend on that same set of frequencies for either a living, safety, or just plain communications.
I know that some people think that everyone will be on the net and no one will need the radio, but there are just too many requirements that will not be met by the net. Maybe if they came up with a safe and world wide wireless system, then net-to-net communications will be viable.
edit: On the third read through, if the power companies did fiber along side the power lines then they may have a gold mine. After all, fiber is immune to any interference except possibly at any repeaters. Thus you could run fiber right next to a 100KV line or a 110 V with no issues. And since in most cases you already have right away to the house, you do not have to gig a new path.
I am not lost, I find myself every time.
| || Well, you are just plain wrong. I have subscribed to a test roll-out of BPL from Progress Energy, Inc. in NC. I have reliable 1.5 MB up and 1.5 MB down. Many times it is 2.9MB down and 2.0 MB up (see dsl speed reports for mindspring or earthlink at zip 27526).|
It may be true that it causes interference, well then argue that point. But don't argue that it is as slow as ISDN, because factually--at least in my case, it is not.
The wireless bridge that connects to the BPL network could not have been easier to setup and use.
I also have cable broadband. In contrast to my cable connection, I have not had any "Blinking" modem lights, failure to connect, or DNS/Router problems with BPL. Not to mention my upload speed is much higher. In short, my BPL bridge has not suffered any failure to connect (maybe 10 times on cable in the same time period). You sound like a mac kool-aid drinker--in fact all of these posters do.
I, for one, am in favor of anything that prevents monopoly. Where I live, dsl is not available, so the only provider is cable via TWC RR. I welcome broadband competition that will lead to better service from broadband service providers. If this is "fools gold", let me be a fool, 'cause it works and works as well (or better) than my cable broadband. In contrast to the opinions in this thread, I actually have facts to back up my opinions. Not kool-aid drinker hyperbole.
| |gwionwild colonial boyPremium,ExMod 2001-08
Do I have to give my thoughts again? Or... ... has everyone already heard my position on this concept? These Tesla wannabes are misdirecting time and resources that should go to future-proof technologies and deployment strategies, not the idle geek musings of a half-century ago. I wish my car doubled as a helicopter... great for rush hour...
I wish I could just buy a washing machine and do my dishes in it and scrub the floors... maybe I could find one I can crawl inside of and get a quick shower, too? After all, it's already there, and it connects to the "water-network"? And I have a dryer, why do I need a "hair" dryer, too?
I wish I could drive on the subway tracks, maybe Detroit can come up with something? I wish my water and gas lines came in on the same pipe, it would save a lot of space, and they could just "de-mux" 'em, as they come in?
Apologies to "Jack's Mother" for stealing her line, but I wish the walls were full of gold... I wish a lot of things...
That my power lines carried my broadband is not one of them.
[PS- great article... Thanks.]
"The seas shall rise up in the twinkling of an eye, and the dust of the ancients shall be restored. The winds shall fight together with a dreadful blast, and their sound shall reach the stars."
Re: That nails it I loved your well thought out and accurate post.
One other aspect of BPL that I don't often hear mentioned is the effect it will have on the average radio *listener*.
These users cannot generate an on-air signal to cause any adaptive BPL technology to move off of a specific frequency. Just as a single couple talking in an empty restaurant causes little discernable noise, many people talking at once can raise that singularly weak noise level to a loud roar.
It is this cumulative effect as more and more BPL systems come online that should be of great concern. The overall noise floor will dramatically rise all across the country as these interfering signals propagate ionospherically. And the interference will be propagated world-wide.
I'd be willing to bet that the competing BPL systems might even begin to interfere with themselves.
Getting back to listeners...
Once the HF spectrum is polluted by BPL, private citizens will no longer have the ability to use inexpensive equipment to tune in to news and opinions from other countries around the globe via international shortwave broadcasts. The U.S. Government will have allowed an "Iron Curtain" to drop over the country, effectively cutting off individuals from the free and unencumbered infrastructure-free exchange of ideas and information.
Even the Soviet Union in the Cold War era was never able to implement a system which will be as effective at blocking the access to the HF spectrum as BPL will be.
Couple this with the disastrous changes the FCC is allowing in the AM band regarding IBOC transmissions (in-band on-channel digital, which is neither in-band, nor completely on-channel) and their wide bandwidth, interference-causing digital mode of operation, and you won't even be able to tune in a U.S. AM radio station from any appreciable distance.
The HF and radio spectrum is a priceless national treasure, one which should be guarded as vigorously as we protect clean air and water.
BPL simply can't work. It can't operate interference free. It may even begin to interfere with itself over time. And, it has no protection from licensed stations which have a legitimate need to operate in this spectrum for public safety. BPL won't affect just hams, it'll affect public safety, government and military, and private listeners too.
What we need are FCC appointees who actually have some engineering knowledge about the thing they are supposed to be implementing, regulating, and protecting.
The current state of affairs at the FCC and the ridiculous rulings coming out of the agency drive this point home far better than any words I might write.
Let's hope it isn't too late for common sense and good engineering to prevail.
Cherry Valley, IL
Say no to BPL
BPL is just as retarded as this.
Look what I can do!
Powell's Folly rf-engineer is right on!
Michael Powell apparently wants to be a hero. Every time he talks about BPL he brings up the potential for service to rural areas.
Except no BPL proponent says that rural service is economical. In fact, UPLC wrote a paper saying that it's impractical except for distribution from a satellite downlink. Do the math.
Mr. Powell also says that BPL will bring broadband internet service to "underserved areas". I suppose this means places that don't have DSL or cable yet. Does anybody really think that the power companies can beat telcos and cablecos to the punch? The powercos tried a few years ago to dip into the REA (Rural Electrification Administration) pot to finance a fiber buildout. That didn't sell, so they're going another way (BPL).
When I write my comments to NPRM 04-37, I will talk about the following:
1. Every BPL installation must have an identifiable signal signature documented, publicly available, easily decoded. There is ample precedent for this in (for example) FCC station identification requirements on amateur, commercial, and public service licensed spectrum users.
2. Every BPL installation must include rapid automatic shutdown capability (that's already suggested in the NPRM).
3. A BPL operator must shut down its operation in any area where harmful interference is reported, and do so within 15 minutes (not weeks or months, as is the current practice with power company noise complaints, documented in FCC correspondence). Interference to public service or to amateur-in-public-service-mode is intolerable and must not be allowed to continue.
4. What we've seen so far in field tests is that (a) some BPL systems create lots of HF noise (Maryland and New York), (b) some BPL systems create little or no HF noise (Washington state). This suggests to me that (a) the current Part 15 limits are inadequate to protect HF, or (b) somebody who is field testing is falsely certifying Part 15 compliance, or (c) somebody is careless with the installation. I suspect that (a) is the closest to the truth.
5. The FCC states in the NPRM that it believes (incorrectly) that Part 15 is doing its job, because there are tons of Part 15 devices out there and there are very few complaints. But the FCC itself, in its literature and on its Web site, discourages complaints ("Take it to the manufacturer"). My microwave oven interferes (harmfully) with the AM radio that I listen to across the house. But do you think Panasonic (the oven maker) is interested? Nope. Maybe it's time to flood the FCC with complaints about Part 15 devices that interfere with licensed services (including AM broadcast).
One thing is certain. Comments to FCC 04-37 that say "I don't like it so don't do it" will be ignored. We need to argue with the NPR's points that are arguable, and do it with the clearest words (and cited references) possible.
Here we go!
HF is from 3 MHz to 30 MHz Mr. RF engineer made a minor slip... HF is not 1 to 30 MHz. Here are some of the bands:
LF: 30 to 300 KHz
MF: 300 to 3,000 KHz (3,000 KHz = 3 MHz)
HF: 3 to 30 MHz
VHF: 30 to 300 MHz
UHF: 300 to 3,000 MHz (3,000 MHz = 3 GHz)
SHF: 3 to 300 GHz
EHF: 300 to 3,000 GHZ (3,000 GHZ = 3 THz)
And now a quote from a little boy:
"screw the amateur radio people!
The future is the internet, and not the amateur radio crap. Please visit the following link at »www.forcvec.com/bplcoop/faqs/radio_int.. article talks about the interference issues that everyone Amateur Radio BUTTHEAD keeps talking about. BRING ON THE INTERNET GLOBAL, THEREFORE WE WON'T NEED AMATUER RADIO."
Spawn123 sounds like and uninformed person. I would not want to be as rude as that little boy seems to be. He seems to believe that if a corporation said it then it must be true. He does not realize that there will be lives lost because of interference during severe weater. He does not realize that fiber to the home is the best way to transmit Internet service. He seems to think that everyone will be happy to lose a free to use service (ARS, HF Broadcast and CB) in return for a pay through the nose service. He seems to think that his Internet signals will be secure on Broadband over PowerLine...Foolish little boy.
Radio Amatuers are so stupid About the following:
I thought you just said the power was out, so how could BPL interfere with mickey mouse radio? You are so stupid!
HEY SPAWN! YOU SUCK DUDE! What happens when the power goes out?? Like a Tornado or Thunderstorm. Your without POWER, INTERNET, AND if you use VoIP, then your without phone or communication. Your Basically SCREWED.... Because the Tornado that just wiped your collective buttocks, has left you injured, trapped, and unable to call for help.
Now my Amateur Radio Self, who could provide communication to the Police, Red Cross, and EMA, can't reach them because of your BPL!