bmn? ? ?Premium,ExMod 2003-06
join:2001-03-15
hiatus | Solution is worse than the problem... quote:
There are some alternative BPL technologies under development, that operate primarily within the unlicensed 5 GHz ISM band. One version of the technology being developed by Corridor systems uses 216mbps capable BPL up to a point, and then connects to the end user via 802.11 wireless gear (see pdf of Corridor's BPL specs). Such BPL alternatives are currently being tested by California PG&E. However there are several technologies that either currently use, or plan to use the 5GHZ band (like 802.11a or the looming 802.11n) - so the interference battle may simply change battlefields.
This "solution" of using the 5Ghz band is just as bad as the current problem... So now they are screwing up another portion of the spectrum to save the HAM spectrum?! I love it. This BPL stuff is turning out to be a radio frequencies shell game of sorts... All I can say is that better stay OUT of the 5Ghz range.
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Male by birth... Geek by choice
The Center is where its at... |
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| No, actually they are going to be using both the original spectrum and the 5 Ghz spectrum, taking up even more spectrum than originally planned.
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CCNA, Comtrain Certified Tower Climber |
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bmn? ? ?Premium,ExMod 2003-06
join:2001-03-15
hiatus | said by cmaenginsb:
No, actually they are going to be using both the original spectrum and the 5 Ghz spectrum, taking up even more spectrum than originally planned.
That's even better...  Must have missed that part in the article.
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Male by birth... Geek by choice
The Center is where its at... |
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| reply to bmn
said by bmn:
This "solution" of using the 5Ghz band is just as bad as the current problem... So now they are screwing up another portion of the spectrum to save the HAM spectrum?! I love it. This BPL stuff is turning out to be a radio frequencies shell game of sorts... All I can say is that better stay OUT of the 5Ghz range.
Actually, the propagation characteristics of 5 Ghz are much, much different than that of the HF spectrum which low speed BPL will interfere with. 5 Ghz is much easier to contain in a geographical area and doesn't have worldwide implications. Also, BPL is a Part 15 device just like all the other devices at 5 Ghz now, so it has equal regulatory footing. It just makes so much more sense from a frequency allocations perspective to put BPL there. Last, the power levels that BPL would use at 5 Ghz along with the propagation characteristics would make it difficult to interfere with WISP operations and in building WLANs.
Also note that low speed BPL doesn't interfere with just "HAM Spectrum". It's HF radio spectrum which is occupied by numerous national and international services. *Ham* Radio uses less than 10% of this spectrum.
It's funny though how everyone is for BPL until it comes into their radio spectrum neighborhood. Not in my backyard, you say ?  |
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bmn? ? ?Premium,ExMod 2003-06
join:2001-03-15
hiatus | said by rf_engineer:
It's funny though how everyone is for BPL until it comes into their radio spectrum neighborhood. Not in my backyard, you say ?
Actually, I was never really "pro-BPL" due to the interference issues. My concern is less with HAM and with more mission critical devices and uses of the impacted frequencies. However, I don't think moving the interference issues to another spectrum (5ghz) and one that is going to be heavily used is a solution. A solution would be to find a range that is vacant and use it.
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Male by birth... Geek by choice
The Center is where its at... |
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| said by bmn:
said by rf_engineer:
It's funny though how everyone is for BPL until it comes into their radio spectrum neighborhood. Not in my backyard, you say ?
Actually, I was never really "pro-BPL" due to the interference issues. My concern is less with HAM and with more mission critical devices and uses of the impacted frequencies. However, I don't think moving the interference issues to another spectrum (5ghz) and one that is going to be heavily used is a solution. A solution would be to find a range that is vacant and use it.
Good point, but that's the kicker, finding vacant spectrum. If BPL interests actually tried to get a real 80 Mhz wide allocation in HF/VHF, they'd be laughed out of Washington. I have often said before that we could perhaps look for a 1 Mhz chunk for BPL. This would be able to support the drops to houses at maybe a 500 kbs rate, but wouldn't be sufficient for the main backhaul. But 2.4 and 5 Ghz is just so much better suited for this, either as a wireless medium or surface propagated on the line (like Corridor). Part 15 rules in the HF band where never meant to support wideband uses in a large geographical area like BPL. On the contrary, it was to support small narrowband consumer devices that occasionally transmit and at most would be a minor occasional nuisance to licensed users in the band. Part 15 in 2.4 and 5 Ghz land, though, allows much higher radiated power levels. This is why the band is ideal for unlicensed WISP use. Also, the 5 Ghz band is also known as UNII or the Unlicensed National Information Infrastructure band, created during the Clinton/Gore administration. It was created and built from the ground up with such applications in mind, and it was recently expanded. BPL type applications really belong there, not in worldwide communications spectrum. But good luck getting a free and clear 80 Mhz chunk in any microwave bands.
Another thing to consider is that comparing the interference issues in the HF spectrum versus the interference that would be present to incumbent users at 5 Ghz is like comparing apples and oranges. Current devices at 5 Ghz are much like wideband spread spectrum or OFDM BPL devices. HF on the other hand is typically narrowband uses with very sensitive receivers. 5 Ghz can't propagate across the globe like HF, therefore interference effects are very localized. It's also much easier to create highly directional antennas to avoid interference, such as in a WISP or WLAN application. HF directional antennas with the equivalent directionality are measured in acres or even square miles !
The mission criticality that you refer to is really in the eye of the beholder. Many Internet citizens consider 2.4 and 5 Ghz "mission critical" because they're aware of it and use it, as do WISPs. HF radio spectrum is "mission critical" for several government services and international entities. Even truckers would consider 27 Mhz (CB) mission critical when trying to get directions in an unfamiliar town, or calling for emergency help. You'll find that most any chunk of spectrum has users which depend on it, so don't dismiss Ham or HF use in general as not being mission critical.
BTW, "Ham" is not an acronym so it's not really proper to refer to it as "HAM" |
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 Radio ActiveMy pappy's a pistolPremium
join:2003-01-31
Fullerton, CA | reply to rf_engineer
said by rf_engineer:
It's funny though how everyone is for BPL until it comes into their radio spectrum neighborhood. Not in my backyard, you say ?
Plenty of room in the 5GHz spectrum.
Although individuals make valid points regarding UNII and ISM, there is plenty of room to integrate *new* BPL into this spectrum, and the nature of Spread Spectrum will allow this to happen without obliterating the usability of cordless phones and other consumer Part 15 wireless devices.
I could operate quite happily in the 5GHz band without having ANY interference issues from *new* BPL, all players are invited to come into my backyard and "do their thing"...
Even the "N.I.M.B.Y."s...
Cheers.
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I once accidentally spilled spot remover on my dog and he disappeared. You know what I hate? Indian Givers... No, I take that back. »www.folsomtech.com |
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