I've still never found an explanation for what this frequency is used for in the US, if anything.
Wi-Fi Channel 14 is centered on 2484 MHz, and is 22 MHz wide, so it covers 2473-2495 MHz. Like channels 12 and 13, it's not used in the US because the US ISM band ends at 2483.5 MHz; the channels contain significant energy outside the ISM band.
In the US, 2483.5–2500 MHz is allocated to ancillary terrestrial components used in conjunction with mobile-satellite service systems (47 CFR 25.254). These are the terrestrial transmitters used to provide service to mobile low-Earth-orbit satellite service users (think satellite radio, although I don't think XM/Sirius uses this band) when the user is in a tunnel, or the satellite signal is otherwise blocked.
2450-2500 MHz is also allocated to radidetermination (i.e., direction-finding radar) on both ship and shore, with the proviso that no interference be caused to the fixed and mobile satellite stations mentioned above (47 CFR 80.375(d)). (ISM band users, however, must accept any radar interference they receive.)
The devices and the protocol should be smart enough to optimize spectrum, both by analyzing the noise at various frequencies and choosing the band with the least automatically[...]
You'll be comforted to know that ZigBee devices, and other devices that conform to the IEEE 802.15.4 standard, do this today, and have done so since 2003.
The second part of your wish, that devices dial-down their power to the minimum needed, is certainly possible, but requires that the receiving device send an RSSI (Received Signal Strength Indication) or, better, an RQI (Received Quality Indication) value back to the transmitting device (perhaps as part of the ACK), and that the transmitting device be capable of lowering its transmit power in the first place (it's an extra expense). I don't know of any protocol that does this (other than CDMA protocols, for a different reason), although I expect newer protocols will -- but to save power (extend battery life), not to reduce spectral pollution.
Yes, but the US regulations controlling the export of specific technologies have not been dropped -- the PGP-related regulation was an exception. To the contrary, the regulations have been greatly expanded in both breadth and specificity. They now include a wide range of seemingly innocuous technologies far beyond encryption and other "national security-type" technologies.
They weren't "military secrets." He was not convicted of espionage -- he was convicted of export control violations. The information involved could be given to any US citizen without any problem at all.
The point I'm trying to make is that Dr. Ross believed that academic freedom (the grad students that invented and developed the technology in the first place were from China and Iran) trumped pesky government regulations, in much the way many here are saying that FOSS principles trump those same regulations. I'm saying that SourceForge made the only decision they could make, to avoid ending up like Dr. Ross.
Keep in mind how such cases are slanted in the press, and imagine how some responsible SourceForge executive could be similarly characterized after his conviction for "sending US technology to Syrian terrorists" (just to pick one possible example), were he to have made a different decision than the one announced today.
I fail to see how you are linking the issue of regulating the export of products with respecting freedom of expression.
Some years back, US law was changed so that the export of "technology" was controlled, not just the export of physical goods. You can be convicted of an export control violation by speaking privately to a foreign national about a controlled technology, even while both of you are on US soil. Note that this same conversation with a US citizen is perfectly legal -- we aren't discussing espionage here.
In that sense, export control regulation is directly linked to freedom of expression -- in an inverted way.
Dr. Ross did not sell information to the Chinese, and there were no proceeds to hide. He believed that export control regulations involved only finished physical goods, that they did not apply to the exchange of intellectual ideas in academia, and that they could be ignored when they were inconvenient. These turned out to be serious errors in judgment. (As I've mentioned elsewhere, I don't support his position. Like Mr. Spock, I do not approve. I understand.)
There is no difference between Dr. Ross' belief in the superiority of free academic discourse over US export regulation, and the position espoused by some here of the superiority of FOSS principles over those same regulations. By stopping its export of controlled technology to banned countries, SourceForge made the only rational decision it could make, under the circumstances.
A better argument, and more useful discussion, would be whether or not that technology deserves to be controlled.
Dr. Ross didn't export a military weapon design. He was a plasma physicist. He discussed research on plasma actuators with his own former graduate students, who had developed the technology in the first place, and happened to be Chinese and Iranian. Nothing was ever "delivered" to China; it was shown in court that the information on his laptop was never accessed.
The reason this is exactly on point is that there is a lot of discussion on this post about the "higher calling" of FOSS principles over US law. Dr. Ross believed that the free exchange of ideas was fundamental to academic life, and trumped bureaucratic regulations. He found out to his great regret (I think) that it did not.
I suggest that you read the Commerce Control List, and study carefully the technologies that are controlled, and must be licensed before they can be exported to China. You will find them to be very mundane technologies and, if you do engineering research, the probability that you have controlled material on your main work computer is very high.
Mostly correct -- except that Ross was not convicted of espionage. Plasma actuators were not "military secrets," but a controlled technology that Dr. Ross and his graduate students -- a Chinese and an Iranian national -- had already developed. Dr. Ross thought it was patently obvious that a technology co-invented by his students could not be the subject of an export control issue, especially in an academic environment, so he (stupidly, in my opinion) ignored the regulation.
My point is that those in the FOSS community who believe that FOSS principles supersede government regulation should pay attention to the story of Dr. Ross. Study the Commerce Control List carefully and you may find that there are subjects in your work that you cannot mention over drinks at the next faculty social.
To be sure; I don't defend him. For the record, however, the "foreign nationals" he hired were his graduate students, who knew the material because they'd already been working on it. Also, he was not convicted of presenting any controlled material in China. He was convicted of having the controlled material on his laptop while visiting China, and forensics experts testified at the trial that the files had not been accessed during his trip.
My point is that the export control regulations are extremely detailed, can be rigidly enforced, and are not compatible with the free flow of information usually found in academia (and FOSS). US citizens need to be aware of these restrictions -- which include merely discussing controlled material in the presence of certain foreign nationals, like in private organizational meetings -- and follow them, even if they go against FOSS principles, or run the risk of ending up like Dr. Ross.
To avoid repeating myself, please read an earlier comment. In addition, keep in mind that the "foreign nationals" to whom he shared the information were his graduate students, who had actually been doing the work in the first place.
Read the CCL and see if any of your work is controlled -- you may be surprised.
1. Dr. Roth was not convicted of espionage: He was convicted of export control violations. The information he had could have been given to any US citizen without any violation of US law whatsoever.
2. No evidence was presented at Dr. Roth's trial that the controlled material on his laptop was given to any Chinese national, yet he was convicted of exporting the data anyway.
3. A close examination of the CCL would reveal that the laptop of almost any engineering researcher, in any field, would contain controlled material.
I'm not stating that Dr. Roth did not violate the law -- the law, while not concise, is exact and specific, and he clearly did violate it, in multiple ways and at multiple times. Rather, my point is that "There, but for the grace of God, go you or I." As China develops, it hosts more and more of the world's largest scientific and engineering conferences, and the CCL is so long, and so poorly written, and so outdated, that it's a near-certainty that a randomly-selected US attendee at one of these conferences can also be found to have violated it. Who keeps a second laptop at hand just to take with them to those meetings in China?
And it's not just those meetings in China -- Chinese nationals visit meetings outside China, too, in vastly increasing numbers. One can violate US law by speaking at one of these conferences if (a) a national from the controlled countries list (China is the most prominent) is present, and (b) the controlled material is not presented to the "public", meaning the meeting is a private one, like an industry consortium, and is not intended for publication. Short of having a receiving line before the talk, where all meeting attendees show the speaker their passports, it's almost impossible to avoid this violation. Did you know the nationality of everyone in the room the last time you spoke at a Wi-Fi meeting?
Dr. Roth didn't disclose any "secret" information from a "black" DoD program. He discussed an export-controlled technology on the Commerce Control List with Chinese and Iranian nationals -- graduate students actually doing the research. He also had export-controlled information on a laptop he took with him on a trip to China, and was convicted of its export too, even though forensics showed the files had not been opened during the trip.
What's on your laptop? Checked it against the CCL lately?
I think most people would be surprised to see the list of technologies on the Commerce Control list, and to learn that one can be charged with an export violation merely by talking about one of them in the presence a foreign national. Actual transport of a physical good is not required -- see this comment.
Look at the IEEE Journal of Solid-State Circuits (the leading journal for integrated circuit design), and compare the authorship of the papers in the January 2010 issue with that of, say, the January 1966 issue. The fraction of not just Chinese, but Asian names of all types, has dramatically increased, as has the fraction of papers from Asian institutions (being zero in 1966).
My university experience is similar, and the parent summed it up well: "The students from China tend to be very talented and are willing to work extremely hard." I, too, expect an explosion of quality research coming from China -- the combination of good academics and increasing disposable income (at the national level) from an improving economy will make it so.
Nearby whitespace devices, broadcasting at a maximum of 100 milliwatts with non-directional antennaes, aren't likely to be heard.
Ooohh, yes, they will -- for any number of reasons: (1) the shielding of the television set itself is finite, and certainly less than +20 dBm - (-84 dBm) = 104 dB at RF; and (2) the nulls in the antenna pattern are certainly less than 40 or 50 dB, especially when scattering from nearby objects is considered; just to think of two reasons. Try it and see.
And here, I simply say, I don't care. They're wasting spectrum [...]
Just because television reporters are not using the spectrum for a use you like doesn't mean it's being wasted. It's a perfectly defendable need for a wireless product -- unless you'd like to see a return to wired mics on the six o'clock news -- so they have as much "right" to the spectrum as any other service. If you're going to put your Internet service where they are, you need to offer them an equally viable alternative. Otherwise you're just an autocrat.
There's a lot more to a successful WS system than just sensing -- it's got to sense and do something useful (like Internet connectivity) at the same time. (Just look at the complexity of the IEEE 802.22 draft standard.) I, too, am familiar with the FCC's testing of WS devices (if you only knew...), and thank you for making my point for me. Read the introduction to Clause 4 of the report, regarding the transmitting portion of the tests:
These tests are considered anecdotal for a number of reasons. For example, the use of over-the-air signals implies that little control could be exercised upon significant test variables. In addition, since the tests were performed at a limited number of locations and at particular times of day, variations in signal level occurred which could not be characterized. Also, since the Adaptrum WSD prototype was the only available working device with a transmitter, the interference effects to DTV reception were examined for only the waveform of this particular device, which may or may not be representative of a final TV white space product.
In short, even the FCC says its transmitting tests were meaningless. I stand by my statement: A functioning system in the field has never been satisfactorily demonstrated.
I think we're going to have to declare a truce here, and agree to disagree. Perhaps we can meet again in five years and see whose vision of the future came to pass?
You're leaving out a major stipulation of the FCC's ruling: whitespace devices must listen before transmitting, not just query the database.
You're right, but I was trying not to complicate the argument. Consider the situation, though: The farmer needs a tall tower (30m is not unusual), a high-gain (10-15 dB), directional antenna, plus a low-noise, high-gain mast-mounted preamplifier to watch his television. What are the odds that the sensing system associated with a secondary user also will be able to detect the television station? (Hint: Substantially zero, since it is not economically feasible to sell the associated tower with every secondary use product, even if it could constantly rotate its directional antenna.) The television user's receiving system is far more sensitive than a secondary user's sensing system could possibly be.
If the above weren't bad enough, add in the fact that the co-channel rejection ratio of ATSC digital television is specified at 15.5 dB desired/undesired, meaning that any co-channel interference must be at least 15.5 dB weaker than the desired ATSC signal if the television signal is to be received correctly. This requires the secondary user to be able to detect (but not necessarily decode) the ATSC signal at a level 15.5 dB below that of the television receiving system. These two requirements almost guarantee that there will be unhappy rural television viewers.
There's plenty of truly empty spectrum to use first.
Keep in mind that the spectrum database defines empty spectrum, as far as the secondary user is concerned. He send in a request, and gets a go / no go reply. He has no idea whether the requested spectrum is "truly empty" or not. And if you examine television channel occupancy in the US, I think you'll find that all available channels are occupied by television stations, since they were incredibly profitable for many decades. Considering fringe signals, not just licensed coverage areas, every channel is either occupied, or its adjacent or image channel is occupied. The White Space concept counts on using these fringe areas -- that's the whole idea.
More likely, considering said whitespace device is probably providing him Internet service, he'll turn the TV off and get his TV program through his Internet-providing whitespace device
How many people watching "American Idol" on their home television systems, for which they've paid thousands of dollars (towers, antennas, and large screens aren't cheap), are going to say, "yeah, you're right -- I should just forget that and buy that new White Space Internet service instead"? Especially when they're likely to learn of the Internet service from their TV repairman, called out to fix the interference problem that suddenly started on the first of the month? What if the situation were reversed, and someone took your Internet connection away and, when you complained, told you to watch television, instead? I'm betting you'd be just as ticked.
Re: the wireless mics, you're missing the point. In ENG, they're largely used by the talent to do voice-overs, usually live. The problem isn't whether they're going to cause interference (they're already licensed for operation on television channels, and have been for years), the problem is how to protect them from interference caused by new White Space devices. (Which you want to do: I don't know a faster way to kill a new technology than to turn the media against it.)
When one actually does the engineering of the system, it turns out to be substantially impossible to detect wireless mics at levels required to provide them protection: The transmitting antennas are low (often worn on the belt) and not very efficient, and the transmit power is low, while the receiving antennas are often placed high on the ENG truck's mast, and the receivers are r
Because the Primary user is mobile, or at least portable, and the Secondary user can be fixed (and at least tied to a landline, if nothing else). A lot of the rural US has no cell phone coverage -- trust me.
I've never been comfortable with the entire White Space approach, especially the database idea. A big problem is that primary users are only protected out to a predetermined contour, not to their actual range as used in the field. For example, TV stations are only protected out to a given contour (a specific distance out from the tower, where the station's signal strength is predicted to weaken to a predetermined threshold) specified in their license. However, many, many people in rural areas watch over-the-air television at distances well outside the contour, by using antennas that are larger, and mounted higher (often with mast-mounted preamplifiers), than those assumed when the signal strength threshold was set. Should a secondary user query the Google database from this area, he will get authority to transmit on the television channel, since he's outside the protected contour of the TV station, and would then interfere with the television reception in the area. A homeowner (or, more likely, a farm owner) could complain to the FCC, only to be told that he's outside the protected coverage area of the TV station and has to accept the interference. I doubt he'd be happy with that answer.
A similar problem arises with the licensed wireless microphones used in electronic news-gathering (ENG) trucks. They're quite mobile, and cover large areas. How are they supposed to get Internet connectivity in the field to check the database? Presumably they're out of cellular range, since they're in rural, White Space areas; what do they do? And if they use the channel without updating the database, how is a secondary user going to know he's there? The secondary user will query the database, get an "all clear" and, not knowing the microphone is nearby, transmit on the same channel as the microphone.
It just seems like the practical aspects of all this need some more thought.
Why give a mod point to some unknown individual who won't get proper credit for it?
...so the rest of us can see the really good comments, instead of weeding through the dreck we have to go through otherwise? You know, like how the moderation system is supposed to function?
I think the real key is considering how we get there from here. The ideas are nice, laudable goals -- and maybe even needed -- but they won't happen unless there's a pathway to get to them from today's Internet. Like a chemical reaction, even if the end result is lower energy than the starting reagents, nothing will happen if the work function separating the two is too high.
Slashdot Mirror
Wi-Fi Channel 14 is centered on 2484 MHz, and is 22 MHz wide, so it covers 2473-2495 MHz. Like channels 12 and 13, it's not used in the US because the US ISM band ends at 2483.5 MHz; the channels contain significant energy outside the ISM band.
In the US, 2483.5–2500 MHz is allocated to ancillary terrestrial components used in conjunction with mobile-satellite service systems (47 CFR 25.254). These are the terrestrial transmitters used to provide service to mobile low-Earth-orbit satellite service users (think satellite radio, although I don't think XM/Sirius uses this band) when the user is in a tunnel, or the satellite signal is otherwise blocked.
2450-2500 MHz is also allocated to radidetermination (i.e., direction-finding radar) on both ship and shore, with the proviso that no interference be caused to the fixed and mobile satellite stations mentioned above (47 CFR 80.375(d)). (ISM band users, however, must accept any radar interference they receive.)
Yep. Problems like this are what created the FCC and licensed spectrum in the first place.
You'll be comforted to know that ZigBee devices, and other devices that conform to the IEEE 802.15.4 standard, do this today, and have done so since 2003.
The second part of your wish, that devices dial-down their power to the minimum needed, is certainly possible, but requires that the receiving device send an RSSI (Received Signal Strength Indication) or, better, an RQI (Received Quality Indication) value back to the transmitting device (perhaps as part of the ACK), and that the transmitting device be capable of lowering its transmit power in the first place (it's an extra expense). I don't know of any protocol that does this (other than CDMA protocols, for a different reason), although I expect newer protocols will -- but to save power (extend battery life), not to reduce spectral pollution.
Yes, but the US regulations controlling the export of specific technologies have not been dropped -- the PGP-related regulation was an exception. To the contrary, the regulations have been greatly expanded in both breadth and specificity. They now include a wide range of seemingly innocuous technologies far beyond encryption and other "national security-type" technologies.
For example, the IEEE Journal of Solid-State Circuits.
They weren't "military secrets." He was not convicted of espionage -- he was convicted of export control violations. The information involved could be given to any US citizen without any problem at all.
The point I'm trying to make is that Dr. Ross believed that academic freedom (the grad students that invented and developed the technology in the first place were from China and Iran) trumped pesky government regulations, in much the way many here are saying that FOSS principles trump those same regulations. I'm saying that SourceForge made the only decision they could make, to avoid ending up like Dr. Ross.
Keep in mind how such cases are slanted in the press, and imagine how some responsible SourceForge executive could be similarly characterized after his conviction for "sending US technology to Syrian terrorists" (just to pick one possible example), were he to have made a different decision than the one announced today.
Some years back, US law was changed so that the export of "technology" was controlled, not just the export of physical goods. You can be convicted of an export control violation by speaking privately to a foreign national about a controlled technology, even while both of you are on US soil. Note that this same conversation with a US citizen is perfectly legal -- we aren't discussing espionage here.
In that sense, export control regulation is directly linked to freedom of expression -- in an inverted way.
Dr. Ross did not sell information to the Chinese, and there were no proceeds to hide. He believed that export control regulations involved only finished physical goods, that they did not apply to the exchange of intellectual ideas in academia, and that they could be ignored when they were inconvenient. These turned out to be serious errors in judgment. (As I've mentioned elsewhere, I don't support his position. Like Mr. Spock, I do not approve. I understand.)
There is no difference between Dr. Ross' belief in the superiority of free academic discourse over US export regulation, and the position espoused by some here of the superiority of FOSS principles over those same regulations. By stopping its export of controlled technology to banned countries, SourceForge made the only rational decision it could make, under the circumstances.
A better argument, and more useful discussion, would be whether or not that technology deserves to be controlled.
Dr. Ross didn't export a military weapon design. He was a plasma physicist. He discussed research on plasma actuators with his own former graduate students, who had developed the technology in the first place, and happened to be Chinese and Iranian. Nothing was ever "delivered" to China; it was shown in court that the information on his laptop was never accessed.
The reason this is exactly on point is that there is a lot of discussion on this post about the "higher calling" of FOSS principles over US law. Dr. Ross believed that the free exchange of ideas was fundamental to academic life, and trumped bureaucratic regulations. He found out to his great regret (I think) that it did not.
I suggest that you read the Commerce Control List, and study carefully the technologies that are controlled, and must be licensed before they can be exported to China. You will find them to be very mundane technologies and, if you do engineering research, the probability that you have controlled material on your main work computer is very high.
Mostly correct -- except that Ross was not convicted of espionage. Plasma actuators were not "military secrets," but a controlled technology that Dr. Ross and his graduate students -- a Chinese and an Iranian national -- had already developed. Dr. Ross thought it was patently obvious that a technology co-invented by his students could not be the subject of an export control issue, especially in an academic environment, so he (stupidly, in my opinion) ignored the regulation.
My point is that those in the FOSS community who believe that FOSS principles supersede government regulation should pay attention to the story of Dr. Ross. Study the Commerce Control List carefully and you may find that there are subjects in your work that you cannot mention over drinks at the next faculty social.
To be sure; I don't defend him. For the record, however, the "foreign nationals" he hired were his graduate students, who knew the material because they'd already been working on it. Also, he was not convicted of presenting any controlled material in China. He was convicted of having the controlled material on his laptop while visiting China, and forensics experts testified at the trial that the files had not been accessed during his trip.
My point is that the export control regulations are extremely detailed, can be rigidly enforced, and are not compatible with the free flow of information usually found in academia (and FOSS). US citizens need to be aware of these restrictions -- which include merely discussing controlled material in the presence of certain foreign nationals, like in private organizational meetings -- and follow them, even if they go against FOSS principles, or run the risk of ending up like Dr. Ross.
To avoid repeating myself, please read an earlier comment. In addition, keep in mind that the "foreign nationals" to whom he shared the information were his graduate students, who had actually been doing the work in the first place.
Read the CCL and see if any of your work is controlled -- you may be surprised.
The alternative is to end up like Prof. John Ross of the University of Tennessee, convicted of export control violations and sentenced to 4 years in prison -- at the age of 72.
What few in the US recognize is that the rules are even more stringent than indicated by SourceForge. To be convicted of an export violation, one needs merely to discuss a controlled technology with a foreign national on one of the lists -- which means, in addition to many other individuals, entities, and countries, any citizen of China or Iran. Sending anything overseas is unnecessary to violate the law -- merely speaking to a group containing one such person in the audience (like at a private industry consortium meeting) is all that is needed. And the list of controlled technologies is incredibly long: See the Commerce Control List, especially Category 3 - Electronics, Category 4 - Computers, Category 5 (Part 1) - Telecommunications, Category 5 (Part 2) - Information Security, and Supplement No. 2 to Part 774 - General Technology and Software Notes.
My first programming was putting the little white plastic straws on a Digi-Comp 1.
(And it really was in a snowstorm -- I got it as a Christmas present.)
Perhaps I wasn't clear. My points were:
1. Dr. Roth was not convicted of espionage: He was convicted of export control violations. The information he had could have been given to any US citizen without any violation of US law whatsoever.
2. No evidence was presented at Dr. Roth's trial that the controlled material on his laptop was given to any Chinese national, yet he was convicted of exporting the data anyway.
3. A close examination of the CCL would reveal that the laptop of almost any engineering researcher, in any field, would contain controlled material.
I'm not stating that Dr. Roth did not violate the law -- the law, while not concise, is exact and specific, and he clearly did violate it, in multiple ways and at multiple times. Rather, my point is that "There, but for the grace of God, go you or I." As China develops, it hosts more and more of the world's largest scientific and engineering conferences, and the CCL is so long, and so poorly written, and so outdated, that it's a near-certainty that a randomly-selected US attendee at one of these conferences can also be found to have violated it. Who keeps a second laptop at hand just to take with them to those meetings in China?
And it's not just those meetings in China -- Chinese nationals visit meetings outside China, too, in vastly increasing numbers. One can violate US law by speaking at one of these conferences if (a) a national from the controlled countries list (China is the most prominent) is present, and (b) the controlled material is not presented to the "public", meaning the meeting is a private one, like an industry consortium, and is not intended for publication. Short of having a receiving line before the talk, where all meeting attendees show the speaker their passports, it's almost impossible to avoid this violation. Did you know the nationality of everyone in the room the last time you spoke at a Wi-Fi meeting?
Dr. Roth didn't disclose any "secret" information from a "black" DoD program. He discussed an export-controlled technology on the Commerce Control List with Chinese and Iranian nationals -- graduate students actually doing the research. He also had export-controlled information on a laptop he took with him on a trip to China, and was convicted of its export too, even though forensics showed the files had not been opened during the trip.
What's on your laptop? Checked it against the CCL lately?
I think most people would be surprised to see the list of technologies on the Commerce Control list, and to learn that one can be charged with an export violation merely by talking about one of them in the presence a foreign national. Actual transport of a physical good is not required -- see this comment.
Look at the IEEE Journal of Solid-State Circuits (the leading journal for integrated circuit design), and compare the authorship of the papers in the January 2010 issue with that of, say, the January 1966 issue. The fraction of not just Chinese, but Asian names of all types, has dramatically increased, as has the fraction of papers from Asian institutions (being zero in 1966).
My university experience is similar, and the parent summed it up well: "The students from China tend to be very talented and are willing to work extremely hard." I, too, expect an explosion of quality research coming from China -- the combination of good academics and increasing disposable income (at the national level) from an improving economy will make it so.
Ooohh, yes, they will -- for any number of reasons: (1) the shielding of the television set itself is finite, and certainly less than +20 dBm - (-84 dBm) = 104 dB at RF; and (2) the nulls in the antenna pattern are certainly less than 40 or 50 dB, especially when scattering from nearby objects is considered; just to think of two reasons. Try it and see.
Just because television reporters are not using the spectrum for a use you like doesn't mean it's being wasted. It's a perfectly defendable need for a wireless product -- unless you'd like to see a return to wired mics on the six o'clock news -- so they have as much "right" to the spectrum as any other service. If you're going to put your Internet service where they are, you need to offer them an equally viable alternative. Otherwise you're just an autocrat.
There's a lot more to a successful WS system than just sensing -- it's got to sense and do something useful (like Internet connectivity) at the same time. (Just look at the complexity of the IEEE 802.22 draft standard.) I, too, am familiar with the FCC's testing of WS devices (if you only knew...), and thank you for making my point for me. Read the introduction to Clause 4 of the report, regarding the transmitting portion of the tests:
In short, even the FCC says its transmitting tests were meaningless. I stand by my statement: A functioning system in the field has never been satisfactorily demonstrated.
I think we're going to have to declare a truce here, and agree to disagree. Perhaps we can meet again in five years and see whose vision of the future came to pass?
You're right, but I was trying not to complicate the argument. Consider the situation, though: The farmer needs a tall tower (30m is not unusual), a high-gain (10-15 dB), directional antenna, plus a low-noise, high-gain mast-mounted preamplifier to watch his television. What are the odds that the sensing system associated with a secondary user also will be able to detect the television station? (Hint: Substantially zero, since it is not economically feasible to sell the associated tower with every secondary use product, even if it could constantly rotate its directional antenna.) The television user's receiving system is far more sensitive than a secondary user's sensing system could possibly be.
If the above weren't bad enough, add in the fact that the co-channel rejection ratio of ATSC digital television is specified at 15.5 dB desired/undesired, meaning that any co-channel interference must be at least 15.5 dB weaker than the desired ATSC signal if the television signal is to be received correctly. This requires the secondary user to be able to detect (but not necessarily decode) the ATSC signal at a level 15.5 dB below that of the television receiving system. These two requirements almost guarantee that there will be unhappy rural television viewers.
Keep in mind that the spectrum database defines empty spectrum, as far as the secondary user is concerned. He send in a request, and gets a go / no go reply. He has no idea whether the requested spectrum is "truly empty" or not. And if you examine television channel occupancy in the US, I think you'll find that all available channels are occupied by television stations, since they were incredibly profitable for many decades. Considering fringe signals, not just licensed coverage areas, every channel is either occupied, or its adjacent or image channel is occupied. The White Space concept counts on using these fringe areas -- that's the whole idea.
How many people watching "American Idol" on their home television systems, for which they've paid thousands of dollars (towers, antennas, and large screens aren't cheap), are going to say, "yeah, you're right -- I should just forget that and buy that new White Space Internet service instead"? Especially when they're likely to learn of the Internet service from their TV repairman, called out to fix the interference problem that suddenly started on the first of the month? What if the situation were reversed, and someone took your Internet connection away and, when you complained, told you to watch television, instead? I'm betting you'd be just as ticked.
Re: the wireless mics, you're missing the point. In ENG, they're largely used by the talent to do voice-overs, usually live. The problem isn't whether they're going to cause interference (they're already licensed for operation on television channels, and have been for years), the problem is how to protect them from interference caused by new White Space devices. (Which you want to do: I don't know a faster way to kill a new technology than to turn the media against it.)
When one actually does the engineering of the system, it turns out to be substantially impossible to detect wireless mics at levels required to provide them protection: The transmitting antennas are low (often worn on the belt) and not very efficient, and the transmit power is low, while the receiving antennas are often placed high on the ENG truck's mast, and the receivers are r
Because the Primary user is mobile, or at least portable, and the Secondary user can be fixed (and at least tied to a landline, if nothing else). A lot of the rural US has no cell phone coverage -- trust me.
Nope, it's on the channel, just far enough away (physically) that the television station's service area is not (supposed to be) affected.
I've never been comfortable with the entire White Space approach, especially the database idea. A big problem is that primary users are only protected out to a predetermined contour, not to their actual range as used in the field. For example, TV stations are only protected out to a given contour (a specific distance out from the tower, where the station's signal strength is predicted to weaken to a predetermined threshold) specified in their license. However, many, many people in rural areas watch over-the-air television at distances well outside the contour, by using antennas that are larger, and mounted higher (often with mast-mounted preamplifiers), than those assumed when the signal strength threshold was set. Should a secondary user query the Google database from this area, he will get authority to transmit on the television channel, since he's outside the protected contour of the TV station, and would then interfere with the television reception in the area. A homeowner (or, more likely, a farm owner) could complain to the FCC, only to be told that he's outside the protected coverage area of the TV station and has to accept the interference. I doubt he'd be happy with that answer.
A similar problem arises with the licensed wireless microphones used in electronic news-gathering (ENG) trucks. They're quite mobile, and cover large areas. How are they supposed to get Internet connectivity in the field to check the database? Presumably they're out of cellular range, since they're in rural, White Space areas; what do they do? And if they use the channel without updating the database, how is a secondary user going to know he's there? The secondary user will query the database, get an "all clear" and, not knowing the microphone is nearby, transmit on the same channel as the microphone.
It just seems like the practical aspects of all this need some more thought.
Of course, the first step in your plan is to calculate the digits in the first place...
I think the real key is considering how we get there from here. The ideas are nice, laudable goals -- and maybe even needed -- but they won't happen unless there's a pathway to get to them from today's Internet. Like a chemical reaction, even if the end result is lower energy than the starting reagents, nothing will happen if the work function separating the two is too high.