Dish: With these restrictions, FCC, you are totally crippling us FCC Chair Julius Genachowski has said that Dish Networks will get its licence for a US mobile network, but with restrictions that the company claims will fatally undermine its business. Approval would allow Dish to use frequencies hitherto reserved for satellite communications with an earth-based network, but the restrictions …
Smells like the FCC are trying not to let another Lightsquared situation arise. That debacle has left a whole chunk of spectrum unusable. I may be wrong but I suspect that the FCC hadn't kept an eye on what the GPS industry was up to (unofficially appropriating the hitherto unused adjacent bands as guards) and wasn't telling them to stop doing it.
But not this time, oh no. This time they're determined and are making the guard band and transmission level requirements clear from the outset. It's just like they might actually have done some thinking about the matter. Good for them.
However if Dish are correct and the FCC's order renders it all non-viable then it'll mean yet more spectrum in the US will effectively be declared unusable. Mind you, as others have already pointed out 5GHz isn't that wonderful a band for mobile use anyway, so perhaps it's no great loss.
It does all suggest that there are some hard to solve problems with the current frequency allocations. I wonder what the FCC's plan to resolve those is?
This is not at all what the LightSquared issue was about: the "guard bands" are not something presumed by the "GPS industry" but are inherent in RF engineering: crudely expressed the degree to which an undesired (interfering) signal can be filtered from a desired one depends upon both their relative power levels and the frequency difference between them. Satellite-to-ground signals such as GPS have receiver strengths around 10^-16, 4G cell towers have strengths around 10^3. So a GPS receiver next to a L2 tower is attempting to discriminate between signals of enormously differing power level. This is workable providing they have substantially different frequencies, which is why GPS is in a spectrum block allocated for low-powered transmissions. In essence the guard band is provided by keeping signal strengths compatible, which is why the onus was on L2 to show that wildly dissimilar strengths would not in practice be problematic.
As a crude analogy: a NightSun spotlight on a police helicopter is around 30 million times brighter than a candle. Now imagine picking out that candle flame in the glare of one trillion NightSuns)
It is possible to make much narrower-band filters but at the expense of discarding a much greater proportion of the desired signal, ie GPS receivers would take much longer to acquire a fix and would fail to do so in somewhat marginal conditions that currently work. With current technology such filters are also physically large and power-hungry.
Also noteworthy is that L2 themselves could not propose a filter design which would meet the needs of current GPS devices, setting aside any question of cost and practicality (they did have a paper design but it required both a transmission power reduction and not using part of their spectrum allocation, which L2 proposed only as a temporary measure)
5 MHz is the frequency of WWV, the stable master-clock radio beacon used for numerous purposes such as calibrating test equipment, some time sync applications, and the like. you'd start a war sitting on that.
5 GHz, the X band, is heavily used for earthy microwave links as well as satellite links. phase and polarity are important here, so that's why Dish thinks they might get away with putting some omnidirectional cell phones in the middle. but because it's so widely used for campus data links, remote broadcast, security, and of course commercial satellite, uncontrolled use would start a riot, not a nice little setpiece war.
echoes of Lightsquared... some character wants to make extra money with no regard for what happens to long-standing licensed frequency usage. and like Lightsquared, this should be slapped down hard.
I think that every network operator would dearly love to get their hands on as much spectrum as possible around about 900MHz, which is very well suited to mobile use. The trouble is that other services are already well established around and about 900MHz. Once a service is established it's very difficult to get it moved out of the way. Of course, the difficulty is usually money; who's going to pay to have all that in service kit replaced?
So given the consequently slow pace of adjusting the frequency allocation tables, the only place new operators can go is to unused chunks of the spectrum despite their 'unsuitability' for the purpose. If they can make it pay then one would be forced to conclude that it was suitable afterall, so why shouldn't it be designated for mobile use? Trouble is that it looks like the physics and the economics aren't adding up to profitability...
The only way these matters are going to be sorted out is a proper and significant reorganisation of the frequency allocation tables. The amount of spectrum reserved for mobile use at 900MHz is woefully small. It was quite generous when set decades ago but mobile is now so much more important that it used to be. It's high time governments decided there needed to be a worldwide grand plan to sort this out.
just imagine something like ...
Her Majesty's Government has decided to award the contract for 5G (is there such a thing?) to So-and-So.
So-and-So's bid was the lowest of all received and HMG considered the counter-inflationery forces of customers paying smaller bills for better technology to be in best interest of the nation.
Moreover HMG has impressed upon the Treasury that a state resource should be made available to her majesty's subjects at as low a cost as possible to enable the technology to be taken up by as many as possible for as little as possible.
HMG accepts the principle that a state resource is not an elitist resource.
?
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