Why LightSquared cannot deploy LTE

http://www.extremetech.com/electronics/117127-why-lightsquared-cannot-deploy-lte

by 11031a • 14 years ago

14 22 14 years ago

chc• 14 years ago

This doesn't make much sense at all. Why on earth would they license these frequencies to LightSquared if they didn't want anybody using them?

swalsh• 14 years ago

It would seem the problem is not use in it of itself of the frequencies, but rather the application of the frequencies for an LTE network.

RockyMcNuts3• 14 years ago

They licensed the spectrum for satellite comms, and LightSquared is trying to use a loophole to use it as (much more valuable) cellular LTE.

thechut• 14 years ago

It appears that unlike AT&T and Verizon, LightSquared (formerly known as SkyTerra) did not purchase this spectrum from the FCC. They are only licensed to use that spectrum for low bandwidth satellite communications. The way I see the situation, LightSquared is trying to change the licensing on their spectrum in order to build a wireless network without having to actually pay for any of the spectrum.

It seems there may even be somewhat of a conspiracy about getting the spectrum approved.

See this press release from Chuck Grassley (R-IA): http://www.grassley.senate.gov/news/Article.cfm?customel_dat...

The details seem very murky, I welcome anyone that has a better understanding of how wireless networks work to please inform me.

aidenn02• 14 years ago

Basically they are trying to exploit a loophole in the system: If you have a satellite transmission network, you are allowed to use terrestrial stations to fill-in the gaps. They are essentially trying to deploy a terrestrial network by defining it as an extension of a fairly minimal satellite network.

All of that is just regulatory issues though. What really matters is interference; I don't (and the FCC doesn't seem to) care if a transmission comes from the ground or a satellite, so long as it doesn't mess with anybody else's services.

The two points of view are:

1) LightSquared is operating within their spectrum requirements, so while there are GPS receivers that will go haywire when they deploy, those GPS receivers are faulty (as they don't properly deal with neighboring transmissions on frequencies outside their band).

2) GPS should be granted a special exception to the rules about accepting interference as GPS is very important and the GPS signals are very weak, so therefore a receiver with little filtering on the front end is far superior to one more tolerant of high power signals on neighboring frequencies.

Both arguments have their merit, so it should be interesting to see how things play out. The more you look into how GPS works, it's a wonder that it works at all which such low powers (and satellites in the middle of a radiation belt, no less!)

ImprovedSilence2• 14 years ago

Valid points. If I recall correctly, the Obama administration is also pushing for a nationwide wireelss network (http://www.google.com/webhp?hl=en&tab=nw&q=obama%20w...) , and I believe Lightsquared made a pretty good pitch to them to be able to use the spectrum. I also knew a lawyer who was doing work for the FCC, that was examining the possibility of buying back some of the lesser used satellite bands, for both the lightsquared type of work, as well as for mobile carriers.

bradleyland• 14 years ago

I'm not sure why anyone is surprised. You can't listen to your iPod during take-off on a commercial airliner, despite the fact that there is no proof that they can cause any meaningful interference. How on earth did anyone expect the licensing bodies would accept that LightSquared's technology could be trusted not to interfere with such a critical infrastructure component as GPS?

ImprovedSilence2• 14 years ago

I've known about LightSquared (and their spectrum issue) for awhile now. The impression I get is that there is little technical evidence that using their spectrum will infringe upon and overpower the neighboring GPS and other signals. LTE has VERY tight technical specifications, just to get valid data through, as the throughput is so high, and is unlikely to be a noisy signal out of band, enough so to cause interference with it's neighbors. If you'll notice, the linked article carries very little (or none) technical detail, it almost sounds like some fear mongering politician wrote it. This ain't the 1940's here people, we aren't just sending random analog radio waves out using oscillators with a 10% tolerance ratio. The spec is tight, the technology is bleeding edge, and modern receivers (of GPS and the like) have pretty good front end filters, out of band noise shouldn't be a huge problem for them.

rprasad3• 14 years ago

LTE vs GPS is like the difference between a Tsunami and a dripping faucet.

The problem isn't the noise, it's the volume. The volume alone would overwhelm the GPS filters' ability to filter out the out-of-band noise.

aidenn02• 14 years ago

To expand on the analogy, it's more like GPS receivers have a very wide funnel so that they catch every drop. This funnel extends into the range that lightsquared has. If it weren't GPS, the FCC would just say "fix your damn receivers, they are within the parameters of your license" but GPS is clearly Sui Generis because of the combination of the weakness of the signals and the importance to our infrastructure.

NelsonMinar• 14 years ago

The problem is the spectrum LightSquared wants to use is too close to GPS. They were licensed for one limited application of that spectrum and are now trying to shift to another much higher power application and they don't give a damn if nearby communication is harmed.

Here's a couple of technical articles on the results of testing LightSquared vs. GPS. http://www.insidegnss.com/node/2630 http://www.pcmag.com/article2/0,2817,2389264,00.asp

"A report prepared by the Federal Aviation Administration's Navigation Services division essentially attributes 794 deaths and over $72 billion in additional costs to U.S. taxpayers if the LightSquared LTE system is implemented."

jpastika• 14 years ago

Interference Studies: http://saveourgps.org/interference-studies.aspx

I am by no means an expert on the technical reasons for the interference with GPS, however, I work in the heavy highway construction industry and LightSquared's use of the spectrum is of real concern. The level of accuracy of current GPS guidance systems for construction equipment is astounding and enables significant improvements in job productivity over conventional practices.

I hope the truth and or a solution is discovered, as I do like the idea behind LightSquared and would use the service if available.

jws4• 14 years ago

The FCC wants to deny LightSquared the use of their licensed spectrum because neighboring users (GPS receivers) cheaped out on their receivers and can't tolerate Lightspeed's transmissions.

I'm willing to accept that not breaking GPS receivers is a good thing, and that allowing Garmin et.al. to sell cheap receivers by assuming neighboring bands they do not have licenses to are unused is possibly a good thing.

But, having an independent, nationwide, high speed internet choice is definitely a good thing.

The FCC should take a frequency allocated to government use and swap it to Lightspeed so they have bandwidth they can use. The existing users will pitch a fit about the expense of moving, but a new nationwide cellular internet player will likely save billions of dollars for consumers.

ChrisOstler• 14 years ago

That's only telling part of the story, as far as I understand. Lightspeed wants the FCC to change their license for (lower powered) satellite communication to allow them to use the spectrum for (higher powered) terrestrial use.

Users of adjacent spectrum designed their products properly for being adjacent to lower powered satellite signals. They weren't designed to filter out the much higher power terrestrial signals that Lightspeed is vying for.

The FCC is not denying Lightspeed the use of their licensed spectrum; they are not letting Lightspeed redefine their license to be something different than it is.

RockyMcNuts3• 14 years ago

Exactly, they licensed the spectrum for satellite comms, and LightSquared wants to exploit a loophole to use it as (much more valuable) cellular LTE.

It's kind of like buying land zoned for industrial use next to the airport because you can get it rezoned for residential and make a ton of money. And the airport is saying WTF, now we're going to have to deal with local voters who will want us to change the way we do things.

If you're going to do this sort of thing, you need to make sure you have your engineering down pat, and your local politicians and regulators in your pocket.

see http://brontecapital.blogspot.com/2012/02/lightsquared-some-...

jws4• 14 years ago

I believe their license includes the right to use terrestrial stations to fill in. They are under a conditional waiver not use a satellite at all. They are certainly using spectrum in a way not foreseen, but that is different from forbidden.

The bottom line is that the US has suspiciously high wireless data costs and a duopoly controlling the market. It's either make more players, effectively regulate the existing players, or allow the overpriced drag on consumers to persist.

There are only a quarter million airplanes in the US. Retrofit all of their navigation aids systems and free up a couple hundred MHz of bandwidth and you'd still pay for it with one year's savings from the mobile internet consumers. (And probably have better navigation in the planes.)

CamperBob• 14 years ago

The FCC wants to deny Lightspeed the use of their licensed spectrum because neighboring users (GPS receivers) cheaped out on their receivers and can't tolerate Lightspeed's transmissions.

This is an insane oversimplification. RTFA -- that part of spectrum was never supposed by used by any terrestrial transmitters. GPS and other services were built under the promise that they would not have to contend with powerful, localized transmissions on adjacent channels. There are strong technical reasons why designing receivers to be immune to such adjacent-channel interference is impractical.

The FCC tried to let bureaucrats instead of engineers run the show, and unsurprisingly it's come back to bite them.

Why LightSquared cannot deploy LTE

Related Stories