LightSquared GPS, Aeronautical Communications Interference Could Easily be Fatal

If you have been around spectrum policy long enough, you will early have learned that existing licensed users have enormous political leverage. So the fact that LightSquared interferes with both aeronautical communications and the GPS system could be a fatal problem. A spectrum owner simply will not be allowed to launch a new service that is shown to disrupt existing users, and given the public safety angles to both GPS and aeronautical communications, the demonstrated interference to both types of applications will continue to face a very-high burden of proof.

LightSquared believes it has solutions, but it will have to prove those solutions work to the satisfaction of the existing users who want certainty there will be no interference. Vacating spectrum closest to the GPS frequencies should help, in principle. The issue is that the transmitted power differences between LightSquared signals and GPS satellites is so enormous that even that protection could be problematic.

If adjacent signals transmit at equivalent levels, filters and spacing are effective. The issue for LightSquared is highly unequal transmitted power levels. Cellular networks such as LightSquared's transmit at much higher power than do satellite-based systems, as much as one billion times as high, according to some critics. In tests, the LTE network overwhelmed GPS receivers, such as in-car navigation systems, that were trying to lock on to weaker signals coming from GPS satellites.

GPS device sales total $20 billion per year, and about $3 trillion worth of commerce each year relies on the U.S.-built system, said Roy Kienitz, under secretary for policy at the U.S. Department of Transportation.

One initiative that would be endangered by LightSquared is NextGen, a new air traffic control system designed to improve safety that relies on GPS, Kienitz said. The Federal Aviation Administration and airline industry have already invested $8 billion in NextGen, he said.

LightSquared faces more turbulence over GPS - Computerworld