Could LightSquared's wireless 4G network interfere with GPS?

A nationwide 4G network that could blanket the U.S. with fast wireless Internet access sounds like a dream come true for most consumers. But what if this 4G network's signals interfere with the GPS navigation signals that many consumers, industries, and the U.S. military rely upon?

That's the concern GPS makers, public safety officials, and the U.S. military have with a new 4G LTE network that's about to be turned on by LightSquared, in Reston, VA. The LightSquared network uses space-based satellites in addition to 40,000 earth-based cellphone towers to beam its 4G signals to devices using radio frequencies that are close neighbors of those used by GPS.

The issue, say experts, is that GPS devices are extremely sensitive, since they need to pick up navigation signals sent by space-based GPS satellites alone. High-powered LightSquared signals from nearby cell towers could interfere and degrade the navigation system and endanger public safety, as GPS is also widely used by emergency responders and the military. And while new GPS receivers can be built to filter out the 4G signals, retrofitting existing GPS devices would be prohibitively expensive, say LightSquared opponents.

Both GPS and the new 4G network can co-exist, though, say LightSquared and the Federal Communications Commission, which approved of LightSquared's system back in 2003 as a means of promoting competition in the wireless Internet market.

Government officials told the Associated Press that they will not allow LightSquared to turn on its 4G LTE system this year until they receive assurances that GPS devices will still work. Officials at LightSquared and the FCC, the administration responsible for allocating and managing the nation's electronic airwaves, say they will test to determine the extent of possible interference with GPS. The FCC told the AP that it will also require LightSquared to study the issue further with GPS manufacturers and users.

Planned wireless Internet network threatens GPS [AP via Macon News]
New 4G Network Could Squelch GPS [4GWE]
US wireless network threatens GPS [AP via Google News]

—Paul Eng