LightSquared, a hedge fund-backed start-up viewed as a major enabler of wireless competition in the US, was granted control over a portion of the US spectrum by the Federal Communications Commission (FCC) in order to build and wholesale 4G-LTE wireless broadband service through a nationwide network. According to their own website, “LightSquared will unleash the boundless opportunity of wireless broadband connectivity for all.” But unfortunately this presumed advantage comes at a serious known cost for popular navigation systems used by aviation and first responders.
During initial tests of the network conducted last month, there was significant interference with the Global Positioning System (GPS) receivers used by ambulances and state patrol. These tests were conducted at Holloman Air Force Base in New Mexico where both sets of first responders experienced outages due to the LightSquared cell towers. Bill Range, Director of the state E911 program, stated in a letter that the results of the April tests, “substantiate concerns that the LightSquared network will cause interference to GPS signals and jeopardize 911 and public safety nationwide.”
The problem is that the LightSquared system operates using bands between 1525-1559 MHz and 1626.5-1660.5 MHz while GPS signals operate in the intervening bands of 1559-1610 MHz. Making matters worse, the strength of the LightSquared signal is many orders of magnitude greater than the GPS signal. As a result, the GPS receivers of Otero County ambulances could not establish any connection with the GPS satellites within 60 yards of a tower during testing. The Federal Aviation Administration (FAA) also warned of potential GPS outages within 300 miles of the LightSquared tower in Boulder City, NV. The US Department of Defense (DoD) and Department of Transportation (DOT) also have serious concerns about the impact that the 40,000 cell towers proposed to make up the LightSquared national network will have on GPS receivers. These agencies complain that they “were not sufficiently included in the development of the LightSquared input” and the result is to effectively put commerce before public safety.
Consequently, LightSquared, along with the GPS industry and other federal agencies are conducting additional tests through June to determine the extent of interference between the cellular network and GPS receivers. As your advocate, the Coalition to Save Our GPS is working to minimize the threat to applications and devices that leverage the Global Positioning System. Their website also provides links for contacting your congressional or FCC representatives.