LightSquared has become a subject of debate among US legislators over their plan to use frequencies normally reserved for satellite communication for mobile phone service. Although they have received FCC approval for their service, it was with the condition that they be able to show it won't interfere with GPS equipment.
LightSquared's wireless service would be a wholesale product sold to regional mobile providers, allowing them to expand their networks to offer nationwide coverage.
The original plan was to use two different frequency ranges. That plan was modified when it was determined one of them would interfere with standard GPS communications which use an adjacent frequency range.
Problems remain with the second range of frequencies due to interference with high precision GPS signals used in industries like aviation and agriculture, as well as by the military.
In his letter, LightSquared CEO Sanjiv Ahuja wrote:
Recently, concerns have been raised about interference with GPS devices. We take these concerns very seriously. Despite the fact that the interference is caused by others' inappropriate use of LightSquared's licensed spectrum, we have been proactive in working toward a solution to the GPS issue. We are making a $150 million private investment in the solution for GPS. We have moved our spectrum farther away from the core GPS frequencies and at the request of the FCC, we set up, funded, and ran the largest and most comprehensive testing program this country has ever seen.
Ahuja's accusation is questionable at best. In reality, the problem isn't that GPS systems are using LightSquared licensed frequencies. In fact, the problem is the power of LightSquared's proposed terrestrial signal combined with existing GPS receivers, which were designed with the assumption only lower power satellite signals would be transmitted on adjacent frequencies.
Until last year the only terrestrial transmissions allowed to operate on those frequencies were used to fill gaps in satellite coverage. Those signals, used for services like satellite radio, don't operate at high enough power to interfere with other transmissions.
That was changed with a presidential mandate to consider using the satellite spectrum for expanding broadband Internet coverage.
By LightSquared's own admission, fixing the problem would require retrofitting the affected high precision GPS receivers to filter out their signal or replacing them entirely. They have offered to cover the cost for the federal government while hinting that others would need to bear the expense on their own.
In recent months the issue has taken on a political life of its own thanks to President Obama's apparent hand in pushing FCC approval forward and the ownership stake in LightSquared by a prominent Democratic Party contributor.
It is also opposed by government officials from the Department Of Defense and the National Telecommunications and Information Administration on purely technical grounds.
Unless LightSquared manages to come up with a solution that would allow the problem to be fixed on their end, rather than requiring wholesale replacement of high precision GPS equipment, their network appears to be dead in the water.
Written by: Rich Fiscus @ 28 Sep 2011 11:54