Garmin: LightSquared, GPS systems cannot coexist

Garmin continues to make noise around the potential of LightSquared's satellite-terrestrial LTE network to severely disrupt GPS service.

LightSquared recently received conditional FCC approval to install its network, with restrictions around keeping signals to their assigned frequencies in the L band. It is also required to test existing GPS devices to determine what type of interference its transmitters might cause.

Last month, the National Telecommunications and Information Administration told the FCC that federal agencies are worried about LightSquared's proposed LTE network interfering with GPS satellites and other emergency communications. In the letter, NTIA Administrator Lawrence Strickling said that a fully terrestrial network would require more base stations than a terrestrial/satellite combination network, thereby increasing the likelihood of interference. LightSquared plans to build a network of 40,000 broadband transmission towers around the U.S. The nationwide LTE network would cover 92 percent of the U.S. population. The company has said its wholesale LTE network will allow for terrestrial-only, satellite-only or integrated satellite-terrestrial services (via the terrestrial and MSS spectrum Harbinger scored through a merger last year with satellite operator SkyTerra).

In a letter to the FCC, LightSquared CEO Sanjiv Ahuja promised to work with the commission to ensure that the company's network will not interfere with GPS satellites and other maritime and aeronautical emergency communications. Ahuja promised to not offer commercial service until the FCC is satisfied with LightSquared's resolution of the interference claims.

However, GPS uses a frequency range of 1159 MHz to 1610 MHz, which is next to LighSquared's signals. Garmin's Jessica Myers told AVweb that Garmin has conducted its own testing and found no practical way for the two systems to coexist. She said that even if LightSquared's signals don't move out of its boundaries, they are significantly stronger than the lower-power GPS signals. And while blocking interference with filtering techniques is possible, it might be too expensive, Myers said.

LightSquared has indicated that Garmin's tests are suspect because the company did not use actual equipment that will be installed on the broadband towers. Real-world testing is expected to begin this month.

In related news, LightSquared said that it has signed wholesale deals with two U.S. operators and in discussions with three more. In an interview with FierceWireless, Frank Boulben, LightSquared's chief marketing officer, said the company cannot disclose the names of those operators, except with potential investors who agree to sign a nondisclosure agreement. Boulben also said that the company has an agreement with a major retailer it will name before the end of March.

For more:
- see this AVweb article
- read this FierceWireless article

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