Overview Edit

On February 14, 2012, the Federal Communications Commission, through a public notice, proposed the revocation of its earlier conditional approval of LightSquared's plan to build a satellite-based national LTE network on the grounds that it would cause unacceptable interference to GPS.

The underlying issue was that the requirements for building the LightSquared network could not be determined in advance, since there were no objective criteria by which the extent of harmful interference could be predicted. The LightSquared network was designed following FCC rulemakings in 2003, 2004 and 2005 that incorporated extensive input from the public and Federal agencies. In particular, the FCC adopted recommendations from the GPS Industry Council and NTIA to protect against harmful emissions from Mobile Satellite Service/Ancillary Terrestrial Components operations intruding into other bands, including the GPS frequency bands.

However, the GPS community raised overload interference issues in connection with the FCC's 2011 Conditional Waiver Order, which specified a number of conditions LightSquared would have to meet before offering any commercial service. Overload interference occurs when signals from a transmitter disrupt a receiver susceptible to those signals. In this case, the potentially interfering signals were outside the GPS bands but still detectable by GPS receivers.[1] The de facto emission requirement for the LightSquared network was therefore set by the level of overload interference that pre-existing GPS receivers could tolerate. Unfortunately, the extent to which GPS devices were expected to withstand interference from the LightSquared system was not specified before LightSquared began to design and build its network. Thus LightSquared was unable to determine the complete technical specifications — and therefore the true cost — of its network prior to launch.

Receiver management principles can establish transparency in dealing with such conflicts. If actual GPS receiver capabilities, including susceptibility to overload interference, had been specified in advance, LightSquared could have either designed a network that would not cause interference or else determined that such a design was not feasible or cost effective. Instead, LightSquared discovered the magnitude of the GPS receiver issues only after it had spent billions of dollars.

By defining the interference limit that receivers under FCC and NTIA jurisdiction must cope with and requiring that receiver manufacturers report what interference their devices can tolerate while still delivering reasonable and customary service, the FCC can specify the transmission rights of new spectrum users in a way that would allow them to co-exist with legacy systems in adjacent bands. This clarity will be essential to avoid numerous recurrences of conflicts like the LightSquared-GPS dispute.

Source Edit

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