Iridium Interference Worries 'Absurd," Ligado Says

Iridium's claims that Ligado's proposed broadband terrestrial network is a significant interference risk to its operation in adjacent spectrum (see 1612140061) are based on a flawed model and don't make sense since its ancillary terrestrial component (ATC) operations would better protect Iridium than its satellite-only operations, Ligado said in a filing to be posted Tuesday in FCC docket 11-109. It included a 33-page technical paper in response to Iridium's technical analysis, with Ligado challenging the propagation models Iridium used. Ligado said Iridium has no legal basis for pushing for protection since its mobile satellite service (MSS) downlinks are secondary to Ligado's ancillary terrestrial service, and said the FCC had made clear in different proceedings on Iridium MSS operations and adjacent-band operations that the downlinks were secondary. Ligado said if it didn't get FCC approval to launch ATC services in the lower 10 MHz uplink channel, it would use the band for MSS service to the maximum power and out-of-band emission limits in its license, which are substantially higher than the ATC limits in its application. Ligado said Iridium's analysis ignores the real-world operational and regulatory environment such as the millions of mobile earth station devices currently deployed in the L-band at higher power levels than Ligado's proposed 0.2 watt user terminals. If Iridium's interference analysis was correct, Ligado said, those millions of devices "would be destroying Iridium's service," and that they're not illustrates the flaws in that company's analysis that the FCC should dismiss as "facially absurd ... confabulated spectrum concerns." Iridium didn't comment.