Globalstar, Critics Jousting Over Its Summer TLPS Non-Interference Testing

What Globalstar says was a clear demonstration there are no interference issues between its proposed terrestrial low-power service (TLPS) and either Wi-Fi or Bluetooth is coming under increasing fire from critics. The satellite company still hasn't satisfactorily answered how adjacent broadband radio service (BRS) and educational broadband service (EBS) will be safeguarded from TLPS interference, the Wireless Communications Association International (WCAI) said in a filing in docket 13-213 posted Monday. And in a separate filing posted Friday in the docket, Microsoft said the Globalstar demonstration "overstates the results to the point of being misleading." Globalstar, meanwhile, is trying to rebut point by point some TLPS testing critics.

Globalstar hasn't done any testing designed to evaluate BRS/EBS coexistence with TLPS, let alone shown the FCC how it can be confident that access points that provide TLPS will be able to comply with out-of-band-emission masks at 2,486 MHz without doing any access point model-specific testing, WCAI said. And while Globalstar has talked about how it could use a ViaSat network operating system to control access points, there's no evidence that system can mitigate interference from individual mobile TLPS devices, WCAI said. All that points to the FCC needing to impose "appropriate power and unwanted emissions limits on Globalstar's terrestrial operations ab initio [from the beginning]," the group said.

Globalstar's TLPS demonstration over the summer on a college campus (see 1509110018) was "another managed demonstration ... not a satisfactory substitute for rigorous, peer-reviewable testing," Microsoft said. The problems include using enterprise-grade access points, instead of commercial grade, and thus not representative "of the vast majority of 2.4 GHz Wi-Fi equipment in operation today," Microsoft said. Globalstar also hasn't made public the operational parameters it used during the compatibility demonstrations, including data on the duration of the demonstrations; nor has it addressed such issues as quality of service in real-time two-way communications like Skype in high-density deployments or system-level testing of game consoles that use Bluetooth or some similar communications medium, Microsoft said. It also said it's unclear whether enterprise network operators will thus have to download Globalstar network management software, and what happens to those who don't. Meanwhile, Globalstar's pledge that it won't use LTE-U technologies for TLPS at least until the FCC has signed off on LTE-U deployment leaves open the option of someday deploying LTE-U and whether "its claims of TLPS coexistence with Wi-Fi and Bluetooth ... can be extrapolated to unlicensed LTE technologies and specifically to LTE-U," Microsoft said.

Globalstar didn't comment, but Thursday it submitted a filing that included a declaration by Kenneth Zdunek, chief technology officer at Roberson and Associates, which was responsible for the summertime TLPS test. That filing was aimed at rebutting criticisms from the Wi-Fi Alliance (see 1510160032), Hearing Loss Association of America (see 1510050057) and Bluetooth Special Interest Group (see 1510270050). Zdunek said consumer-grade client devices were used for all measurements in the university demonstration, and that deployment of TLPS "within an existing, representative Wi-Fi deployment" shows there was no premeditated choosing of existing access points to get a positive result.

Zdunek also disputed the transparency of the testing, saying information about such issues as access point power levels, the Wi-Fi and TLPS load factors and the data types used has been made freely available. "The key conclusion of the demonstration -- that TLPS enhances the capacity and throughput of an existing Wi-Fi network without any negative impact on the existing network -- withstands the challenge," Globalstar said. Previous demonstrations at the FCC Technology Experience Center and in Globalstar's summer testing also clearly showed lack of TLPS interference with Bluetooth-equipped hearing aids and other Bluetooth devices, the company said.