GPS, aviation interests and others continued to raise concerns to...

in place to allow UWB operations to move forward. Aeronautical Radio Inc. (ARINC) and Air Transport Assn. of America (ATA) urged FCC to preclude unlicensed UWB operations. FCC sought comments on 5 test reports on potential of UWB devices to interfere with GPS and other licensed operations. Tests were conducted by NTIA, Dept. of Transportation through Stanford U., U. of Tex.-Austin Applied Research Labs and Johns Hopkins U. on behalf of Time Domain and Qualcomm. ATA and ARINC said studies pointed to “inability of unlicensed UWB devices as proposed to share spectrum, especially in restricted bands, with existing licensed services on a noninterference basis.” FCC “might consider” licensed deployment of UWB devices if future testing demonstrates sharing would work for certain devices, but ATA and ARINC still recommended UWB be barred from operating in restricted bands and generally below 5.5 GHz. In other comments: (1) Sprint PCS, citing Qualcomm report, recommended FCC prohibit UWB devices in PCS band. Sprint contended UWB devices would cause harmful interference to PCS CDMA networks even at stricter average power levels listed in notice of proposed rulemaking (NPRM). (2) Motorola suggested setting EIRP (effective isotropic radiated power) limit for UWB devices that would be 35 dB below current Part 15 limit for certain signals. (3) Lockheed Martin suggested need for “some form of regulatory mechanism for UWB devices” beyond current Part 15 limitations, saying that could be laid out in further NPRM. Among UWB proponents, Time Domain said different conclusions reached in studies largely resulted from “certain assumptions as to what should be deemed to constitute harmful interference.” Both NTIA and Stanford tests “assumed unrealistic operational scenarios and employed mathematical modeling to reach erroneous conclusions dependent on the flawed underlying assumptions.” Johns Hopkins study drew upon test results at U. of Tex. that covered both outdoor radiated testing in conjunction with indoor testing and extensive simulations. Time Domain said that meant that Johns Hopkins could provide FCC with several operational GPS measures of performance. Time Domain said all reports showed that with white noise-like signals, interactions with GPS signals were predictable “given the extensive body of knowledge” in that area. UWB implementation that Time Domain has developed is like white noise, company said. “When realistic propagation models and deployment scenarios are considered, the reports support the conclusion that UWB signals that appear much like white noise can be authorized at the Part 15 general limits without posing a risk of harmful interference to GPS,” Time Domain said. Sirius Satellite Radio took opposite view of test results, recommending FCC undertake “staged investigation” that focused on specific classes of UWB applications. Commission should define specific categories of UWB devices, including technical and operational characteristics, and quickly identify areas where more testing was needed, including effects of multiple UWB devices. Sirius said agency should develop specific proposed rules for each UWB device category, including its application, allowable average and peak power levels, allowable ranges of pulse characteristics in time domain, allowable spectrum masks.