NASA CITES POTENTIAL OF ULTRA-WIDEBAND TO INTERFERE WITH GPS
NASA Administrator Daniel Goldin warned Commerce Secy. Donald Evans that ultra-wideband (UWB) devices -- even at power levels below Part 15 requirements -- “have significant potential for disruption of critical operations by GPS.” Goldin asked that NTIA: (1) Urge FCC to issue further notice of proposed rulemaking on UWB, not final order. (2) Recommend that further notice propose rules for UWB devices above 6 GHz and limit out-of-band UWB emissions below 6 GHz to restrictions outlined by NTIA in draft proposal. “The potential for disruption becomes especially acute if UWB devices are allowed to proliferate unlicensed and operate in widespread networks,” Goldin said in letter obtained by Communications Daily. “This is a critical concern for NASA as such interference will undermine our ability to support the Department of Transportation in meeting the nation’s air traffic and aviation safety challenges.” Letter was written July 25 but hasn’t been widely circulated. Sources said Transportation Secy. Norman Mineta had written similar letter to Evans. He asked that Administration not take position on UWB that would allow “intentional, unlicensed emissions in current restricted bands” such as GPS. Mineta and Goldin both asked Evans to obtain consensus of federal agencies on UWB, although one source said Administration-wide position wasn’t expected until Dept. of Defense weighed in on issue.
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Goldin told Evans that allowing UWB devices to operate on unlicensed basis under Part 15 would require unprecedented changes in rules on unlicensed transmitters. Such changes would include “removal of current prohibitions on intentional transmissions into and across restricted bands such as those used for safety-of-life and scientific services,” said Goldin, who cited GPS as example. “Allowance of intentional, commercial emissions into restricted bands will undermine U.S. leadership in international efforts to protect aviation safety and radio navigation satellite services from interference,” Goldin wrote. He said that in recent World Radio Conference meetings, efforts to protect GPS took several years of work and cooperative effort. “We now face a potentially more serious threat if UWB devices are not carefully controlled and allocated to appropriate segments of spectrum,” he said. He said his agency wanted rules for UWB devices “whose necessary bandwidths are confined to a segmented band above 6 GHz” and that would ensure adequate management of noise floor in band. Below 6 GHz, out-of-band emissions should be limited to levels specified in “current draft proposed rule” from NTIA.
NTIA is preparing response to letters from Mineta and Goldin, spokesman said Fri. He declined to comment on draft rule from agency cited by NASA. However, several sources said draft provided conservative emissions mask for UWB that would be more stringent than existing Part 15 limits.
NASA concerns center on potential for interference, with more testing needed to ascertain particulars of possible problems, spokeswoman said. “NASA, as well as other government agencies, are very interested in this technology. We just want to make sure that it is deployed in a way that it doesn’t interfere with the safety of air transportation” and other services, she said. “Obviously one of the key areas of interest to us and to other government agencies is that GPS is used for aircraft navigation,” spokeswoman said. “If there were any sort of interference with GPS, that would clearly be a concern to air transportation in the U.S.”
Asked about potential interference concerns expressed by Goldin, Time Domain Vp-Corporate Strategy Jeff Ross said, “The ultra-wideband community appreciates there are some concerns from the federal user community and we hope and expect those concerns will be addressed through the regulatory process by NTIA working with the FCC.”
Mineta, whose department oversees civilian uses of GPS and FAA, raised some of same points about UWB’s potential to interfere in safety-of-life bands, source said. In separate letter to Evans in late July, he asked that FCC undertake further notice rather than final rule on Part 15 rules for UWB. He asked that further notice outline specific rules for UWB devices above 6 GHz that addressed noise floor management in that band. DoT couldn’t be reached for comment. But spokesman said earlier that agency wasn’t releasing letter itself because it represented “confidential” communication (CD Sept 10 p2). Several sources said Pentagon hadn’t sent letter on position to Evans yet, with one source saying Pentagon still was sorting through feedback from both UWB users and officials concerned about potential GPS interference.
Meanwhile, stream of ex parte filings on pending UWB rulemaking has continued at FCC. Sprint PCS, in Sept. 10 filing, reiterated that it and other wireless carriers had found “harmful interference will result if UWB devices are permitted to use the 1.9 GHz band licensed to PCS service.” Sprint PCS cited analysis submitted to FCC in conjunction with UWB developer Time Domain. Sprint PCS said data showed emissions level of -53 dBm for UWB devices, which is 12 dB lower than Part 15 levels, wouldn’t protect its PCS network from interference. Instead, Sprint said FCC would have to set emissions level 29 dB below Part 15 levels “before UWB devices would no longer cause harmful interference to Sprint PCS.” Sprint also disputed some arguments by supporters of UWB that devices were same as unintentional radiators such as hair dryers and should be covered by Part 15 in same way. “Conventional Part 15 devices are designed to have narrowband emissions, and they will interfere with PCS service when operating in close proximity and within the bandwidth of the PCS handset,” Sprint PCS said. “Because UWB devices are designed to operate on a wideband basis, a UWB device need only be operating in close proximity to cause harmful interference.”
Broad group including GPS interests and representatives of aviation and wireless industries wrote to DoD this month outlining recommendations for commercial UWB operations. Recommendations include: (1) Not overlaying UWB communications devices and networks in 1-6 GHz bands. (2) Not altering current Part 15 rules to change prohibition against intentional emissions in restricted bands. (3) Allowing commercial UWB devices to operate above 6 GHz under new part of FCC rules. In Sept. 5 letter, coalition told John Stenbit, assistant defense secy. for command, control, communications & intelligence, that approach focused on commercial UWB applications under FCC jurisdiction.
“The federal government clearly has an interest in UWB technology, particularly for military use,” letter said. Coalition said govt. could authorize UWB technology under conditions established by Interdepartment Radio Advisory Committee (IRAC). “The concerns of the members of the industry coalition have been focused on the ubiquitous proliferation of unlicensed commercial UWB devices, particularly if authorized to operate across restricted bands,” letter said. It was signed by 31 companies and groups, including Air Transport Assn. of America, AT&T Wireless, Delta Airlines, Ericsson, Lockheed Martin, Nokia, Nortel, Sirius Satellite Radio, United Airlines, U.S. GPS Industry Council, WorldCom, XM Radio. Groups said IRAC can develop “appropriate safeguards” for operations by govt. agencies, including DoD. “On the other hand, once the FCC authorizes the sale and use of unlicensed commercial UWB communications devices and networks, there is very little accountability for their use,” groups told Stenbit.