Industry Seeks Changes to White Spaces Rules, as Disagreements Persist

“Chipmakers, device manufacturers, and other innovators are watching this proceeding carefully to determine whether the regulatory framework for white-space devices will support a vibrant unlicensed ecosystem,” Microsoft said in its recon petition.

The order on the whole is positive, but would benefit from two changes, Google said. Google asked the FCC to change one aspect of the rules identified as a problem by the White Space Database Administrator Group (see 1512230053), a requirement that databases “push” information to white space devices in an area where licensed wireless microphones will be used to prevent interference.

“The Commission correctly recognized that requiring devices to ‘pull’ information from databases at rapid intervals would create unreasonable operational burdens on databases and devices and appropriately declined to establish such a rule,” Google said in its petition. “But the Commission did not provide adequate notice that it was considering a ‘push’ mandate in the alternative and, accordingly, was unaware that a ‘push’ mandate has the same disqualifying problems, and to an even greater degree.” The requirement, if left intact, “would dramatically increase database server utilization (possibly increasing database fees for users) and reduce the battery life of unlicensed devices,” Google said.

Google also asked the FCC to rethink the protections provided for hospitals that use wireless telemetry in channel 37. Wireless telemetry advocates scored what some saw as a late win as the order was on the eighth floor with the FCC agreeing to allow hospitals to apply for a waiver giving them expanded protection zones upon the filing of a waiver request (see 1508060025). The FCC also said it would limit test deployments of unlicensed services in channel 37 to only one or two markets before authorizing nationwide rollout.

The uncertainty created by the FCC on channel 37 will “undermine investment in the development of unlicensed equipment for use in the 600 MHz and repurposed television bands, and slow unlicensed network deployments,” Google said. It urged the FCC to clarify that it will consider test deployment requests even before the deadline for healthcare facility registration has passed, look at reducing the separation distances required by the order depending on test results and “establish a date by which it intends to authorize nationwide deployment of unlicensed services in Channel 37.”

WISPA said the order takes an “overly conservative approach to interference management, at the expense of WISPs and others that have supported the development of the white space industry with the intent to responsibly deploy needed broadband services.” WISPA said the rules should be changed to allow fixed device "antenna directivity" to determine channel availability.

“The reasons cited in the Report and Order for failing to consider antenna directivity fail to recognize what is already common industry practice,” WISPA said. “The measurement of antenna horizontal beamwidth, as defined by the -3 dB (half-power points) is universally recognized throughout the industry and is an integral part of the Commission’s own equipment certification process. Moreover, antenna beamwidth specifications are published and a matter of public record for virtually all commercially manufactured antennas.”

WISPA also asked the FCC to allow taller antennas than the 30 meters above ground level (AGL) and 250 meters maximum height above average terrain (HAAT) now allowed, at least in uncongested areas. WISPA noted it had urged the FCC to allow antennas that are 100 meters AGL and of 500 meters HAAT. “Any legitimate concerns about potential interference to protected facilities can be overcome by doing what the Commission has done throughout this proceeding -- establish reasonable distance separation criteria to adequately protect authorized facilities,” WISPA said.

Like Google, Microsoft sought changes to rules for channel 37. In addition, Microsoft asked the agency to “harmonize” the conducted and radiated power limits for low-power fixed devices with those adopted for personal/portable devices. “Clearly, an indoor-only fixed device presents even less interference risk than a personal/portable white-space device operating at the same power level,” Microsoft said. “The Commission’s rules should account for this fact.”

Protecting Wireless Telemetry

But GEHC said the FCC erred in not doing enough to protect the Wireless Medical Telemetry Service (WMTS) in channel 37. “As a safety-of-life service, WMTS cannot tolerate even small or episodic incidents of interference,” GEHC said in its petition. “For example, a single source of interference can cripple an entire WMTS system and be extremely difficult to identify, all the while endangering patients and diverting the attention of hospital staff.”

The FCC should increase the required separation distances to protect wireless telemetry from harmful interference, GEHC said. The FCC used a flawed propagation model and then “misapplied that model” when it calculated separation distances, the company said. “For example, the Commission neglected to include a factor for the Signal to Noise Ratio (SNR) required by WMTS radios, ignored the potential for multiple" white space device interferers and "wrongly assumed that most WMTS antennas are no more than 10 meters high.” The FCC should require separation distance of about three times those mandated to protect medical use of channel 37, the company said. “The Commission should eliminate the material errors that plagued its initial analysis and adopt alternative protection distances that will, in fact, provide adequate protection,” GEHC said.

The WMTS Coalition also sought reconsideration. “Unfortunately, in many of the assumptions that were made in calculating the separation distances at which unlicensed devices must operate, the Report and Order favored the avoidance of overprotection of hospitals in some directions at the expense of under-protection where WMTS systems are likely to be vulnerable to harmful interference,” the coalition said.