2/25 - OTI Reply Comments on Unlicensed TV White Space Channels After the Incentive Auction

On February 25, OTI filed comments on the Commission’s rules for unlicensed operations in the television bands. Read the full comments here


The Open Technology Institute at New America (“OTI”) and Public Knowledge (“PK”) hereby reply to certain of the Comments regarding proposed changes to certain of the Commission’s Part 15 rules. OTI and PK commend the Commission for opening this proceeding as a means of implementing the agency’s decision in last May’s Incentive Auction Report & Order to allow unlicensed operations in the 600 MHz duplex gap and other guard bands, Channel 37, a set-aside channel for sharing with microphones in every market, as well as the opportunity to update the current white space rules to reflect new realities and the proven effectiveness of the TV Bands Database system. As our groups and others have explained in previous filings, the emergence of a mass market for unlicensed chips, devices and services in this unique low-band spectrum – including the integration of the 802.11af standard into Wi-Fi chipsets – is wholly dependent on access to three or more 40 mW, 6 MHz channels in every market nationwide. OTI and PK applaud the Commission for its thoughtful proposals which, taken together and with some minor improvements, can fulfill that promise. 

OTI and PK strongly support the Commission’s efforts to ensure that at least three to four 6 MHz channels will be available for unlicensed WSDs in every market. The record clearly supports the Commission’s tentative conclusion that the duplex gap, as well as a lower guard band of 9 or 11 MHz, can provide a contiguous 6 MHz channel for unlicensed WSDs at a power level of 40 mW or more without undue risk of harmful interference to Part 27 services. Technical studies using real-world assumptions about filtering and propagation loss, such as Broadcom has filed and reprised in its comments, suggest that the power limits for unlicensed WSDs in the duplex gap could be at least 100 mW with a 4 MHz separation form LTE downlink. We are heartened the Commission appears to have learned from its first effort to placate the hyper-inflated interference concerns of broadcast industry licensees concerning WSDs that overly restrictive rules can deter and suffocate the tremendous potential of low-band unlicensed technologies.

OTI and PK strongly support the 4-6-1 duplex gap band plan proposed in comments filed by other leading parties in the unlicensed community. Broadcom’s analysis and the Commission’s own proposal to permit a 6 MHz unlicensed channel at 40 mW in the 9 MHz guard bands indicates a recognition that 3 MHz of separation is sufficient to protect LTE downlink operations from harmful interference. 

OTI and PK question whether licensed microphones should operate in the duplex gap at all. If there is a single point of agreement among all major parties in this proceeding, it is that Part 74 microphone operations and unlicensed WSDs cannot productively cohabit the duplex gap and sufficiently protect licensed Part 27 operations. While public interest groups and other unlicensed advocates support a compromise around a 4-6-1 plan as the best balance between the needs of the various stakeholders, the microphone and wireless industries are divided on this question in a way that strongly suggests the Commission should move Part 74 microphones out of the duplex gap entirely. 

On the issue of unlicensed microphone operations in the duplex gap, OTI and PK agree with Microsoft that the Commission’s proposal to “require” wireless microphone users to check a database manually to obtain a list of available frequencies is not “[u]nlicensed use . . . rely[ing] on a database” in the sense that Congress intended. OTI and PK also oppose any increase in the 3 Commission’s proposed 20 mW power limit for wireless microphones operating in the duplex gap or other guard bands. 

Channel 37 represents one of the three or four channels that will make or break the emergence of robust national markets for unlicensed WSDs. OTI and PK therefore strongly support the consensus among commenters that the Commission should permit all three types of WSDs (fixed, Mode I and Mode II) to operate subject to protection zones that are based on real-world assumptions about propagation and interference risk. By neglecting to factor in real-world assumptions about terrain concerning RAS and the fact that WMTS operates indoors, the Commission risks a reversion to the same over-protective, one-size-fits-all problem that plagued the original set of white space rules in 2008 and which the Commission is, ironically, proposing to remedy in other portions of this same NPRM. 

OTI and PK concur with the overwhelmingly support among commenters for the Commission’s proposal to relax the stringent out-of-band emission limits that inhibit the use of Channels 35-39. These restrictions are unnecessary since, under the Commission’s proposal to open Channel 37 for shared use, any necessary separation can be more effectively enforced by the TV Bands Database. 

OTI and PK strongly support and Commission’s proposal to help offset the incentive auction’s huge reduction in the number of channels available for unlicensed WSDs by removing the prohibition on personal/portable device operation on channels 7 to 20. Similarly, our groups agree with the clear consensus among commenters that the Commission should adopt its proposal to allow fixed WSDs to use Channels 3 and 4. OTI and PK see little if any justification to delay making these channels available. 

Finally, OTI and PK strongly support the Commission’s proposal to permit WSDs to continue operating in the 600 MHz band post-auction until the licensee gives notice that it will “commence operations” in a local area. The Commission’s proposal simply maintains the status quo since today the majority of 600 MHz spectrum is available for opportunistic unlicensed use, subject to permission enforced by the TV Bands Database. Contrary to CTIA’s efforts to maintain its members’ ability to warehouse vacant spectrum, PEAs should not be used as the geographic foundation for excluding WSDs from access to underutilized spectrum. PEAs can be larger than states and even Cellular Market Areas can extend hundreds of miles beyond a single urban area where a carrier may initially provide service. No standardized licensing area comes close to replicating what the TV Bands Database can do given very straightforward data points that are readily available to licensed carriers that, before they deploy, carefully planned out the coverage areas and link budgets for each and every base station and cell site. In reality, the reporting “burden” on licensees (to notify a TV Bands Database administrator) would be de minimus and not involve collecting any data the operator does not already have readily at hand for their own purposes. 

Download the full comments below:

OTI Comments on "Use-It-or-Share-It" Rules for Citizens Broadband Radio Service