TAC Spectrum Recommendations Draw Measured Support

While suggesting various tweaks and expressing some concerns, numerous companies and groups have generally offered supportive comments regarding spectrum policy recommendations made by the FCC’s Technological Advisory Council. In a December public notice seeking comments, the FCC’s Office of Engineering and Technology observed that “the TAC has recommended that the Commission adopt a policy statement, setting forth spectrum management guidance and principles based on TAC recommendations made to the FCC, including the following: [1] Implement and formalize the TAC’s recommendations for Basic Spectrum Principles as policies, and set clear expectations about the affected system’s capabilities regarding interference, such as harm claim thresholds. [2] Adopt risk-informed interference assessment and statistical service rules more widely. [3] Implement steps for improving interference resolution, including a next-generation architecture for radio spectrum interference resolution, creating a public database of past radio-related enforcement activities, and incorporate interference hunters in the resolution process” (TR Daily, Dec. 1, 2017).

In its comments in ET docket 17-340, T-Mobile US, Inc., argued the TAC principles could form the basis of a framework for FCC spectrum allocation rulemakings.  But, the company said, the FCC should “remain mindful that each frequency band has its own unique challenges when considering whether to reallocate spectrum or modify service rules.”

If the FCC decides to apply the TAC principles in rulemakings, T-Mobile said it “cautions the Commission that their application cannot come at the expense of reducing the flexibility licensees currently enjoy to design, build, and manage their networks to deliver the service consumers expect. Furthermore, application of these principles, particularly with respect to interference protection rights, cannot be contingent on requirements for licensees to divulge company sensitive or proprietary information.”

Among other things, T-Mobile said it is “fully supportive of any Commission initiative that results in more timely interference resolution,” and added the commission should “focus its resources on quickly resolving interference issues that have not been otherwise resolvable.”

CTIA said the TAC recommendations “merit close consideration” by the Commission.

The group also said it supports the TAC’s view that a “one policy fits all” regarding interference mitigation “is not possible with such disparate requirements of various services.”

The Commission should also be “cautious about any attempt to establish top-down interference principles or rules, particularly if they were to be applied to commercial mobile services,” CTIA said.

The Telecommunications Industry Association said it “commends the work of the Commission’s Technological Advisory Council (‘TAC’) for proposing principles by which radio spectrum can potentially be utilized more intensively vs. prior uses, while also providing guidance the Commission can use in administering and resolving cases of potential harmful interference that will arise. We also support the view that a principle-based approach to interference mitigation would be preferable to the adoption of mandatory receiver standards, requirements or rules. We look forward to continued progress by the TAC, and to working with them and with the Commission on these issues.”

The Wireless Broadband Alliance (WBA) said it supports adopting the TAC principles, which would generally “help guide both the Commission and industry by incenting good engineering practices in equipment design and network deployment.” WBA said it favored the TAC’s recommendations the FCC adopt non-binding principles rather than mandatory rules or regulations.

“Due to the variety of existing and likely future radio technologies, and the complexities of introducing more band sharing across a very diverse set of incumbencies, WBA supports the use of policy guidance, and opposes mandatory rules,” the group said. The group also said the FCC should “proceed cautiously and incrementally with respect to using interference limits in enforcement or rulemaking.”

The National Spectrum Management Association (NSMA) argued that “further investigations are needed before broad statements of ‘receiver responsibilities’ are to be considered as generally applicable to all classes of receiving devices” regarding interference.

Among other things, NSMA also took issue with what it said was the TAC’s contention that all services require the same level of interference protection. “That is simply not true,” NSMA said. “In fact, not all services have the same concept of degradation. Public safety and critical infrastructure services demand a higher level of protection than do streaming movies. An understanding of these distinctions is necessary to effectively assess compatibility of new spectrum allocations.”

The Technology Policy Institute (TPI) said mitigating interference is not only a technological issue. “[W]hile mitigating interference and its effects in real time is a technological issue, truly dealing with the problem in a longer-term, more robust way requires thinking about it as an economics and incentives problem,” TPI said. “We would expect a flexible, market-based system to provide the best incentives to address interference problems in a cost-effective manner and to promote efficient use of the spectrum.”

Though TPI praised the TAC recommendations for generally favoring a market-based approach over regulation, some of the principles are “worded in ways that may not be consistent with overall cost-minimization,” such as suggesting that systems should use interference mitigation techniques “at all levels of the stack,” regardless of cost.

“Maximizing spectrum value also implies that it will not be optimal to mitigate all instances of interference,” TPI said. “For example, reducing interference to zero everywhere will likely not be optimal, because at the margin the costs of doing so would be high while the benefits would be low.”

In joint comments, Inmarsat, Intelsat Corp., Iridium Constellation LLC., SES Americom, Inc., and Telesat Canada contended that if the FCC adopts the TAC principles and then decides to impose further regulations, “A full review would be necessary because the TAC recommendations are based on broadly stated spectrum principles, and whatever elements of those principles the Commission decides to reflect in its rules and processes would have to be examined in the context of specific facts and frequencies.”

The satellite companies said many of the TAC recommendations are already “well ingrained” in existing regulations, such as allowing access to spectrum by different services. “These processes, which are intended to ultimately support meaningful commercial service, appropriately balance the need to minimize interference, thereby ensuring successful operations, and the complexity of producing detailed analysis of the potential for interference. Accordingly, the [satellite companies] do not see any need to change the FCC’s Part 25 rules related to licensing and operation of satellite and earth stations based on these principles,” the satellite companies said.

In addition, they said, the practice of service providers reaching negotiated agreements regarding interference mitigation are working well. “If there is no problem, there is no need to develop a complicated process to address it,” they said.

In joint comments, Echostar Satellite Operating Corp. and Hughes Network Systems, LLC sounded a note of caution. “The Commission should proceed very carefully before adopting general principles to which it would refer to guide future decisions regarding so many aspects of spectrum policy, from allocations and service rules to licensing and resolution of interference complaints,” the companies said.

The principles that the TAC recommended are “very general” and “could be used as tools to rationalize decisions made on other grounds and to politicize the process of adopting allocations, defining service rules, and resolving interference complaints,” they said.  In addition, the companies said, the general principles “are no substitute for careful deliberation” of particular bands, and  “may lead to spectrum decisions that are in conflict with the critical spectrum policy goals of technology neutrality, certainty, and flexibility that Echostar, Hughes, and others have pursued with great success, in recent years.”

Space Exploration Technologies Corp. (SpaceX) said it supports the TAC recommendations regarding risk-informed interference assessment (RIIA) because it considers “both the likelihood and the severity of potential interference scenarios,” rather than “severe” rules for “unlikely” scenarios.

When it adopts rules to minimize interference, the FCC “must to be able to discern which interference mechanisms can benefit from receiver improvements and which must be addressed at the offending transmitter facilities.”

The Wi-Fi Alliance praised the TAC recommendations and said the FCC, as the “steward of the electromagnetic spectrum,” must “affirmatively manage that resource to maximize its effective use in the public interest.” The FCC, the Wi-Fi Alliance said, “should therefore make clear that it is Commission policy that new operations may be introduced that do not harmfully affect incumbent users that reasonably maintain and upgrade their systems. At the same time, it is unnecessary for the Commission to mandate the use of particular technology or equipment upgrades.” The group also suggested the FCC make some changes to the recommendations, such as providing “clarity” on what constitutes “harmful” interference.

“The TAC should be commended for its multi-year effort to study how spectrum decisions are made and how the Commission can increase the simplicity and certainty of the regulatory process to reach decisions that result in more efficient spectrum use. The fruits of that work are a set of principles that can truly advance the Commission’s spectrum decision-making,” said Ligado Networks LLC. “In particular, Ligado recommends that the Commission promptly adopt principles 4, 5 and 6 to establish appropriate responsibilities for managing interference and adopt Principles 3 and 9 to advance the use of quantitative assessments on a case-by-case basis in its spectrum decision making.”

The GPS Innovation Alliance said that it “appreciates the effort that the TAC has undertaken to help the Commission manage spectrum. Missing from those efforts to date is a recognition of the critical difference between communications and navigation systems and the internationally established criteria – a 1 dB decrease in C/N0 – as an interference protection criterion which ensures that a harmful interference level is prevented in the first place so that systems operating in the same or adjacent bands do not interfere with one another. When the TAC refines its recommendations to the Commission based on the comments received in response to the recent Public Notice, it should incorporate these points, which are critical to the continued robust position that GPS-enabled technologies enjoy in our national infrastructure. Doing so is consistent with the Commission’s statutory obligation to manage spectrum, rather than abdicating that role in favor of an approach that ignores differences between technologies and applications.”

The National Public Safety Telecommunications Council (NPSTC) said the TAC’s recommendations regarding receiver characteristics and increased use of quantitative analysis in spectrum sharing “have merit,” but also cautioned that setting interference thresholds will be “especially complex and challenging.”

The Enterprise Wireless Alliance (EWA) said it “appreciates the TAC’s balanced approach” to spectrum policy. “[I]t is neither reasonable nor realistic in today’s wireless environment to assume that any service or system is entitled to absolutely interference-free operation,” EWA said. “The TAC is correct that prudent spectrum management demands that services anticipate non-harmful interference and plan for ‘occasional service degradation or interruption. The Commission should not base its rules on exceptional events.’”

The American Radio Relay League (ARRL) said the TAC recommendations are not expansive enough because they do not consider the area of man-made ambient noise levels and the radio noise floor. —Jeff Williams

Courtesy TRDaily