Parties Call for Action To Address Rising Noise Floor

August 12, 2016–A variety of parties say that the spectrum noise floor has increased over the years in a variety of bands—due to incidental, unintentional, and intentional radiators—and that the problem should be addressed through methods that could include new FCC rules or guidance and beefed-up enforcement. Comments were filed by yesterday’s deadline in ET docket 16-191 in response to a public notice released in June by the FCC’s Office of Engineering and Technology. The public notice announced that the FCC’s Technological Advisory Council plans to conduct a noise-floor technical inquiry.

The TAC “is investigating changes and trends to the radio spectrum noise floor to determine if there is an increasing noise problem, and if so, the scope and quantitative evidence of such problem(s), and how a noise study should be performed,” the public notice said.  “The TAC is requesting input to help answer questions about the study of changes to the spectrum noise floor over the past 20 years. Noise in this context denotes unwanted radio frequency (RF) energy from man-made sources. Like many spectrum users, TAC members expect that the noise floor in the radio spectrum is rising as the number of devices in use that emit radio energy grows. However, in search for concrete evidence of increased noise floors, we have found limited available quantitative data to support this presumption. We are looking to find ways to add to the available data in order to answer important questions for the FCC regarding this topic.”

In its comments, CTIA said it “shares the TAC’s concern that the sky-rocketing number of man-made devices in the marketplace may have altered the noise floor, causing interference to licensed services. To that end, CTIA generally supports initiatives by the TAC to study the impact that the proliferation in device usage has had on the radio spectrum noise floor. New measurement data may help enhance the Commission’s ongoing efforts to detect and remove interfering devices, and thus may play a helpful role in the enforcement context.” CTIA urged “caution, however, that investigation of the noise floor should not lead to the erosion of licensees’ rights to fully utilize their spectrum, nor be leveraged to support the introduction of unlicensed or underlay experiments in the Commercial Mobile Radio Service (‘CMRS’) spectrum. The Commission’s well established exclusive, flexible use licensing policies have been essential in promoting investment and innovation in CMRS spectrum, cementing the United States’ leadership role in the global wireless industry. The TAC’s noise inquiry should not infringe upon this tested and successful framework.”

CTIA said that “the explosive growth in the number of man-made devices in the marketplace may have led to changes in the radio spectrum noise floor. Several different kinds of devices, including incidental radiators and unintentional radiators, may contribute to the noise floor by generating unwanted RF emissions. Incidental radiators, like electric motors, light dimmers, and power supplies, for example, are not designed to generate or emit RF energy, but do so as a result of their operation. Unintentional radiators, on the other hand, are designed to generate RF energy for internal use or send RF signals by conduction, but are not intended to emit RF energy. Examples of unintentional radiators include high efficiency lights, computers, and garage door receivers. Both incidental and unintentional radiators may emit unwanted RF energy. … Anecdotally, CTIA believes that the increase in device usage has caused interference to licensed, exclusive use spectrum.”

“As it undertakes this investigation, the TAC and the Commission should be mindful of the different considerations that govern resolution of interference issues that arise between licensees and those arising from incidental, accidental, and unlicensed radiators,” said Verizon Communications, Inc. “Because of the nature of our service and the impact of interference on the customer experience, we constantly are resolving issues related to noise and interference. As we have said elsewhere, ‘it is critical to our business that we’re able to negotiate and resolve quickly most, if not all, rights and interference issues without seeking intervention or assistance of the Federal Communications Commission.’ The FCC has given us the tools, in large part, to solve interference problems with other licensees through private negotiations, and we believe it is important that the FCC not adopt burdensome requirements that would undermine licensees’ rights to reach these private agreements with other authorized users and to otherwise resolve interference issues.

“On the other hand, the FCC should use its regulatory authority to manage radio interference to address the issues that the TAC raises about the rise in the noise floor as a result of incidental, unintentional, unlicensed, and Industrial, Scientific, and Medical (ISM) radiators,” Verizon added. “It could reassess and consider reducing permitted radiation levels of Part 15 and Part 18 devices; account for density and realistic deployment scenarios, such as with high-efficiency fluorescent lighting ballasts that are more likely to be installed by the thousands and yet are tested under Part 15 as single units; provide clarification and/or guidance, where appropriate, to manufacturers of incidental radiators to help prevent interference; and update its guidance on switched mode power supply (‘SMPS’) devices, which have changed considerably since the last FCC guidance. And it could step up its enforcement efforts by monitoring national retailers and taking steps to take non-FCC certified products off the market.”

“The last 20 years has brought an explosion in technological innovation that has led to the unprecedented availability of high-tech consumer products—computers of all shapes and sizes, electronic treadmills, global positioning system (‘GPS’), smartphones, electric cars, light-emitting diodes (‘LEDs’), Wi-Fi, and solar panels. The noise floor has increased correspondingly because the switching power supplies in all of these and other electrical devices can create noise,” AT&T, Inc., noted. “These noise sources are evident in wireless and wireline communications systems in both public and private spaces. Also, incidental radiators, such as FM station cabinets and data busses and interfaces in computing devices, continue to be troubling noise sources. Noise from each of these sources has the potential to substantially degrade licensed and unlicensed services, to the detriment of the service providers and their customers. Thus, AT&T supports the TAC noise study.”

AT&T added, “Though some noise can be easily mitigated through ‘good engineering practices,’ a lack of clear design and testing standards for some devices and a lack of regulatory clarity impede the understanding of those ‘practices’ and who needs to perform them. The result is often intransigence, delay, and inefficient processes to resolve a problem that could be easily and inexpensively resolved at the source during design. Industry efforts to develop better and more complete standards and Commission guidance would go a long way to resolving these issues. This TAC study would benefit the Commission in that endeavor and set the stage for a cleaner spectrum environment.”

The National Association of Broadcasters said the FCC should “address noise interference aggressively and expeditiously, consistent with the Commission’s duty to manage the use of RF spectrum. Failure to do so risks devaluing licensed spectrum and drowning licensed users in a sea of noise.” NAB said that “AM radio is particularly susceptible to interference from electronic devices of all types, including such ubiquitous items as video displays, electric motors, vehicle electrical systems, fluorescent lighting, computers, and power lines.” And it said FM radio “has also been the victim of noise interference.”

The FCC “should review the general Part 15 emission limits to determine what improvements are necessary to protect licensed services, and adopt strict and enforceable limits that will limit noise interference,” NAB argued. “We urge the FCC to undertake a comprehensive noise study that considers factors such as digital transmission and reception and receiver sensitivity.” The FCC also “should re-examine Section 15.13 of its rules,” NAB said. “Section 15.13 specifies that manufacturers of incidental radiators shall employ ‘good engineering practices to minimize the risk of harmful interference.’ However, the Commission provides no guidance as to what constitutes ‘good engineering practices.’”

“This noise study has been necessary for well more than two decades,” said the Society of Broadcast Engineers. “The Commission critically needs at least preliminary results from this study in order to make time-critical spectrum management decisions. Spectrum planning cannot objectively be done without this noise information and it is unfortunate that the initiative has been delayed this long. SBE and its members and chapters are able to be of use in gathering data for the noise study, premised upon the prerequisite need to develop a standardized and valid methodology for conducting the study.”

The group said it hopes that its “comments will serve as a catalyst for a re-evaluation of the policies of spectrum enforcement and sanctions against operators of incidental and unintentional radiators which are causing long-term interference problems, such as power lines. The unwillingness of the Commission to issue meaningful sanctions has led to the virtual absence of any incentive by power utilities to comply with the Commission’s Part 15 non-interference obligations.”

SBE also said it hopes “that the noise study will provide for the first time a useful, objective basis for spectrum overlays and other allocation decisions in the future. SBE further requests that the TAC focus its attention on a plan to reduce RF noise in at least the medium-wave band. There are other steps that will inevitably improve AM broadcasting, but SBE considers the issues to be addressed by the TAC to be the most urgent of these.”

“Changes in the noise floor have a much more significant impact on GPS and GNSS than on other services,” said the GPS Innovation Alliance. “Consequently, GPSIA supports the TAC effort to study and quantify the rise in the noise floor and looks forward to assisting the TAC in understanding the unique aspects of GNSS services and their relationship to the noise floor in the RNSS bands.”

“Based on available technical data, GPSIA believes that there is quantitative evidence of noise floor increases in key areas of the radio frequency spectrum,” the coalition added. “Technical studies conducted in 2004 and 2008 measured and quantified the noise level in the GPS L1 band in a variety of locations and environments. The 2004 study found that the GPS L1 band was then ‘relatively pristine’ compared to two other observed bands, at 2.0 GHz and 2.4GHz. The 2008 study, however, notes that the noise floor is increasing and concluded that ‘there is a serious risk that the aggregate signals from multiple devices may cause severe interference in safety-critical applications such as aviation.’ The 2008 study considered cell phone spurious emissions, man-made background noise, and ultra-wideband devices as contributors to increased noise floor levels.”

A noise floor study should “be conducted as a government activity, at government expense, and not delegated to private parties or quasi-governmental resources that may rely on private funds to conduct the study,” according to the alliance. “As a second point, GPSIA urges that any testing must account for that diversity and be cognizant of GNSS’ unique vulnerability. … Third, TAC should work to ensure that the measurement levels and bandwidths in any study are useful to GNSS systems.”

Deere & Company said it “offers its enthusiastic support for a fulsome examination of developments in the radio spectrum noise floor. Deere concurs with the expectations already stated by TAC members that the ‘noise floor in the radio spectrum is rising as the number of devices in use that emit radio energy grows,’ and that the ‘limited available quantitative data’ on this virtually certain trend must be addressed in order to ensure the future integrity and utility of an irreplaceable and finite resource — radio spectrum. Deere also emphasizes that harmful interference due to a rise in the noise floor represents a particular problem for sensitive receivers such as Global Navigation Satellite System (‘GNSS’) devices, which look for faint signals from power limited spacecraft thousands of miles removed in orbit. For GNSS devices, even a subtle rise in the radio spectrum noise floor in-band may create sufficient interference to degrade performance or render a device inoperable. Moreover, a rise in the noise floor creates in-band, co-channel interference, a problem that cannot be fixed by reengineering or otherwise modifying the victim receiver.”

The National Public Safety Telecommunications Council noted that it surveyed the public safety community about interference from energy-efficient lighting. “The overall results of the questionnaire indicate that while not yet large in number, energy-efficient lighting is a source of noise in the radio spectrum,” it said. “Given the growing deployment of energy-efficient lighting products for traffic control, commercial lighting and residential lighting, it is likely that contributions to the noise floor from these devices will grow as well. Therefore, NPSTC recommends this issue be examined further with the goal of preventing noise and interference rather than having to resolve it after the fact once energy-efficient lighting devices are deployed ubiquitously in the field. That process could include clarity on the applicable Commission rules, measurements on sample devices by the Commission laboratory or members of the TAC, educational efforts, and if needed, additional enforcement.”

“NPSTC also recommends the Commission and the TAC consider the potential increase in noise from out of band emissions as cell sites proliferate, use higher bandwidth channels and co-locate multiple systems on the same on structure where external intermodulation products can increase,” the filing added. “NPSTC also recommends the Commission and the TAC consider the need for additional study on potential RF noise from wind farm systems and solar system power inverters.”

The California Governor’s Office of Emergency Services said, “During the last 20 years, and even more so over the last 5 years we have encountered more and more interference from sources that were not causing interference prior to that time.  We have experienced interference to CHP low band radios at CHP Area Offices immediately after new energy efficient fluorescent light fixtures were installed.  Interference to the extent that previously received signals from distant base stations were no longer received.  In another instance, CHP officers conducting a traffic stop of a motorist in a residential neighborhood were unable to receive a low band signal and lost communications with their dispatch center. The interference source was identified as an owner installed DOSIS [sic] 3.0 cable modem at a nearby residence that was radiating the uplink signal on an unused Satellite TV antenna mounted on the side of the house but that was still connected to the house TV cabling. These are only a few of the recent incidents of interference from non-traditional sources of radio interference.

“As technology moves more and more towards wireless connected devices, and the Internet of Things (IoT) becomes prevalent, the potential interference sources, and the intermodulation products of all these signal sources mixing will become a real challenge to those trying to design, operate, and maintain communication systems,” the filing added. The office recommended that “[a] managed forum could be developed to identify types of equipment that cause interference.  As RF community members sample sites and coverage problem areas for sources of interference, they can note it and report it to the forum.  All observations will be vetted by the independent technical moderating team before any posts are made.  This shared information can be used by the greater community and when necessary, by the FCC for rule planning.”

Shure, Inc., a wireless microphone manufacturer, said, “Wireless microphone users have observed and been adversely affected by harmful interference resulting from various emitters that unintentionally elevate the radio spectrum noise floor above acceptable levels including, for example, LED lighting (energy-efficient lighting which causes electromagnetic interference resulting in static or harmful interference with wireless microphone operations); LED video walls (high brightness indoor displays often composed of tens or hundreds of individual panes, which have become popular in a number of settings, including large venues, often cause harmful interference to wireless microphones in close proximity); and industrial control systems and other technologies (e.g., unintentional radiators such as HVAC controls, alarm systems, remote monitoring equipment, security devices such as cameras and video monitors).”

“Although appropriate when written, certain rules governing the emissions of various incidental and intentional radiators may need to be reviewed and revised in view of the fact that very large numbers of these devices, individually tested and certified, are now being deployed en masse, resulting in high-density use,” Shure added. “In other cases, the problems may be due to a need for stepped-up enforcement of existing emissions standards. In some instances, in situ testing may be a more appropriate avenue for evaluating noise generated by devices operated concurrently in large clusters after installation.” Shure also discussed an effort to collect ambient noise levels where wireless mics are used.

The American Radio Relay League noted that discussions about the noise floor have cropped up at the FCC before, including in a 2002 report by the agency’s spectrum policy task force that recommended the adoption of “a new metric—the interference temperature—to quantify and manage interference” (TRDaily, Nov. 7, 2002).“In summary, it is surprising that, despite repeated expressions of strong agreement among spectrum management professionals and eminent technicians that RF noise studies are critical to any progressive spectrum management program, no such noise studies have been commenced,” ARRL said. “Instead, the Commission has since 1999 skipped the urgent step of evaluating the RF environment before repeatedly and constantly making allocation decisions. This, to ARRL, puts the cart squarely before the horse.

“In ARRL’s view, an RF noise study is a necessary prerequisite to any spectrum allocation decisionmaking going forward (especially in making any provision for unlicensed broadband services); and the study should include actual spectrum measurements of the RF noise/interference floor,” the filing added. “In order to obtain quantitative data regarding the noise floor in various environments and trends over time, the TAC should adopt a standard methodology for measuring the noise floor. Further, as was urged more than a decade ago, there should be created a public/private partnership for a long-term noise monitoring network and for the archiving of data, for use by the Commission, NTIA and the public, to facilitate next-generation spectrum management. The Amateur Radio Service provides a fertile ground for high-quality data gathering and measurements in all types of environments.”

“The explosive growth of both intentional and unintentional radiators over the past 20 years raises important questions regarding the radio noise floor and its effect on reliable and efficient wireless communications,” Pericle Communications Company and the Government Wireless Technology and Communications Association said in joint comments. “There are very few scientific surveys of radio noise relevant to this problem and our view is that the radio noise floor is not well understood, except in a few radio astronomy bands, and then only in the vicinity of the radio telescope. It is important to know whether the wireless industry is on the cusp of an exponential growth in radio noise that may severely handicap reliable and efficient use of the spectrum. If the U.S. can understand and quantify the rise in the noise floor, government and industry may be able to mitigate the problem before it gets out of hand. The proliferation of noisy LED lamps is a prime example of the potential for this problem to escalate quickly.”

The National Electrical Manufacturers Association said, “The question of whether the noise floor has been rising is still controversial. It seems rational to expect that the man-made noise has been increasing just by the fact that the consumer electronics industry has developed quickly over the last 20 years (Chandler et al., 2009). However, the digitalization of consumer electronics, the transformation of the TV broadcasting from analog to digital, and United S[t]ates Department of Energy minimum energy conservation standards imposing significantly lower power consumption limits on consumer electronic goods may have resulted in lower man-made noise levels for some products. This seems supported by the above noted findings from several researches indicating that consumer electrical environment noise has been reduced.” The NEMA said it “believes that a need exists to conduct a new study … because such a study is the best way to inform our combined understanding of the current noise floor levels and likely trends.”

Philips Lighting said, “We support and agree with the comments submitted by the National Electrical Manufacturers Association (NEMA). A new noise floor study seems to be a critical requirement to establish future spectrum policy that enables the full potential of the Internet of Things (IoT) and Machine to Machine (M2M) communications (NIST, 2016). New man-made noise issues need to be fully researched and understood; the National Research Council has issued a report expressing concerns with interference from new sources like the LTE wireless networks and automobile anti-collision radar with weather satellites and radio telescopes (Cohen et al., 2010).” —Paul Kirby,

Courtesy TRDaily