Saturday, February 24, 2018

Is harmful radio interference going down?

Spectrum analysts (including me) often proclaim that harmful interference is a growing problem, or at the very least a growing risk. That sounds plausible, given the growing profusion of radios, packed more and more densely together. But what if the opposite is true?

Data on interference trends are hard to come by. Anecdotes abound, and published information usually covers just narrow slivers of time, space and frequency. The FCC doesn’t publish comprehensive data on interference incidents, in spite of repeated calls to do so. (It does publish a non-comprehensive list of Amateur Radio Service enforcement actions, but at the time of writing it covers only 2009–2016. FWIW, the number of RFI incidents reported by amateurs is flat over this period.) When the FCC’s panel of technical advisors (the TAC) launched a formal inquiry in 2016 to find out whether there was an increase in background radio noise, many commenters pointed at data, but nobody offered a thorough analysis. The TAC didn’t come to any firm conclusions about whether radio noise was increasing or not.

The perception of increasing harmful interference is skewed by cognitive biases. There is certainly selection bias: for example, the people who file comments about a rise in radio noise are predominantly the ones that believe there’s a rise in radio noise. Since we tend to over-estimate the likelihood of events which are recent, unusual or emotionally charged, availability bias also plays a role: striking stories about exceptional interference sway our judgment. And last but not least, there’s confirmation bias: once we’ve taken a position – that harmful interference is getting worse, for example – we’re likely to search out, focus on, remember and interpret data in a way that confirms our preconceptions.

The obvious null hypothesis is that the incidence of harmful interference isn’t changing in either direction. However, experience with other technologies suggests that the most plausible hypothesis is that it’s probably declining  – in spite of lamentations to the contrary.

For example, consider car accidents in the United States (Wikipedia). The US population more than doubled from 127 million in 1935 to 321 million in 2015, and the number of vehicle miles traveled (VMT) increased more than tenfold from 229 billion to 3,095 billion per year. However, the total number of road deaths stayed flat (34,494 in 1935 and 35,485 in 2015), and the number of fatalities per mile driven decreased tenfold from 15.09 to 1.15 per 100 million VMT.

I’m no expert, but I imagine improved vehicle safety, i.e. technology like crumple zones and anti-lock brakes, played a major role in reducing fatal collisions – that is, in reducing “harmful interference” between vehicles.

Wireless technology has also improved dramatically over the last few decades, and those improvements have made radios less vulnerable to interference. Examples include transmitters leaking less interference outside their transmit bands, receivers becoming more resistant to interference outside their receive bands, and more directional antennas that only accepts signal from desired direction. Hence, it’s reasonable to expect that there is less harmful interference today than there was in the past.

Regulation – such as requiring seat belts, and better enforcement of drunk-driving laws – presumably played a role in reducing automobile fatalities. By comparison, few new regulatory mandates to improve the interference-resistance of radios have been added. Limits on transmitter leakage have hardly changed, and there are effectively no requirements on receiver performance. I don’t believe government-mandated receiver standards are the solution, but rules that clarify expectations about the interference environment, like harm claim thresholds, would help. An automotive comparison would be CAFE (Corporate Average Fuel Economy) standards: the government sets targets for average fleet fuel economy, without telling manufacturers how to meet them.


Here are the regulatory definitions of interference given in the FCC rules, 47 CFR 2.1, which echo the ITU Radio Regulations (RR) and the annex to the ITU Constitution (CS):
Interference. The effect of unwanted energy due to one or a combination of emissions, radiations, or inductions upon reception in a radiocommunication system, manifested by any performance degradation, misinterpretation, or loss of information which could be extracted in the absence of such unwanted energy. (RR)
Harmful Interference. Interference which endangers the functioning of a radionavigation service or of other safety services or seriously degrades, obstructs, or repeatedly interrupts a radiocommunication service operating in accordance with [the ITU] Radio Regulations. (CS)

One can multiply examples of other technologies where rates of harm have declined even as usage has increased. Take aircraft safety, as reported in The Economist:

For air pollution, this image from a recent statistical release by by UK Department for Environment, Food & Rural Affairs is instructive:

Thursday, February 22, 2018

Constellation satellite broadband: the first shoe drops

I’ve never been convinced about the business model for satellite constellation broadband. However much smarter (and much, much richer) people than me have invested billions in these businesses.

SpaceX’s behavior will be a useful leading indicator for this sector, since I think Elon Musk sees broadband as a cash cow to fund his Mars mission. If SpaceX deployment lags or slows, it’ll be a good sign that NGSO broadband isn’t a good business.

A story in today’s WSJ is an early sign of bad news: “SpaceX Throttles Back Broadband Hopes --- Fast global internet likely to take longer than anticipated”. Some highlights:

“Acknowledging there are no final cost estimates or engineering designs yet for its proposed broadband constellation, spokesman John Taylor revealed substantial delays from initial project timelines. [The] company signaled that development of its high-profile satellite network has been significantly slower -- and seemingly more complex -- than many inside and outside SpaceX originally anticipated.”

“SpaceX said in Tuesday night's statement, "we still have considerable technical work ahead of us to design and deploy" some 4,400 similar satellites. The tentative goal of starting limited service by 2020 now appears unrealistic based on that language, but the company didn't provide an alternate schedule.”

“SpaceX engineers are still considering the most appropriate and cost-effective space and ground technologies to embrace, without firming up subcontractors or completing production plans.”

“… technical and financial details of anticipated ground equipment for subscribers -- considered critical elements in any such project -- are still undetermined.”

Sunday, May 21, 2017

Permissionless Innovation, the Precautionary Principle, and Gardening

Adam Thierer’s insights about “soft law” being the middle ground between permissionless innovation and the precautionary principle reminded me of Michael Pollan’s portrayal of gardening as mediating between the wilderness ethic and humans micromanaging nature.

Tuesday, May 02, 2017

Note on receivers in the EU Radio Equipment Directive and ETSI standards

The European Union has focused new attention on radio receiver standards through terms in the Radio Equipment Directive (RED) which came into force last year. The RED’s requirements that any “receiver [must have] a level of performance that allows it to operate as intended and protects it against the risk of harmful interference, in particular from shared or adjacent channels” have been reflected in new ETSI standards.

Friday, April 14, 2017

Traditional ethics and standards of scholarship

The astrophysicist Simon White concluded his introduction (pdf) to the 2016 Ringberg workshop on galaxy formation by asking how one developed consensus about what is well established. (Thanks to Petri Mähönen for bringing it to my attention.)

White’s answer: “Re-emphasise traditional ethics and standards of scholarship.”

Thursday, March 09, 2017

Templates and narratives for change

At the end of a conversation with David Runciman about powerful women on the Talking Politics podcast (reposted on the LRB podcast; their chat starts around 18:00), Mary Beard had this to say:
The idea that women have a model for doing [changing the structures within which women can think of themselves as ambitious, as powerful, as clever, as articulate, and able to make that kind of difference in the world] -- and I don't mean a kind of role model, but I just mean a kind of cultural template for doing that -- until we can provide a narrative and a template, then I think we've got a problem.
This resonates with what I try (and fail) to do in policy innovation. It's not sufficient to have a new idea (= template). You also need to have a story (= narrative) that explains why anyone should care, and why it makes sense.

Friday, February 10, 2017

Spectrum is not a scarce natural resource

Almost every policy or technology story about radios starts with the litany that Spectrum is a Scarce Natural Resource. I will argue that this claim is false, and that it matters.

In short:
  • Spectrum is no more a scarce natural resource than sound.
  • It is more accurate and productive to talk about radio operation.
  • Rather than saying “spectrum is scarce”, it’s better to say “radio coexistence is hard.”
The pay-off is that this alternative language makes us focus on what matters – the best way to arrange the operation of radios – rather than on ways to manage a resource (spectrum) that may or may exist.

Sunday, January 08, 2017

Sunday, September 25, 2016

Thursday, July 28, 2016

Fitting square pegs into bicycles

To this non-lawyer, jurisprudence often seems to be metaphor mongering/mangling/wrangling -- as in Judge Easterbrook's contention that that there was no more a “law of cyberspace” than there was a “Law of the Horse" ("Cyberspace and the Law of the Horse" (1996); see also Larry Lessig's "The Law of the Horse: What Cyberlaw Might Teach").

From a recent CS Monitor comes the latest in this inexhaustible genre: "Is bitcoin money? Are Airbnbs hotels? Why courts have trouble deciding."

Friday, April 15, 2016

Hypnosis, placebo and meditation

In its recent package on The Power of Mind (issue no 3064, 12 March 2016), New Scientist includes an interview with Laurence Sugarman at Rochester, who uses hypnosis in clinical settings -- and believes that mindfulness meditation is an example of hypnosis.

Monday, August 31, 2015

FCC approves robotic lawn mower, rejects worst case analysis

On August 12, 2015 the FCC granted a waiver (pdf) of some Part 15 rules to allow iRobot to market a robotic lawn mower transmitting in the 6240-6740 MHz range (Order in Proceeding 15-30). The National Radio Astronomy Observatory (NRAO) had expressed concern that the waiver could lead to interference to radio astronomy operations.

Worst case in interference analysis for medical interference

In its second order on reconsideration regarding the incentive auction released on June 19, 2015 (docket 12-268, pdf) the FCC noted that its analysis interference into wireless medical telemetry systems its work "is a worst case analysis and in most installations one or more of the parameters we assumed here will provide additional protection" (recon order at para 119).

Friday, July 31, 2015

Q&A: Risk-assessment, harm claim thresholds and adjudication

In my testimony before the Senate Commerce Committee on Wednesday July 29, 2015 I recommended three spectrum management reforms. A summary and links to the written testimony and video are in an earlier blog post. This post offers some Q&A.

The three reforms were: (1) moving away from worst case interference analysis and using risk-informed methods that consider not only the consequences but also the likelihood of harmful interference; (2) providing more clarity about operators’ interference rights and obligations by specifying harm claim thresholds; and (3) giving any spectrum user the option of taking action directly against any other, either in front of an FCC judge or in a federal Court of Spectrum Claims.

Wednesday, July 29, 2015

Senate Testimony: Risk-assessment, harm claim thresholds and adjudication

I testified today before the Senate Commerce Committee hearing on “Wireless Broadband and the Future of Spectrum Policy.” My written testimony is here; this is the summary I presented during the hearing. I’ve posted some Q&A in a subsequent post. My remarks are recorded in the archived webcast, starting at 58:02; see also a question from Chairman Thune and my reply starting at 2:05:43.