Wednesday, January 09, 2019

Spectro-Loki: The trickster in radio spectrum

In Techno-Loki, I argued that the Norse trickster god is a good metaphor for technology. I described how tech, like Loki and his exploits, has to be coerced into doing the right thing; follows impulse, skipping from one thing to the next; produces effects both good and bad, which are sometimes hard to distinguish; and is a shapeshifter. The examples in the previous post were a grab-bag of technologies; here are some from my current specialization, radio and spectrum.

Coercion and sanction

Radio innovations constantly bubble up, with both good and bad side effects. The state often has to lean on the techies (by which I mean both entrepreneurs and inventors) to fix the problems they cause.

Since radio signals leak out of their allocated frequency bands, and real-world receivers admit signals from neighboring bands, externalities (e.g., costs imposed on a party who did not choose to incur it) are a perennial problem. Spectrum operating rights are seldom well enough defined, or the number of parties small enough, for externalities to be resolved in the marketplace. (The frequent deals between cellular companies are the exception.) Regulations have to impose limits on out-of-band emissions, and setting them is a never-ending tussle between interest groups. Requirements on receivers are fervently resisted, and (at least in the US) have never really been used; the regulator is too weak to adopt even requirements that give a lot of flexibility like harm claim thresholds (my pet idea).

Innovators live by Hopper’s Rule: it’s easier to ask for forgiveness than permission. For example, Swarm Technologies had to pay the FCC $900,00 for launching satellites after the agency had dismissed Swarm’s application for an experimental authorization (SpaceNews). The FCC said Swarm’s satellites, only a quarter the size of a standard single-unit cubesat, were too small to be reliably tracked once in orbit; this posed a risk of collision, and a catastrophic cascade of orbital debris.

The FCC’s action against Swarm probable set a good example. When sanctions are ineffective, however, problems persist and get worse. For example, it is illegal to use, sell or market jammers in the United States (FCC FAQ). However, there is no effective bar on import and sale of GPS or cellular jammers; searching for jammers brings up any number of online vendors. It’s hard to see this getting better before it gets worse. Major enforcement actions are few and far between. The FCC’s Enforcement Bureau is notoriously underfunded; for example, it closed nearly a dozen field offices in 2016-17.


Crafty, creative people follow their noses. Just as with Loki, though, each technology solution leads to new problems, and thus to new solutions. For example, the invention of radio was a boon, but led to interference. This necessitated licenses, which had to be assigned somehow. When first-come-first-served no longer worked, we got beauty contests: petitioners had to persuade the FCC that they were the most worthy. The process was patently arbitrary, which prompted license lotteries – which generated windfalls and bankruptcies. That was solved with license auctions (cellular!), and unlicensed bands (Wi-Fi!). Both have brought great benefit, but have downsides too: auctions lead to market concentration and don’t deliver the universal coverage politicians want; and unlicensed has an indeterminate number of stakeholders by construction, all with equal rights, so that it becomes very hard to negotiate change when novel situations arise.

Good and evil

Like all technologies, wireless can be used for good or ill. For example, as the 2016 FCC TAC white paper on next-generation radio interference resolution pointed out, the exponential growth in demand for radio services has been addressed through a variety of new techniques, including squeezing services closer together, dynamic resource sharing, wider bandwidths, sophisticated modulation and signal compression techniques, and the use of software-programmable radios.

This innovation was facilitated by precipitous drops in processing cost, which not only increases the yield of radio operation, but also makes it more vulnerable to both intentional and unintentional interference. An increasingly dynamic shared spectrum environment also requires proportionately faster interference resolution – traditional methods aren’t up to the task. Conversely, while there is a raft of urgent new interference resolution challenges, many of the same technological developments that created them have also led to dramatically improved capabilities for detecting, classifying/identifying, locating, and reporting interference.

Many if not all radio systems are vulnerable to jamming and spoofing. Exploits include unlocking almost any recent vehicle using cheap, off-the-shelf software defined radios (, and using a $225 GPS spoofer to send satnav-guided vehicles into oncoming traffic (ArsTechnica).

Cellular systems, even the most up-to-date ones, are also vulnerable. Increasingly affordable cell-site simulators (aka IMSI catchers, also known by the Harris Corp product name StingRay) can trick cellphones into connecting with them without their owners’ knowledge. They have been used by law enforcement for years, but anyone with suitable expertise can build and deploy them (NYTimes). In April 2018, the U.S. government publicly acknowledged the existence in Washington, DC of what appear to be rogue devices that could be tracking individual cellphones, and intercepting calls and messages (AP). One doesn’t even need to be an engineer to pinpoint a phone within a few hundred meters; $300 paid to the right fixer will do the trick (Motherboard).

Appearance ≠ Reality

In the age-old shapeshifter tradition, things are often not what they seem in spectrum. The most striking current example is 5G. It was originally sold on the benefits of moving to millimeter-wave (frequencies above 30 GHz or so), but it now turns out that most of the deployment is going to be in microwave (below 3 GHz or so). Politicians around the world were persuaded that giving cellular companies that goodies they asked for – including, in the U.S., huge bandwidth allocations, and exemptions from state and local rules on smallcell deployment – was a matter of national competitiveness, and even national security. I believe it’s really about manufacturers selling a new generation of equipment, and operators locking in cheap spectrum licenses on the off-chance they’ll need them in future.

Bait and switch is a time-honored trick in the spectrum business: obtain a mostly worthless license, and then get the regulator to provide a waiver to the license rules that enable a lucrative new business. The founders of Fleetcall (later Nextel) bought a raft of  800 MHz Land Mobile Radio (LMR) licenses at a substantial discount compared to the cost of equivalent (cellular) bandwidth available via auction (Everipedia). Using Motorola’s iDEN technology, and a rule waiver from the FCC that allowed iDEN to be used for cellular and not just “high tower/high power” LMR deployments, Fleetcall made a made Morgan O’Brien the poster boy for subsequent spectrum entrepreneurs. LightSquared tried (and has so far failed) to pull off a similar trick: convert cheap satellite licenses into valuable terrestrial cellular licenses by obtaining an FCC waiver.

In an example of the good-and-bad phenomenon, Nextel’s base stations caused interference with conventional LMR systems in the band, notably with public safely (Everipedia). One of the reasons was that Nextel licenses were interleaved with everyone else’s, and this doesn’t work for coexisting cellular and LMR systems. To resolve the problems, the FCC allowed Nextel to relocate to a contiguous, non-interleaved part of the 800 MHz band in return for bearing everyone’s cost of “refarming” the band – at much lower cost than they would’ve paid for this spectrum at auction. Loki triumphed again.

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