Open spectrum
Movement for shared, unlicensed radio-frequency spectrum for all.
Open spectrum, sometimes called free spectrum, is a push to persuade the Federal Communications Commission to make more radio-frequency bands available without requiring a license, so anyone can use them. Supporters of this "commons model" want a future where all spectrum is shared. In that vision, people would communicate using Internet protocols, and smart devices would automatically pick the best power level, frequency, and method for transmission. The current government rules that decide who gets to operate a station would be eliminated, giving everyone an equal chance to run their own radio or TV station, or even broadcast a website. A well-known backer of this idea is Lawrence Lessig.
Right now, national governments—sometimes following guidelines from the International Telecommunication Union—set aside certain spectrum bands for anyone to use, as long as they follow technical limits, especially a cap on total transmission power. Unlicensed spectrum works in a decentralized way: there are no license fees and no central authority controlling users. But to keep unlicensed devices from interfering with each other, techniques like power limits, duty cycles, and dynamic frequency selection are required.
Traditional gadgets that use unlicensed spectrum include cordless phones and baby monitors. Newer technologies taking advantage of it include Wi-Fi, Ultra Wideband, spread spectrum, software-defined radio, cognitive radio, and mesh networks.
Radio astronomy has a stake in this issue. Astronomers rely on radio telescopes to study objects like pulsars in our galaxy and distant radio galaxies up to about half the observable universe’s distance. When radio frequencies are used for communication, it creates pollution from an astronomer’s viewpoint—at best adding noise, at worst completely blinding certain observations of very faint objects. As more frequencies get used for communication, astronomical observations become harder.
Efforts to protect the parts of the spectrum most valuable for observing the universe are mostly led by the international astronomy community, working as a grassroots effort coordinated by the Scientific Committee on Frequency Allocations for Radio Astronomy and Space Science.
- Notable advocate
- Lawrence Lessig
Lore & Background
Open spectrum advocates argue for a shift away from licensed, centrally controlled spectrum allocation toward a decentralized commons model. In this model, anyone can use the airwaves for their own radio station, television station, or even broadcast a website, without license payments or central control. However, unlicensed spectrum requires technical mitigation techniques—such as power limitation, duty cycle, and dynamic frequency selection—to prevent interference between devices.
Traditional users of unlicensed spectrum include cordless telephones and baby monitors. Newer technologies taking advantage of this spectrum include Wi-Fi, Ultra Wideband, spread spectrum, software-defined radio, cognitive radio, and mesh networks. National governments currently allocate bands of spectrum, sometimes based on guidelines from the ITU, for unlicensed use as long as users respect technical limits, most notably a cap on total transmission power.
Reader's Guide
The open spectrum movement is significant because it challenges the traditional model of spectrum licensing, proposing instead a decentralized, shared approach that could democratize access to the airwaves. By advocating for more unlicensed spectrum, proponents aim to enable widespread innovation and communication without the barriers of license fees or central control. This approach has already facilitated the growth of technologies like Wi-Fi and mesh networks, which rely on unlicensed bands. However, the expansion of unlicensed spectrum also raises concerns about interference, particularly for radio astronomy. As more frequencies are used for communication, astronomical observations become more difficult, with radio pollution creating noise or even blinding observations of faint objects like pulsars and distant radio galaxies. The international astronomical community, coordinated through the Scientific Committee on Frequency Allocations for Radio Astronomy and Space Science, works to defend the parts of the spectrum most useful for observing the universe. The legacy of open spectrum lies in its potential to reshape how spectrum is governed, balancing innovation and access with the protection of scientific uses.
Did You Know?
- Open spectrum is also known as free spectrum.
- A notable advocate for open spectrum is Lawrence Lessig.
- Unlicensed spectrum users must respect technical limits, including a cap on total transmission power.
- Radio astronomy observations are increasingly difficult due to communication use of radio frequencies.
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