FCC wants to open 1,200 MHz of spectrum to unlicensed users, and that’s a lot

25 October 2018 by Steve Blum
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The Federal Communications Commission is considering a radical overhaul of the way licensed spectrum is managed, and shared with unlicensed users. Besides upping the stakes for wireless Internet service providers this week, the FCC began considering a plan to open up a massive 1,200 MHz slice of spectrum in the 6 GHz range to WiFi, Internet of things (IoT) and other new and unlicensed uses.

It’s a lot of bandwidth. The 2.4 GHz band originally used for WiFi is only 83 MHz wide, and the newer 5 GHz band is 150 MHz.

Two methods are proposed. In 850 MHz of sub-bands assigned to “fixed” uses, where transmitters and receivers stay in one place – links between TV studios and transmitters, for example – unlicensed users would be able to transmit at standard power levels, so long as they avoid interfering with license holders, via a hardware-based coordination system yet to be established. There are a lot of details to be worked out, but the idea is that unlicensed equipment would be automatically prevented from interfering with a nearby, licensed user.

A similar system is in place for coordinating fringe frequencies – aka white space – assigned to TV stations, and another is specced for managing wireless broadband service in the 3.5 GHz band, but neither involve the huge swath of spectrum in the 6 MHz plan.

Other sub-bands – a total of 350 MHz – are assigned to transmitters that move around, such as TV news trucks. Coordination would be too complicated. Unlicensed users in those ranges would be restricted to low power, indoor equipment – WiFi or Bluetooth for example – that couldn’t, or shouldn’t, cause interference.

The FCC and its predecessor, the Federal Radio Commission, have been setting aside bands for particular purposes, and giving exclusive licenses for specific frequencies in those bands to individual users for 90 years. It made sense in the analog era. But the widespread adoption of digital transmission technology changed the game. The same bandwidth that was needed to broadcast one low definition, analog television channel can support many high definition, digital ones.

And television is just one example. Existing users in the 6 MHz band include utilities, railroads and telecoms companies. With digital technology, they don’t need anywhere near the amount of spectrum they now control. At least not to do the same things they were doing in the analog days. Arguably, they can do more now, and often need to, but technology has come a long way: spectrum sharing is technically feasible. The FCC has to figure out the best way to implement it, so no great harm is done, but it is doing the right thing.