What Is C-Band, and What Does It Mean for the Future of 5G?

What's New Now / 5G

- By Sascha Segan

A half-dozen companies are potentially ready to spend $80 billion for C-Band, a new set of airwaves that promise to fix the perilous state of American 5G, at an FCC auction. That’s a vast amount of money, and it shows how important C-Band is. But what is C-Band, and what does it mean for 5G? Do you need a C-Band phone? Is C-Band a new frequency? Should you be scared of C-Band? I can explain.

RECOVERING THE SATELLITES

According to wireless testing firm Rohde and Schwarz, the C-band is all frequencies between 4GHz and 8GHz. When US wireless geeks talk about C-Band, though, they’re talking about 3.7GHz to 4.2GHz—and specifically, in this case, the range from 3.7GHz to 3.98GHz.

This frequency had been used for satellite TV since the 1970s, but as C-Band satellite reception requires “big, ugly dishes” up to 10 feet in diameter, it was largely replaced by more flexible systems with smaller dishes on the Ku band, such as Dish and DirecTV. C-Band is currently used for the “satellite downlink” for broadcast television distribution.

With more advanced methods of digital encoding than they had in the 1970s, the satellite companies can now “repack” their broadcasts into the upper portion of the C-Band, leaving the lower portion available for cellular companies to use.

The C-Band sits between the two Wi-Fi bands, which are at 2.4GHz and 5GHz. It’s slightly above and very similar to the 2.6GHz band that Clearwire and then Sprint used for 4G starting in 2007, and which T-Mobile currently uses for midband 5G. And it sits immediately above CBRS, a band from 3.55GHz to 3.7GHz that’s currently being deployed for 4G. So its transmission characteristics are very well known, and its safety is well established.