Author
Andrew Beck
Categories
Venue & Campus NetworksThe Citizens Broadband Radio Service (CBRS) operates in the 3550-3700 MHz radio band. When the Federal Communications Commission (FCC) allocated this band for use, it created three tiers of access for users: Incumbents, Priority Access Licenses (PALs) and General Authorized Access (GAA). PALs are awarded by the FCC based through competitive bidding, while GAA permits open, flexible access to the band for the widest possible group of potential users such as enterprises and other organizations. GAA users can use any portion of the CBRS band not assigned to another tier user and may also operate opportunistically on unused Priority Access channels.
When the CBRS PAL licenses were issued and deployments began back in April, many GAA users assumed they immediately had 70 MHz less spectrum available to them because the PAL winners in each county now consumed seven of the 10 MHz channels; however, that's not the case.
FCC rules (47 C.F.R. §96.25) require the CBRS Spectrum Access System (SAS) to protect PAL users only in the regions where they deploy and only when they deploy. A PAL license encompasses an entire county, but only the coverage of the actual CBRS devices deployed in a county by the PAL users are protected by the SAS from GAA interference. While PAL users have started their deployments, these are moving slowly. And the good news is that all of the unused PAL spectrum is available for GAA use.
More Spectrum available for GAA users
In addition, the higher tier incumbents are using less CBRS spectrum. When CBRS went commercial in January 2020, there were almost 7,300 small regions across the country declared as Grandfathered Wireless Protection Zones (GWPZs). GPWZs are protected by the SAS from interference in the upper 50 MHz of the CBRS band (3650-3700 MHz). Gradually, as many of these Part 90 Grandfathered Wireless Broadband Licenses (GWBLs) have expired, users have transitioned to CBRS or to another band. The expired GWPZ regions are now available for full GAA use. Today there are under 700 GWPZ regions protected, a tenfold decrease from where we started. All remaining licenses will expire by January of 2023.
A similar trend is occurring with the Fixed Satellite Site (FSS) incumbent CBRS users. With the C-Band auction complete, many of the FSS sites will either move out of the band or discontinue operation. Thus, they will move out of the CBRS band and free up additional spectrum in the upper 100 MHz of the band (3600-3700 MHz). Today there are about 300 FSS earth stations protected from CBRS interference, but by the end of the year, over 250 of these are expected to relocate to another band.
The CBRS rules created 150 km exclusion zones around FSS earth stations under special circumstances. By rule, if there exists a Part 90 GWBL within 150 km of an FSS site, then CBRS operation in the upper 50 MHz of the band (3650-3700 MHz) is prohibited within that 150 km radius. However, the expiration of Part 90 GWBLs and the FSS relocations also means that the exclusion zones around some FSS sites will go away. When the GWBL or FSS site is no longer applicable, that 50 MHz in the 150 km region will be available for GAA use.
In short, this all means that more spectrum is becoming available in CBRS for GAA users, just in time to offset PAL users’ deployments.
