Citizens Broadband Radio Service

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Citizens Broadband Radio Service (CBRS)[1] is a 150 MHz wide broadcast band of the 3.5 GHz band (3550 MHz to 3700 MHz). Some of this spectrum will continue to be used by the United States government for radar systems,[2] but will be available for others where not needed by the Navy. In 2017, the Federal Communications Commission (FCC) completed a process begun in 2012 to establish rules for commercial use of this band. Wireless carriers using CBRS might be able to deploy 5G mobile networks without having to acquire spectrum licenses.[1]


The creation of a new publicly available transmission band in the 3.5 GHz band was identified as a possibility by the National Telecommunications and Information Administration (NTIA) for shared federal and non-federal use in its 2010 Fast Track Report.[3][4] This band was identified as the Citizens Broadband Radio Service in a Notice of Proposed Rulemaking released by the FCC in December 2012, which the FCC found would "promote two major advances that enable more efficient use of radio spectrum: small cells and spectrum sharing".[5] The record was thereafter supplemented by a Commission-level public notice and two workshops to discuss technical issues related to the proposed Service. In April 2014, the Commission released a Further Notice of Proposed Rulemaking that included detailed proposed rules to govern the new service.[6]

In 2016, six companies interested in promoting CBRS technology and driving adoption formed the CBRS Alliance.[7] As of mid-2017, the CBRS Alliance listed over 60 members,[8] including Alphabet[8] AT&T,[1] Druid Software, Charter Communications,[1] Cisco Systems,[4] Comcast,[1] the CTIA,[8] Ericsson,[4] Federated Wireless,[8] Intel,[4] Nokia,[4] Qualcomm,[4] Ruckus Wireless,[4] SpiderCloud Wireless,[7] Motorola Solutions, Sprint Corporation, and Verizon Wireless. Beginning in 2017, a number of CBRS trial projects were initiated in various cities. In February 2017, Nokia, Alphabet and Qualcomm tested LTE technology in a CBRS-band broadcast of "live high-definition video of cars racing on a track in Las Vegas".[1] In April, Kansas City, Missouri "approved a Google test of 3.5GHz shared wireless in more than eight locations in that area for up to 18 months".[9] In May, Google received permission from the FCC to test wireless technology within the CBRS band at four NASCAR race events held during the summer of 2017, in Bristol, Tennessee, Brooklyn, Michigan, Darlington, South Carolina, and Richmond, Virginia.[10] By August 2017, Verizon Communications had formed a consortium "to carry out the first use of CBRS (Citizens Broadband Radio Service) band 48 spectrum in a 4G LTE Advanced (LTE-A) carrier aggregation demonstration".[2] In November 2017, the CBRS Alliance entered into an agreement with the Wireless Internet Service Providers Association (WISPA) "to cooperate closely in the advancement of the Citizens Broadband Radio Service (CBRS) spectrum band".[11] In March 2019, Motorola Solutions launched MOTOTRBO® Nitro™, the first fully managed CBRS platform and product offerings. MOTOTRBO® Nitro™ is a line of business-critical, CBRS communications and data products, including the SLX2000(CBSD), SLX4000(CBSD) and SLN1000, the first purpose-built OnGo portable radio. Deployment of MOTOTRBO® Nitro™ infrastructure allows for services such as Nitro Cloud management, and is inter-operable with existing MOTOTRBO® networks.[12]


The Citizens Broadband Radio Service is governed by a three-tiered spectrum authorization framework to accommodate a variety of commercial uses on a shared basis with incumbent federal and non-federal users of the band. Access and operations will be managed by a dynamic spectrum access system, conceptually similar to the databases used to manage Television White Spaces devices. The three tiers are: Incumbent Access, Priority Access, and General Authorized Access.[6]

  • Incumbent Access users include authorized federal and grandfathered Fixed Satellite Service users currently operating in the 3.5 GHz Band.[6] Under the rules promulgated by the FCC, these users, particularly including U.S. Navy radar operators,[7] will be protected from harmful interference from Priority Access and General Authorized Access users.[6] Existing 3650–3700 MHz band operations "are grandfathered for up to 5 years", with the Wireless Telecommunication Bureau and Office of Engineering and Technology charged with soliciting public comment on "the appropriate methodology for defining the grandfathered wireless protection zone contours".[13]
  • The Priority Access tier consists of Priority Access Licenses (PALs) that will be assigned using competitive bidding within the 3550-3650 MHz portion of the band. Each PAL is defined as a non-renewable authorization to use a 10 megahertz channel in a single census tract for three-years. Up to seven total PALs may be assigned in any given census tract with up to four PALs going to any single applicant. Applicants may acquire up to two-consecutive PAL terms in any given license area during the first auction.[6][7]
  • The General Authorized Access tier is licensed-by-rule to permit open, flexible access to the band for the widest possible group of potential users. General Authorized Access users are permitted to use any portion of the 3550-3700 MHz band not assigned to a higher tier user and may also operate opportunistically on unused Priority Access channels.[6][7]

Use of the CBRS band will not require spectrum licenses, and is expected to reduce the cost of data transmissions.[10] This will enable carriers "to deploy 5G faster and easier, using the shared airwaves instead of trying to acquire spectrum licenses at auction or through deals".[1] Since these frequencies have historically been used for government purposes, users of the CBRS band will be required to "take care not to interfere with others already using nearby airwave bands in some locations, including military radar stations and satellite receiver stations".[10] As with Wi-Fi, CBRS equipment will be deployed to individual building owners, and those owners (or end users occupying the property) would pay a fee for spectrum allocation through a server.[7]

Expected impact[edit]

Bloomberg Technology has described CBRS as potentially being "[m]ore reliable than Wi-Fi" and "technology that risks making Wi-Fi outmoded", and quotes CBRS Alliance president Michael Peeters characterizing CBRS as possibly "a better option for factories, airports and ports".[1] Network World has noted that it is "quite likely that the band will be used for 5G, and that might synch nicely with services offered in other countries that are actually targeting the band for 5G services".[4] It is further proposed that such a 5G network "promises to let consumers download a high-definition movie in less than a second".[1]


In January 2019 the Global Mobile Suppliers Association reported that there were 11 companies investing in CBRS trials in the USA, including AT&T Mobility, Boingo Wireless, Charter Communications, Comcast Corporation, Google, Midcontinent Communications, T-Mobile US, US Cellular, Verizon Wireless and Windstream.[14]

Mobile Country Code 315 and Mobile Network Code 010 have been assigned for IMSIs in CBRS systems in the USA.[15] The LTE frequency band for CBRS in the USA is referred to as band 48 in the 3GPP standards.


  1. ^ a b c d e f g h i Kharif, Olga (March 9, 2017). "A World Without Wi-Fi Looks Possible as Unlimited Plans Rise". Bloomberg Technology.
  2. ^ a b "Verizon-Led Team to Test Carrier Aggregation Over CBRS Band". Nasdaq. August 29, 2017.
  3. ^ "An Assessment of the Near-Term Viability of Accommodating Wireless Broadband Systems in the 1675-1710 MHz, 1755-1780 MHz, 3500-3650 MHz, 4200-4220 MHz, and 4380-4400 MHz Bands" (PDF). National Telecommunications and Information Administration. October 2010.
  4. ^ a b c d e f g h Brown, Bob (March 14, 2017). "FAQ: What in the wireless world is CBRS?". Network World.
  5. ^ "Notice of Proposed Rulemaking and Order: In the Matter of Amendment of the Commission's Rules with Regard to Commercial Operations in the 3550-3650 MHz Band" (PDF). Federal Communications Commission. December 12, 2012.
  6. ^ a b c d e f "3.5 GHz Band / Citizens Broadband Radio Service". Federal Communications Commission. Retrieved August 30, 2017.
  7. ^ a b c d e f Chambers, David (November 10, 2016). "What is CBRS Shared Spectrum for in-building small cell wireless?". ThinkSmallCell.
  8. ^ a b c d "CBRS Alliance Members". CBRS Alliance. Retrieved September 9, 2017.
  9. ^ Hamblen, Matt (May 26, 2016). "Multiple U.S. trials underway for shared 3.5GHz wireless spectrum". CIO.
  10. ^ a b c Pressman, Aaron (May 31, 2017). "Google's Secret Wireless Plan to Test at Nascar Races". Fortune.
  11. ^ Alleven, Monica (November 16, 2017). "CBRS Alliance, WISPA team up to advance 3.5 GHz ecosystem". FierceWireless.
  12. ^ "MOTOTRBO Nitro - Motorola Solutions". Retrieved 2019-03-19.
  13. ^ "3650-3700 MHz Radio Service". Federal Communications Commission. April 27, 2017.
  14. ^ GSA: LTE in Unlicensed and Shared Spectrum: Trials, Deployments and Devices (January 2019)
  15. ^ "CBRS assignments". IMSI Admin. Retrieved 2019-06-12.


This article incorporates some material from the Federal Communications Commission report, 3.5 GHz Band / Citizens Broadband Radio Service, accessed August 30, 2017, a source in the public domain.

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