CBRS is the short for Citizens Broadband Radio Service. In 2015 the US Federal Communications Commission (FCC) approved the spectrum for CBRS (Citizens Broadband Radio Service).
The bandwidth of the CBRS spectrum is 150MHz, and the CBRS spectrum ranges from 3550 to 3700MHz (or 3500MHz to 3700MHz in some definition), with frequency allocations spanning the existing LTE Band 42 (3400 MHz to 3600 MHz) and LTE Band 43 (3600 MHz to 3800 MHz).
The frequency band of CBRS is Band 48, TD-LTE standard, which supports voice, SMS, and data services. This spectrum is shared by the U.S. government and other commercial and corporate entities as shared spectrum.
Those who have historically held exclusive rights to the band, namely satellite ground stations and the US Navy.
In 2020, priority licenses were auctioned, allowing licensors (Internet service providers such as Verizon and Comcast) to use frequency bands in specific U.S. counties as long as they did not interfere with existing frequency bands and tolerated possible interference in existing frequency bands. While authorized access allows users to use the frequency band as long as they do not interfere with the other two types of users.
CBRS Pros
CBRS overcomes the limitations of WIFI and provides a more efficient option for large commercial enterprises. WIFI coverage and capacity are limited. CBRS provides commercial enterprises with twice the capacity and four times the WIFI range.
CBRS Alliance
The CBRS Alliance consists of 120 member companies. The CBRS Alliance believes that LTE-based solutions in the CBRS band, leveraging shared spectrum, can enable building and outdoor coverage and massive capacity expansion. To maximize the full potential of CBRS, the CBRS Alliance aims to build a robust ecosystem to provide LTE-based CBRS solutions.
The mission of the CBRS Alliance is to promote LTE-based CBRS technologies, use cases and business opportunities, while driving the technological developments needed to accomplish the mission, including multi-operator LTE capabilities. The alliance will also establish an effective product certification program for LTE equipment in the 3.5GHz band in the United States, ensuring multi-vendor interoperability.
CBRS spectrum sharing allocation method
The difference between CBRS and the public network operator frequency band is the way the spectrum is allocated to each user.
CBRS does not sell spectrum on a large scale to operators with wide-area coverage, nor does it fully expose free trial frequency bands like WIFI. Instead, use within each building is individually requested and allocated on a case-by-case basis. If it is no longer needed, it would be returned to others.
The process of allocating spectrum is automated, with several Spectrum Allocation Servers (SAS) coordinating the scheme across the country. As part of the registration request, each small unit reports its horizontal position within 50 meters and its vertical position within 3 meters. SAS uses terrain data and a radio propagation model to calculate the effect on other small cells nearby. Additional outdoor radio measurement receivers (environmental sensors) are also used to assess background levels. If the RF power density is less than -80dBm (1×10-11 watts), the SAS authorizes spectrum use.
This is based on the idea that spectrum is a valuable national asset that should be harnessed, not lie dormant.
In conclusion, Citizens Broadband Radio Service is shared wireless spectrum in the 3.5GHz band that could have big implications for building private LTE networks and extending public 4G and 5G services.