An introduction to CBRS

CBRS, or Citizens Broadband Radio Service, is a spectrum band in the 3.5 GHz range that is being made available for shared use by commercial wireless operators and other interested parties. This is a significant development in the world of wireless communications, as it allows for more flexible and efficient use of this valuable spectrum.

But what exactly is CBRS and how does it work? In this blog post, we will provide an introduction to CBRS and explain the key concepts and technologies that make it possible.

First, it’s important to understand the concept of spectrum and why it is a critical resource for wireless communications. Spectrum refers to the range of electromagnetic frequencies that are used for transmitting and receiving data over the air. These frequencies are a finite resource, and different types of wireless services require different bands of spectrum to operate effectively.

Traditionally, the allocation of spectrum has been controlled by government regulators, who assign specific bands of spectrum to licensed users, such as wireless carriers and broadcasters. This approach has worked well for many years, but it has also resulted in inefficiencies and limitations, such as the inability to easily accommodate new users and services.

CBRS is a new approach that seeks to address these challenges by allowing for more flexible and dynamic use of the 3.5 GHz band. This band is particularly well-suited for CBRS because it is relatively wide (150 MHz) and has good propagation characteristics, making it ideal for providing coverage over a large area.

At the heart of CBRS is a system known as the Spectrum Access System (SAS), which is responsible for managing access to the 3.5 GHz band and ensuring that users are able to use it in a coordinated and fair manner. The SAS is a complex system that incorporates various technologies and algorithms to enable dynamic spectrum sharing, including databases, sensors, and algorithms for spectrum allocation and interference management.

Under the CBRS framework, the 3.5 GHz band is divided into three tiers: the Priority Access Tier (PAT), the General Authorized Access Tier (GAA), and the Incumbent Access Tier (IAT). The PAT is reserved for licensed users, such as wireless carriers, who have been awarded spectrum licenses by the FCC. These users are granted exclusive access to the band and have the highest priority for using it.

The GAA is the largest and most flexible tier, and it is available for use by anyone who registers with the SAS and complies with its rules. This tier is intended for use by unlicensed devices, such as WiFi routers and small cells, as well as other services that do not require exclusivity.

The IAT is reserved for incumbent users, such as federal government agencies and satellite operators, who were already using the 3.5 GHz band prior to the introduction of CBRS. These users have the right to continue using the band and are protected from interference from other users.

In summary, CBRS is a new and innovative approach to spectrum management that allows for more flexible and efficient use of the 3.5 GHz band. By using advanced technologies and algorithms, CBRS enables dynamic spectrum sharing among a variety of users and services, providing benefits for both licensed and unlicensed users.

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