The Citizens Broadband Radio Service – An Overview

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The Citizens Broadband Radio Service (CBRS), is a spectrum sharing plan that provides a more efficient alternative to the traditional methods of allocating spectrum. In April 2016, the FCC finalized rules for spectrum sharing, authorizing 150 MHz of new spectrum – originally used by the Navy and other Department of Defense personnel – for commercial uses on a shared basis with the incumbent users of the spectrum.

Background: The Traditional Approach to Spectrum

Connectivity is an integral part of our digital lives, with smart phones and apps constantly changing the way people live. The driving force behind this connectivity is radio spectrum. In particular, licensed spectrum is used for mobile connectivity and satellites while unlicensed spectrum is used for Wi-Fi, Bluetooth, and the internet of things. Unfortunately, spectrum is a limited resource – mostly held by the federal government – and the demand for it remains high. Accordingly, it remains important to use it efficiently so as to ensure that there is enough to keep up with demand.

The Federal Communications Commission (FCC) and National Telecommunications and Information Administration (NTIA) are the two federal agencies responsible for allocating radio spectrum. The FCC, an independent regulatory agency, assigns spectrum for non-federal uses (i.e., state and local governments, commercial businesses, and private use). The NTIA, an agency of the Department of Commerce, assigns spectrum for federal use (i.e., the Army, Federal Aviation Administration, and Federal Bureau of Investigation).

The FCC allocates licensed spectrum through an auction system. The licensee – typically a major wireless carrier – is assigned a spectrum band for a given geographic area. When the license expires, the band is cleared and reallocated for either licensed or unlicensed use. Licensed spectrum is free of interference at 99.9% predictable reliability. However, the cost of a license is passed on to customers, who will pay significantly more than those who use unlicensed spectrum for their wireless connection. Unlicensed spectrum – available for all wireless carriers to use – is a cheaper alternative but it is susceptible to interference if multiple providers operate on the same frequency band in the same area. Carriers avoid this problem, however, by operating short-distance connections between their own transmitter radio and the customer’s receiving radio; this reduces the chance of another provider operating on the same frequency. Carriers also conduct spectrum analysis to determine a suitable frequency for the wireless connection.

Overview of The Citizens Broadband Radio Service

The FCC Part 96 rules establish a three-tier framework for use of CBRS spectrum: Incumbent Access, Priority Access, and General Authorized Access. Incumbent Access users are at the top of the hierarchy, having the highest priority for protection from harmful interference and for access to the spectrum. When an incumbent user is on part of the spectrum, other users must relocate to unused portions of the band. Priority Access users are at the second level of the hierarchy. These users are assigned Priority Access Licenses (PALs) through an auction system based on competitive bidding. PALs are offered for three-year terms, not subject to any renewal expectancy, and entities can obtain up to four PALs to operate within a limited geographic area. Finally, General Authorized Access users are at the bottom of the hierarchy, lacking protection from harmful interference. These users can operate on any portion of the spectrum that is not being used by an Incumbent or Priority Access user. This reduces waste and results in a more efficient use of spectrum.

A Spectrum Access System (SAS) coordinates and manages spectrum sharing in the three-tier framework. To operate on the spectrum, users must register with and request a spectrum grant from SAS. The automated system assesses potential interference to other users before authorizing the request and specifies the frequency range for each grant. If the environment for a geographic area changes after spectrum has been authorized – particularly if there is incumbent activity – SAS will either switch the radio nodes to an alternate frequency or stop transmitting. In addition, when portions of the spectrum are no longer being used, SAS frees up the band so that other users can operate on it with minimal interference. In practice, multiple SAS vendors will be available to manage the spectrum, sharing information with each other to gain a better understanding of the environment.

Another system being developed to protect users from interference is the Environmental Sensing Capability (ESC). ESC sensors will be positioned along the coasts in order to detect incumbent signals in the area. Upon detection, the system will inform the SAS vendors so that any potential interference – either from Priority Access or General Authorized Access users – can be avoided. Specifically, SAS will reassign such users to other frequencies.

Benefits of the Citizens Broadband Radio Service

CBRS provides a number of benefits to individuals and businesses. Under the traditional approach, major wireless carriers spend billions of dollars buying the exclusive rights to licensed spectrum. This leads to a marketplace that is dominated by four national carriers – as new entrants cannot afford to buy spectrum – and facilitates the practice of hoarding spectrum. In contrast, CBRS allows more users to operate on 150 MHz of spectrum.  By making spectrum more abundant and affordable, the new sharing plan creates new wireless opportunities for both traditional and non-traditional mobile operators. In particular, mobile operators can provide increased capacity without raising costs or making significant network changes.

In addition to creating new opportunities for mobile operators, CBRS allows other entities – such as enterprises, schools, hotels, and hospitals – to set up their own private LTE networks without having to rely on a wireless carrier or Wi-Fi. Specifically, since the spectrum does not have to operate through a wireless carrier, it can serve as a private in-building network. This can facilitate increased security and flexibility, and lower operating costs. An airport, for example, could control connectivity for baggage tracking and flight updates, while a hospital could control connectivity for mobile medical devices and patient health information. CBRS is also ideal for corporate data security and internet of things applications. In addition, commercial property managers will be freed of complaints that their tenants’ smartphones do not work inside the building. With access to robust LTE services, tenants will not have to depend on spotty Wi-Fi. At the same time, their costs will not increase – tenants will pay the same amount or less for better coverage.

Notably, CBRS affords building owners and commercial real estate developers the opportunity to implement cellular coverage and capacity in an economical and simple manner. The cost of PALs is expected to be significantly lower than that of licensed spectrum. This means that network owners can afford 150 MHz of spectrum on every floor of their building. In fact, the overall costs will be comparable to that of Wi-Fi. Moreover, the process of deploying the spectrum is simple. As with Wi-Fi, network owners must purchase the gear, which will be certified by the FCC and compatible with SAS, and then register the equipment online. Next, they must select a SAS vendor, which will ensure that the operator does not interfere with the Incumbent Access users. Given the low barriers to entry and readily deployable technology, CBRS has the potential to transform wireless communications – not only resulting in increased competition among carriers but also fostering new products and services across various industries. In fact, based on the number of filings with the FCC, many companies believe that CBRS will be well suited for a variety of applications.

Another benefit of CBRS is the option for neutral hosts. In public venues such as sports arenas, concert halls, and theme parks, it is not feasible for each network operator to deploy its own radio systems independently. Neither is it cost effective for a network operator to provide indoor coverage in locations such as malls, hotels, and conference centers. In such cases, an entity (other than a wireless carrier) could operate a private network and serve as a neutral host. CBRS can facilitate this process. Venue owners can install their own LTE systems which can “host” mobile operators on the network – software will make it appear that the user is operating on AT&T or Verizon (or whichever carrier he or she uses). Through this process, neutral hosts can manage their traffic and send it to the Internet via traditional carriers. At the same time, they will be providing a superior and more affordable service. In addition, this system does not require permission from wireless carriers, and it can operate independently or co-exist with installed Wi-Fi systems. Overall, this option benefits the venue owner, mobile operator, and the consumers.

Finally, the three-tier hierarchical structure provides some additional benefits. At all times, incumbent radar systems necessary for national defense will be protected from interference. In other words, spectrum sharing will not interfere with the federal government’s current operation of mission-critical radiolocation services. In addition, the hierarchy affords new users the flexibility of choosing Priority Access when protection from interference is important or General Authorized Access when such protection is less crucial. Accordingly, CBRS can prove useful for a variety of commercial purposes.

Overall, CBRS may be beneficial for all stakeholders. Commercial real estate developers, investors, and building owners may be able to take advantage of CRBS and set up their own private LTE networks.

The CBRS Alliance

In August 2016, six companies – Google, Federated Wireless, Nokia, Qualcomm, Intel and Ruckus Wireless – formed the CBRS Alliance. The organization’s goal is to support the development, commercialization, and adoption of the CBRS band. Specifically, the Alliance believes that shared spectrum can facilitate in-building and outdoor coverage and capacity expansion at a large scale. Toward this end, its mission is to evangelize LTE-based CBRS technology, drive technology developments necessary for that mission, and establish a product certification program for LTE equipment in the CBRS band. Ultimately, the Alliance seeks to make LTE-based CBRS solutions available and ensure multi-vendor interoperability.

The CBRS Alliance currently includes more than 80 companies, including the nation’s four major wireless carriers. These companies have collaborated on detailed specifications that will facilitate the transition to and interoperability of CBRS. Google is one of many companies that will be providing databases to run the spectrum system. These database providers applied for FCC certification in February and hope to be approved within the next few months. Moreover, Verizon expects to have CBRS-capable devices, including smartphones, by the end of this year. Wireless carriers have said that they plan to use the General Authorized Access portion of the band as well as the Priority Access License portion when it becomes available.

In addition, there has been a tremendous amount of industry momentum as companies have been testing CBRS in real-world applications. In January 2017, Nokia, Qualcomm and Alphabet built a virtual reality zone inside stock race cars. These companies set up a private LTE-network inside the race cars using CBRS spectrum and live-streamed 360-degree, 4K video out to spectators. Fans had the unique opportunity to experience what it is like to be in a race car that is traveling at 185 mph. This demonstration not only revealed the potential for new audience experiences through the combination of the CBRS band and other technologies, but also the ability of venues and enterprises to offer new services by setting up their own private LTE networks.


CBRS holds a huge amount of promise. The use of shared spectrum among different players will increase efficiency: if a company does not make use of its portion of spectrum, it is free for others to use. This approach makes the valuable commodity more plentiful. Besides efficiency, CBRS will create new opportunities for various industries that recognize its potential. By using the CBRS band to set up their own private LTE networks, companies may be able to offer new products and services, leading to increased competition and innovation.

The FCC is expected to approve parts of the spectrum sharing plan soon and begin certifying devices within the next few months. Companies are hopeful that commercial deployments of the CBRS band will be possible before the end of the year. A former FCC commissioner recently estimated that the market value of the spectrum is $7.5 billion to $15.6 billion, and the total value to consumers could be as much as $260 billion.

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