CBRS: A Solution for the High Cost of Spectrum, Unleashing New Opportunities


There are a few major trends driving the rapid increase in data traffic on the network. At the top of the list is the Internet of Things (IoT), 5G and the convergence of mobile broadband and media traffic.

As the volume of traffic increases, so too does the demand for spectrum availability, which the Communications Service Providers (CSPs) and Mobile Network Operators (MNOs) are competing for, so they can expand their capacity and grow their businesses. As available auctioned spectrum grows scarce, the cost of spectrum keeps climbing.

The ballooning cost and scarcity of spectrum is a big problem for CSPs and MNOs. If today’s allocation model of auctioning and licensing spectrum remain the only option, there’s little relief in sight. It’s highly likely there will be a spectrum shortage within the next few years.

Thankfully, there is a solution that’s gaining traction: shared access of the 3.5 GHz spectrum. This option allows the connection of both mobile users and smart devices, paving the way to unleash the innovation potential of IoT and 5G.

After a decade of study, a couple of new sharing models have recently emerged and have been standardized, most notably Europe's 2013 Licensed Shared Access (LSA), which was announced in 2013 and piloted in 2016. Not too far behind, in 2015, the US Federal Communications Commission (FCC) released a report paving the way for a unique Citizens Broadband Radio Service (CBRS) that would permit commercial use of 150 MHz of spectrum in the 3550-3700 MHz band (3.5 GHz).

The CBRS band (3.5-3.7 GHz) is currently occupied by military and government users. The US Department of Defense uses the 3550-3650 MHz spectrum for radar systems and fixed-satellite services (FSS), while commercial wireless broadband services and FSS users are grandfathered into the top 50 MHz of the spectrum.

The Wireless Innovation Forum (WIF) formed a committee to—among other things—implement new spectrum sharing rules allowing both industry and government agencies to implement a common, efficient ecosystem around this technology. So far, CBRS has been introduced for WiMax and LTE-compatible bands, primarily targeting small-cell applications that complement primary mobile networks.

While still a nascent market, over 40 CSPs are developing technology and promoting solutions to be used in the CBRS band. For example, the LTE-U Forum—including Alcatel-Lucent, Ericsson, Huawei, Nokia, Qualcomm, Samsung, Siemens and Verizon—is working on protocols for unlicensed 3.5 GHz spectrum operations. The FCC defines CBRS as an 'innovation band,' where it can assign spectrum to commercial mobile broadband systems, such as 3GPP LTE, on a shared basis with incumbent users.

The CBRS band has a formal hierarchy of users consisting of three tiers:

  • Tier 1: Incumbent Access (IA) These users are primarily military ship-borne radar and ground-based radar, as well as fixed-satellite-service earth stations that receive but do not transmit.
  • Tier 2: Priority Access (PA) This group includes critical access users at hospitals, utilities and government departments as well as non-critical users such as MNOs. The PA licenses are between 3550-3650 MHz.
  • Tier 3: General Authorized Access (GAA) These users are permitted to use any portion of the 3550-3700 MHz band not assigned to either IA or PA users and may operate opportunistically on unused PA channels.

There are two likely scenarios for utilizing CBRS:

  • New entrants, such as a cable operator, looking to build out their LTE networks.
  • Companies looking to develop private LTE networks, like Wi-Fi to run enterprise - or venue-specific applications for mobile devices, that are designed for use by employees or consumers.

In addition, CBRS opens up exciting new opportunities for improving in-building coverage using neutral host models that are being commercialized through larger, more expensive DAS systems. This new framework lets building owners, enterprises, and systems integrators deploy equipment, using a neutral host RAN model. There’s potential for neutral-host providers to create a major new category of mobile coverage, funded by the enterprise or property owner.

The shared spectrum model is an innovative approach. It’s also a bold and historic shift in spectrum allocation in the US that has the potential to create many exciting opportunities for MNOs, CSPs and other telecommunications service companies.

Click here to know how dynamic sharing and scalable use of the 3.5 GHz spectrum will increase the efficiency of spectrum use in delivering fast growing and converging mobile broadband and media traffic services while paving the way for new innovations such as Internet of Things (IoT) and 5G networks.


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