Exploring U.S. CBRS Spectrum Use through Crowdsourcing

By WePlan Analytics

This report is meant to be an educational tool and reflects the views of the authors.

The telecommunications landscape is evolving rapidly, with new models emerging to foster competition in spectrum regulatory frameworks. One such innovation is the Citizens Broadband Radio Service (CBRS) in the United States, which introduces an innovative shared-access framework that allows for more dynamic and flexible use of the 3.5 GHz band (3.55–3.7 GHz). While this model opens new opportunities for various stakeholders to access spectrum, it also presents challenges, including interference management and the complexity of coordinating multiple users and access tiers.

A new study conducted by researchers from WePlan Analytics, Universidad Politécnica de Madrid (UPM) and the Massachusetts Institute of Technology (MIT) explores how CBRS is being utilized across the different stakeholders in the telecommunications market, using crowdsourced network measurements by WePlan Analytics. The academic paper will be presented at IEEE DySPAN 2025, the premier global forum for cutting-edge developments in spectrum technology and policy.

How does CBRS work?

CBRS operates within the 3.5 GHz spectrum through a three-tier access system managed by a Spectrum Access System (SAS) administrator. The tiers include incumbents (e.g., military radar systems), Priority Access License users (PAL) and General Authorized Access (GAA). For the benefit of the reader, a SAS administrator assigns spectrum access priorities in the following order:

1. Incumbents. These users, such as military radar systems, hold the highest priority and are fully protected from interference.
2. PAL users. This tier includes stakeholders who acquire county-level licenses through auctions, granting them priority access within their licensed areas over lower-tier users.
3. GAA users. They may access the spectrum opportunistically, but only if the SAS administrator determines that they do not interfere with either incumbents or PAL users.

What differentiates CBRS from conventional spectrum management is its flexible access model. Various stakeholders – including Mobile Network Operators (MNOs), Regional MNOs, Mobile Virtual Network Operators (MVNOs), Wireless Internet Service Providers (WISPs), Neutral Hosts, and Private Networks – can gain access to the spectrum. This fosters competition and innovation but requires complex management to avoid harmful interference.

What approach have U.S. Network Providers used?

A key question is how CBRS has impacted the U.S. telecom market and whether it can serve as a model for future global spectrum management frameworks.

WePlan Analytics’ crowdsourcing methodology provides valuable insights into CBRS adoption, as the data collected directly from end users helps uncover key strategic insights about how different stakeholders are leveraging this spectrum. The insights obtained complement the existing knowledge about CBRS – such as the official reports from the NTIA [1] – from a very novel vantage point. Below are some key findings from the research study mentioned above.

MNOs are not extensively using the CBRS spectrum for primary serving cells, likely due to radiated power limitations imposed by regulations aimed at protecting incumbents from interference. However, we have found that Verizon has taken a proactive approach, extensively using the CBRS band with secondary serving cells to increase network capacity and leveraging Carrier Aggregation (CA) capabilities in LTE. This places Verizon as the stakeholder with the broadest CBRS coverage in the entire U.S. As a result, a significant number of CBRS cells are measured for this use, particularly in counties where Verizon acquired PAL licenses, as illustrated in Figure 1.

Figure 1. Relationship between Verizon’s total payments for PAL licenses (in thousands of dollars, based on public information available from[2]) and the number of cells deployed as Secondary Component Carriers (SCCs).

The data reveals a moderate correlation coefficient of 0.54, indicating a notable connection between investment in PALs and the density of secondary carrier cells deployed by Verizon in counties where it holds licenses.

On the other hand, MVNOs affiliated with large cable companies, such as Charter or Comcast, are identified as the only stakeholder with an intensive deployment of 5G cells using CBRS spectrum, enabling these operators to offload traffic to their own networks and reduce dependence (and costs) on MNO roaming agreements. Their deployments are concentrated in states with counties where they acquired PAL licenses.

Figure 2. Number of cell deployments by state in Contiguous US.

Figure 2 illustrates the geographic distribution of the total number of detected CBRS cells by state. The use of CBRS among stakeholders varies widely across states. States with the highest total number of cells (over 2,500) consistently include deployments by Verizon, largely driven by its extensive use of secondary cells through Carrier Aggregation. In terms of primary cell usage, several of these states with high numbers of CBRS cells — such as North Carolina or Georgia — also feature notable 5G deployments by MVNOs, contributing to the overall number of detected cells. In contrast, states without relevant MVNO activity — such as California, Colorado, and Michigan — show prominent neutral host deployments. Notably, all these states contain major urban areas, which likely contribute to the high concentration of detected cells. This distribution reflects the varied deployment strategies employed by different stakeholders to leverage CBRS spectrum to enhance network capacity and coverage.

Comparison with C-Band

Building on the findings of this academic study, our team has broadened the use of crowdsourced data from WePlan Analytics to explore new dimensions of analysis. By comparing CBRS and C-Band signal strength, the study highlights how regulatory frameworks shape network performance, influencing coverage, use cases, and network strategies. The C-Band (3.7–3.98 GHz), mid-band spectrum exclusively licensed to MNOs, allows higher power levels, enabling stronger signal propagation. In contrast, CBRS operates under strict power limitations designed to protect incumbent users, such as military radar systems.

This distinction is reflected in Reference Signal Received Power (RSRP) measurements, which quantify the average power of a cell reference signal received by a device and are expressed in dBm. RSRP values typically range between -140 dBm (weakest) and -44 dBm (strongest). The analysis reveals that CBRS deployments average -96.9 dBm, while C-Band achieves -87.4 dBm, resulting in a ≈10 dB advantage for C-Band, as can be observed in Figure 3.

Figure 3. Average RSRP measurement comparison between CBRS and C-Band.

This difference has practical implications for coverage and use cases. While C-Band supports macro-cell 5G coverage with enhanced capacity and speed, CBRS is a valuable tool suited for small-cell deployments, private networks, and capacity augmentation through Carrier Aggregation. Rather than competing directly with C-Band, CBRS complements it by serving specialized applications that require localized connectivity and flexible spectrum access. This synergy underscores the importance of tailored spectrum management approaches in balancing innovation with regulatory constraints. As the telecommunications landscape evolves, understanding these dynamics will be crucial for optimizing future network strategies.

Conclusions

These findings underscore the complementary roles of CBRS and C-Band in the U.S. telecommunications landscape. They also highlight the success of regulators and stakeholders in fostering innovation through tailored spectrum management approaches. By balancing regulatory constraints with opportunities for shared access, CBRS exemplifies how spectrum policies can drive competition while addressing diverse connectivity needs. The U.S. telecommunications market is at the forefront of innovation in spectrum management, with different stakeholders actively working to improve quality of service, customer experience, and close the Digital Divide[3] across the nation.

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[1] https://www.ntia.gov/report/2024/analysis-aggregate-cbrs-sas-data-april-2021-july-2024

[2] https://www.fcc.gov/auction/105

[3] For further information on the U.S. Digital Divide, please refer to our article on the WIA: Crowdsourced data reveals depth of U.S. Digital Divide