5G Deployment: CBRS or C-Band?

Without a doubt, 5G is the future of wireless communications, enabling better user experiences and transforming the way we live. However, many technologies related to 5G can create more confusion than clarity, such as mmWave, 5G NR, sub-6, C-Band, CBRS, mid-band, high-band, etc.

The available radio spectrums involved in the deployment of 5G technology can be particularly complex and confusing. These spectrums vary depending on the region, with each spectrum enabling specific capabilities and services. Among the spectrums available for 5G deployments are those in the C-Band and the Citizens Broadband Radio Service (CBRS).

Both belonging to the mid-band spectrum, C-Band and CBRS are often mistakenly thought to be the same thing. To further benefit from the advanced technology of 5G, it is essential to understand the differences between these two and know how best to use each one.

The Lower C-Band

The recent C-Band auction licensed 280 MHz of spectrum between 3.7 and 3.98 GHz.  Previously, this spectrum was used for satellite transmission in areas where heavy rain degraded signals, but the usage of these frequencies declined over the years.

Negotiations for the release of C-Band spectrum for 5G use took several years to resolve. In 2020, the US Federal Communications Commission (FCC) conducted an auction that enabled telecommunications providers to purchase rights to use the spectrum for their 5G networks. Verizon, AT&T and T-Mobile were among the largest spenders in this auction, spending billions of dollars to gain exclusive rights to chunks of the C-Band frequencies.

Why were telcos willing to invest such massive amounts of capital in this frequency band?  The band contains enough spectrum to support larger 5G channels, while the frequency is still low enough to propagate well.  Whereas higher frequencies, such as in the mmWave bands, have very short transmission distances.

Currently, in the United States, only T-Mobile has access to spectrum capable of supporting 100 MHz 5G NR channels in their 2500TDD band 41.  The C-Band spectrum opens up the possibility for large 5G channels for all of the major network operators.  The promise of enhanced mobile broadband (eMBB) to provide a superior mobile experience depends on large 5G channels.

The Citizens Broadband Radio Service (CBRS) Band

CBRS occupies 150 MHz of spectrum between 3.55 and 3.7 GHz. Three tiers of users with different levels of priority share this spectrum.

The first tier consists of incumbent users, such as satellite ground stations and the US military, making use of the CBRS band for mission-critical situations. Next are the priority access license (PAL) holders comprised of carriers, internet service providers and large enterprises who received licenses in the 2020 auction. Each license provides 10 MHz, and each PAL licensee could obtain up to four licenses in an area. The remaining channels are for general authorized access (GAA). These are essentially the same as the unlicensed Wi-Fi spectrum, which anyone can use freely as long as they do not interfere with traffic on the first two tiers.

The CBRS auction generated only 21 cents per MHz/pop. This is significantly lower than the 94 cents per MHz/pop generated by the C-Band auction. One plausible explanation for this is that CBRS license size limits the usefulness of the spectrum for 5G service requiring large channels.  However, it still plays a key role in building private networks, mostly based on 4G LTE, within large organizations.

C-Band vs. CBRS

The vast frequency range of C-Band makes it a prime spectrum choice for service providers. Its broad, dedicated channels and decent range provide plenty of bandwidth for wireless carriers using existing cell sites. However, not all 280 MHz of spectrum will be available right away after the auction. Existing satellite services must relocate first, and 5G networks must build the infrastructure to use the new frequencies. These tasks take time, so consumers will not benefit from this technology until 2022.

In contrast, CBRS is available now.  Most service providers initially intended to use this band for enhancing 4G LTE capabilities, but are also intent on using it to augment their 5G networks. However, the use of CBRS has been limited so far.

The bottom line is that spectrum is precious, and more spectrum is better.  Yet, while both bands provide access to more spectrum, the exclusivity that the C-Band provides yields more reliable use of spectrum for 5G and a longer timeframe to recover network investment.

What are the differences in use cases of C-Band and CBRS?

While they are both categorized under the mid-band spectrum, C-Band and CBRS have different strengths. Simply put, C-Band increases overall 5G capabilities and access. At the same time, CBRS is geared more toward augmenting 4G capacity, as well as novel solutions for private networks and entrepreneurial activity such as wireless ISP (WISP) services.

5G Deployment

Mainstream 5G deployments today mostly use general enhanced Mobile Broadband models. With 280 MHz of bandwidth, C-Band enables eMBB use cases for 5G. The abundance of its available spectrum and its propagation characteristics heighten its performance in indoor and enterprise situations that go beyond data communications services.

C-Band takes advantage of cutting-edge cellular technologies such as carrier aggregation and massive MIMO antennas. Aside from the large amounts of the spectrum it provides, it also performs well in non-line-of-sight conditions and indoor penetrations. These make it ideal for large deployments and will likely pave the way for new applications and connectivity services.

Although used mostly to complement LTE networks, CBRS also enables service providers to deploy 5G networks without acquiring spectrum licenses. However, it is better suited for private LTE and private 5G networks due to some limitations that make it ineffective for broad 5G use. For one, the channels in this spectrum are not universally accessible by all network operators. Moreover, there is the limitation on transmitted power that restricts its useful range for mobile applications, making CBRS more suitable for small coverage areas.

Enhanced 4G LTE

Due to its power limitations and other restrictions that make it inefficient as a base coverage layer, CBRS can add capacity within the 4G network and help bridge the shortcomings of Wi-Fi. In general, Wi-Fi technology is prone to suffering from insufficient coverage and network congestion. Private LTE addresses these problems by supporting up to twice the Wi-Fi capacity and protecting against network interference. For today’s enterprises, this increases app performance and facilitates more efficient workflows.

Aside from this, CBRS used in enterprise LTE provides a higher level of privacy and more secure access. Running enterprise LTE on the CBRS bands ensures that sensitive business data remains within the confines of a corporate network because access restrictions through login requirements and SIM cards avert potential hacking. These are crucial to sectors such as healthcare and financial services that require high levels of security.

Specialized IoT Applications

The Internet of Things (IoT) is transforming the digital economy. GPS navigation, utility meters, smart assistants, health trackers—these applications are becoming more prevalent and changing the way we live. With the immense benefits it brings, the IoT sector continues to expand, and mobile services play an important role in the growth of this market.

C-band supports IoT as well as personal mobile services relatively easily. This makes it the spectrum of choice for wide-area IoT services, with the capacity and coverage capabilities needed to deliver high-quality IoT services. Wireless service providers can control usage levels with this licensed spectrum to provide guaranteed service levels for IoT apps in critical-use situations, such as those in security and medical applications. While the higher bandwidths of mmWaves can undoubtedly deliver more bandwidth and lower latencies, C-band still plays a crucial role in broadening IoT use.

CBRS is also usable in specialized IoT applications. For example, PALs are likely to use private LTE deployed on CBRS for industrial, agricultural, and enterprise applications. Private networks maintain connections among IoT devices that automate industrial processes in factories and warehouses. CBRS-based private networks also can increase farm yield by using sensors on agricultural equipment to monitor repairs and environmental conditions.

Seamless Connectivity

Both spectrum bands will enable users to switch between access points seamlessly. They will reduce connectivity issues related to Wi-Fi, such as dropped calls and intermittent signals.

In residential and public spaces, such as multi-family dwellings, auditoriums, and shopping malls, CBRS-based private networks improve in-building connectivity. In business establishments, it can enhance both employee and customer experiences. Additionally, CBRS spectrum can also be used to provide connectivity in remote areas for telecommuting, e-learning or virtual classes, albeit with limitations.

Alternatively, C-Band presents a better choice for deployment to deliver wireless connectivity in low-density suburban and rural areas because its high-power limits, minimal coordination requirements, and large licensing areas make it more efficient and cost-effective for this use case. In coverage-limited deployments, CBRS can require as much as seven times more cell sites to achieve the same coverage that C-Band provides.

Deploy What Is Right for Business

The success of deploying cellular technologies relies heavily on the right choice of spectrum bands. While both C-Band and CBRS are essential for 5G network developments, the C-Band appears to have the edge in making the 5G eMBB use case more successful and profitable.

Still, there are continuous developments in the industry that may eventually change this. What is clear, though, is that the mid-band spectrum will be crucial in enhancing coverage and bandwidth to provide better user experiences.

As with all new technologies, the best practice is to start with a targeted deployment plan. Consider the current and future use cases of each technology to understand their potential impact in the long term.  When you are ready to deploy technology in either of these bands, SOLiD is here to help.  The SOLiD ALLIANCE 5G DAS provides full band coverage for both CBRS and C-Band.  And the edgeROU Fiber2Antenna DAS provides up to eight commercial cellular and private networking frequency bands over a single fiber strand to a lightweight, low-power, aesthetically pleasing DAS remote with high-performance integrated antennas.Visit https://solid.com/us/what-is-cbrs/ to learn more.