The evolution to 5G is moving at a blistering pace.  In fact, the adoption of 5G is happening faster than any previous generation of mobile communications technology.  Yet we still have not realized the true vision of this new mobile technology.  In the U.S., this is primarily due to a shortage of suitable radio frequency spectrum.

To achieve the full potential of 5G, mobile network operators (MNOs) require broad, dedicated channels, ideally 100 MHz or larger.  The 5G standards permit channel bandwidths up to 100 MHz in frequency range 1 (FR1) below 6 GHz and up to 800 MHz in frequency range 2 (FR2) above 6 GHz, typically higher mmWave spectrum from 24 to 40 GHz.  All major network operators possess licenses in FR2, but building a network to provide ubiquitous coverage with mmWave is cost-prohibitive due to the very short transmission distances at high frequencies.  Therefore, FR1 bands large enough to support 100 MHz channels are the best alternative to provide wide-area 5G coverage that also offers true 5G capabilities.

Except for the 2.5 GHz BRS band used by T-Mobile, each of the legacy bands previously used for 3G and 4G typically provide just 10 to 40 MHz of bandwidth to each network operator, so they could not support 100 MHz channels.  As a result, the initial 5G deployments in the U.S. did not enable wireless service providers to maximize their networks’ speed and capacity. Still, they did enable coverage maps showing large areas of 5G coverage.  Finally, the Federal Communications Commission (FCC) released additional spectra in the C-Band 3.7 to 3.98 GHz and 3.45 to 3.55 GHz to enhance the MNO’s 5G capabilities.  The U.S. C-Band is a sub-set of the frequency band identified as n77 by the global 3GPP organization that spans 3300 MHz to 4200 MHz.

C-Band will offer significant improvements over the previously released millimeter-wave spectrum for wide-area 5G network deployments.  The n77 spectrum has already been used in 5G networks for two to three years by MNOs worldwide, and most 5G networks operate in this mid-band spectrum.  Here in the U.S., however, MNOs just recently started switching on their C-Band 5G networks after intense negotiations with the Federal Aviation Administration (FAA) over concerns about interference with airplane radar altimeters.

Now that the U.S. Tier One service providers are using C-Band in their 5G networks, it’s important to ensure that existing mobile communications infrastructure is compatible — including your in-building distributed antenna system (DAS) equipment.  For building owners, enabling seamless 5G connectivity is crucial to keeping tenants happy as more subscribers adopt this next-generation technology and MNOs begin to turn off previous mobile generations.  And for those enterprises wanting to benefit from the latest innovations such as IoT connectivity, analytics powered by machine learning, and smart manufacturing, 5G private networks are the answer to achieving this as smoothly and efficiently as possible.

Learn the ABCs of C-Band

The C-Band was previously reserved for satellite TV transmissions. Still, with advanced digital encoding methods, the satellite companies can “repack” their broadcasts into the upper portion of the band to free up the lower portion for 5G.  Interestingly, after auctioning the frequency licenses last year, the FCC is making C-Band available in two phases as they clear the spectrum.  This means that MNOs’ timeframes for the availability of 5G in the C-Band will vary considerably depending on their licenses, with roll-outs extending from early this year to the end of 2023 and different portions of the band being used in various markets.  In other words, the overall deployment picture is far from simple.  For example, one MNO received an initial spectrum allocation this year that will shift 80 MHz higher within the band in 2023.

C-Band offers greater capacity with an increased channel size, but the coverage area will be reduced or require more output power to achieve the same footprint as previous frequencies.  Additionally, the C-Band spectrum offers just one-fourth of the legacy mobile communications bands’ signal propagation characteristics because it spans higher frequencies.  As a result, achieving the same coverage footprint with C-Band will require a higher effective output power from the antenna.

Likewise, the higher frequencies also do not penetrate building materials as well as lower frequencies.  This means that coverage from outdoor networks is less likely to provide service inside buildings.  On the plus side, in-building coverage systems, such as Distributed Antenna Systems (DAS), will have less outdoor network interference to overcome.

A dedicated in-building system can provide reliable C-Band coverage, but the interior building materials impede these higher frequencies.  In comparison to legacy mobile communications frequencies at the same power level, indoor C-Band coverage is roughly 15 percent per antenna.  For example, an antenna providing a little more than 1,000 square feet of coverage for a 4G 20 MHz channel in the legacy Advanced Wireless Service (AWS) band would cover a little more than 150 square feet with a 5G 100 MHz channel in the C-Band, assuming an office environment with sheetrock walls.

If you have an existing 4G DAS, it may or may not support the new frequencies.  However, even if it does, it will certainly require amplifiers that provide 4 to 10 times more output power to match the existing footprint.  Yet providing higher power is not feasible if the existing system already uses high output power amplifiers.  Under that circumstance, use an overlay system for the higher frequencies, engineered for specific coverage requirements.  With the SOLiD Link Budget Analysis tool, you can easily analyze factors unique to your deployment to maximize capacity and coverage.

SOLiD ALLIANCE DAS provides a modular high output power C-Band remote and a lower power fiber-to-the-edge (edgeROU) solution for overlay applications.  The modular high output power (20W) remote supports all 380 MHz of licensed C-Band and Auction 110 spectrum with up to 2×2 MIMO in one chassis.  The edgeROU also supports the full C-Band with 2×2 MIMO and is available with integrated antennas or external antenna ports.  These options enable at least three approaches to add C-Band to your coverage infrastructure.  The high-power remote may be integrated with your existing DAS on a remote-by-remote basis if the existing remotes are 2W or 5W.  The edgeROU with integrated antennas may provide a complete overlay solution as simple as deploying Wi-Fi.  The edgeROU with external antenna ports may integrate with your existing DAS at each antenna location either with the existing antenna, if appropriate, or by replacing the antennas with a model that supports both legacy bands and the C-Band.

All of SOLiD’s C-Band amplifiers support the full instantaneous and occupied bandwidth.  Full band capability ensures that the system will support the initial spectrum allocations and later transitions when satellite incumbents release the upper end of the band in 2023.

To ensure that your in-building DAS platform is ready for 5G service in the C-Band, select a solution that supports the full C-Band frequency allocation from day one, with multiple output power options to meet the unique needs of your venue.

Transition to Tomorrow

As 5G advances and new frequency bands become available, in-building wireless systems need to keep pace or be left behind.  Today’s building tenants and enterprise employees expect excellent quality of service everywhere, even indoors, and 5G is no exception.  Are you ready to support the C-Band to take advantage of the true 5G promise?

To learn more about how to upgrade your in building DAS system to fully realize 5G, watch our webinar “Are you ready for 5G mid-band?”