5G deployment: why C-band is so important


After all the regulatory wrangling, aviation industry panic, and last-minute delays, C-band spectrum is finally live on carrier networks AT&T and Verizon in the United States. At this point, you might be so overwhelmed with coverage of potential dangers that you’ve forgotten what the technology could offer you and other smartphone owners across the country. Let us shed some light by explaining the current 5G landscape and showing you exactly why C-band is so important.

The flavors of 5G

The carrier frequencies that power 5G and earlier mobile networks can generally be divided into three categories:

  • Low band: anything below 1 GHz.

  • Midband: Anything between 1 GHz and 6 GHz. This range is where the C band lives (3.7 GHz to 3.98 GHz in the US).

  • High Band: Anything above 6 GHz, including mmWave signals, which operate between 30 GHz and 300 GHz.

5G services currently offered by T-Mobile, AT&T, and Verizon Wireless operate in all three categories, although only T-Mobile uses low-band 5G frequencies (600 MHz, specifically).

Why so many groups?

Wireless signal frequencies have different characteristics depending on whether they are low or high on the spectrum.

Generally speaking, the lower the frequency, the farther the signal can travel from its cell tower and the better it penetrates buildings. This is especially important in rural environments with widely spaced towers and in urban environments where cell phones are often embedded deep in reinforced concrete buildings. The trade-off is that the lower the frequency, the lower the data transmission speed it can typically provide.

On the other end of the spectrum, the high band frequencies, especially the mmWave bands, are great for delivering extremely fast speeds, but terrible for reaching very far or entering buildings. This is because the ultra-fast signal oscillations of high band transmission are extremely susceptible to degradation when traversing only a few hundred feet of open air or a single concrete wall.

How has each carrier handled these limitations?

Each of the “big three” U.S. carriers has historically handled the limitations and tradeoffs of low-band, mid-band, and high-band 5G frequencies differently.


Why is my 5G so slow? Compare hype to reality


Verizon’s solution was to roll out very fast, but very geographically limited, 5G service areas. While its speeds could easily exceed 1 Gbps under ideal circumstances, those speeds were typically only available within a few blocks of an mmWave tower, assuming an unobstructed line of sight. This resulted topping T-Mobile in some regional speed tests, while trailing nationally due to the fact that the majority of its nationwide 5G is powered by what is essentially multiple 4G LTE connections combined into a single data stream.

Verizon actually recognizes on its own coverage map that its “Nationwide 5G” service “works alongside Verizon 4G LTE, with similar performance.” Essentially, it’s 5G that works like 4G LTE because it’s 4G LTE in all but name. Most such connections would be lucky to exceed 50 Mbps under real world conditions.


T-Mobile’s 5G network is, by almost any measure, the most widely available in the United States. This is due, in large part, to its choice to rely on low (600 MHz) and mid-band (2.5 GHz) broadband spectrum. The 600 MHz part was its own build, while the 2.5 GHz components were originally acquired as part of its purchase of Sprint. Since both frequencies offer excellent range and penetration, and 2.5 GHz can be used to transmit an impressive amount of data, T-Mobile can provide an average, at national scale speeds of 150 Mbps.


Like Verizon, AT&T offers mmWave 5G service. As you would expect, these services are very fast and very limited in scope. The company also uses 850 MHz connections, which exist on the slower but more extensive end of the spectrum. Unfortunately, this combination of low-band and high-band deployments prevented it from delivering the ubiquitous blend of range and speed that T-Mobile has achieved through mid-band deployments, earning it third place in many many recent 5G tests.

So how does C-Band compare?

C-Band is considered by many analysts to be the ultimate “sweet spot” for wireless spectrum. It can provide an ideal balance between range, penetration and transmission speeds. Early testing by our sister site CNET showed that these speeds on Verizon’s network can reach up to 1.4 Gbps when directly under a tower, with a more realistic 400 Mbps easily achievable over an impressive geographic area. Illustrating the versatility of C-Band, CNET was also able to achieve a consistently respectable 90 Mbps, even deep within an underground parking structure.

AT&T’s much smaller initial rollout received similar, if rarer, praise due to the inclusion of far fewer markets.

T-Mobile, of course, knows it will face competition from C-Band. While its exact plans remain somewhat hazy, its midband 2.5GHz deployments are close enough to the C-band range to already deliver many of the same benefits. CNET found that T-Mobile’s established network can already deliver a very similar 400 Mbps in the same dense urban areas as Verizon’s new C-Band offering, while its slightly lower frequency pushed an even more impressive 100 Mbps. in this same underground parking scenario. .

And after?

While the fate of C-band deployments near airports in the United States remains somewhat unclear, it’s back on the table thanks to a deal between the Federal Aviation Administration, AT&T and Verizon Wireless. It remains to be seen exactly which airports will receive approval and how extensive these service areas will be.

In the meantime, expect 5G C-band to proliferate across the rest of the country like wildfire. Verizon has already massively expanded its own true 5G with its initial launch, while AT&T has similar designs, albeit a bit slower. T-Mobile, meanwhile, will likely continue to expand and leverage its current 2.5GHz network to maintain its own bid for 5G leadership.

Ultimately, the big winners here will be consumers. As a whole new leg of the wireless network arms race begins to heat up, C-Band will be the first glimpse many Americans have of the promised 5G speeds we’ve been hearing about for so many years.


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