Why mid-band matters.

To understand how useful mid-band spectrum is, it helps to consider the three primary usage categories in the planned evolution of 5G. Current and future use cases for 5G can be categorized into three main buckets: enhanced mobile broadband (eMBB), critical IoT with ultra-reliable low-latency communication (URLLC), and massive IoT with massive machine-type communication (mMTC). Mid-band spectrum is the one flavor of 5G that’s likely to be employed for all three of these usage categories.

Category 1: enhanced mobile broadband (eMBB).
The eMBB usage category is what it sounds like: an iterative enhancement of the mobile broadband we’re already familiar with. So its use cases include phones, tablets, hotspots, laptops, and fixed wireless. The high-speed upload and download capabilities will also support initial augmented reality use cases and mobile work applications like virtual desktops or digital workspaces.

Faster throughput and much greater capacity will make applications with dense data types, like video, work better and more smoothly. To achieve this, the eMBB usage category will use mid-band along with low- and high-band spectrum.

One of our big advantages over our competitors is a durable lead in our network buildout and coverage. Here’s why.

For some time, we’ve been using a “layer cake” analogy to describe the network approach we pioneered. It’s a strategy our competitors are gradually adopting as they realize the limitations of relying too heavily on high-band spectrum to build out a 5G network.

The analogy works like this. Think of low-band spectrum as the bottom foundation layer of the cake. It has a long reach, with the ability to cover very large areas and penetrate walls. With it, we can bring 5G virtually everywhere across the country, even to far-flung places like small towns and rural areas. The tradeoff is it doesn’t deliver the fastest speeds of the frequencies higher up in the spectrum.

The top layer of the cake is high-band mmWave spectrum, which is super fast and has enormous capacity, but doesn’t travel very far and requires a direct line of sight between the user and the radio. As you can imagine, the signal is easily obstructed. But because of its capacity, it’s good for high-density situations like a bustling city street corner or a crowded stadium.

Once 5G matures, when you’re out in the country and you reach the suburbs, you won’t just suddenly switch from low-band to mid-band; rather, you’ll get both stacked together. And when you continue into the city to an area covered by mmWave, that high-band spectrum will be added to the low- and mid-band spectrum that covers that same area too, so you’ll have access to all three bands.

This is thanks to a technology called carrier aggregation. T-Mobile has already started to use carrier aggregation, combining two channels of our mid-band 2.5 GHz Ultra Capacity 5G spectrum to increase capacity. Additionally, we’ve expanded carrier aggregation of 2.5GHz and 600 MHz to cities across the country. The upshot of all this: a significant boost in speed and performance for our customers.

The vast amount of spectrum and wider set of spectrum bands available to be stacked together are unique to 5G. These are among the factors that give the network flexibility to operate in more environments and support a much broader range of use cases than 4G. Mid-band is critical to 5G spectrum because it bridges the speed, capacity, coverage, and penetration gaps between low-band and mmWave.

With that balance of speed, capacity, coverage, and penetration, a rich 5G mid-band network offers more versatility and more utility than any network that’s lacking in mid-band spectrum.