In context: One of the most confusing parts of new 5G cellular networks is recognizing that not all 5G is the same. In fact, it’s not even close. There are actually multiple “flavors” of 5G that are tied to different bands of radio frequencies (RF). In some ways, it’s kind of like a traditional radio with AM bands and FM bands, where each band can travel different distances at different quality levels, and there are specific frequencies assigned to different stations.
In the case of 5G, these different “flavors” vary dramatically in how fast they can deliver data and how far the signals can travel—in other words, their coverage area.
Diving deep into RF spectrum can be confusing, but the basics of it aren’t that tough to understand. Plus, they’re worthwhile to know—if nothing else, to impress your friends and family with your wireless knowledge! (if you are interested in more details on RF, here’s another piece I wrote on the topic.)
By the way, with previous “Gs”, like the current 4G LTE that most of us still use, we never really had to worry about this because most of the RF spectrum used for 4G was in a fairly limited range. With 5G, however, things are very different.
Initially, we were all told there would be two types of 5G signals: millimeter wave (commonly referred to as mmWave), which runs from about 24 GHz up to 39 GHz, and sub-6, which means frequencies below 6 GHz. In reality, however, we’ve learned that there are two important sub-segments of sub-6: low-band, which is typically under 1 GHz, and mid-band, which is typically in the 2.5-3.5 GHz range.
Mid-band frequencies offer a great compromise in that they can travel a mile or two and deliver about a 10x improvement over 4G—something most people would be happy with.
The reason this matters is easily measurable. Low-band frequencies, like the 600 MHz signals that T-Mobile is using for its newly completed nationwide 5G network, can travel for tens of miles from a cell tower. However, the speeds on low-band aren’t much different from 4G. Millimeter wave signals, on the other hand, have been used to deliver 50x greater speeds, but essentially only travel about a city block from a cell tower. Mid-band frequencies offer a great compromise in that they can travel a mile or two and deliver about a 10x improvement over 4G—something most people would be happy with.
In fact, most countries outside the US have adopted mid-band spectrum as the primary type of RF for their 5G networks. The problem in the US is that a great deal of the mid-band frequencies have been used by either various parts of the military, or other industries for many years. Understandably, they’ve been a bit reluctant to part with them. Recognizing the importance and global challenge in getting to 5G, however, the US government and military institutions have recently made several changes that will free up some of that radio spectrum. The result will be a dramatic reshaping and improvement of 5G networks in the US—though some of the changes are going to take few years.
The most recent development was an announcement made this week by the FCC that will allow an auction for 100 MHz of frequencies (from 3.45 to 3.55 GHz) in the highly desired mid-band range. This will allow companies like the major telcos, such as Verizon, AT&T, T-Mobile, etc., to bid on the usage of these frequencies. The auction isn’t scheduled until December 2021 however, and access to those signals won’t likely be available for consumer use until the summer of 2022.
Thankfully, this isn’t the only mid-band 5G frequency development that’s been planned in the US. In fact, an even bigger and much more important auction is scheduled this December for what’s called C-Band spectrum—a chunk of about 500 MHz (from 3.7 GHz to 4.2 GHz). This band has primarily been used for old-school large satellite dish TV services, but a portion of it is going to be switched over to 5G usage in several stages. Specifically, 280 MHz will be up for auction this December and the first 100 MHz of it will theoretically be available for use next summer and then the remaining 180 MHz at some point after that.
Finally, there’s yet a third interesting mid-band frequency spectrum development happening in the US called CBRS, or Citizens Broadband Radio Service, that’s going through an auction as we speak. Unlike the newly released 100 MHz band and the 280 MHz swath of C-Band spectrum—both of which will be broken up into chunks and licensed exclusively to certain carriers—CBRS has 150 MHz of spectrum (from 3.55-3.7 GHz) that can be used in a new shared, semi-licensed model. The details of CBRS can get complicated quickly, but suffice it to say that portions of it will also be used to enhance 5G mid-band spectrum here in the US—hopefully by sometime early next year.
The bottom line is that, after a slow start, there’s quite a bit of action and momentum around mid-band 5G spectrum in the US, and that should lead to significantly faster and more robust 5G networks in the near future. Lots of work still needs to be done, but the opportunities and potential for 5G to finally start delivering what we were promised are starting to look a lot better.