01 January 2021
I recently finished up my Masters in Engineering at Cornell University in Ithaca, NY. As part of the graduation requirements, candidates are expected to work on a design or research project in an area of their choosing. My project, entitled “5G Deployment in the United States: Considerations, Challenges, and Concerns with a Focus on End-User Experience,” dealt with the practicalities and expectations of 5G deployments across America. I’ll be summarizing some of my research in this post and a few more posts to come
5G, as implied by the name, is the fifth generation of cellular networks. Unlike carriers and marketing experts would have you believe, 5G is not a singular fix-all technology; rather, 5G is a collection of some really cool technological evolutions and one massive revolution, but we’ll get to the specifics later. For now, know that 5G isn’t going to singlehandedly bring us self-driving cars, robotic surgery, or even multi-gigabit download speeds for all–at least not right this moment. 5G, much like the decade of 4G (LTE) rollout before it, will take time to reach end users, only reaching its full utility once it becomes truly ubiquitous.
As an aside, you’ll often see download speeds quoted as a key feature of 5G. They definitely are, but it’s important to know how they’re calculated and presented. As these measurements are typically measured in bits per second, it’s important to remember that 1 byte = 8 bits, and 1 Mbps is 1 Million bits per second, and 1 Gbps is 1 Billion bits per second. If we assume an average HD movie to be about 5 GB, a 1 Gbps connection would download the movie in 5•8/1 = 40 seconds. A 100 Mbps connection would download the movie in 5•8/0.1 = 400 seconds. Similarly, if we assume an average photo taken on a phone is about 5 MB in size, given one minute = 60 seconds, a 1 Gbps connection could download 1500 photos in one minute, while a 100 Mbps connection could download 150 photos in the same minute.
At the risk of sounding too critical, 5G brings a massive set of improvements to end-users. For most, access speeds should be improved, with the greatest improvements available in dense, congested areas, like airport terminals, stadiums, and city streets. In all other everyday cases, access speeds should average marginally better than the latest iteration of 4G LTE (LTE Advanced Pro). Higher efficiency in radio wave capacity should eventually allow greater capacity to each individual user, minimizing waste and providing benefit to the user in the form of more consistent access speeds.
It’s also worth revisiting some history of cellular technologies.
Now that you’re thoroughly confused, let’s talk more about what 5G does (and does not) bring to the table. We can generally classify 5G as two different flavors: high-band and low-band (there’s really three, but we’ll discuss that in a later post).
We’ll discuss specifics in a later post as well, but, for now, know that high band 5G refers to the flavor of 5G known as millimeter wave (mmWave). It’s marketed as 5G+ by AT&T or 5G Ultra-Wideband (5G-UWB) by Verizon; these refer to the same set of technologies and aren’t different from each other. mmWave 5G brings super fast, ultra high speed download speeds to handsets. In the best-case, I’ve seen speeds as high as >3 Gbps (3000 Mbps) or nearly 20x the average home broadband download speed in the U.S. In more average cases, I’m seeing speeds in the 200-600 Mbps range.
While these speeds are very impressive, it’s important to note a giant caveat that mmWave 5G has. Due to the high frequency nature of the radio waves it uses, high-band mmWave 5G cannot propagate easily through walls, glass, or really anything in sight. It may seem weird to think about, but radio waves are really just energy waves traveling all throughout space. You can’t see them, but they’re there nonetheless. All radio waves have a physical property by which their propagation distance (how far they can reach) is inversely proportional to their frequency (with higher frequencies comes lower reach). 5G mmWave, by nature, uses higher frequencies than ever used by cell phones before. At frequencies upwards of 5-10x higher than Wi-Fi, their propagation distance is extremely limited, but more than that, the signal doesn’t pass through buildings, glass, or even people. This essentially means that you need (or your phone, rather) needs to “see” (have unobstructed line-of-sight to) the cell tower. In my own limited field testing, I found a 2-3x reduction in speeds just by turning my back to the cell tower.
the signal doesn’t pass through buildings, glass, or even people
In order to combat this, carriers are building more cell sites (micro-cell sites) than ever before, completely lining city blocks and dousing streets in mmWave 5G. This does however mean that reach is limited entirely to right next to where the mmWave site has been deployed, which is only in dense cities for now. There’s also another technology, called beamforming, that offers a little bit more “smarts” when it comes to directing the signal towards your phone. Still, with densest areas likely the highest benefactors of additional bandwidth (more data capacity), mmWave 5G is poised to provide more bandwidth than ever before, if you can find it.
Low-band 5G, on the other hand, is much more ubiquitous and is likely the 5G that users will interact with the most. As we’ve discussed briefly, the propagation distance of radio signals is inversely proportional to the frequency. Low-band 5G uses frequencies similar to that of 4G LTE, and in some cases it even overlaps with current LTE deployments. Because of this, low-band 5G can be practically available anywhere where there’s a current LTE deployment–basically nationwide. T-Mobile was the first carrier to launch it’s low-band 5G network, and, in fact, its entire 5G strategy initially hinges on low-band 5G. AT&T has its low-band 5G fully operational now as well, and Verizon recently launched its low-band 5G, dubbed “5G Nationwide.” Speeds on low-band 5G, initially, due to the fact that the carriers are supporting LTE and 5G simultaneously, aren’t drastically better than LTE and in some cases, are even slower than the 4G network it’s replacing. This is due to another 5G technology called dynamic spectrum sharing (DSS), and while we’ll explain more in a separate, more detailed post, think of it as analogous to sharing lanes on a highway. Let’s say we have a five lane road with fast lanes and slow lanes separated by a median. The fast lanes here are 5G, the slow lanes 4G, and the entire road the set of spectrum (frequency) allocated to the mobile network. Let’s also say we have a set of cars driving on this road that represent user’s phones. Initially, since there are more 4G cars (phones), carriers are allocating more lanes to 4G, and fewer to 5G, since there just aren’t that many users with 5G phones at the moment. Since we’re all sharing the same highway, it inevitably becomes a balancing act to figure out how to alleviate and best allocate the lane balance. Since 5G phones have fewer lanes, that means more congestion and fewer ways to spread out and go faster, while the 4G lanes enjoy the majority of the space. Over time, as 5G phones reach more and more adoption, the lanes will be reallocated, and the carriers will shift the median accordingly; eventually the 5G side will become much faster, phasing out the 4G lanes altogether. This isn’t exactly spot on, and there are a couple ways for carriers to do this spectrum sharing, but this is a working start for understanding.
It’s important to note that this phenomenon only occurs on low-band 5G since it shares the existing allocated frequencies with 4G LTE. High-band mmWave 5G introduces a whole new highway altogether, eliminating the sharing problem.
Carriers are also pulling another set of shenanigans with the rollout of 5G. In 2011, when 4G LTE rolled out, anyone with a 3G data plan simply received access to the upgraded technology. Now, with the rollout of 5G, and smartphones as ubiquitous as ever, carriers are using 5G as an incentive for users to upgrade to newer, in some cases more expensive, plans. For carriers like Verizon, users have to step up to more expensive, mid-to-high tier priced unlimited plans to even have access to mmWave 5G. This stratification in the market further confuses customers on legacy plans hoping to make use of their new phones. For users hoping to upgrade to the latest and greatest smartphone, 5G access has yet another hurdle, and in most cases, will require a complicated and potentially costly plan switch.
5G is making its way into U.S. networks and smartphones alike. 2021 will see an even greater rollout of novel 5G technologies, and as users begin to upgrade their phones, they’ll begin to see the LTE phase into 5G in their smartphone status bars. Still, the promises of low-latency, super-fast connectivity everywhere, and applications like self-driving cars just aren’t yet here today, but just as 4G LTE revolutionized the smartphone experience over the past decade, 5G stands to push that trend even further.
For more posts on my ongoing 5G research, visit here.