What is 5G: A Primer


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What is 5G? Part One

This is a brief on 5G. What is is, and how it will be implemented. I’ve been wanting to write this for some time and I’m hopeful that this in some way informs more folks, who will then will be better able to carry on an intelligent conversation about the topic going forward. This is not in any way an attempt to debunk anything, but only an attempt to inform. In that vein I have taken some liberties with the link policy as this is an attempt to educate rather than prove or disprove a factual point.

Other than a couple of diagrams, I’m going to post the external reference links as a bibliography at the bottom.

So, what is 5G? A History Lesson

Simply put, it’s the next evolution in mobile cellular technology. 2G technology was primarily about making phone calls better. With the switch from analog calls (1G), to digital calls it also allowed texting/messaging (SMS and MMS, as well as small images).

3G was all about increasing and adding cellular data capabilities. It was introduced in 2001, but, when the first iPhone was released in 2007-8, it didn’t even fully support 3G’s 4x data speeds. The initial success of mobile data devices that were produced and consumed in the succeeding years drove cellular data demand upwards exponentially.

That led to the 4G LTE specification in 2009 and it took off in a hurry. While current statistics on 4G are impressive, keep in mind that more than a decade later, worldwide 4G adoption is still well under 50%.

I’ll use 4G and 4G LTE interchangeably from here on, although note that the first rollout of 4G and 4G LTE (Long-Term Evolution) are different technologies and only 4G LTE carries forward to 5G. Originally, LTE was a marketing term that carriers introduced to indicate that, over the long term, they were evolving to full 4G, which included benchmark speeds of 100 Mbps. A decade later, very few carriers and geographical areas can achieve the benchmark speeds. Long-Term indeed. The 4G LTE labelling and implementation plans also allowed phone manufacturers and service providers to charge a lot more money for their services and some have speculated that that led the the tie-in between cellular carriers and phone manufacturers, as the phones became much more expensive to manufacture and thus unaffordable to many.

That brings us to 5G. Just like the other generations before it, 5G is an evolution of the previous generation, 4G, and the focus is almost entirely on mobile cellular data speeds. At its most basic, it’s a specification that defines the required technology so that vendors can build an infrastructure that provides compatibility with existing infrastructure while moving towards the specified goal of massively enhanced mobile cellular data, as much as 600x what the typical user sees from 4G and maybe 10x what Google Fiber users sees at home. It also promises much lower latency, which is the lag time between your device and the resource (web site or data) you are trying to access. The goal is to drop the current urban latency from about 50ms to 1ms. As we’ll get to later, 5G is in its infancy right now, so you might want to consider this a goal rather than a product.

How does a cellular network, work?

I think it’s best to contrast 5G by starting with how today’s 4G network functions. That seems to be the easiest way to point out how 5G is different.

First, a general cellular network diagram from: https://www.conceptdraw.com/solution-park/computer-networks-telecommunication

In this diagram your cell phone, on the left, connects to a cell tower, which is called a base station, mostly because transmitters & receivers are now mounted on buildings instead of towers. When you turn your mobile phone on, the cellular chipset, the SIM card, and the operating system all conspire to exchange enough information to connect you to the strongest signal, and make sure you’re authorized to use the system, i.e., you’ve paid your bill, you have roaming privileges, etc.. Ignore all orange & blue the stuff to the right of the blue base station (generally called the Mobile Central Office or MCO in the US), but suffice it to say that when you enter a phone number, or open a browser or mobile app, the base station and all that other stuff routes you to one of the blue clouds on the far right.

The base stations also contain multiple transmitters and receivers so that they can connect with the widest range of cellular mobile devices as possible; and that your online activity goes to either the Public Switched Telephone Network, or the Internet, the blue clouds. Both are routed, metered, and logged by the MCO to make this happen and to make sure you get an expensive invoice every month from your cellular carrier.

Now, how is 5G different?

Let’s start with the vision for the infrastructure. Here is a diagram to get you started: https://www.researchgate.net/figure/A-general-5G-cellular-network-architecture_fig19_280873356

There’s a lot going on here, partly because I couldn’t find a 4G and 5G diagram done by the same artist, but let’s start with what’s the same. The base station is still here on the middle left. That’s the blue tower in the diagram. That base station will use both 4G LTE and 5G radio technology. Today, they’re almost entirely 4G so your first 5G phone will use 4G LTE base stations, but some will be upgraded to use 5G signals. This is how it was rolled out in South Korea and what is in progress in the US.

The MCO that I told you ignore in the 4G diagram is shrunken down into the pink/fuchsia boxes scattered about the diagram. There is more MCO gear than before but we can still ignore it for now because it more or less does the same thing it did before. The PSTN is missing from this diagram, but a flaw in the diagram as the PSTN is still there. Remember that 5G is all about data, so this diagram is all about the data and ignores the phone calls. One potential benefit of 5G is that carriers could increase call quality but none of them are touting this benefit so I question whether they have plans to do so.

What’s with all the new stuff? Here’s where it gets interesting. The most important change, at the moment, is all those bright lime green mini antennae called Mobile Small Cell Network (MSCN). There’s also a Small Cell that you can install in your house, for example, just like your WiFi router today. If you search the internet for 5G components you will also turn up the term “Femtocell”, which seems to be more widely used outside the US. While you’re looking at those lime green parts, please also note the red and orange dotted lines called Control Plane and Resource Link. The MSCN will use MIMO technology (Massive Input Massive Output) which allows it to run your data across multiple high speed antennae at once, greatly increasing bandwidth (i.e. data transfer rate). You may have a MIMO WiFI router in your house right now and if your mobile tech is up to date, you may already be taking advantage of the extra antennae with standard WiFi.

The way 5G enhances data speeds is that when your phone and the network do their connection conspiracy dance, the network and phone also exchange information about whether your phone is capable of 5G, how much of the standard does it use, whether the base station and MCO can “do” 5G and to what degree, and whether your phone is in range of a Mobile Small Cell Network (MSCN) or Small Cell (AKA Femtocell). If you request a phone call, it proceeds as it did in 4G. If you request data, and all the phone and network infrastructure align, the Control Plane takes your 4G request and redirects all your upload and download data to the MSCN. The Resource Link allows the 4G components to connect you to the Internet resource you want, and maintain that link, without further involvement on the part of the 4G Control Link portion of the diagram. We’ll get technical in Part 2, later, but that essentially means your phone calls work the same as before, but your data takes an entirely different path, and even uses a different antenna and different MCO infrastructure.

The other interesting opportunities on the diagram are Internet of Things (IOT) and Device-To-Device (D2D) networking and relay. The legend on the right side of the diagram gives you plenty of jargon to Google. I like D2D because it literally allows you to use someone else’s better connection to get faster data throughput, but quite frankly, even if I don’t get charged for it and it’s secure, I have a hard time imagining that I will give up battery life to enhance someone else’s movie experience at the mall.

Technical Lite

Now let’s hit the high level technical details on how this really works. As I mentioned earlier, the whole 5G promise is a conspiracy sales effort collaboration between cell phone manufacturers, chipset manufacturers, cellular service providers, and your government. It’s dependent on device compatibility, cellular network infrastructure, and government cooperation.

The milestones to reaching 5G nirvana are interleaved in a chicken and egg manner. To have full 5G and achieve the ultimate bandwidth and latency objectives, you need the phone (or other cellular device, IOT or not), some or all of the chips in that phone, a 5G carrier network, and government permission to use more radio spectrum than is currently used under 4G.

As far as phones, Apple was planning on introducing their first 5G chipset in 2020 but that is now questionable due to coronavirus issues. Android-based 5G phones were introduced last year, and I have only done initial research into how much support those phones and chipsets provide, but they appear to be limited to Asia and the Middle East, with some inroads in Europe and some initial support in New York City.

Today, in the US, service providers like AT&T and Verizon are upgrading their base stations in urban areas to enhance the network. The first step toward 5G is adopting the frequency standard of 5G which means doubling the frequency of the radio side of the equation, which in turn doubles the bandwidth of the connection. Unfortunately, that also halves the physical distance the base station covers. That means you have to increase the power output to maintain the same coverage. Check my inverse square law math on this but I think the means 4x the power just to maintain the same geographical cell coverage.

I’ve also seen discussions about implementing MIMO on the base station antennae, but details are sparse and probably proprietary, but that would increase the power requirements even further as each antenna now needs 4x the power to multiple antennae. The GSMA document in the references below estimates that about $200 billion will be required to upgrade all the base stations in the US, which, they say, means you shouldn’t expect 5G base stations across the country any time soon.

Other than power, the network also needs a larger data pipeline between the base station and the MCO. They call this backhaul. The MCO resides in a Proprietary Data Center (PDC) and the link between the base station and the PDC is owned or leased by the carrier/provider. The PDC might also need to acquire more bandwidth from the PDC to connect the MCO to the Internet. Cheap if you’re AT&T and own part of the Internet, but expensive if you’re lower down in the internet carrier hierarchy. Backhaul also includes power for the aforementioned geographical footprint, so the net cost and effort impact is significant.

Anecdotally, I live in a semi-rural area, served by base station towers. Over the last 9 months, I have observed a long-term project which saw a microwave relay tower on a nearby hillside upgraded and major changes done to our local cell tower. Being rural, there are no wires for that cellular backhaul to the MCO so we use microwave towers that beam the signal to and from the MCO in the nearest town. In talking to the workers at the relay, they upgraded the microwave antennae, built a building to hold power and MCO components, and then built a series of power poles up the side to the hill to bring them enough power to run the whole thing. Work appears to be nearing completion as of this writing and I recently received a mailer from a local internet provider offering astounding speeds if only I would switch. Last week, we began experiencing cellular outages for several days as a crane, clearly visible on the mountain, began replacing the various cellular antennae on the nearby cellular tower. The net results was a large increase in the number of antennae, and just last week, the installation via helicopter of another microwave antennae on the tower itself.

Time to move on to a write-up of the technical details in Part 2. Before I do that, here is my bibliography for the narrative so far. I have been designing and implementing internet and data communications technologies since the 80’s. I also worked for the telecoms in the early 2000’s designing and implementing cloud computing resources including both public and private cloud infrastructure, premises connections and mobile. I currently design and develop big data, analytics, and machine intelligence systems, in the internet, cloud, and on premises, for organizations throughout North America. If you dispute any of my assertions, please quote the exact phrases you dispute to avoid confusion. I will confess up front that I will probably agree with you on any detail you wish to clarify as I realize that I have taken liberties while attempting to simplify this primer. There are also competing visions of the "standards" which make any type of middle-of-the-road primer a bit problematic.

Here are the references:

A lightweight history of the evolution of mobile standards: https://www.brainbridge.be/news/from-1g-to-5g-a-brief-history-of-the-evolution-of-mobile-standards

Another take on history: https://www.wired.com/story/wired-guide-5g/

A somewhat cynical, but nonetheless accurate take on the technology: https://www.wilsonamplifiers.com/blog/the-difference-between-4g-lte-and-5g/

Kind of a side track, but I found this one while looking for network diagrams. The captions on the diagrams provide different views into all sorts of networks and their components:

This one is link to a PDF from GSMA, a mobile industry group which appears to be involved in technical and standards advocacy. Initial sections cover the promises of 5G and then it goes into a decent level of detail on how this will all work together to deliver on those promises. The top site, gsma.com, has a lot of interesting information about technology and advocacy. Here is the link to the PDF I used as source: https://www.gsma.com/wp-content/uploads/2019/04/The-5G-Guide_GSMA_2019_04_29_compressed.pdf

Technical 5G: Stay tuned

The promise of 5G is that all these technologies will evolve and be implemented based on the massive increases in data bandwidth and low latency. The reality is that the current and future state are over-stated and that the technology is misunderstood. The next part will attempt to describe what is currently being implemented, and how.