More on 5G Standards

I wrote a blog last week about the new 5G standard being developed by the International Telecommunications Union (ITU). This standard is expected to be passed this November. However this standard is not the end of the standards process, but rather the beginning. The ITU IMT-2020 standard defines the large targets that define a fully developed 5G product. Basically it’s the wish list and a fully-compliant 5G product will meet the full standard.

But within 5G there are already a number of specific use cases for 5G that are being developed. The most immediate three are enBB (enhanced mobile broadband, or better functioning cellphones), URLLC (ultra-low latency communications to enhance data connectivity) and mMTC (massive machine type communications, to communicate with hordes of IoT devices). Each use case requires a unique set of standards to define how those parts of the 5G network will operate. And there will be other use cases.

The primary body working on these underlying standards is the 3GPP (3rd Generation Partnership Project). This group brings together seven other standards bodies – ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC – which demonstrates how complicated it is to develop a new wireless technology that will be accepted worldwide. I could talk about what each group does, but that would take a whole blog. Each standards group looks at specific aspects of radio communications such as the modulating schemes to be used, or the format of information to be passed so that devices can talk to each other. But the involvement of this many different standards groups explains a bit about why it takes so long to go from a new technology concept like 5G to functioning wireless products.

There is currently a lot work being done to create the specific standards for different portions of a 5G network. This includes the Radio Access Network (RAN), Services and System Aspects (SA) and Core Network and Terminals (CT).

The 5G RAN group, which looks at radio architecture, began work in 2015. Their first phase of work (referred to as Release 15) is looking at both the eMBB and the URLCC use cases. The goal is to define the specific architecture and feature set that is needed to meet the 5G specification. This first phase is expected to be finished in the fourth quarter of 2018. The 5G RAN group is also working on Release 16, which looks more specifically at getting radios that can comply with all of the aspects of IMT-2020 and is targeted to be completed in December of 2019.

The 5G SA group has already been actively working on the services and systems aspects of 5G. The preliminary work from this group was finished last year and final approval of their phase 1 work was just approved at the Mobile World Congress. But the SA group and the RAN group worked independently and it’s expected that there will be work to be done at the end of each phase of the RAN group to bring the two groups into sync.

The work on the core network has begun with some preliminary testing and concepts, but most of their work can’t be started until the RAN group finishes its work in 2018 and 2019.

The reason I am writing about this is to demonstrate the roadblocks that still remain to rolling out any actual 5G products. Manufacturers will not commit to making any mass-produced hardware until they are sure it’s going to be compatible with all parts of the 5G network. And it doesn’t look like any real work can be done in that area until about 2020.

Meanwhile there is a lot of talk from AT&T, Verizon and numerous vendors about 5G trials, and these press releases always make it sound like 5G products will quickly follow these trials. But for the most part these trials are breadboard tests of some of the concepts of the 5G architecture. These tests provide valuable feedback on problems developed in the field and on what works and doesn’t work.

And these companies are also making 5G claims about some technologies that aren’t really 5G yet. Most of the press releases these days are talking about point-to-point or point-to-multipoint radios using millimeter wave frequencies. But in many cases these technologies have been around for a number of years and the ‘tests’ are attempts to use some of the 5G concepts to goose more bandwidth out of existing technology.

And that’s not a bad thing. AT&T, Verizon, Google and Starry, among others, are looking for ways to use high-bandwidth wireless technologies in the last mile. But as you can see by the progress of the standards groups defining 5G, the radios we see in the next few years are not going to be 5G radios, no matter what the marketing departments of those companies call them.

Standards for 5G

itu_logo_743395401Despite all of the hype that 5G is right around the corner, it’s important to remember that there is not yet a complete standard for the new technology.

The industry just took a big step on February 22 when the ITU released a draft of what it hopes is the final specification for 5G. The document is heavy in engineering detail and is not written for the layman. You will see that the draft talks about a specification for ‘IMT-2020’ which is the official name of 5G. The goal is for this draft to be accepted at a meeting of the ITU-R Study Group in November.

This latest version of the standard defines 13 metrics that are the ultimate goals for 5G. A full 5G deployment would include all of these metrics. What we know that we will see is commercial deployments from vendors claiming to have 5G, but which will actually meet only some parts of a few of these metrics. We saw this before with 4G, and the recent deployment of LTE-U is the first 4G product that actually meets most of the original 4G standard. We probably won’t see a cellular deployment that meets any of the 13 5G metrics until at least 2020, and it might be five to seven more years after that until fully compliant 5G cellular is deployed.

The metric that is probably the most interesting is the one that establishes the goal for cellular speeds. The goals of the standard are 100 Mbps download and 50 Mbps upload. Hopefully this puts to bed the exaggerated press articles that keep talking about gigabit cellphones. And even should the technology meet these target speeds, in real life deployment the average user is probably only going to receive half those speeds due to the fact that cellular speeds decrease rapidly with distance from a cell tower. Somebody standing right next to a cell tower might get 100 Mbps, but even as close as a mile away the speeds will be considerably less.

Interestingly, these speed goals are not much faster than is being realized by LTE-U today. But the new 5G standard should provide for more stable and guaranteed data connections. The standard is for a 5G cell site to be able to connect to up to 1 million devices per square kilometer (a little more than a third of a square mile). This, plus several other metrics, ought to result in stable 5G cellular connections – which is quite different than what we are used to with 4G connections. The real goal of the 5G standard is to provide connections to piles of IoT devices.

The other big improvement over 4G are the expectations for latency. Today’s 4G connections have data latencies as high as 20 ms, which accounts for most problems in loading web pages or watching video on cellphones. The new standard is 4 ms latency, which would improve cellular latency to around the same level that we see today on fiber connections. The new 5G standard for handing off calls between adjoining cell sites is 0 ms, or zero delay.

The standard increases the demand potential capacity of cell sites and provides a goal for the ability of a cell site to process peak data rates of 20 Gbps down and 10 Gbps up. Of course, that means bringing a lot more bandwidth to cell towers and only extremely busy urban towers will ever need that much capacity. Today the majority of fiber-fed cell towers are fed with 1 GB backbones that are used to satisfy upload and download combined. We are seeing cellular carriers inquiring about 10 GB backbones, and we need a lot more growth to meet the capacity built into the standard.

There are a number of other standards. Included is a standard requiring greater energy efficiency, which ought to help save on handset batteries – the new standard allows for handsets to go to ‘sleep’ when not in use. There is a standard for peak spectral efficiency which would enable 5G to much better utilize existing spectrum. There are also specifications for mobility that extend the goal to be able to work with vehicles going as fast as 500 kilometers per hour – meaning high speed trains.

Altogether the 5G standard improves almost every aspect of cellular technology. It calls for more robust cell sites, improved quality of the data connections to devices, lower energy requirements and more efficient hand-offs. But interestingly, contrary to the industry hype, it does not call for gigantic increases of cellular handset data speeds compared to a fully-compliant 4G network. The real improvements from 5G are to make sure that people can get connections at busy cell sites while also providing for huge numbers of connections to smart cars and IoT devices. A 5G connection is going to feel faster because you ought to almost always be able to make a 5G connection, even in busy locations, and that the connection will have low latency and be stable, even in moving vehicles. It will be a noticeable improvement.

What is 5G?

Cell-TowerThe International Telecommunications Union (ITU) has created an official plan to bring 5G data to the market by 2020. So what is 5G and how does it differ from 4G? The goal of 5G is to increase the data capacity of cell sites, reduce latency, and increase the distance that can be served from a cell site. The goal of 5G is to build a wireless data path with built-in intelligence that can maximize the data delivery to a given handset or device. There is no specific bandwidth goal in the 5G plan, but it’s assumed to be a lot faster than today’s 4G networks.

But there are a lot of challenges to overcome to get to that future vision. Delivering more bandwidth is going to require more spectrum. Every slice of spectrum in use has limitations imposed by physics, and since today’s spectrum is already stressed, achieving 5G will mean adding more bands of spectrum into the cellular network.

It looks like the ITU is depending upon using both existing WiFi spectrum as well as a lot of higher frequencies that are not in use today. I’ve recently written about the wireless industry’s hope of poaching existing WiFi spectrum and I hope the FCC stops that attempt in its tracks. If 5G is ever allowed to use WiFi then that spectrum will quickly become a cellular spectrum that won’t be useful for anything else.

There is a lot of development work to be done to use higher frequencies, particularly for handsets. The higher the frequency used, the bigger the challenge to hold a connection with a non-fixed receiver like a handset. Even if they solve these issues, the higher frequencies they are considering, by definition, travel very short distances, and so the higher frequency portion of 5G will only benefit those very close to a cell site. This might be a great solution inside of a convention center, but not so much in the outside world.

What all of this means is that a 5G network is going to require a lot more cell sites packed closer together than today’s network. That has a lot of implications. First, it means a lot more investment in towers or in mini-cell sites of some type. But it also means a lot more fiber to feed the new cell sites. And those two factors together mean that any 5G solution is likely to be an urban solution only, or a suburban solution only for those places where a lot of users are packed tightly together. No wireless company is going to invest in a lot more 5G towers and fiber to cover suburban housing sprawl and certainly nobody will invest in the technology in rural areas.

We already have a cellular wireless divide today with urban areas getting pretty decent 4G and rural areas with 3G and even some 2G. Expect that gulf to become greater as high-bandwidth technologies come into play. This is the big catch-22 of wireless. Rural jurisdictions have always been told to wait a while and not clamor for fiber because there will eventually be a great wireless solution for them. But nobody is going to invest in rural 5G any more than they have invested in rural fiber. So even if 5G is made to work, it’s not going to bring a wireless solution to anywhere outside of cities.

I’ve read a number of technologists who are skeptical about the targeted 2020 date for 5G, but it’s the nature of progress to set aggressive goals in order to goad improvement. But when you look at all of the issues that must resolved to implement 5G, 2020 looks unrealistic.

Instead, what is likely to happen is that the carriers will implement some pieces of 5G over time as each technological challenge is solved. This means we are likely to see a whole series of incremental upgrades over the next decade rather than one big flash-cut to a faster data network. This will provide numerous marketing opportunities and I would expect that by the time that the ITU’s version of 5G is fully implemented we will be calling it 10G. After all, we are still a long way from meeting the original specification for 4G, which was to implement 100 Mbps data speeds for a moving user in a car and 1 Gbps for a stationary user. Even the planned 5G isn’t going to do that.