Gigabit LTE

Samsung just introduced Gigabit LTE into the newest Galaxy S8 phone. This is a technology with the capability to significantly increase cellular speeds, and which make me wonder if the cellular carriers will really be rushing to implement 5G for cellphones.

Gigabit LTE still operates under the 4G standards and is not an early version of 5G. There are three components of the technology:

  • Each phone has as 4X4 MIMO antenna, which is an array of four tiny antennae. Each antenna can make a separate connection to the cell tower.
  • The network must implement frequency aggregation. Both the phone and the cell tower must be able to combine the signals from the various antennas into one coherent data path.
  • Finally, the new technology utilizes the 256 QAM (Quadrature Amplitude Modulation) protocol which can cram more data into the cellular data path.

The amount of data speeds that can be delivered to a given cellphone under this technology is going to rely on a number of different factors:

  • The nearest cell site to a customer needs to be upgraded to the technology. I would speculate that this new technology will be phased in at the busiest urban cell sites first, then to busy suburban sites and then perhaps to less busy sites. It’s possible that a cellphone could make connections to multiple towers to make this work, but that’s a challenge with 4G technology and is one of the improvements promised with 5G.
  • The amount of data speed that can be delivered is going to vary widely depending upon the frequencies being used by the cellular carrier. If this uses existing cellular data frequencies, then the speed increase will be a combination of the impact of adding four data streams together, plus whatever boost comes from using 256 QAM, less the new overheads introduced during the process of merging the data streams. There is no reason that this technology could not use the higher millimeter wave spectrum, but that spectrum will use different antennae than lower frequencies.
  • The traffic volume at a given cell site is always an issue. Cell sites that are already busy with single antennae connections won’t have the spare connections available to give a cellphone more than one channel. Thus, a given connection could consist of one to four channels at any given time.
  • Until the technology gets polished, I’d have to bet that this will work a lot better with a stationary cellphone rather than one moving in a car. So expect this to work better in downtowns, convention centers, etc.
  • And as always, the strength of a connection to a given customer will vary according to how far a customer is from the cell site, the amount of local interference, the weather and all of those factors that affect radio transmissions.

I talked to a few wireless engineers and they guessed that this technology using existing cellular frequencies might create connections as fast as a few hundred Mbps in ideal conditions. But they could only speculate on the new overheads created by adding together multiple channels of cellular signal. There is no doubt that this will speed up cellular data for a customer in the right conditions, with the right phone near the right cell site. But adding four existing cellular signals together will not get close to a gigabit of speed.

It will be interesting to see how the cellular companies market this upgrade. They could call this gigabit LTE, although the speeds are likely to fall far short of a gigabit. They could also market this as 5G, and my bet is that at least a few of them will. I recall back at the introduction of 4G LTE that some carriers started marketing 3.5G as 4G, well before there were any actual 4G deployments. There has been so much buzz about 5G now for a year that the marketing departments at the cellular companies are going to want to tout that their networks are the fastest.

It’s always an open question about when we are going to hear about this. Cellular companies run a risk in touting a new technology if most bandwidth hungry users can’t yet utilize it. One would think they will want to upgrade some critical mass of cell sites before really pushing this.

It’s also going to be interesting to see how faster cellphone speeds affect the way people use broadband. Today it’s miserable to surf the web on a cellphone. In a city environment most connections are more than 10 Mbps today, but it doesn’t feel that fast because of shortfalls in the cellphone operating systems. Unless those operating systems get faster, there might not be that much noticeable different with a faster connection.

Cellphones today are already capable of streaming a single video stream, although with more bandwidth the streaming will get more reliable and will work under more adverse conditions.

The main impediment to faster cellphones really changing user habits is the data plans of the cellular carriers. Most ‘unlimited’ plans have major restrictions on using a cellphone to tether data for other devices. It’s that tethering that could make cellular data a realistic substitute for a home landline connection. My guess is until we reach a time when there are ubiquitous mini-cell sites spread everywhere that the cellular carriers are not going to let users treat cellular data the same as landline data. Until cellphones are allowed to utilize the broadband available to them, faster cellular data speeds might not have much impact on the way we use our cellphones.

5G Networks and Neighborhoods

With all of the talk about the coming 5G technology revolution I thought it might be worth taking a little time to talk about what a 5G network means for the aesthetics of neighborhoods. Just what might a street getting 5G see in new construction that is not there today?

I live in Asheville, NC and our town is hilly and has a lot of trees. Trees are a major fixture in lots of towns in America, and people plant shade trees along streets and in yards even in states where there are not many trees outside of towns.

5G is being touted as a fiber replacement, capable of delivering speeds up to a gigabit to homes and businesses. This kind of 5G (which is different than 5G cellular) is going to use the millimeter wave spectrum bands. There are a few characteristics of that spectrum that defines how a 5G network must be deployed. This spectrum has extremely short wavelengths, and that means two things. First, the signal isn’t going to travel very far before the signal dissipates and grows too weak to deliver fast data. Second, these short wavelengths don’t penetrate anything. They won’t go through leaves, walls, or even through a person walking past the transmitter – so these frequencies require a true unimpeded line-of-sight connection.

These requirements are going to be problematic on the typical residential street. Go outside your own house and see if there is a perfect line-of-sight from any one pole to your home as well as to three or four of your neighbors. The required unimpeded path means there can be no tree, shrub or other impediment between the transmitter on a pole and each home getting this service. This may not be an issue in places with few trees like Phoenix, but it sure doesn’t look very feasible on my street. On my street the only way to make this work would be by imposing a severe tree trimming regime – something that I know most people in Asheville would resist. I would never buy this service if it meant butchering my old ornamental crepe myrtle. And tree trimming must then be maintained into the future to keep new growth from blocking signal paths.

Even where this can work, this is going to mean putting up some kind of small dish on each customer location in a place that has line-of-sight to the pole transmitter. This dish can’t go just anywhere on a house in the way that satellite TV dishes can often be put in places that aren’t very noticeable. While these dishes will be small, they must go where the transmitter can always see them. That’s going to create all sorts of problems if this is not the place in the home where the existing wiring comes into the home. In my home the wiring comes into the basement in the back of the house while the best line-of-sight options are in the front – and that is going to mean some costly new wiring by an ISP, which might negate the cost advantage of the 5G.

The next consideration is back-haul – how to get the broadband signals into and out of the neighborhood. Ideally this would be done with fiber. But I can’t see somebody spending the money to string fiber in a town like Asheville, or in most residential neighborhoods just to support wireless. The high cost of stringing fiber is the primary impediment today for getting a newer network into cities.

One of the primary alternatives to stringing fiber is to feed neighborhood 5G nodes with point-to-point microwave radio shots. In a neighborhood like mine these won’t be any more practical that the 5G signal paths. The solution I see being used for this kind of back-haul is to erect tall poles of 100’ to 120’ to provide a signal path over the tops of trees. I don’t think many neighborhoods are going to want to see a network of tall poles built around them. And tall poles still suffer the same line-of-sight issues. They still have to somehow beam the signal down to the 5G transmitters – and that means a lot more tree trimming.

All of this sounds dreadful enough, but to top it off the network I’ve described would be needed for a single wireless provider. If more than one company wants to provide wireless broadband then the number of devices multiply accordingly. The whole promise of 5G is that it will allow for multiple new competitors, and that implies a town filled with multiple wireless devices on poles.

And with all of these physical deployment issues there is still the cost issue. I haven’t seen any numbers for the cost of the needed neighborhood transmitters that makes a compelling business case for 5G.

I’m the first one to say that I’ll never declare that something can’t work because over time engineers might find solutions for some of these issues. But where the technology sits today this technology is not going to work on the typical residential street that is full of shade trees and relatively short poles. And that means that much of the talk about gigabit 5G is hype – nobody is going to be building a 5G network in my neighborhood, for the same sorts of reasons they aren’t building fiber here.

Please Stop Hinting at Gigabit Cellular

SONY DSCLast week there were several press releases announcing that AT&T was working with a major corporation to provide a test of 5G technology. A few days later the industry found out that the company taking part in the test is Intel, which will be making the chips involved in the tests. Intel will apparently be beta testing early units for providing high-speed bandwidth at one of their locations.

It really bothers me every time I see one of these announcements, because the whole industry seems to have bought into the hype from companies like AT&T that conflate two totally different technologies under the name of 5G. The AT&T and Intel test is going to be for a technology to provide faster indoor wireless connections using millimeter wave spectrum in competition with WiFi.

But most of the world sees the term ‘5G’ and assumes it means the next generation of cellular technology. And that means that most people reading about the AT&T press release think that we are just a few years away from having gigabit cell phones. And we are not.

I don’t know who decided to use the term 5G for two drastically different technologies. My guess is that the confusion has been purposefully sown by AT&T and Verizon. Certainly the average consumer is more likely to pay attention if they think their cell phones will soon be blazingly fast.

But this kind of confusion has real life negative consequences. Politicians and decision makers read these articles and assume that there is a fast cellular alternative coming in a few years – and this allows them to take the issue of faster landline broadband off the plate. It’s not a hard mistake to make and I’ve even seen this same confusion from smaller telco and cable company owners who see the headlines but don’t dig deeper. I assume one reason this confusion is being promoted is that both AT&T and Verizon benefit if fewer companies are investing in fiber last-mile networks to compete with them.

The millimeter wave technology that Intel is going to alpha test is to provide gigabit speed wireless connections for very short distances. It’s a technology that can distribute gigabit speed connections around an office suite, for example. The gigabit speeds are good for about 60 feet from a transmitter which fits the indoor environment and desire for speed. But even in that environment the technology has a major limitation in that these frequencies won’t pass through almost anything. Even a wall or possibly even a cubicle divider can kill the signal. And so these early tests are probably to find the best way to scatter the bandwidth around the office to reach all the nooks and crannies found in the real world.

This technology is being called 5G because the technology will use the 5G standard, even though that standard is not yet developed. But we already know that the 5G standard will have one major benefit over WiFi. WiFi is a bandwidth sharing protocol which gives equal preference to every transmission. If one WiFi device in an office is demanding a large amount of bandwidth and another data-hungry device comes online the protocol automatically shares the bandwidth between the two devices. 5G will allow the router to guarantee the bandwidth at different levels to each device without sharing.

But this millimeter wave trial at Intel has almost nothing else in common with cellular data transmissions other than the fact that they use the same standard. Cellular networks use much lower frequencies which have been chosen because they travel a decent distance from a cell tower, and for the most part cellular frequencies are good at penetrating walls and trees and other obstacles.

Cellular networks are not going to use millimeter wave frequencies to get to cellphones. To make that work would require mini-cell sites of some sort every hundred feet or so. That can be made to work, but really is a totally impractical application in the real world unless we someday find a way to put little cell sites literally everywhere. Using these frequencies for cellular would be a niche application that might only work in a place like a conference center and the cellphone companies are not going to automatically build this technology into cellphones. It takes chip space, extra power and new antennae to add another frequency and nobody is going to add that extra cost to a cellphone until most of the world can use it – and that literally could take many decades, if ever.

Instead, the 5G standard will be used in cellphones to improve data speeds – but not at anything near to gigabit speeds. The early versions of the 5G specification have a goal of being able to deliver 50 Mbps data speeds to large numbers of phones out of a cell site. That’s a 4 – 5 times increase in cellular speeds from today and is going to make it a lot more enjoyable to browse the web from a cellphone. But 50 Mbps is very different than gigabit cellular speeds. The big companies really need have to stop implying there is going to be gigabit cellular. That is extremely misleading and is very far from the truth.

My Thoughts on AT&T AirGig

PoleBy now most of you have seen AT&T’s announcement of a new wireless technology they are calling AirGig. This is a technology that can bounce millimeter wave signals along a series of inexpensive plastic antennae perched at the top of utility poles.

The press release is unclear about the speeds that might be delivered from the technology. The press release says it has the potential to deliver multi-gigabit speeds. But at the same time it talks about delivering 4G cellular as well as 5G cellular and fixed broadband. The 4G LTE cellular standard can deliver about 15 Mbps while the 5G cellular standard (which is still being developed) is expected to eventually increase cellular speeds to about 50 Mbps. So perhaps AT&T plans to use the technology to deploy micro cell sites while also being able to deliver millimeter wave wireless broadband loops. The link above includes a short video which doesn’t clarify this issue very well.

Like any new radio technology, there is bound to be a number of issues involved with moving the technology from the lab to the field. I can only speculate at this point, but I can foresee the following as potential issues with the millimeter wave part of the technology:

  • The video implies that the antennas will be used to deliver bandwidth using a broadcast hotspot. I’m not entirely sure that the FCC will even approve this spectrum to be used in this manner – this is the same spectrum used in microwave ovens. It can be dangerous to work around for linemen climbing poles and it can create all sorts of havoc by interfering with cable TV networks and TV reception.
  • Millimeter wave spectrum does not travel very far when used as a hot spot. This spectrum has high atmospheric attenuation and is absorbed by gases in the atmosphere. When focused in a point-to-point the spectrum can work well to about half a mile. But in a hot spot mode it’s good, at best, for a few hundred feet and loses bandwidth quickly with distance traveled. The bandwidth is only going to reach to homes that are close to the pole lines.
  • Millimeter wave spectrum suffers from rain fade and during a rain storm almost all of the spectrum is scattered.
  • The spectrum doesn’t penetrate foliage, or much of anything else. So there is going to have to be a clear path between the pole unit and the user. America is a land of residential trees and even in the open plains people plant trees closely around their house as a windbreak.
  • The millimeter wave spectrum won’t penetrate walls, so this will require some sort of outdoor receiver to catch millimeter wave signals.
  • I wonder how the units will handle icing. Where cables tend to shake ice off within a few days, hardware mounted on poles can be ice-covered for months.
  • The technology seems to depend on using multiple wireless hops to go from unit to unit. Wireless hops always introduce latency into the signal and it will be interesting to see how much latency is introduced along rural pole runs.
  • For any wireless network to deliver fast speeds it has to be connected somewhere to fiber backhaul. There are still many rural counties with little or no fiber.

We have always seen that every wireless technology has practical limitations that make it suitable for some situations and not others. This technology will be no different. In places where this can work it might be an incredible new broadband solution. But there are bound to be situations where the technology will have too many problems to be practical.

I’ve seen speculation that one of the major reasons for this press release is to cause a pause to anybody thinking of building fiber. After all, why should anybody build fiber if there is cheap multi-gigabit wireless coming to every utility pole? But with all of the possible limitations mentioned above (and others that are bound to pop up in the real world) this technology may only work in some places, or it might not work well at all. This could be the technology we have all been waiting for or it could be a flop. I guess we’ll have to wait and see.

Looking Closer at 5G

SONY DSCCisco recently released a white paper titled Cisco 5G Vision Series: Laying the Foundation for New Technologies, Use Cases, and Business Models that lays out their vision of how the cellular industry can migrate from 4G to 5G. It’s a highly technical read and provides insight on how 5G might work and when we might see it in use.

As the white paper points out, the specific goals of 5G are still in the process of being developed. Both 4G and 5G are basically a set of detailed standards used to make sure devices can work on any network meeting the standards. Something that very few people realize is that almost none of the supposed 4G networks in this country actually meet the 4G standards. We are just now seeing the deployment around the world of the first technologies – LTE-Advanced and WIMAX 16m – that meet the original 4G standards. It’s been typical for cellular providers to claim to have 4G when they’ve only met some tiny portion of the standard.

And so, long before we see an actual 5G deployment we are first going to see the deployment of LTE-Advanced followed by generations of improvements that are best described as pre-5G (just as most of what we have today is pre-4G). This evolution means that we should expect incremental improvements in the cellular networks, not a big swooping overhaul.

The paper makes a very clear distinction between indoor 5G and outdoor 5G (which is cellular service). Cisco says that already today that 80% of cellphone usage is done indoors, mostly using WiFi. They envision that in places with a lot of people, like stadiums, shopping centers or large business buildings, that there will be a migration from WiFi to millimeter wave spectrum using the 5G standard. This very well could ultimately result in gigabit speeds on devices with the right antennas to receive that signal.

But these very fast indoor speeds are going to be limited to those places where it’s economically feasible to deploy multiple small cells – and places that have good fiber backhaul. That’s going to mean places with lots of demand and the willingness to pay for such deployments. So you might see fast speeds inside wireless in hospitals, but you are not going to see gigabit speeds while waiting for your car to be repaired or while sitting in the dentist waiting room. And most importantly, you are not going to see gigabit speeds using millimeter wave spectrum outside. All of the early news articles talking about having outdoor gigabit cellular speeds were way off base. This misunderstanding is easy to understand since the press releases from cellular companies have been nebulous and misleading.

So what can be expected outdoors on our cell phones? Cisco says that the ultimate goal of 5G is to be able to deliver 50 Mbps speeds everywhere. At the same time, the 5G standards have the goal of being able to handle a lot more connections at a given cell site. That goal will mean better reception at football games, but it also means a lot more connections will be available to connect to smart cars or Internet of Things devices.

But don’t expect much faster cellular speeds for quite some time. Remember that the goal of 4G was to deliver about 15 Mbps speeds everywhere. And yet today, the average LTE connection in the US is at about half of that speed. The relatively slow speeds of today’s LTE are due to a number of different reasons. First, is the fact that most cell sites are still running pre-4G technology. The willingness of the cellular companies to buy sufficient bandwidth backhaul at cell sites is also a big contributor. I’ve seen in the press that both Verizon and AT&T are looking for ways to reduce backhaul costs – that’s thought to be the major motivation for Verizon to buy XO Communications. Another major issue is that existing cell sites are too far apart to deliver fast data speeds, and it will require a massive deployment of small cell sites (and the accompanying fiber backhaul) to fix the spacing problem.

So long before we see 50 Mbps cellular speeds we will migrate through several generations of incremental improvements in the cellular networks. We are just now seeing the deployment of LTE-Advanced which will finally bring 4G speeds. After that, Cisco has identified what looks to be at least three or four steps of improvements that we will see before we achieve actual 5G cellular.

How long might all of this take? The industry is scheduled to finalize the 5G standards by 2020, and perhaps a little sooner. It looks like there will be a faster push to find millimeter wave solutions for indoor 5G, so we might see those technologies coming first. But it has taken us a decade since the large cellular companies announced deployment of 4G cellular until we are finally starting to see networks that meet that standard. I can’t imagine that the 5G migration will go any faster. And even when 5G gets here, it’s going to hit urban areas long before it hits rural areas. One doesn’t have to drive too far into the country today to find places that are still operating at 3G.

Upgrading to 5G in steps will be expensive for the cellular providers and they are not likely to implement changes too quickly. We will likely see a series of incremental improvements, like they have been doing for many years. So it would not be surprising to be at least until 2030 until there is a cellular system in place that fully meets the 5G standard. Of course, long before then the marketing departments of the wireless providers will tell us that 5G is here – and when they do, everybody looking for blazingly fast cellphone speeds are going to be disappointed.