Tag: LTE-U

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Technology

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.

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Regulation - What is it Good For?

FCC Issues for 2016

In what seems to be the new normal the FCC has a lot of issues on their plate at the end of this year. Following are the regulatory issues that I think will most affect small telcos, cable companies, and ISPs in the coming year.

Net Neutrality: Assuming that the courts don’t completely overturn this, this is liable to be at the top of the list for several years to come. The ink is barely dry on the new rules and companies like Comcast, T-Mobile, and Verizon are pushing new products that will test the FCC’s resolve to implement net neutrality. And if the courts uphold the law, expect to see a slew of arbitrations between content providers and ISPs. If the courts overturn parts of the new rules, expect the FCC to take one more shot at fixing the parts that don’t pass court muster.

TDM to IP Conversion: This is an ongoing process that is looking at modernizing the backbone telephone network to IP. The large telcos like AT&T and Verizon have commandeered the docket to try to use it as a way to get rid of rural copper lines. The FCC has been micromanaging this process so far and there should be a lot of activity in 2016.

USF Reform: The FCC wants to transition the Universal Service Fund from paying for rural telephone lines to paying for high speed data connections. This process has already started but there is still a lot to be decided. Further, the FCC is facing a crisis in funding the USF and the latest USF contribution factor, representing the ‘tax’ on interstate telecom services, is up to an astounding 18.2% for the first quarter of 2016. The FCC is going to have to find some other ways to help fund this as interstate telecom revenues keep shrinking. This is becoming a big burden on carriers that are buying interstate special access.

Lifeline Reform: Lifeline is another part of the USF that is used to help pay for telecom services for low income households. The FCC decided last year that this should cover both telephone and data expenses for low income households and there is not enough money in the fund to do that. So this year they need to figure out a way to make it work.

Skinny Bundles and OTT: There has been a docket open for most of 2015 that asked for comments on how the FCC ought to regulate video services on the web. There hasn’t been a lot of talk about this for a while, but it’s likely that the FCC is going to have to do something with this in 2016, and anything they do will be groundbreaking. Further, the FCC is in the process of cleaning up their operating rules and Congress is also mandating that they resolve dockets sooner, so this is liable to be forced to come to a head in 2016.

WiFi versus LTE-U: The large wireless carriers really want to dip into WiFi to make cellular data connections using a technology they are calling LTE-U. In places where cellular data is already overloaded this would almost certainly swamp WiFi, making it hard for anybody else to use. The FCC is going to have to decide if and how cellular carriers might be allowed to do this. In a related area, the FCC is also likely to look at opening up new public spectrum next year.

Federal Legislation: While this is nothing to count on, there has been a lot of noise about seeing a new telecom act of some sort out of Congress. If that happens there is no way to predict what Congress might tackle. If a new law passes expect the FCC to get swamped with implementing new law like they did after the Telecom Act of 1996.

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Regulation - What is it Good For? Technology

LTE-U

Recently, the NCTA asked the FCC to make sure that wireless carriers don’t interfere with WiFi spectrum. I wrote a blog a few weeks ago talking about all of the demands on WiFi, and the threat that the NCTA is warning about is another use of the already busy WiFi spectrum.

Cellular carriers are using LTE technology to deliver 4G data. Cellular carriers today deliver 4G data and voice using spectrum for which they have paid billions (at least in the US and Europe). But in urban areas the LTE spectrum is already stressed and the demand for the existing spectrum is growing far faster than the carriers can find new spectrum to offload the extra demand.

The cellular carriers have had their eye on the 5 GHz unlicensed band of spectrum that is used for WiFi. This is a big swatch of spectrum that in some markets is larger than the band that some carriers have for LTE. Recently, various carriers have been experimenting with using this public spectrum to deliver LTE. Huawei and NTT demonstrated this capability last August; Qualcomm showed this capability at the CES show earlier this year. It’s rumored that T-Mobile plans to run a trial of this technology this year.

This new technology is being called LTE-U (for Unlicensed). NCTA filed at the FCC on behalf of their cable company members who use this WiFi spectrum to deliver WiFi for various uses such as distributing data wirelessly around a home or to bring data to settop boxes. They are worried that if the cellular companies start using the spectrum that they will swamp it and make WiFi useless for everybody else, particularly in urban areas where WiFi is under the most pressure.

That certainly is a valid concern. As my recent blog noted, the list of companies and technologies that are planning on using WiFi spectrum is large and growing. And there is already notable stress on WiFi around crowded places like large hotels, convention centers, and stadiums. The fear is that if cellular carriers start using the spectrum this same crowding will spread to more places, making the spectrum useless to everyone.

The cellular carriers argue that the swath of WiFi is large enough to allow them to use it without hurting other users. They argue that nobody can use all of the 400 MHz of spectrum in that band all at once. While that is true, it doesn’t take a huge pile of LTE-U customers at one time to locally overdraw the WiFi spectrum in the same manner that they are overloading the cellular spectrum today.

Engineers tell me that LTE uses the spectrum more efficiently today than does most WiFi technologies. This is due to the fact that the LTE specifications very neatly limit the bandwidth that any one customer can draw while most WiFi applications will let a user grab all of the bandwidth if it’s available. This means you can fit a lot more LTE customers into the spectrum that might be assigned to one WiFi customer.

There is a characteristic of WiFi that makes it incompatible with the way that LTE works. WiFi has been designed to share spectrum. When one customer is using WiFi they can grab a huge swath of spectrum. But when another customer demands bandwidth the system dynamically decreases the first connected customer to make room for the second one. This is very different than how LTE works. LTE works more like a telephone network and if there is enough bandwidth available to handle a customer it will assign a band to the customer or else deliver a ‘busy signal’ (no bars) if there us not enough bandwidth. The problem with these two different operating systems is that LTE would continually grab spectrum until it’s all used and the WiFi users are shut out, much like what you might get in a busy hotel in the evening.

The LTE providers say they have handled this by introducing a new protocol called LAA (Licensed Assisted Access) which introduces the idea of coexistence into the LTE network. If it works properly, LAA ought to be able to coexist with WiFi in the same manner that multiple WiFi customers coexist. Without this change in protocol LTE would quickly gobble all of the free WiFi spectrum.

But this still doesn’t answer the concern that even with LAA there could be a lot of people trying to grab bandwidth in environments where the WiFi is already stressed. Such a network never shuts anybody out like an LTE system will, but rather will just keep subdividing the bandwidth forever until the amount each customer gets is too small to use.

It will be interesting to see what the FCC says about this. This was discussed years ago and the FCC never intended to let licensed cellular holders snatch the public WiFi spectrum. I will also be curious to see if wireless carriers try to charge customers for data usage when that data is being delivered over a free, unlicensed swath of spectrum. And how will customers even know that is where they are getting their data?

I hope the FCC doesn’t let the wireless carriers run rampant with this, because I think it’s inevitable that this is going to cause huge problems. There are already places today where WiFi is overloaded, and this new kind of data traffic could swamp the spectrum in a lot more places. The wireless carriers can make promises all day about how this won’t cause problems, but it doesn’t take a huge number of LTE-U users at a cell site to start causing problems.

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Technology

Are We Expecting too Much from WiFi?

I don’t think that a week goes by when I don’t see somebody proposing a new use for WiFi. This leads me to ask if we are starting to ask too much from WiFi, at least in urban areas.

Like all spectrum, WiFi is subject to interference. Most licensed spectrum has strict rules against interference and there are generally very specific rules about how to handle contention if somebody is interfering with a licensed spectrum-holder. But WiFi is the wild west of spectrum and it’s assumed there is going to be interference between users. There is no recourse to such interference – it’s fully expected that every user has an equal right to the spectrum and everybody has to live with the consequences.

I look at all of the different uses for WiFi and it’s not too hard to foresee problems developing in real world deployments. Consider some of the following:

  • Just about every home broadband connection now uses WiFi as the way to distribute data around the house between devices.
  • Comcast has designed their home routers to have a second public transmitter in addition to the home network, so these routers initiate two WiFi networks at the same time.
  • There is a lot of commercial outdoor WiFi being built that can bleed over into home networks. For example, Comcast has installed several million hotspots that act to provide convenient connections outside for their landline data customers.
  • Many cities are contemplating building citywide WiFi networks that will provide WiFi for their citizens. There are numerous network deployments by cities, but over the next few years I think we will start seeing the first citywide WiFi networks.
  • Cable companies and other carriers are starting to replace the wires to feed TVs with WiFi. And TVs require a continuous data stream when they are being used.
  • Virtual reality headsets are likely to use WiFi to feed the VR headsets. There are already game consoles using WiFi to connect to the network.
  • There is a new technology that will use WiFi to generate the power for small devices like cellphones. For this technology to be effective the WiFi has to beam continuously.
  • And while not big bandwidth user at this point, a lot of IoT devices are going to count on WiFi to connect to the network.

On top of all of these uses, the NCTA sent a memo to the FCC on June 11 that warned of possible interference with WiFi spectrum from outside through the LTE-U or LAA spectrum used for cellphones. Outside interference is always possible, and in a spectrum that is supposed to have interference this might be hard to detect or notice for the average user. There is generally nobody monitoring the WiFi spectrums for interference in the same ways that wireless carriers monitor their licensed spectrum.

All of these various uses of the spectrum raise several different concerns:

  • One concern is just plain interference – if you cram too many different WiFi networks into one area, each trying to grab the spectrum, you run into traditional radio interference which cuts down on the effectiveness of the spectrum.
  • WiFi has an interesting way of using spectrum. It is a good spectrum for sharing applications, but that is also its weakness. When there are multiple networks trying to grab the WiFi signal, and multiple user streams within those networks, each gets a ‘fair’ portion of the spectrum which is going to somehow be decided by the various devices and networks. This is a good thing in that it means that a lot of simultaneous streams can happen at the same time on WiFi, but it also means that under a busy load the spectrum gets chopped into tiny little steams that can be too small to use. Anybody who has tried to use WiFi in a busy hotel knows what that’s like.
  • All WiFi is channelized, or broken down into channels instead of being one large black of spectrum. The new 802.11ac that is being deployed has only two 160 MHz channels and once those are full with a big bandwidth draw, say a virtual reality headset, then there won’t be room for a second large bandwidth application. So forget using more than one VR headset at the same time, or in general trying to run more than one large bandwidth-demanding application.

It’s going to be interesting to see what happens if these problems manifest in homes and businesses. I am imagining a lot of finger-pointing between the various WiFi device companies – when the real problem will be plain old physics.

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