Spectrum and 5G

All of the 5G press has been talking about how 5G is going to be bringing gigabit wireless speeds everywhere. But that is only going to be possible with millimeter wave spectrum, and even then it requires a reasonably short distance between sender and receiver as well as bonding together more than one signal using multiple MIMO antennae.

It’s a shame that we’ve let the wireless marketeers equate 5G with gigabit because that’s what the public is going to expect from every 5G deployment. As I look around the industry I see a lot of other uses for 5G that are going to produce speeds far slower than a gigabit. 5G is a standard that can be applied to any wireless spectrum and which brings some benefits over earlier standards. 5G makes it easier to bond multiple channels together for reaching one customer. It also can increase the number of connections that can be made from any given transmitter – with the biggest promise that the technology will eventually allow connections to large quantities of IOT devices.

Anybody who follows the industry knows about the 5G gigabit trials. Verizon has been loudly touting its gigabit 5G connections using the 28 GHz frequency and plans to launch the product in up to 28 markets this year. They will likely use this as a short-haul fiber replacement to allow them to more quickly add a new customer to a fiber network or to provide a redundant data path to a big data customer. AT&T has been a little less loud about their plans and is going to launch a similar gigabit product using 39 GHz spectrum in three test markets soon.

But there are also a number of announcements for using 5G with other spectrum. For example, T-Mobile has promised to launch 5G nationwide using its 600 MHz spectrum. This is a traditional cellular spectrum that is great for carrying signals for several miles and for going around and through obstacles. T-Mobile has not announced the speeds it hopes to achieve with this spectrum. But the data capacity for 600 MHz is limited and binding numerous signals together for one customer will create something faster then LTE, but not spectacularly so. It will be interesting to see what speeds they can achieve in a busy cellular environment.

Sprint is taking a different approach and is deploying 5G using the 2.5 GHz spectrum. They have been testing the use of massive MIMO antenna that contain 64 transmit and 64 receive channels. This spectrum doesn’t travel far when used for broadcast, so this technology is going to be used best with small cell deployments. The company claims to have achieved speeds as fast as 300 Mbps in trials in Seattle, but that would require binding together a lot of channels, so a commercial deployment is going to be a lot slower in a congested cellular environment.

Outside of the US there seems to be growing consensus to use 3.5 GHz – the Citizens Band radio frequency. That raises the interesting question of which frequencies will end up winning the 5G race. In every new wireless deployment the industry needs to reach an economy of scale in the manufacture of both the radio transmitters and the cellphones or other receivers. Only then can equipment prices drop to the point where a 5G capable phone will be similar in price to a 4GLTE phone. So the industry at some point soon will need to reach a consensus on the frequencies to be used.

In the past we rarely saw a consensus, but rather some manufacturer and wireless company won the race to get customers and dragged the rest of the industry along. This has practical implications for early adapters of 5G. For instance, somebody buying a 600 MHz phone from T-Mobile is only going to be able to use that data function when near to a T-Mobile tower or mini-cell. Until industry consensus is reached, phones that use a unique spectrum are not going to be able to roam on other networks like happens today with LTE.

Even phones that use the same spectrum might not be able to roam on other carriers if they are using the frequency differently. There are now 5G standards, but we know from practical experience with other wireless deployments in the past that true portability between networks often takes a few years as the industry works out bugs. This interoperability might be sped up a bit this time because it looks like Qualcomm has an early lead in the manufacture of 5G chip sets. But there are other chip manufacturers entering the game, so we’ll have to watch this race as well.

The word of warning to buyers of first generation 5G smartphones is that they are going to have issues. For now it’s likely that the MIMO antennae are going to use a lot of power and will drain cellphone batteries quickly. And the ability to reach a 5G data signal is going to be severely limited for a number of years as the cellular providers extend their 5G networks. Unless you live and work in the heart of one of the trial 5G markets it’s likely that these phones will be a bit of a novelty for a while – but will still give a user bragging rights for the ability to get a fast data connection on a cellphone.

Recovering Television Spectrum

Rabbit_Ears)Lately, the FCC finds itself in sales mode as it works to convince television station owners to sell their existing spectrum. For those not familiar with what the FCC is doing, this process is being referred to as an incentive auction for the 600 MHz band of spectrum. This spectrum today is owned by UHF TV stations.

This is spectacular spectrum and probably has the best characteristics for delivering wireless data. The spectrum easily carries to the horizon and it blasts through just about anything. I remember as a kid watching TV in a basement from a transmitter that was on a mountain on the far horizon. There is no better spectrum for the cellular companies than these bands.

This is called an incentive auction because TV stations are not being mandated to leave this spectrum. So the FCC is now engaged in a series of regional meetings to try to convince the stations to sell their spectrum. The auctions are expected to be lucrative, and station owners and the FCC will share the auction revenues. The AWS auction last November was wildly successful for the FCC. The FCC had set a minimum threshold on the spectrum at just over $10 billion and the final auction raised over $34 billion, and AWS spectrum is not even close to the great coverage characteristics of the 600 MHz spectrum. The TV spectrum should be far more lucrative since this is basically the holy grail of spectrum.

But many stations are hesitant to sell their spectrum, even at the billions they are likely to reap. The FCC has put together a complicated proposal to ‘repack’ the spectrum so that a station that sells its spectrum can stay on the air. But that is the part of the whole process that has stations nervous. It’s possible that a station could be given a slice of spectrum that is used by somebody else, such as sharing the space with wireless microphones. The repacked spectrum also doesn’t have as much of a cushion around each channel as exists today, which makes stations worried about out-of-band interference.

Having no interference is vital for television stations for several reasons. Historically, local stations got their revenues from advertising, and the rates they can charge are based upon how many theoretical eyeballs can watch them plus their rating in the local market. TV transmission is a tricky thing. For homes near the base transmitter, the power of most TV stations can overpower most interference. But, as you get to the further edges of the transmission path interference becomes a real issue. And in TV, interference is manifested by poor reception and pixelization. So TV stations are worried that their effective delivery circle will get smaller and that there will be significant interference in parts of that area.

The financial issue is further complicated by the fact that local stations (or their corporate owners) today make a lot of money from local transmission agreements. These are fees that are charged to cable providers that want to retransmit their station on cable systems. The fear here is the same in that they are worried that cities near the fringes of their service area might argue that they no longer owe retransmission fees due to degraded quality.

Unfortunately there is no way to pre-test the delivery in one of the repacked blocks. Spectrum engineering is really complicated stuff and the quality of a transmission will vary widely in different pockets of a spectrum delivery area based upon local conditions. The only way to test it is to send out the signal and see what kinds of complaints you get from viewers.

The FCC is putting everything they have into these meetings with Chairman Tom Wheeler attending most of these regional meetings to talk with television station owners. There are already a number of stations that have said that they are interested in joining the auction, but the FCC needs a significant number of them to join before the auction can proceed.

Big cellular companies won’t be the only ones to benefit from the spectrum; the FCC has promised that there will be slices of this spectrum set aside for WiFi and other public uses. So the whole country is on hold waiting to see if the FCC can convince enough stations to move. The billions that the stations can collect from the auction is certainly an incentive, but we are going to have to wait to see how many of them actually make the big leap. It ought to be an interesting summer.

The 600 MHz Incentive Auction

001-Signal-Command-SSIThe FCC has again delayed the incentive auction for the 600 MHz spectrum. In a recent public notice the FCC in FCC 14-191, the agency is seeking comments on bidding procedures for the upcoming auction. Most of the document deals with the non-technical aspects of the auction such as bid pricing and procedures.

For those not familiar with this spectrum, today much of it is used by UHF television stations. The upcoming auction is being called an incentive auction because TV stations willing to give up their public spectrum or to be relocated within the spectrum will share in the proceeds of the sale of their spectrum.

But stations aren’t being mandated to leave this spectrum and the recent public notice discusses for the first time what might happen to stations that elect to remain on the public airwaves. The FCC proposes to ‘repack’ a stations frequency and to put it anywhere within the 600 MHz range in such a way as to optimize the 600 MHz frequency in a given market.

The controversial part of the idea is that stations could be placed into spectrum that is used by somebody else. For instance a TV station could be put into spectrum that is reserved today for wireless microphones. Or even more controversial, a station could be placed into what is called the duplex gap, which is a spectrum buffer that sits between major pieces of spectrum and that is used to reduce interference between different technologies. The easiest way to think of the duplex gap is to envision it as a buffer channel that nobody gets to use.

This FCC’s ideas aren’t pleasing anybody. TV stations are now worried that they will end up in parts of the spectrum that will be polluted by other traffic and that will mar transmission quality. And the wireless carriers are unhappy since the TV stations might end up interfering with cellular calls. It’s going to be interesting to read the comments that the FCC gets on this issue and to see how they can resolve it. The auction will quickly fall apart if the stations all decide to not participate.

There are many other interesting parts to this auction. The FCC would like to assign some of the 600 MHz band as unlicensed spectrum for use for WiFi. The 600 MHz band is one of the more useful spectrum bands around in terms of transmission characteristics. It can go long distances and can travel easily through walls and buildings (just think back to the ease of receiving UHF channels on your TV in the basement). The FCC also wants to create more room for ‘white space devices’ that can use the spectrum for high-speed wireless data transmission.

But not everybody is enthusiastic about the ways that the FCC plans to do this. The FCC’s plans are to very aggressively squeeze as much use as possible out of the spectrum and to allow white space devices to operate in the guard bands at power levels that might impair licensed spectrum. AT&T has said that it might not participate in the auction if it believes that the spectrum it buys will be compromised.

The fear expressed by radio engineers is that the current proposal will cause noticeable interference. For example, they say that a device using the white space, say a tablet, and a cellphone using a licensed portion of the 600 MHz might interfere with each other when used together in the same room.

There are already a lot of devices using this frequency today. In addition to the low power TV stations it’s used widely by wireless microphones, medical telemetry and radio astronomy, and there is fear that the repackaging is going to harm all of these uses.

I don’t know if the FCC has anything harder to solve than our shortage of spectrum. The demand for spectrum has grown rapidly and many of the existing bands get easily congested with traffic at peak times. The wireless carriers are clamoring for more spectrum while at the same time there are dozens of other uses of the spectrum including public safety and the military that must be considered in any wireless plan.

I don’t know if it would be possible to develop a good spectrum allocation plan if you started from scratch today, but it seems nearly impossible to satisfy everybody as we try to fit new uses of spectrum over top of a spectrum allocation that was made in a very different time. I don’t envy the FCC the task of figuring this out.

The Upcoming AWS Spectrum Auction

Transmitter_tower_in_SpainThe FCC’s auction for new cellular data spectrum will begin on November 13. This is the first big spectrum auction in six years, so it’s worth watching. The spectrum being auctioned is being referred to as AWS or Advanced Wireless Spectrum. There are three separate bands being auctioned that go from 1,695MHz to 1,710MHz, from 1,755MHz to 1,780MHz and from 2,155MHz to 2,180MHz.

The FCC has set aside a reserve big for the auction at $10.5 billion. That means that if they don’t receive bids totaling at least that much in the first round that the FCC has the right to cancel the auction. Assuming that price is met, then the normal FCC bidding process will take place and one would expect the auction to go for a few more rounds.

The AWS spectrum is expected to be used almost entirely for data, and both Verizon and AT&T already own some spectrum that sits next to these new blocks. That is going to make it fairly easy for carriers to incorporate the spectrum into handsets. Further, this same spectrum is used in Europe for wireless data, meaning that there are already a wide array of handsets capable of using the spectrum.

Because it’s high frequency, this spectrum is capable of handling a lot of data. However, like other high frequencies it’s not great at penetrating building walls and other obstacles. Contrast this to the next auction that’s on the horizon. In two years the FCC will be auctioning chunks of the 600 MHz spectrum that is being vacated by television stations. This frequency can penetrate into elevators but doesn’t carry as much data per channel as the higher frequencies.

As you would expect the bulk of the spectrum is going to be auctioned to the largest carriers. It is expected that T-Mobile is going to be aggressive in the auction with AT&T and Verizon also buying a lot of spectrum. Sprint is expected to sit out the auction since they already own a lot of high frequency bandwidth. The wildcard player is going to be Dish Networks which may go after a lot of this spectrum. Dish has announced plans to offer a fixed data product using wireless spectrum that will also be used to deliver a cable TV line-up. This spectrum would give them more bandwidth for that offering.

The AWS spectrum is not immediately available since the Department of Defense and a few other government agencies still occupy some of the spectrum. It is expected that the bulk of the government usage will be gone in about two years, but these kinds of transitions almost invariably take longer than expected. This means that it’s unlikely that the bandwidth will have much of an impact on wireless data speeds until the two to three year time frame.

The spectrum is being auctioned off by market and as you would expect this means a wide variance in the interest by the carriers in any given market. In similar auctions in the past some markets went unclaimed, meaning that nobody was willing to pay the FCC’s minimum bid for the market, and if that happens again you can expect a second auction of the leftover, and certainly rural markets. This auction does have some incentives for small bidders and while the big carriers will grab the vast majority of the spectrum you can expect to see smaller companies going after secondary and rural markets.

The auction is expected to be tactical is that each carrier has holes they are trying to fill in certain markets. And the big carriers are keeping the upcoming 600 MHz auction in mind and may hold off on bidding now in markets where they would rather have that spectrum. This makes the auction a big chess game by market. The funny thing is that the carriers know exactly what each other already owns in terms of spectrum, so they know basically what each other is most interested in. But because there are two auctions close together or very different spectrum, nobody is going to know each other’s strategies until the first round bidding is done. The auction is often finished after the first round for a lot of markets and the following rounds are usually only for the prime markets.

I just looked at the amount of spectrum that cellphone users consume late last week. The current statistics show that the average landline connection is using almost 100 times more aggregate data in a month (download and upload combined) than the average cell phone. With that said, Cisco has predicted that the amount of wireless data usage will triple over the next five years, and many analysts think this is conservative.

It’s obvious that cellphone data is never going to rival landline data usage or even come close. I chuckle whenever I see somebody say that wireless data will win the bandwidth battle. There just is not enough wireless spectrum for that to ever happen. While cellular data usage is now doubling every five years, landline data is doubling every three years and one has to carry that trend out twenty years to see that the average landline home connection might be using nearly a terabit of data each month.

But we like using data on our cellphones. The wireless carriers have trained us to be very cautious in that usage because of the severe data caps and the horrendously high price for exceeding your data cap. But even with those restrictions, the wireless carriers need more spectrum and are expected to make this an interesting auction.