There has been a lot of unrealistic hype around fifth generation (5G) wireless technology. There has also been a lot of ink spilled outlining why that hype is unjustified. Both views have some justification. Unfortunately both are often based on an incomplete view of wireless technology. For example it is obvious many writers don’t even understand exactly what 5G means. The fifth generation of what?

So let’s begin with some history before we get into the more technical weeds. Over the years cellular mobile phone carriers have used a series of mutually incompatible methods of providing wireless services to their customers. As time moved forward technology advanced. Each carrier occasionally adds new technology and then slowly retires the older technology.

Many times these additions are minor and cause few issues for the average subscriber. But in some cases the new technology is substantially better, but completely incompatible with the old.  So much so that previous devices won’t function on the new system. Since these types of changes are quite disruptive so they don’t occur often. But when they do occur they are quite noticeable to everyone and so have become known as generational upgrades.

What is now known as first generation or 1G wireless technology mainly refers to the first of several of analog cell phone systems that were deployed in the late 1980’s and early 1990’s (mostly the AMPS system in the US). While each functioned a little differently most were just wireless versions of a landline phone. These systems allowed you to dial a number and talk to someone, but that was about it.

In the mid 1990’s the first 2G digital systems began to be introduced. In this case “digital” mainly referred to the digitization of voice calls, although they also introduced text messaging as an added service. The main advantage was the ability to squeeze more phone calls into the same amount of radio space and increasing the total number of calls the system could handle.

While most systems were eventually expanded to include some form of packet switched data connections to the internet (think glorified dial-up), the focus was primarily on maximizing the number of circuit switched voice calls to landline phones. In the US four competing systems were deployed: GSM, CDMA/IS-95, D-AMPS/TDMA (Cingular) and iDEN (Nextel).

With the increased use of the internet starting to occur in the late 1990’s, two of the previous 2G systems, GSM and CDMA, evolved to include high speed data connections. However the focus was still mainly on voice calling. While most people still referred to 3G systems by their previous 2G names, technically they were known as CDMA2000 1X/EVDO and UMTS/HSPA+.

By the mid 2000’s the amount of internet data being transmitted over the various wireless networks began rapidly overtaking the amount of voice data being transmitted. A new wireless system was needed and by this time almost everyone in the wireless industry was finally willing to support a single worldwide standard. To do this most of the various organizations that had developed many of the previous standards decided to become a part of a group called the 3rd Generation Partnership Project (3GPP).

What the group developed was a system called Long Term Evolution or LTE. Unlike previous standards, LTE was an entirely packet switched based data system. Actually until the introduction of voice-over LTE technology years later (or more accurately GSMA IR.92 IMS Profile for Voice and SMS), you couldn’t even make a traditional voice call over the system. Most carriers had to continue operating their old 2G and 3G systems for this purpose.

The LTE standard was first outlined in 2008 in a series of documents known as 3GPP Release 8. The standard has been updated and extended several times since in Releases 9, 10, 11, 12, 13 and 14. However the new enhancements have all retained backward compatibility with Release 8.

After years of successful use, the industry is now at a point where it is starting to bump up against the limits of the LTE standard. One of the big ones is that the LTE standard never really defined how carriers should use radio frequencies beyond 6 GHz. Nature makes working with frequencies beyond 6 GHz difficult (the wavelengths at these frequencies are small so even the tiniest objects can block or absorb them) and in 2008 using them just didn’t seem terribly practical.

But technology has continued to march forward and using extremely high radio frequencies is now at least technically viable. In addition new techniques have been developed over the past 10 years to increase spectral efficiency (the ability to squeeze more bits on a given amount of radio bandwidth). The problem is most of these new methods are completely different from the methods used by the LTE standard.

So after much deliberation the members of the 3GPP decided it was time to make a jump. They decided that 3GPP Release 15 would introduce a new method of transmitting data over radio waves that unfortunately would also be completely incompatible with LTE. That new method is called 5G New Radio or 5GNR (linguistic creativity obviously not being a strong trait among wireless engineers).

In addition to increasing spectral efficiency, the 5GNR standard also makes working with frequencies up to 100 GHz easier. This basically makes available 94 GHz of extra bandwidth to work with or more than 15 times the roughly 6 GHz LTE was designed to use. As a result the potential amount of data that 5G devices will be able to squeeze out of the air is multiple times greater than anything that would have been possible with LTE devices. The optimists are correct on this point.

But as always, the devil is in the details. Theoretically 5GNR makes it possible to transmit 15-30 bits per second for every cycle (Hz). But in the real world this will likely translate to only about 30% more data than LTE.  So when the mobile carriers upgrade their existing bandwidth to use the 5GNR method, most users will only see about a 30% bump in performance. Significant, but hardly earth shattering. Most people won’t even notice the change.

5gnr sumary
Summary of 5G characteristics

Also the natural challenges of transmitting data over radio frequencies beyond 6 GHz still exists. While we can cram tons of data into the 94 GHz that will be potentially available, earth’s atmosphere makes it difficult to send it very far (think feet/meters vs miles/kilometers). Here is a chart (courtesy of Verizon) that shows the relative distance that can be transmitted using existing frequencies below only 2.5 GHz (the actual distance depends on a combination of the effective radiated power of the transmitters, the sensitivity of the receiving antennas, terrain and several other factors).

 

 

Propegation

What this means is that to take advantage of all that bandwidth above 6 GHz the carriers will have to build huge numbers of new towers very close together (probably roughly every 1000 feet (300 meters) or less). While these won’t have to be the big towers we often see to today , each of them will still normally need to be connected to the internet via their own fiber cable (if you can’t send a signal very far anyway, there is no point in having an antenna 250 feet in the air).

But in the end no matter how you look at it, building all these radio towers will be extremely expensive. This might be financially viable in extremely dense urban areas (this technology would work great in a packed football stadium). They are unlikely to be workable in suburban or rural areas anytime soon. In those cases it will probably just be cheaper to string fiber to every home. So the pessimists are correct on this point.

So why am I optimistic? The problem with the 5G pessimists is that they are implying that all the bandwidth below 6 GHz that can be used for mobile phone service has already been deployed and is being used. The reality is only a fraction of this bandwidth is currently being used. Of the four major US carriers, only Sprint has rights to more than 200 MHz (0.2 GHz) of that 6 GHz (here is how it is being used).

The bottom line is regardless of the efficiency of the method that is used to transmit data, overall performance is still mostly depends on the amount of available bandwidth the carriers have to use. Give them more bandwidth and your mobile device will naturally work faster.

While much of sub 6 GHz bandwidth is being used for other important uses (e.g. airplanes, broadcast television and radio, GPS, the military, etc.), a surprising amount of new bandwidth will still likely soon become available. Even among the existing spectrum, much of it is underutilized.

Here is a list of places much needed extra bandwidth will come. Each alone will only give an incremental boost. But together it will ensure a fast 5G future even if carriers never transmit a single bit on a frequency over 6 GHz.

850 MHz – refarming 2G and 3G spectrum

As I mentioned LTE is data only. Until recently most carriers have had to continue operating their old less efficient 2G and 3G networks in order for their customers to be able to make calls. This changed recently with the widespread deployment of voice-over LTE (VoLTE) technology that enabled users to start making traditional voice calls over LTE.  Since LTE has much better spectral efficiency than the old 2G and 3G networks, that old bandwidth can now be put to much better use. Over the next year or two most carriers will completely shut down these old networks freeing it for use by either LTE or 5GNR.

600 MHz

A few years ago the FCC auctioned off almost all of the bandwidth between 600 MHz and 700 MHz (formerly known as UHF TV channels 38-51). Most of this bandwidth was purchased by T-Mobile and is now being gradually deployed as legacy TV broadcasters slowly vacate the spectrum. The process should be complete by the middle of 2020.

T-Mobile was the only US carrier that lacked significant low band spectrum (below 1000 MHz (1.0 GHz)). In addition to dramatically improving T-Mobile’s coverage in rural and suburban areas, it will also significantly increase total capacity in urban areas.

Personally I think the rest of the UHF TV band (channels 14-36 or roughly between 500 and 600 MHz) will also eventually be auctioned off. I have serious doubts most traditional linear television will survive the cord cutting era. But it will probably be another 10 years before all of that fully plays out.

600 MHz and 1.7/2.1 GHz – Squatters

This is a particular annoyance of mine. During the past couple of major bandwidth auctions (600 MHz and AWS-3) a couple of parties have purchased big chunks of spectrum just to sit on it. The parties are speculating that eventually the value of this spectrum will increase substantially and they intend to sell it at a significant profit when it does (looking at you Charlie Ergen).

Technically the FCC has rules requiring buyers put to use any spectrum they purchase from the government within a certain amount of time. But the reality is people often play games to get around these rules for years or even decades. This forces everyone else to unnecessarily pay more for substandard service.

This is not a technical problem. It is a political problem. Charlie Ergen’s Dish Networks alone is currently sitting on almost 100 MHz of quality bandwidth. It alone holds almost as much bandwidth as Verizon. This needs to stop. We need an FCC with the guts to tell these people to either deploy now or give the spectrum back.

2.5-2.7 GHz – former Broadband Radio Service (BRS) and Educational Broadcast Service (EBS) bands.

Back many years ago the FCC made available about 200 MHz of spectrum for “Wireless Cable” service. About half the spectrum was set aside for commercial use and the other half for educational use. Only a few TV services were built using the spectrum and the FCC eventually changed the rules on using it making it available to wireless carriers. Through a series of purchases and long term leases Sprint has ended up with most of it.

But Sprint, as the smallest of the four major carriers in the US, has never been able to raise the capital necessary to fully deploy the spectrum. As a result in most areas of the country the spectrum is unused. However the pending merger of Sprint with T-Mobile should provide the capital needed to start making use of this resource. My guess is T-Mobile will likely start using the spectrum shortly after the mergers approval.

But I don’t think the FCC should assume it will happen. At the very least the FCC should make the approval of this merger dependent on T-Mobile quickly deploying this spectrum. If they don’t they should be forced to sell it to someone who will. It is far too valuable a resource to waste.

3.5-3.7 GHz – Citizens Broadband Radio Service (CBRS)

This is a new band of spectrum that should be available in the US shortly. These frequencies have historically been used by the US military. The biggest user being the US Navy who use it for radar.

For the most part this radar is only used at sea and is rarely used inland. Because of this the FCC decided the spectrum could potentially be shared. While the US Navy will continue to have priority in using this band, this will probably only be a significant issue near its ports. Everywhere else both wireless carriers and unlicensed users will be able to use it. In some ways the system will work similar to WiFi. But it will be different in the sense that the carriers will have the option of paying for the right to force unlicensed users to switch channels if they decide to use it. It is also different in that users will have the option to deploy high power base stations (50 watt ERP vs WiFi’s 1 watt limit).

The FCC is hoping to encourage smaller companies and individual to make the most use of this spectrum (hence the term “Citizens Band”). Personally I will be interested in seeing how this plays out. Since it is mid-band spectrum my own guess is that at least one or more major carriers will quickly deploy it in the major urban areas (Verizon seems the most interested). But the FCC is capping how much bandwidth they can use. Also the big carriers will probably continue to ignore most rural areas under the (probably mostly correct) belief that their low band towers can provide sufficient service.

As a result this may open up opportunities for communities that find themselves on the fringes of existing carrier coverage. The cost of priority licenses in these areas should be modest and may not be needed at all. With most new phones likely having support for the CBRS band built in (LTE Band 48), small providers (like small town telephone and cable companies) should be able to just throw up a high power tower and and start handing out sim cards. Newer phones containing a second eSim should make deployment even easier since these devices can support using two carriers simultaneously (few people are likely to be willing to sacrifice the service of a major carrier or carry a second device). It’s a little to early to tell how things will turn out, but this at least has the potential for being a win-win situation for both urban and rural users.

3.7-4.2 MHz – the “C” Band

Back about 30 years ago older readers may remember people putting large dish antennas in their backyards in order to receive what were, for a short time, freely available cable TV stations like HBO. Those big dishes were being pointed at satellites that were broadcasting analog transmissions to cable TV providers across the country. These providers picked up the signal with their own dishes and then passed them on to subscribers. Needless to say companies like HBO weren’t happy with people other than cable TV subscribers watching their shows for free. It wasn’t long before these signals were encrypted and these viewers asked to pay up.

While the backyard pirates have now disappeared, this radio band is still used by cable broadcasters to send their now encrypted digital content to cable providers. But the FCC has recently noticed that the band isn’t being used as efficiently as it could. As a result it has opened up discussions with the cable industry about sharing at least part of the band with mobile phone carriers. The negotiations are still in an early stage, but the industry has already mostly agreed to share at least part of this band. It is mainly a question of how much of the bandwidth they are willing to offer given various monetary incentives.

Currently it appears the wireless carriers will gain access to somewhere between 200 and 300 Mhz of bandwidth (out of a total of nearly 500 MHz). This is nearly as much as the entire industry is currently using. Potentially this type of bandwidth could finally enable true gigabit level service on a mobile device. Unfortunately it will probably be about another 5 years before everything is finalized.

Conclusion

As you can see, there is plenty of available bandwidth to enable near gigabit service at some point in the next 5 or 6 years without having to use any bandwidth over 6 GHz. Indeed any deployments of extremely high frequency bandwidth will likely be just a bonus. Since the propagation characteristics of all this new sub 6 GHz bandwidth shouldn’t be that substantially different from that which is already being deployed, most of it should work fine on existing towers.

But there is one caveat. Deploying all this bandwidth still won’t be cheap even if the carriers won’t need to build huge numbers of new towers. What gets built will ultimately be based on how much money the carriers can justify spending.

Personally my guess is most of the available bandwidth over 2 GHz will end up being deployed almost exclusively in urban areas. The propagation characteristics of this bandwidth (read short range) make it hard to justify in rural areas. That said the combination of T-Mobiles 600 MHz spectrum, the 600 MHz spectrum Charlie Ergen is squatting on and the original 850 MHz cellular band (CLR) both Verizon and AT&T should soon be refarming soon should provide substantial capacity. Throw in the rest of the 500 MHz UHF TV band in the future and even deep rural areas should be fine.

The problem is the further you are from a tower, the slower the speed. There is still a limit on how far apart towers can be placed and still retain reasonable service. Based on my own experience working in rural areas of southeast Minnesota, the current arrangement is far from ideal. Local deployment of CBRS base stations may help fill in some of the gaps, but even a handful of low bandwidth towers would likely do a much better job.

Unfortunately it appears the economics of rural areas make these towers difficult to justify. Similar to rural electrification efforts back in the 1930’s through 1950’s, there just aren’t’ enough users living in these areas to make the investment profitable. So some level of subsidisation is likely necessary to make something like this possible.

In addition note that wireless technology, no matter how good it gets, will probably never be able to fully replace a direct fiber or even coaxial cable link. Even cheap coaxial cable using the DOCIS 3.1 standard can potentially provide a 10 Gbit connection in both directions. We are a long way from wireless carriers being able to provide that kind of performance at a reasonable price. I will agree that most cable providers need to up their game (something cord cutting should speed along). But if you like watching lots of Netflix on a big 4K TV I wouldn’t start looking for Verizon, AT&T or T-Mobile to replace them anytime soon.

Finally don’t look for big price drops. The cost of providing wireless service is relatively fixed. To provide X amount of coverage/capacity you need X amount of towers for a given amount of spectrum. The use of 5G won’t change the equation much. On the other hand I don’t think you will see significantly higher prices either. What you should see is increasingly better coverage and progressively faster and more reliable service.