Existing 4G Spectrum

I suspect that most people don’t realize the small number of frequencies that are used today to support cellular service. Below is a list of the frequencies used by each US cellular carrier for providing 4G LTE. Except for Sprint, they all use the same basic frequencies.

Frequencies (in MHz)

AT&T  – 1900, 1700 abcde, 700 bc

Verizon – 1900, 1700 f, 700 c

T-Mobile – 1900, 1700 def, 700 a, 600

Sprint – 1900 g, 850, 2500

The letters represent separate licenses for specific sub-bands of the various frequencies. For example, the 1700 MHz band has been licensed in bands a through f and the carriers own rights to various sub-bands rather than to the whole spectrum. The same is also true for 1900 MHz and 700 MHz spectrum. In many cases, the licenses for the various spectrum bands are not nationwide. This means the frequencies used in Cleveland by one of the carriers might be slightly different than the spectrum used in San Francisco.

The carriers are using these limited spectrum bands today to support both 4G voice and data. In metropolitan areas, the carriers are in big trouble. They are finding it impossible to satisfy customer requests for data service, which is resulting in customer blockages or greatly reduced broadband speeds.

One of the primary reasons that the carriers are running into blockages on 4G data is that they aren’t deploying enough different bands of spectrum for broadband. The carriers have three remedies that can be used to improve cellular data – use more bands of spectrum, build more cell sites (small cells), and implement 5G which will allow for more simultaneous connections.

The CTIA, the lobbying group for the wireless carriers has been heavily lobbying the FCC to allocate 400 MHz of additional mid-range spectrum for cellular data. The FCC is considering repositioning numerous bands of spectrum and the CTIA wants to grab everything possible for data purposes.

Unfortunately, spectrum alone is not going to provide the solution the wireless carriers are hoping for. One of the primary reasons that the cellular carriers only use a few different bands of spectrum today is to simplify handsets. There is a huge price to pay for using multiple bands of spectrum in a cell phone. The more bands of spectrum, the more antennas that must be supported and the more power that is used.

If the cellular companies try to load many more bands of mid-range spectrum onto cellphones they will have majorly overstressed the battery life of phones. Most cellphone customers are not likely going to want to trade faster data speeds for shorter battery lives. As I look forward at the strategies of the cellular carriers, the battery life of cellphones might be their biggest limitation. The question is not so much about how much data a cellphone can handle, but rather how much battery life must be sacrificed to gain broadband  performance. The only solution for this is likely some new battery technology that is not yet on the horizon.

I don’t believe that the average cellphone user values cellular data speeds in the same way that they value fast landline data speeds. 4G today is easily capable of streaming video and there’s no reason on a cellphone to stream more than one video stream at the same time. 4G is reasonably okay today at operating most celular apps. The one group of cellphone users that always want more bandwidth are gamers – but there is no way that cellphones are ever going to be able to match the capabilities of gaming systems or gaming computers using landline broadband connections.

I scratch my head every time I hear 5G claims about providing gigabit cellular service. I don’t want to sound like an old-timer who sees no need for greater speeds. But I think we need to be realistic and ask if superfast cellular bandwidth is really needed today – after all, there are still no landline applications for homes that require anything near to a gigabit of bandwidth. The primary reason homes need faster download speeds is to handle multiple big bandwidth applications at the same time, something that is not today a requirement for cellphones.

The idea of gigabit cellular is mostly coming from the imagination of the cellular company marketers. The 5G standard calls for eventual ubiquitous 100 Mbps cellular speeds. Even achieving that much speed is going to require tying together multiple mid-range bands of spectrum. I’m having a hard time seeing the additional revenue streams that will pay for the massive upgrades needed to reach the 100 Mbps goal. The cellular companies all know this but aren’t talking about it because that would dilute the message that 5G will transform the world.

Clearing Mid-range Spectrum

The FCC is in the process of trying to free up mid-range spectrum for 5G. They just opened a Notice of Proposed Rulemaking looking at 2.5 GHz spectrum, located in the contiguous block between 2495 and 2690 MHz. Overall this is the largest contiguous block of mid-range spectrum. Over half of the spectrum sits idle today, particularly in rural America. The history of this spectrum demonstrates the complications involved in trying to reposition spectrum for broadband and cellular use.

The frequency was first assigned by the FCC in 1963 when it was made available to school systems to transmit educational TV between multiple schools. The spectrum band was called Instructional Television Fixed Service (ITFS). The band was divided into twenty channels and could transmit a TV signal up to about 35 miles. I grew up in a school system that used the technology and from elementary school onward we had a number of classes taught on the TV. Implementing the technology was expensive and much of the spectrum was never claimed.

In 1972 the FCC recognized the underuse of the spectrum and allowed commercial operators to use the bands of 2150 to 2162 MHz on an unlicensed basis for pay-TV transmissions to rooftop antennas. The spectrum could only carry a few TV channels and in the 1970s was used in many markets to transmit the early version of HBO and Nickelodeon. This spectrum band was known as Multipoint Distribution Service (MDS) and also was good for about 35 miles.

Reacting to pressure from cellular companies, the FCC reallocated eight additional channels of the spectrum for commercial use. Added to the MDS spectrum this became known as Multichannel Multipoint Distribution Service (MMDS). At the time this displaced a few school systems and anybody using the spectrum had to pay to move a school system to another workable channel. This spectrum was granted upon request to operators for specific markets.

In 1991 the FCC changed the rules for MMDS and allowed the channels to be used to transmit commercial TV signals. In 1995 any unused MMDS spectrum was sold under one of the first FCC auctions, which was the first to divide service areas into the geographic areas known as Basic Trading Areas (or BTAs) that are still used today. Before this auction, the spectrum was awarded in 35-mile circles called Geographic Service Areas (GSAs). The existing GSAs were left in place and the spectrum sold at auction had to work around existing GSAs.

The FCC started getting pressure from wireless companies to allow for the two-way transmission of data in the frequency (up to now it had been all one-way delivery to a customer site). In 2005 the FCC changed the rules and renamed the block of spectrum as Broadband Radio Service (BRS). This added significant value to licenses since the spectrum could now be repositioned for cellular usage.

At this point, Clearwire entered the picture and saw the value of the spectrum. They offered to buy or lease the spectrum from school systems at prices far lower than market value and were able to amass the right to use a huge amount of the spectrum nationwide. Clearwire never activated much of the spectrum and was in danger of losing the rights to use it. In 2013 Sprint purchased Clearwire, and Sprint is the only cellular company using the spectrum band today.

Today the spectrum band has all sorts of users. There are still school districts using the spectrum to transmit cable TV. There are still license holders who never stopped using the 35-mile GSA areas. There are still MMDS license holders who found a commercial use for the spectrum. And Sprint holds much of the spectrum not held by these other parties.

The FCC is wrestling in the NPRM with how to undo the history of the spectrum to make it more valuable to the industry. Education advocates are still hoping to play in the space since much of the spectrum sits idle in rural America (as is true with a lot of cellular and other mid-range spectrum). The other cellular carriers would like to see chunks of the spectrum sold at auction. Other existing license holders are fighting to extract the biggest value out of any change of control of the spectrum.

The challenge for repositioning this spectrum is complicated because the deployment of the spectrum differs widely today by market. The FCC is struggling to find an easy set of rules to put the genie back in the bottle and start over again. In terms of value for 5G, this spectrum sits in a sweet spot in terms of coverage characteristics. Using the spectrum for cellular data is probably the best use of the spectrum, but the FCC has to step carefully to do this in such a way as to not end up in court cases for years disputing any order. Reallocating spectrum is probably the most difficult thing the FCC does and it’s not hard to see why when you look at the history of this particular block of spectrum and realize that every block of spectrum has a similar messy past.