How much spectrum does the mobile industry have, and how much do they really need?

Fred Goldstein

Several few years ago, the big topic in American telecom policy was the race to 5G. The so-called race was sensationalized: the country’s economy depended on deploying 5G mobile service faster than China. This was accompanied by more spectrum auctions and major capital expenditures by the mobile industry. In this article, we ask, “Has the race to 5G had much of a positive impact? Was it more of a way for a few vendors to sell more equipment to the carriers? Or did it help the carriers tighten their grip on the scarce radio spectrum to the exclusion of private or local users?

Spectrum Evolution

The mobile phone industry began in the 1980s with analog cellular service, with two licenses per market area, operating on former TV channels 70-83 in the 800 MHz range. Its success led to the 1996 auctioning of the 1800 MHz PCS radio band, with six licenses per market. Sprint and the predecessors of T-Mobile-US got their start there, although a fair number of licenses were purchased for trading purposes, essentially using a model of licenses as financial assets rather than providing services.

Since then, several other bands have been assigned for mobile operation, or what the FCC now calls flexible use. Higher-frequency bands tend to have wider channels, higher bit rates for mobile data, and shorter range, while “low bands” below 1 GHz have better coverage but lower bit rates. Mobile devices switch seamlessly to find the best available service from their carrier.

The mobile industry has continued to seek new spectrum as it grows. Since little spectrum is unused, regulators have rearranged bands and moved some users out of the way to make room for them; for example, television channels again became a major source.

The Digital Dividend

Early this century, broadcast TV made the transition from analog to digital. In most cases TV stations were given second channels, so they could transmit both analog and digital. While 1950s analog receivers worked best in the VHF bands (channels 2-13, below 216 MHz), most digital TV (DTV) was UHF (then channels 14-69, above 470 MHz). Most analog TV was shut off in 2009.

TV channels 52-69, the 700 MHz band, were auctioned off to mobile carriers in two stages. The first channels auctioned in 2002 went cheap, since the licenses were not usable for several years. Once the transition was real, channels auctioned were (more) expensive. Delaying the next auction a year at a time, until 2008, also allowed Congress to count the same anticipated auction revenues towards the budget deficit in several fiscal years!

Incentive Auction

In 2016, the FCC held an incentive auction in two parts. TV stations were invited to a reverse auction to relinquish their broadcasting rights, after which channels 38-51, the 600 MHz band, were auctioned off to mobile carriers. TV stations could move back from UHF to the now less desirable VHF channels, or they could double up by using one DTV transmitter to carry more than one video stream. By this time, most viewers were using cable or streaming services, so over-the-air (OTA) quality was now less important than before, but having an OTA transmission was still important in many areas where viewers were close enough to TV transmitters and able to get good reception without having to pay a monthly cable or streaming bill. And OTA allowed the station to choose must-carry or retransmission fees from cable operators in its service area.

Mobile carriers were then invited to the forward part of the incentive auction for the repurposed spectrum. Many of the licenses again went to speculators. T-Mobile has used that spectrum to improve its service coverage. Dish/Echostar won licenses too, and after Sprint was acquired by T-Mobile, it was allegedly going to become the fourth national carrier, but that goal has proven to be financially elusive. This band sees far less use than 700 MHz, which has become much of the backbone for Verizon and AT&T’s public safety-oriented FirstNet.

6G is the new game

The original 800 MHz channels, of course, have also been recycled for 4G (LTE) and 5G use. The carriers have also, over the years, gained access, via auction, to several more exclusive-use bands, including 2.1 GHz, 2.5 GHz, 3.45 GHz, 3.7 GHz, and millimeter wave bands at 24 and 28 GHz. What’s next?

Naturally, mobile carriers are seeking more spectrum.. “6G” is the new game, and while this generation of cellular technology is still undefined, mobile carriers will insist that they will need additional spectrum. The mobile carriers want the federal government to free up spectrum that is currently used for national defense purposes, including radar. At least some of this spectrum will be shared: while spectrum sharing already exists on a few bands, most of those are only lightly used by the government.

The Rich Get Richer

In the US, when the big carriers ask for and receive more spectrum, there’s less for everyone else. In much of Europe, enterprises can license private broadband networks to cover their own facilities or campuses. The United States has considerable unlicensed spectrum usable for private networks such as Wi-Fi, but no spectrum for locally licensed, protected private broadband networks. Private microwave and land-mobile licensing still use spectrum paradigms from the 1980s or earlier, when voice was king.

The CBRS band at 3.55 GHz is a creative mix of medium-power licensed-protected (Priority Access Licenses) and license-exempt (General Authorized Access) secondary broadband use, but the FCC has an open docket to change its rules to be more like the mobile bands. It is popular among wireless ISPs (a key Interisle constituency) and cable, but its “small cell” power limit, while much higher than Wi-Fi, has not attracted much support from the big mobile carriers.

Closing Remarks: Opportunities lost?

Ironically, though, the big carriers are missing an opportunity. There’s a concept out there by which mobile service providers, instead of adding more spectrum to handle more capacity, simply reduce the geographic coverage of congested base stations. In this way, base stations with smaller coverage areas allow the same spectrum to be reused more often in crowded areas. It’s rather novel, it seems, but there is a name for it: Cellular. Perhaps they should try it.