Move Fast, Break Things: How carriers could break networks in the race to 5G

In the race to deploy 5G networks across the U.S., the big carriers have adopted a “move fast, break things” mentality that threatens to break existing network architectures for the speculative promise of faster speeds and better networks. This mentality is in large part motivated by the narrative that 5G is a race where the U.S. is competing against China to deploy the next generation mobile network. This narrative of a race even led AT&T to push out an OTA update to certain phones that displayed a “5Ge” logo in the upper-hand corner when users were actually connected to was a legacy 4G LTE network with specialized updates. While modestly faster, it certainly fell short of a generational change in mobile telecommunications. 

What is 5G?

For the uninitiated, 5G refers to refers to a set of standards for the next generation of mobile networks. Here is a good summary for those looking for a deep dive on what makes 5G different. Broadly speaking 5G makes three key improvements over 4G LTE networks: 

(1) higher speeds

(2) lower latency

(3) the ability to connect to more devices at once

Like other mobile networks, 5G depends on spectrum allocations through the Federal Communications Commission (FCC), that authorizes carriers to transmit through cell towers and cell phones at a specific radio frequency. However, unlike other networks, 5G relies on a wider array of spectrum allocations in order to provide more data to consumers. Generally speaking, lower frequency bands provide better coverage over longer distances, but typically don’t provide as much data bandwidth, making low band ideal for rural applications. As frequencies increase, signals typically fall off over a shorter range, but can provide higher data bandwidth. Legacy 4G LTE systems already operate on low and mid band spectrum, but new spectrum allocations in high bands, like millimeter wave (mmWave), promise significantly higher data capacity. 5G also depends on network optimizations to reduce backhaul latency to deliver faster speeds. This is what AT&T tried to argue that they deployed with “5Ge” before eventually settling a lawsuit alleging false advertising.

High Band Issues: Problems with mmWave and the 24 GHz disaster

While new high-band allocations promise the biggest potential in speed gains over legacy 4G LTE networks, these benefits will likely only be available to a select few Americans in specific areas within the biggest metropolitan centers. Due to the propagation characteristics of mmWave technologies, the towers have a very limited range – at best only a couple hundred meters – compared to up to 50-150 km for 3G/4G towers. Thus, to effectively deploy a network using mmWave technologies, a very high degree of “network densification” is necessary to provide service. Essentially, while the 5G towers are smaller, a city needs hundreds, even thousands to reach the density required for a functioning network. While this “densification” is logistically possible and economically feasible in major cities, and football stadiums, the potential promise of downloading movies in seconds will likely remain unavailable for rural Americans. 

Another issue with high-band spectrum is the recent “24 GHz disaster”, which threatens the reliability and accuracy of weather forecasts for the promise of better networks. In the recent “Spectrum Frontiers” auction, the FCC sold access to carriers for blocks of spectrum in the 24 GHz band for use in 5G networks. However, this auction was conducted despite objections from NOAA and NASA that mobile allocations in that band would cause significant interference issues with weather satellites that depend on the unique characteristics of the band 24 GHz to observe water vapor in the atmosphere. Once mobile service is active in the band, interference issues could potentially reduce the accuracy of hurricane forecasts by decreasing the forecast lead time. As strong hurricanes become more common and hit increasingly underprepared cities, this band allocation could result in an increase in property damage and potentially even additional loss of life from superstorms. 

Mid-Band Issues: C-Band & 6 GHz

Beyond the 24 GHz band, other bands the carriers are seeking for 5G have additional interference problems that could threaten incumbent services that are still critical to our telecommunications infrastructure. In the C-Band Proceeding, the FCC is considering a reverse auction to relocate or substantially reduce the number of companies using the using the 3.7-4.2 GHz band for satellite communications. These C-Band incumbents include satellite companies, cable companies, rural broadband providers, and television broadcasters. While a number of these incumbents are likely to participate in the reverse auction and sell their current licenses, some incumbents have indicated that they are either unwilling or unable to relocate their services out of the band. Mobile carriers and satellite incumbents are also fighting over exactly how the 500 MHz of spectrum should be divided between incumbents and entrants, and whether or not guard bands are necessary to protect earth stations from interference. Regardless of what decision the FCC makes, there will likely be impacts for rural Americans who depend on satellite services to receive internet, television, or other services. 

In the nearby 6 GHz band carriers are currently in conflict with manufacturers of unlicensed devices (think Wi-Fi routers), over a proposed change for service rules in the band that would allow unlicensed users to share spectrum with licensed users subject to an “automated frequency coordination” scheme designed to prevent interference. This “AFC” technology would be required to be installed on any unlicensed device that operates within the 6 GHz band, and would prevent these devices from broadcasting signals if it might cause interference with a licensed user broadcasting nearby. Unlicensed users argue that as American’s appetite for data increases, more spectrum will need to be allocated for unlicensed use to provide more room for WiFi services. While WiFi devices are predominantly low power and used indoors, mobile carriers argue that AFC rules should be applied to all unlicensed devices operating in the band. AT&T argues that without AFC rules applied to all unlicensed devices, interference with mobile operations will be inevitable. In these arguments the carriers stress that while expanded spectrum for WiFi may be critical, 5G should also be considered a possible solution to America’s expanding appetite for data. 

Dynamic Efficiency: Critics Claim a Flawed Premise for the T-Mobile/Sprint Merger

In their filings and messaging around the proposed merger, T-Mobile/Sprint argue that as a combined firm they will be able to provide better 5G service than any existing carrier will be able to do alone. This assertion is justified in part by the complementary spectrum assignments each company holds (see the figure below.) Together, these assignments will give the ‘New T-Mobile’ access to more spectrum than any other carrier, enabling them to deliver better service. Essentially, a dynamic efficiency gain that outweighs the potential danger of static efficiency losses. 

However, the Department of Justice placed conditions on the merger that require Sprint to sell some of their spectrum to DISH, a company that has a history of hoarding spectrum. According to critics, this idea is unnecessarily complicated as there are currently four carriers, and DISH won’t be a viable option for quite some time. Additionally, the spectrum divestiture somewhat undermines the initial premise of the merger – the combined spectrum portfolios would empower the ‘New T-Mobile’ to provide better service than anyone else.

A false premise of the race to 5G?

Ultimately, the narrative of a race to 5G may turn out more beneficial to carriers than to consumers. Critics of the 5G race argue that there is likely no harm to consumers, and possibly even US carriers, if China succeeds in deploying 5G before the United States – because the Chinese government controls spectrum allocations, major carriers, and device manufacturers, it is significantly easier for China to rapidly deploy 5G. In effect, China can ignore all dissent and centrally manage their economy. In this way, a race analogy benefits US carriers because it motivates the FCC to take a light tough regulatory approach, effectively coordinating or allowing carriers to coordinate in a way that could mirror a centrally managed economy. This may reflect the White House’s focus on delivering “wins” for America, even if those wins come at a heavy cost or start to ape a communist approach to the economy.

Join the CTLJ Content Team at the Silicon Flatirons Saving Our Spectrum Conference on October 10, 2019 at CU Law. Luminaries in the field of spectrum governance and radio propagation will examine these issues, in particular the security vulnerabilities emerging with the next generation of connected devices.