Cellular carrier ownership of mmWave 5G spectrum creates challenges for fixed deployment
With huge recent acquisitions of 5G spectrum licenses in the 28 GHz and 39 GHz frequency bands in the US by the major cellular carriers, the landscape for 5G deployment is taking shape, and is at risk of excluding future fixed wireless access deployments using these frequencies.
Of course, no one can blame the major cellular carriers for acquiring all this spectrum. Clean licensed spectrum is their lifeblood, and one major part of how they can be sure that the networks they spend billions building, operating and maintaining are capable of providing the service their customers expect, not to mention protecting their own investments.
Without the assurance licensed spectrum provides, traditional wisdom says it’s highly likely that the major cellular carriers would not invest in network deployment at the rate which they do today, negatively impacting the availability and performance of networks we all use for critical tasks every day.
But does this thinking still make sense when we consider the shorter ranges these mmWave frequency bands are restricted to, compared to the far-reaching licensed lower frequencies such as 700 MHz that the major cellular carriers have typically deployed services in up to this point?
The 28 GHz band
As one of the most talked-about frequency bands for 5G, 28 GHz licenses are a hot item today.
In the US, the 28 GHz band is now licensed on a per-county basis. In total, the band is 850 megahertz wide, split into two 425 megahertz licenses. A single license entitles the owner to both fixed and mobile operation, and although there are spectrum aggregation policies, it’s possible for one entity to hold both of these licenses for a given county.
The deployment model for mobile 5G using 28 GHz spectrum looks to be one of ‘islands’, with many small cells providing comparatively short-range coverage, rather than the broad geographic coverage achievable with considerably lower frequencies such as 700 MHz, used for LTE cellular services today.
This means that although a carrier may obtain a license for a county, it is very likely that their 28 GHz services for mobile use will only be deployed in major urban centres, at least to start, which in many counties leaves a significant (often majority) area of that county with no high-speed 28 GHz service.
However, where mobile 5G services are not deployed in 28 GHz, such as semi-rural or suburban areas which are not suffering hugely from inadequate capacity on today’s LTE networks, there exists an opportunity to improve broadband internet connectivity by using the 28 GHz band.
Fixed wireless access operators
Fixed wireless access networks, deployed primarily in the 5 GHz, 3 GHz and 2.4 GHz bands, serve many of these areas today not just in the US but worldwide. Unlike mobile, they use a fixed deployment model, and typically provide broadband internet connectivity to homes and businesses that are underserved by other technologies such as cable and fibre.
Although mmWave frequencies aren’t capable of covering the same distances that their lower-frequency cousins can, a 28 GHz fixed wireless access system could feasibly deliver 100 Mbps broadband internet service to fixed subscribers 5 kilometers away. In many areas, this is achievable; the access point or base station can be brought close enough using microwave backhaul or a local fibre connection to make the distance gap between mmWave and lower frequencies all but irrelevant.
There are fixed wireless access operators in many parts of the US and many other countries worldwide, all with one thing in common: none of them come close to the scale of a major cellular carrier. Even the largest of these operators would be very hard-pressed to outbid for a spectrum license against an AT&T or a Verizon, especially if their chosen county included a major urban centre.
Even outside of major urban centres, fixed wireless access deployment at mmWave frequencies is not a priority today for the major cellular carriers. All eyes are set on delivering the initial promise of 5G, that of super-fast and flexible mobile connectivity, and the initial place to do that is a dense urban area.
Mobile first, or mobile only?
So where does that leave our fixed wireless access network operators? Let’s assume that all the 28 GHz licenses are bought up across the entire United States by the major cellular carriers. This may not be too far-fetched, when the appetite for spectrum acquisition has been clearly shown in recent weeks and with the spectrum seen as a key anchor for 5G.
At the beginning, it looks certain that mobile first will be the dominant use of this spectrum. But the question is over time, will we see a holding of this position, or a movement towards mobile only?
The case for remaining mobile first is reasonable; unless appetite exists at the major cellular carriers to extend 28 GHz mobile coverage to more than major urban centres, traditional concerns about interference in licensed spectrum are mitigated due to the restricted ranges of networks at 28 GHz.
But, the alternative outcome is also feasible. If the major cellular carriers have the ambition to cover more and more areas in 28 GHz mobile coverage, or simply wish to keep it their own to maintain exclusivity on the highest-speed wireless service, mobile or fixed, other users will be excluded.
Couldn’t one of the major cellular carriers simply deploy their own fixed wireless access network at 28 GHz? They hold the licenses, they have the capability to deploy infrastructure, and seem unlikely to turn down the opportunity to sign up more paying customers. Yes, they could – but their investment is more likely to be focused on improving their mobile services, and a 5G network rollout will not be inexpensive.
Meeting in the middle
A possible solution to this problem is that a fixed wireless access network operator could work out an arrangement with the major cellular carrier that owns the spectrum in a given county, carving it up into finer geographical areas and establishing the boundaries between mobile and fixed services in the band.
Would major cellular carriers be inclined to participate in such an arrangement, given that they seem to hold all the cards? Well, as each 28 GHz license allows for both fixed and mobile use, it is reasonable to assume that the FCC had in mind some fixed use of the band during its recent rule changes.
Can we expect the FCC to ask the major cellular carriers to allow paying fixed wireless access network operators to deploy and operate fixed services, in defined geographic areas within a county in this way?
Unless there is significant attention brought to this question, it seems unlikely that the FCC will rock the boat too much at this stage when 28 GHz deployments are looking to begin in earnest in the near future.
Conclusion
Regardless of who deploys them, my hope is that fixed wireless access networks are able to be deployed at 28 GHz, in areas where they are capable of bringing significant improvements in broadband internet connectivity to homes and businesses underserved by other options today.
