Hat’s off to Fierce Wireless and Allnet Insights for an extensive graphically rich report on the current spectrum holdings by each of the main US cellular operators. This highlights the clear contrast between high and low spectrum of each of the key players and how that affects their network strategy.
This article references a Fierce Wireless report that can be found here
Low, Mid and High band classification
Allsight have broken down the frequency bands into three clear categories
- Low: sub-1GHz
- Mid: Around 2GHz
- High: 2.3-2.6GHz
Low band is best for wide area coverage of rural areas and deeper in-building penetration. Higher bands have shorter range but can be re-used more often, hence providing more capacity for a given area.
Any of these frequencies can be used for 4G and are widely supported by a growing number of end user devices.
Regional Variations
The report drills down to provide regional charts for each of the band classes for each of main operators. For example, this shows low band availability for Verizon and AT&T respectively.
Now these don’t directly relate to the level of coverage or service that you might receive in any specific area, just the permission that each operator has to use spectrum in that area.
Can you have too much spectrum?
We often hear cries of a spectrum shortage and how networks would really like to have as much as possible. There are limits to how much can be used at any individual cellsite. Many countries have limits to the total amount of RF radiation allowed – for example Italy is quite a lot more restrictive than some – so simply having a fewer absolutely massive capacity tower sites wouldn’t be feasible.
For densification and highest capacity, it’s best to reuse the spectrum as much as possible and having lots of it can be counter productive. It seems to me that Sprint has an excess of high band capacity and not nearly enough low band for coverage. This means it can achieve very good speeds and performance in the cities but will struggle to deliver good coverage in more remote areas. It’s strategy includes using their high band spectrum for backhaul by using LTE relays rather than fibre or microwave.
If AT&T wanted to dedicate its high-band spectrum exclusively for indoor use, then it might squeeze out enormous benefits although not all end user devices are compatible with this band yet.
A more controversial view would be for Sprint to permit (or be forced to allow) use of some of its 2.6GHz spectrum for private LTE indoor use, effectively providing a CBRS like service that is more compatible with existing smartphones.
Should the often mentioned merger/takeover between T-Mobile and Sprint ever take place, the combined operation would have copious amounts of all types of spectrum to play with.
The 3.5GHZ CBRS spectrum will be open to all-comers and if mainly used indoors will provide huge amounts of capacity limited only by the availability of compatible handsets.
The spectrum battle for 5G is already underway
Whatever you think about the timeframe or potential for 5G, the major US operators are already eyeing up potential to landgrab spectrum for it.
FierceWireless comments that “If AT&T closes its purchase of FiberTower and Verizon closes its purchase of Straight Path, the two carriers stand to own the bulk of the nation’s available, licensed millimetre-wave spectrum.”
Conclusion
When mobile networks were first launched, access to spectrum assets was a key factor for success. Only those with licences could operate networks. The balance of spectrum greatly affected the number of cellsites required to provide blanket coverage.
But once you start moving into capacity upgrades, less new spectrum is required and reuse of existing spectrum (particularly high band) can be very effective.
The US provides an illustration of how unbalanced the spectrum assets can become. Spectrum shortage? Not really. We just need to make better use of what we already have.
