Private LTE has received a fair amount of interest of late, particularly in the citizens broadband radio service (CBRS) frequencies. Moreover, there is talk that private LTE being looked at as a replacement for public Wi-Fi, again, particularly in the CBRS spectrum. It is interesting what is being discussed around this.
In one of my feeds, there was a discussion about a company called Cradlepoint, a company that is championing the CBRS band as an opportunity to provide private LTE to enterprises. An excerpt from the company missive states its wireless routers can be used in conjunction with the CBRS spectrum to provide enterprises with a way to escape from Wi-Fi.
That is a slightly slanted perspective, IMHO. Wi-Fi has done a fairly decent job, in many cases. However, it was never intended as the be-all and end-all of public or private networks. However, upcoming Wi-Fi 6 is a “whole ‘nother animal” and is going to change the Wi-Fi landscape, as we know it.
There is no doubt that private LTE networks are a platform that has potential. There is also no doubt that there are applications, with a large number of devices that require ample bandwidth, where Wi-Fi struggles. However, it is unlikely that CBRS will replace public or private Wi-Fi, as some are suggesting.
Why? For a number of reasons. Building a core-based network is not practical for such contained applications (say, a warehouse with tons of production monitoring cameras), because the delay in and out of the core is too lengthy (there is also the economic issue). A multi-access edge computing network (MEC) is also too expensive, as is licensed LTE. Both are overkill for such applications.
Moreover, except for private LTE in the shared spectrum, other private LTE services are too expensive, as well. Finally, while some iterations of pre-Wi-Fi 6 have decent specifications, most are simply too bandwidth, and speed constrained, or too little flexibility and device counts, even with its updates.
However, with the emergence of Wi-Fi 6, this may all become a bit cloudier. How Wi-Fi 6 will challenge this will be discussed in an upcoming dialog.
LTE does have advantages over current Wi-Fi iterations. For one, there is better security and reliability and the choice among licensed, shared, and unlicensed spectrum. In addition, it is ubiquitous and well established. Therefore, private LTE has the potential to emerge as an economical, and technically capable, platform for applications such as warehouses or manufacturing facilities, as a primary vertical.
However, the CBRS band is filled with incumbents. CBRS-based private LTE has the potential for large, multi-device installations, but there a possibility that certain incumbent applications, both on land and on the sea, can become compromised by new CBRS players if the spectrum is not precisely managed.
With private LTE in shared spectrum, management is much more complex. It relies on a process called the spectrum allocation system (SAS). SAS is a complex, three-tier, spectrum authorization framework, designed to accommodate a variety of commercial uses, on a shared basis, with incumbent federal and non-federal users of the band.
Access and operations will be managed by a dynamic SAS, conceptually similar to the databases used to manage television white space (TVWS) devices. Essentially, it is a priority system that allows unused spectrum to be used by multiple players when available. Depending upon which type of license, users can have access to bands from 5 megahertz to, hopefully, 150 megahertz.
However, if TVWS history is any indication of how this kind of spectrum sharing is going to fare, we are in a bit of trouble. TVWS has not been successful. Why that is, is up for some debate, but essentially, it was positioned as an alternative to Wi-Fi and a panacea for rural connectivity – some similar use cases for private LTE.
Moreover, the FCC’s TVWS space policy, to date, has been a flop. There has just been no market adoption for several reasons. One example is that the maximum data rates for TVWS devices range from 3.25-16 Mbps, which is below the FCC’s new threshold for what constitutes broadband. Other challenges include a 4-watt power limit and the risk of interference from short-range devices.
It is unlikely that the CBRS shared private LTE project will have identical issues. The FCC is much wiser about CBRS, but still, it has some bandwidth constraints. Furthermore, it has a similar, complex spectrum management policy that has not been a success in TVWS.
All that aside, there is a lot of optimism for private LTE. Not just in the CBRS band, but overall in 5G. However, the money seems to be in CBRS, for the moment, for a couple of emerging applications.
That being said, however, there is one serious specter that looms over the CBRS band – bandwidth. There is only a 100- to 150-megahertz swath being made available. While that is much better than many bandwidth slices from, 450 MHz to, 2 GHz, even 5 GHz, it is not the “unlimited” chunks that are being anticipated at the higher mmWave frequencies. The FCC has indicated there may be some additional spectrum that can be made available here, but that is only speculation for the time being.
Bandwidths, of 500 megahertz to 2 gigahertz for 5G mmWave, are what the industry has been touting for that elusive 1 < and > 1 µs/Gbps goal. Therefore, one must not lose sight of that and promise beyond what the realities of CBRS are.
Another potential obstacle to CBRS is Wi-Fi 6. In addition, how well SAS will actually function among all the players has not been proven. From a pragmatic perspective, I am a bit concerned that the early excitement of CBRS-based private LTE may be premature.
However, if it turns out that all the challenges can be overcome, private LTE does have the potential to enable a number of different verticals, across a number of wireless segments. Let us hope it lives up to its potential.