Because the only real deliverable from 5G is a somewhat faster version of the mobile data service we already had, the mobile industry has tried to make a convincing case that this 5G thing was worth the trouble. To this end, we’re now hearing about marvelously creative (though largely speculative) new applications for 5G. What these visions have in common is an utter disregard for reality or entrenched competitors.
My favorite is fixed wireless, or the idea of using 5G as an alternative to cable or fiber for home internet access. If you can put aside for the moment the fact that 5G’s mobile broadband service is a lot slower and is generally less reliable than cable or fiber, you come to find out the fixed wireless service only available in magical places where you can get 5G, but the cellular network is underutilized to the degree the carrier determines they can offer 5G as an alternative.
After wrapping your head around that sales argument, maybe it’s not a surprise that we hear more about the carriers’ plans to offer private 5G networks—particularly ones using the recently released Citizen Broadband Radio Service (CBRS) frequency band. This news is big because it’s a new way for enterprises to implement private wireless networks operating on the licensed radio spectrum. Additionally, most new cellular devices (including Apple’s soon-to-be-released iPhone 13) support the CBRS band, so device availability shouldn’t be a problem (i.e., you only require a SIM for the private network).
Private 5G offers a new value proposition, but no one seems to have pointed out its major Achilles heel: scalability.
Capacity Limits On CBRS-Based Private 5G?
Wi-Fi, the current private wireless workhorse for enterprises, operates exclusively on unlicensed channels, which does introduce the potential for interference from other users. However, with the newly released 6 GHz unlicensed band, Wi-Fi now has approximately 2 GHz of radio spectrum in which to operate. It’s unlicensed, but Wi-Fi’s limited transmission range means that if you’ve got a big property footprint, you pretty much own the unlicensed channels in that area anyway. If interference from your neighbors is a problem, you can select from a plethora of other channels. The entire CBRS band they are looking at for private 5G is 150 MHz, typically parceled out in 10 M or 20 MHz channels.
For perspective, one standard Wi-Fi channel occupies 20 MHz. Newer Wi-Fi standards like Wi-Fi 6/802.11ax support concatenated channels up to 160 MHz wide. That means a single Wi-Fi channel can be bigger than the entire CBRS band. Most Wi-Fi networks aren’t using 160 MHz channels. But customers are already running bunches of 40 MHz or larger channels around their campuses, so it’s hard to imagine the carriers could be serious about their hopes of supplanting Wi-Fi in enterprises.
I stumbled onto a capacity paradox almost by accident when I was reviewing the specs of one of the access points being proposed for private 5G. The unit had a maximum downstream capacity of 135 Mbps and would cover an area of 25,000 square feet.
By comparison, Wi-Fi access points typically cover 3,000 to 5,000 square feet and have capacities measured in gigabits. To anyone with the slightest bit of insight into the wireless business, there’s no way to fit all of our current Wi-Fi traffic (forget about growth) into a total of 150 MHz of CBRS spectrum. Case closed.
What Can a CBRS-based Private 5G Network Do?
As it turns out, I found a kindred spirit when I interviewed Ozer Dondurmacioglu, marketing VP for private 5G vendor Celona
. He flat out said the company isn’t talking about replacing Wi-Fi. Instead, its focused on specialized applications that can take advantage of what a private network built exclusively on the licensed spectrum can deliver.
In defense of the limited radio spectrum, Mr. Dondurmacioglu did make the valid point that the cellular network standards make far more structured and efficient use of the radio capacity than Wi-Fi’s contention based access. However, that’s nowhere near the scale needed to offset the spectrum deficit. Further, that capacity can be allocated in very granular fashion with network slicing.
Network slicing is the ability to subdivide the radio network to support different users, or to support different traffic types with different requirements for latency, jitter and packet loss.
Network slicing is a term that is unique to the cellular business, but for those in the data networking community, they’re talking about differentiated services. Network slicing could allow you to divide your network capacity between best effort data and specialized low-latency control channels for robots.
Celona is pursuing several opportunities in this vein that don't involve replacing Wi-Fi, such as a mobile service provider that's overlaying a CBRS network on their existing cellular infrastructure to offer a broader range of offerings in their service area.
However, the message for enterprise buyers should be clear—we must start thinking about private 5G in terms of what it can realistically do, and truthfully, it can’t do what Wi-Fi does. We should consider private 5G applications in terms of scarce, precious bits, not bulk wireless capacity.
The Big Surprise: Private 5G For Indoor DAS
In our discussion, Mr. Dondurmacioglu brought up another potential application of private 5G that took me completely by surprise. It caught my attention because it addressed one of my biggest concerns with 5G in general—indoor coverage. It turns out, Celona is also looking at private 5G as a new alternative to a distributed antenna system (DAS), the carriers’ legacy solution for indoor coverage problems.
A traditional DAS captures the cellular signal from the carrier’s outdoor network and uses a system of cables, amplifiers, and antenna heads deployed throughout the facility to distribute it so that all users can get a good signal to make and receive calls. Our primary cellular carrier would often deploy a DAS in our facility, and then offer the other carriers the option to connect to the system for a monthly fee so their subscribers could the same improved indoor coverage. That type of multi-carrier implementation gets referred to as a neutral host.
The key element in the private 5G DAS play is that all the new cellphones can support the CBRS frequencies. For example, a venue operator could install a private 5G network and sell slices of that network capacity to the different operators to use as their indoor roaming solution. Carriers would only need to add those private CBRS channels to their list of available channels, so the transition would be transparent to the user. Their device would roam from the carrier’s outdoor network to the CVBRS-based private network when they enter the venue.
I realized a long time ago, what we need from 5G indoors is voice capability. Smartphones default to Wi-Fi for data service, so if there’s Wi-Fi available, it covers data. But how do you make or receive phone calls? From the venue operator’s standpoint, they choose how mobile users in their venue get served.
New Options Emerging
One thing is certain in the wireless industry: new options will continue to emerge. Those responsible for providing a wireless capability for users will have to be alert to these opportunities but wary of their potential. Even the late (and great) Paul Allen, a co-founder of Microsoft, lost a bundle as the primary backer for Metricom’s Ricochet wireless Internet service
back in the late-1990s. It’s tough to pick a good horse in this wireless race.
It’s also tough to obtain an objective analysis about these emerging options, as much of the reporting I’ve seen appears to be funded by mobile operators. On a cautionary note, established carriers are buying up all of the licensed spectrum they can lay their hands on—investing billions of dollars in the process. A business model like this one ensures the ongoing viability of the cellular network but also effectively blocks out any other potential solutions for how that spectrum gets used. Unless, of course, the carriers become spectrum wholesalers—but I’m not betting on that option.
In any event, enterprise buyers must analyze the full range of available 5G options, assess their viability as well as their technical merits, and make informed decisions.
To learn more about private 5G, Wi-Fi developments, and more, join me during my Enterprise Connect Virtual session, “Mobility Update: Where Are We With 5G & Other Wireless Technologies
,” on Monday, September 27.
This post is written on behalf of BCStrategies, an industry resource for enterprises, vendors, system integrators, and anyone interested in the growing business communications arena. A supplier of objective information on business communications, BCStrategies is supported by an alliance of leading communication industry advisors, analysts, and consultants who have worked in the various segments of the dynamic business communications market.