For OT reliable wireless connectivity Private Wireless also wins on TCO
I was recently involved in a bid for a private wireless network for a large paper mill that had no wireless network deployed; what we would call a greenfield deployment. We were competing with a well-known Wi-Fi 6 vendor. Like most paper mills, the plant was massive with very big machines, high ceilings, lots of metal, many moving assets — meaning, like in most industrial sites, a very complex radio environment with the need for extensive and pervasive coverage.
As well as large indoor, we needed to cover the outdoor area. The Wi-Fi vendor proposed close to several hundred Wi-Fi access points (APs) to ensure indoor and outdoor coverage. With our private wireless (LTE/4.9G) solution, we could do it with just a few tens of Micro-BTS outdoors, and a few Indoor-Pico BTS. Unsurprisingly, our bid came in lower, but even we were surprised at how much lower, close to 20% of the competitor’s bid.
That got me thinking that when talking about private wireless vs Wi-Fi, we often focus only on the reliable performance, latency, security, and mobility differences and fail to address the common, but mistaken, perception that Wi-Fi is cheaper, simply because the technology is mass market and each access point is cheaper.
It is admittedly an extreme case. But looking at other customer cases and why the bids were so different and breaking down the details, we can learn a lot about where Wi-Fi makes sense and where a cellular solution, such as 4.9G/LTE or 5G, is the clear winner.
The first thing that struck me and the rest of the team, was that our total bid came in lower than the competitor’s Wi-Fi site survey cost. This is a critical point about Wi-Fi. When you are trying to cover a large area, especially a yard where many objects are stored and being moved, things get tricky. This is because Wi-Fi coverage is relatively limited and Wi-Fi is not great at managing radio interference. Just trying to figure out how to place the access points in a difficult radio environment to ensure solid coverage is a major and expensive undertaking. In comparison, because of LTE/4.9G’s much increased penetration, consistent coverage and ability to deliver reliable high performance in interference-prone environments, the planning stage for Nokia was almost a walk in the park.
But it goes beyond that. If objects causing radio interference or reflections move, or are others are added, then you have to move the Wi-Fi access points or adjust the antennas to adjust the coverage and the new interference patterns. Companies that have deployed Wi-Fi for large outdoor areas of this nature, such as yards, ports and open-pit mines, often discover that there is an ongoing cost associated with regularly adjusting the Wi-Fi coverage. If things move too quickly and too often, they find that they can’t possibly keep up and just have to accept the existence of holes in the coverage. This is one of the many reasons they come to us looking for alternatives.
Where Wi-Fi clearly makes sense is in very static indoor environments, such as offices, where things don’t change much and the traffic isn’t mission-critical. You still have to be careful about placement to account for interference from walls, absorption and reflections, but generally, you only have to do it once.
4.9G or 5G cellular technologies, in contrast, were initially designed to provide reliable mobile coverage for outdoor wide areas and dense urban centers, where interference levels are very different and the environment changes: trees grow, new building pop-up, trucks move through the coverage area, etc. While interference and radio environments in factories, outdoor yards, and underground mines raise complex issues to consider whatever the radio technology used, they are much less of an issue due to the much-increased coverage of 4.9G and 5G and their excellent capabilities for handling interference. As many radio planners will tell you, coverage matters as the performance is directly proportional to the quality of the coverage (a factor of RF power and quality of the signal).
Getting into the nuts and bolts of why cellular technologies are so much better at providing coverage is beyond a blog post, but we have a long form white paper that covers the main points without being too technical. In short, cellular uses different radio spectrum with longer waves and higher RF emissions. This is why a single BTS small cell, which is roughly similar to a Wi-Fi access point in size, can cover the same area as 10 or more Wi-Fi access points. In one customer’s open pit mine, we used 10 micro BTS small cells to replace 150+ Wi-Fi access points and, yet, we were able to improve the site coverage. In the most extreme cases, using just one large mini-macro cell (a small cell with the RF output power of a macro BTS), we can support a cell radius from 10 to 20kms.
Even in the same spectrum and with the same output power as Wi-Fi, MulteFire, which is an LTE standard for use in the unlicensed 5.x GHz spectrum, is able to offer twice the cell radius (4x time the cell area) compared to a Wi-Fi access point (AP) because of sturdier modulation and a superior scheduler.
From a cost point of view, you can easily imagine how much the increased coverage per BTS will help reduce the price vs. a similar Wi-Fi deployment, but there is one more factor: real life performance. While Wi-Fi and 4.9G/5G offer similar user peak performance in the same conditions (as limited by the laws of physics: distance from the cell center, bandwidth, the number of MIMO pipes, etc.), the real-life performance of 4.9G/5G is significantly better.
The performance advantage is due to the improved coverage and penetration, better handling of interference and the ability to guarantee performance even when a large number of devices are connected, thanks to the very advanced radio schedulers in today’s BTS. In our deployments, we see that 4.9G can typically support 10–30x more users per AP than Wi-Fi (5 or 6) before the sector throughput starts to degrade. This also reduces the number of BTS required in capacity-driven deployments.
Fewer APs means proportionally cheaper deployments, not just because of the hardware CAPEX, but also due to the reduced costs for radio planning, installation, wiring, etc. In addition, better coverage also means reduced OPEX, because the network will better handle changes in the radio environment — thus there’s less need to re-engineer the network or add more cells each time a new machine is installed, a partition is put in, shelves are filled up, etc.
The last point on cost is that 4G and 5G have been engineered to support all traffic types, which Wi-Fi has not. The most notable are mission-critical voice and IoT traffic from sensors and other devices (sensors typically require low data rates but need increased coverage and different communication protocols to ensure very long battery life). Mobile cellular was first designed for voice traffic, and it is possible to use these networks to replace TETRA and other push-to-talk and push-to-video services. From a cost perspective, this means that most enterprise customers can consolidate their low-power IoT (SigFox, LoRa), TETRA and other legacy wireless networks onto one.
All of these variables make the business case for one or the other technology complicated. At the extremes, if you need coverage for the IT needs of an office, choose Wi-Fi. For critical OT needs in large outdoor areas, large and high-ceiling indoor industrial plants, and high interference environments, choose a private 4.9G/5G solution.
Unfortunately, life isn’t always so clear cut and many of our customers find themselves somewhere in the middle. For them, we have designed a tool for understanding the total cost of ownership of the different technologies. It allows you to insert the major characteristics of your operating environment, the scale of operations, typical use cases and whether it is a greenfield installation or not. It also covers which area of the world you are in, which relates to the spectrum available for private use. The tool compares the TCO for Wi-Fi 6, private LTE/4.9G and Multefire.
The tool doesn’t take into account everything you need to determine the exact price of the network suited for your needs, but it will give you a general idea and help you to understand which technologies you should be focusing on, or whether you need to dig a little deeper — and we are here to help you take the analysis further if you like.
It is our belief that 4.9G and 5G-based private wireless networks will prove to be disruptive technologies that will launch many new Industry 4.0 use cases. We call them “industrial-grade” private wireless for this reason. Except for a small subset of cases where either Wi-Fi or 4G/5G make sense from a technical or cost perspective, they are not really in competition with each other. We hope that the tool will help make it clearer which you should be considering as part of your Industry 4.0 technology platform.
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