LoRaWAN - Designed for Wireless Sensor Networking

I’ve been hearing about LoRaWAN networking as a solution for connecting wireless sensors at long distances, while extending battery life. To learn more about it, I interviewed Mike Fahrion, CTO of Multi-Tech Systems, Mounds View, MN.

Edward Brown:

What is LoRa, what are its advantages and limitations?

Mike Fahrion: The LoRa Alliance^® was founded in 2015 as a group of companies getting together to advance the technology. Their approach allows for extremely good receive-sensitivity across very low bandwidth. So, if you only have 10s of bytes or so to send, you could get extremely good receive-sensitivity that allows you, with the same kind of output power that you would use with Zigbee, to pick up an additional 50 or 60 dB of link margin. That allows LoRaWAN to travel incredible distances — easily 5 kilometers and more outdoors. Indoors in a commercial building, you might be able to cover an entire four-story commercial building with two to four gateways. LoRa is a gateway-based technology — a powered gateway that nodes can talk to.

Brown: Could you tell me a little about the technology.

Fahrion: LoRa leverages a spread-spectrum chirp strategy that transmits over several frequencies to the end nodes, allowing for gateways to optimize the way they exchange data with devices by adapting to changing conditions. The ability to adapt and change frequencies as a response to interference or weather-related issues makes it possible for LoRa to reliably keep end nodes connected.

It broadcasts variable length chirps that get decoded into data using the spectrum. It can happen over different channels, and at a number of different data rates. If it’s a very short-range connection, then LoRaWAN will go to a higher data rate — hundreds of kilobits. The advantage of that is it can then stay on the air for a much shorter period of time if it has a decent amount of data to send. But if it’s a very long range, it could go down to a low data rate in order to cover that range.

The lower the bandwidth, the longer the range, is a general principle of physics with wireless technology.

Brown: In buildings and factories, how does it deal with problems of obstacles and interference?

Fahrion: It’s quite noise resistant — it works just fine with all the 2.4 GHz stuff out there. LoRa uses 900 MHz in North America and 868 MHz in in Europe, so it stays away from a lot of that traffic. And its chirping technology is quite different than what is traditionally used with things like Wi-Fi and Bluetooth. So, it does quite well in in those environments. It’s a sensing technology — most of the applications are for things like sensing a level in a bin, the vibration level of a machine, or the temperature of the environment — it’s not for low-latency real-time control.

Brown: Is LoRaWAN compatible with sensor edge computing?

Fahrion: There are a couple of levels. So, one thing that’s unique about LoRaWAN that’s put it at an advantage compared with some other technologies, is you can have either a public LoRaWAN network or a private LoRaWAN network. Public uses something like a cellular model — you can have a carrier to whom you pay a fee, and the carrier will maintain the gateways, etc. That’s been more popular in Europe, but there are some companies, especially in major cities in the U.S. that offer public LoRaWAN coverage. So, you can subscribe to that service and send your data up to their gateway. But with a private LoRaWAN network, which we see as the most popular, you buy your own gateway that has some edge intelligence. You can choose to configure your network in such a way that you aggregate the sensor data at the gateway itself and then make decisions on whether you want to forward it to a remote location.

If you’re in a chemical plant, for example, you might want not want any of that data to leave your building — for safety and security reasons, you might want to process the data and act on it locally. In that case, you would use a private network with a gateway to which you could add additional intelligence. You can go also go all the way down to the sensor — we do some of that today, in vibration sensing for example. We have a small microcontroller analyzing data from a vibration sensor, processing it locally. We can’t send 10s of thousands of samples over LoRaWAN, but we can process 10,000 samples locally and then provide the statistical results from that over LoRaWAN.

The places where we’re seeing LoRaWAN really take off is for commercial or enterprise applications. It’s helping enable a whole series of connected-product service type solutions. Some of these are the same things we may have talked about eight years ago around the emerging IoT space, but then it was more platitudes, like “Here are all the things we think could happen someday… we’ll reschedule, we won’t send service people out everywhere whether they need to be there or not, we’ll have intelligent devices that tell us when they need service,” etc.

Frustratingly, a lot of that didn’t happen for so much longer than we thought it would. One part of that was the technology — confusion about which competing standards to use. And the integration was harder then than it is now. A lot of the software tools and cloud-based services have now advanced so much. And there are far more engineers who are trained and up-to-speed in all the technologies.

The other thing that was a challenge then, was that companies weren’t necessarily willing or ready to embrace all the business process changes they would have to make in order to absorb that data. It’s one thing if I give you data that tells you: here’s the level in all these bins. But if you’re going to start using that to schedule your service folks, you’d have to make a lot of process changes in your systems and in your personnel.

In the last few years, we’ve seen that not only has the technology matured, but for businesses, post-pandemic, the amount of acceptance to change is quite a bit different now — we’ve all had to accept vast changes. Many of us are working remotely; there’s shortage of field service labor; there’s a shortage of things like trucks. So, people have gotten quite serious about this, it’s no longer just a nice-to-have. Now I need to have a connected product or a connected service because I only have half of the staff available that I used to, and I can’t get all the vehicles I used to use. Before, it was about reducing costs but now it’s become about sustaining your business.

A Better Mousetrap

Companies with large field service staffs are finding big benefits from getting a little bit of data from the field — the sorts of things we’ve talked about for a decade now. For example, things like smart pest control traps that can tell us whether a particular pest trap needs to be emptied or does it need to be re-baited?

Brown: This is the first time I’m hearing that one.

Fahrion: Yeah, the smarter mousetrap is really happening now. If you’re in commercial pest control, it makes a huge amount of sense. Think of a large warehouse and the amount of labor it takes somebody to go out and inspect all those traps and decide whether they need to be re-baited. Or they could see “there’s been no activity on this site” or “only these 12 traps out of the 400 out there need activities.” That can bring a massive return from improvements in cost and effectiveness.

Having plenty of available link budget makes it easy to deploy successfully in a traditional commercial building. We usually place one gateway on every floor or maybe every other floor. But many times, you don’t get to put those gateways in optimum spots because you need to put them where you have access to a backhaul connection like Ethernet or close enough to a window where you get good LTE coverage if you’ve got cellular backhaul. And you also need need power available for the gateway. So, we end up putting those gateways in an IT closet or utility closet, where they work really well in terms of providing the backhaul for any kind of sensing.

Applications

Brown: Can the gateway be mounted outdoors?

Fahrion: Yes, and agriculture is a good example of an outdoor application. Data sensing in vineyards is a particularly good application because they’re very sensitive to moisture so there’s a high payoff for getting it right. You can deploy things like soil moisture sensors and traditional weather sensors. You could put up one gateway in an elevated location like the top of a building and get a three- to five-mile radius.

Although you might have put it in there initially for soil moisture sensing, once you have the infrastructure you might say, “It’d also be nice to know whether this gate is opened or closed? Or what’s the utilization of this particular piece of equipment?”

We have a slow vibration sensor, not like a vibration analysis, but you can put it on the side of a piece of equipment and it would tell us if the engine is running. Then you could do simple inferences, say: “this piece of equipment is used four percent of the time.” You could get data from things you might not even have previously considered collecting data from before.

A user typically starts with one core business case — one problem they’re trying to solve that’s driving the investment. However, once the LoRaWAN network is installed, it’s relatively inexpensive to add additional sensors to multiply the benefits.

Brown: What do you see for the future of LoRaWAN?

Fahrion: LoRaWAN has finally broken through as the go-to standard for wireless networking, for one thing, because of the power of the LoRaWAN alliance. LoRa is the chip technology — that’s the wireless technology, but it doesn’t have anything to do with the network layers. LoRaWAN is the spec for the network layers that ride on top of the LoRa physical layer. Because that ecosystem has gotten so strong, we’ve crossed a tipping point. There are 400 to 500 members of the LoRaWAN alliance, including folks like Microsoft and Amazon Web Services as well as Chevron and lots of large OEMs that have gone in collectively. Having that large and growing ecosystem is what you need to get something like this going.

You could certainly buy a gateway and some sensors from MultiTech, but we don’t have all the sensors in the world. So, if you want some specialty sensor, you can buy anybody’s LoRaWAN sensor and you get interoperability — which is just so important. And if you want to use MultiTech gateways for everything in North America but for whatever reason, you want to use to use Brand X gateway elsewhere, you can mix and match all that as well.

This article was written by Ed Brown, editor of Sensor Technology. For more information, go here .

---