Cellular or low-power WAN: Choosing the right approach for your IIoT deployment
The market opportunity for industrial IoT (IIoT) has been widely forecast to be enormous due to the many advantages of enabling wireless connectivity of devices. Much of the opportunity will come from enabling low-cost, long-range data communications via devices and sensors that can run in the field for years without maintenance.
As cellular providers begin standardising on narrowband LTE technologies to support IoT communications, they will compete more directly with incumbent non-cellular M2M hardware and software providers, says Jay Kilby, director of product management at Digi International.
Users will now have more choice, but it’s also confusing. Which scenarios are better suited for cellular versus low-power wide area networking (LP-WAN)?
In short, it comes down to determining four key factors: access to cell coverage, the need for localised intelligence, the number of sensor points being managed and the cost. For instance, it may be cost-prohibitive and inefficient to place a cellular module on 200 sprinklers in a field. But it may be the best approach for monitoring a few high-value oil assets in a confined area that receives strong cell coverage.
The best way to understand these factors is to examine a few use cases:
- Precision agriculture – Wireless sensors in modern agricultural practices are used to monitor seed and feed management systems, irrigation and soil moisture levels, and a range of other operations. While farms can cover large areas, the sensor data collected is being used to make local decisions about operations within the confines of the farm.
Without the need for an internet connection, non-cellular radio frequency (RF) wireless solutions often make the most sense. It’s a one-time cost to get the system up and running, unlike a cellular solution that results in monthly recurring charges. Additionally, the data gathered by an RF wireless solution can always be aggregated and transmitted to an offsite location with a single cellular connection if necessary.
- Oil pipeline monitoring – At various points along an oil pipeline, there are pumps, filters and associated sensors in place to help monitor and ensure all systems are working as designed. Where there is cell coverage, a cellular solution will make the most sense.
But for remote locations lacking coverage, LP-WAN solutions can be used to aggregate the data along the pipeline until it can be transmitted by a cell signal. In both scenarios, sensor data is sent to a central monitoring and control application, which helps the oil company gain valuable operational insights and spot trends across the entire pipeline.
- Intelligent street lighting – Oil pipeline monitoring is not the only scenario where both cellular and LP-WAN can work together as a hybrid deployment. For example, in a group of 50 street lights, a local area network RF technology can be placed on every light to create a wireless mesh network. In each subnet of lights, one light has both an LP-WAN and cellular module installed.
The cellular module acts as a gateway, collecting data from the other lights and then transmitting it via the internet to a central monitoring and control application. The city receives the benefit of more intelligent street lighting, while minimizing recurring costs by aggregating and reducing the number of cellular take-out points.
As cellular data plans become less expensive, there will continue to be more overlap. For example, a likely scenario is that instead of creating a mesh network, each street light will have its own IP address and connect directly to the internet.
For many, this begs the question of what the future holds for non-cellular solutions. But even here, there is no clear cut answer – not in the foreseeable future.
Cellular will likely overtake some areas where LP-WAN is now dominant; however, mesh networks will continue to thrive in certain environments, such as the commercial solar space. And new LP-WAN technologies, such as LoRa and SigFox, may have some advantages in situations where infrequent communications with very low data rates are required.
Ultimately, organisations need to evaluate these criteria and determine the approach that works best for them. For IIoT providers, it means helping customers understand the benefits of each approach, and working with them to create a flexible roadmap with solutions that can evolve with their needs, and the market opportunity.
The author of this blog is Jay Kilby, director of product management at Digi International, a global provider of mission-critical M2M and IoT connectivity products and services.
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