Asset tracking is one of the best applications of IoT technology. By simply attaching sensors (e.g. GPS receivers, accelerometers, etc.) to items we want to track, we can dramatically increase a business’ efficiency.
Shipping companies can determine whether or not a truck will deliver on time. Hospitals can ensure that expensive equipment is never lost. Car dealerships can make sure vehicles aren’t driven off the lot. These are just three of many possible use cases.
Of course, there’s no point in collecting all this sensor data if we can’t get it into the hands of end users. We need some method of transferring the information from the sensors to the internet. In this article, we discuss different connectivity options for asset management.
There are many different ways to connect an IoT device to the internet. We’ll discuss the pros and cons of the following popular connectivity methods: Low Power Wide Area Networks (LPWANs), cellular, satellite, RFID systems, WiFi and Bluetooth.
LPWAN is an umbrella term for any network that allows communication over large distances (i.e. several miles) using minimal power. There are many different ways to implement such a network, including LoRa/LoRaWAN, Ingenu/RPMA and Sigfox. [Read here for a more detailed explanation of LPWAN and the competing implementations.]
This solution is ideal for use cases where the frequency/size of messages is small (i.e. low bandwidth), large range is needed, and power usage is a concern. For example, smart trash bins would be a good fit for LPWAN connectivity. The sensor on a smart trash will likely run on battery power and may be very far away from the gateway/router it needs to communicate with. However, it doesn’t need to send much data.
Sending an update a few times a day on metrics like fullness level, temperature level and toxic gas level (i.e. ammonium) is probably sufficient. Since LPWAN implementations use low power, you could rest assured that they would last at least a few months (usually a few years) before the batteries need to be replaced.
Another way that an IoT device can connect to the internet is using a cellular network, the same way your cell phone sends and receives data. Like LPWAN, cellular is great choice when you need to communicate over long distances (i.e. to the nearest cell tower). One of the benefits of using cellular is that you can send more data (higher bandwidth) than a LPWAN solution. However, this comes at the cost of using more power. Newer generations of cellular networks like NB-IoT and LTE CAT-M1 aim to address these concerns.
One unique upside is that the cellular infrastructure already exists. If you’re using a LPWAN, you may need to set up gateways/routers for your IoT devices to communicate with the internet. But as you already know, companies like Verizon and AT&T already have cell towers set up across the country. This makes cellular connectivity an attractive choice for tracking shipments as they travel over very long distances.
Satellite communication is also a high bandwidth/high range option, but at the cost of extremely high power. One solution to this is to use LPWAN connectivity to communicate between IoT devices and a gateway, then use the gateway to relay the data over satellite to the internet.
The unique benefit of satellite is that it works anywhere on Earth. If you’re trying to track shipping containers as they travel across oceans (and thus can’t connect to cellular networks), then satellite communication may be the only option available.
While some asset tracking solutions involve tracking fixed objects (e.g. trash bins) most involve tracking moving objects (e.g. shipments of goods). This means installing a GPS sensor in your IoT device and using that to get latitude/longitude readings.
However, GPS doesn’t work indoors. Therefore, we need a different way of collecting location information indoors. Furthermore, power usage may be less important since our devices could be connected to a wall outlet. Likewise, range is less of a factor since we are inside a building. We likely need a few hundred feet of range as opposed to miles of range.
RFID tags are a common way of keeping track of assets indoors. One useful application of this is to measure the speed of an automotive assembly line. RFID tags are applied to vehicles at the start of the assembly line and are scanned by fixed RFID scanners as they progress down the line.
RFID tags are cheap (as little as 10 cents per tag) which makes large scale deployments financially feasible. However, it is important to remember the ID part of RFID. RFID tags can only communicate the identity of an object (and therefore its location using the scanner as a reference point). If you want to send temperature information or some other statistic, you’re out of luck.
Furthermore, you’ll need to figure out how to relay the data collected by the RFID scanners to the internet (probably WiFi or ethernet connection).
Another way of determining a device’s location is using Bluetooth or WiFi. Using multiple Bluetooth or WiFi access points, you can triangulate a connected device’s location. This option provides more precise location information than setting up RFID readers at fixed locations. [Watch this demo of an implementation of a Bluetooth/WiFi based positioning system].
One useful application of this technology is hospital device tracking. You can keep track expensive medical equipment (to avoid searching the hospital for lost equipment) and perhaps set up geozones to make sure a device never leaves the hospital.