The proliferation of IoT technologies has revolutionized operations in many industries. The challenge is there are several different technologies (beacons, sensors, gateways, and frequencies) used in IoT solutions. While companies have leaned into adopting these innovative technologies, choosing the right solution for your business can be challenging. Your asset tracking needs are key to determining which technology to use. Depending on a company’s specific circumstances, one IoT solution may be more suitable than another.
The following considerations should guide your decision-making:
- Desired accuracy of location data
- Number/value of assets being tracked
- Update rates for assets being monitored
- Physical environment of assets
- Cost of buying/maintaining infrastructure
Following is a layman’s guide to understanding the alphabet soup of solutions – BLE, RFID, and UWB.
Bluetooth Low Energy
Bluetooth Low Energy (BLE) is the most recent entrant to IoT offerings, with a large number of supplier and tag options. BLE solutions operate with fixed BLE beacons which communicate with BLE tags. Most BLE systems use Received Signal Strength Indicator (RSSI) methods to determine proximal asset location with 1-3 meter accuracy. RSSI is an estimated measure of the power level that an RF device receives.
BLE can also calculate location data using direction-finding methods like Angle of Arrival (AoA) and Angle of Departure (AoD), with the addition of multiple BLE beacons and gateways. BLE with AoA allows asset locations to be identified within 1 meter given ideal conditions, such as large, open spaces. These devices face operational limits in certain environments. BLE does not function particularly well around metal or reflective surfaces. Some solutions offer workarounds by including additional WiFi-connected gateways. However, this can cause added network latency and interference.
Active environments with many moving parts are a challenge for BLE because RSSI methods can be thrown off by temporary obstacles which move in and out of asset tracking zones. BLE refresh rates tend to be between 2 to 10 seconds, but in some scenarios can be 30 seconds or longer, particularly when checking stocked assets that rarely move. Motion-triggered beacons can also be used to provide variable update rates.
Emerging BLE
When BLE solutions were first introduced, their adoption was constrained by the cost of battery-powered BLE tags. BLE solutions could only provide proximal location data if multiple beacons were deployed. This made BLE options less cost-effective compared to RFID. However, companies such as Wiliot are seeking to increase the scalability of BLE solutions by lowering the cost. The company released IoT Pixels, a battery-free BLE tag powered by harvesting RF energy from its surroundings and nanowatt computing operations. These tags are some of the least expensive BLE tags on the market with a read range up to 10 meters.
Kontakt.io Inc is also helping fuel the growing popularity of BLE solutions. Kontakt.io focuses on smart buildings in healthcare and carpeted spaces. In 2021, Kontakt.io released the Nano Tag – the world’s smallest BLE beacon and first disposable, wearable tag. The Nano Tag has a battery life of approximately 3 months and weighs 2 grams. This BLE device helps monitor visitor movements inside facilities. In a healthcare setting, it was used to track movement patterns to assist in patient monitoring and improving workflows.
A collaborative effort between Energous and Atmosic was announced which aims to provide low-cost wireless systems with battery-free BLE beacons. These systems can be energized via RF transmissions and send data back to a server. The cost of BLE beacons can be significantly reduced if batteries can be removed. Energous made early reports that their transmitters can successfully charge tags up to 13-meters in distance.
With recent developments and a decrease in cost, BLE stands to become one of the faster-growing options for asset tracking systems. According to Industry Arc, “The global Bluetooth Low Energy (BLE) market is estimated to surpass $16.7 billion by 2026. Growth will be at an estimated CAGR of 19.68% during the forecast period 2021 to 2026.”
RFID
Radio Frequency Identification (RFID) technology enables unique IDs encoded in RFID tags to be detected using radio waves. The primary components of an RFID solution are an RFID reader, antennas, and tags. RFID tags are broadly categorized as passive vs. active. Passive tags reflect radio wave signals emitted by antennas back to a reader. Passive RFID is an ideal asset tracking solution when cost-per-asset is the priority, as the tags are low-cost. These RFID systems detect asset presence, not precise locations. RFID is a very attractive option from a cost perspective if a business is looking to track inventory or prevent losses. Readers are set up at chokepoints (entries, aisles, or doorways), and detect tagged assets as they move in or out of a zone.
Active RFID tags have built-in batteries which extend read range and allow real-time location monitoring. This technology is very good for indoor position locating, although costlier than passive RFID due to ongoing battery and/or sensor replacement costs.
Newer passive RTLS solutions use antenna arrays to track the location of objects tagged with passive RFID tags. These systems are gaining traction and can provide 1m – 3m accuracy at a cost closer to low-cost passive RFID.
Ultra-Wideband
Ultra-Wideband (UWB) is a wireless standard that delivers more precise locating than any other technology. This technology can accurately determine asset location within 1 foot (30 cm). UWB solutions utilize techniques such as Angle of Arrival (AoA) and Time-Distance-of-Arrival (TDoA) methods to determine locations with precision. UWB has refresh rates in the hundreds of milliseconds.
These features make UWB optimal for locating and tracking assets in industrial environments. UWB is also ideal for tracking high-value assets where inaccuracy poses considerable risks or delays, such as in aerospace assembly, electronics manufacturing, healthcare, and safety and security applications. UWB performs with pinpoint accuracy, low power, and little to no interference, even in challenging RF environments. These sensors and tags provide the most accurate data, longest read range, and longest battery life of any RTLS system, although UWB is generally higher cost in comparison to other solutions.
Better Together
A wide range of use cases, spanning automotive, consumer, industrial, and smart home, benefit from the combination of BLE, RFID, and UWB for localization. The success of combining these technologies has been demonstrated by Apple’s AirTag. AirTags unite the technologies of IoT, providing proximal location tracking with BLE and precise location finding with UWB. A user can view their iPhone (which has an integrated UWB chip) to locate its exact location. Furthermore, a person’s contact information can be linked to an AirTag and accessed with any NFC-enabled smartphone or device.
IoT capabilities for asset tracking and asset management are constantly improving with ongoing developments in BLE, RFID, and UWB technologies. Each solution has advantages for different use cases. If you would like guidance on which asset tracking technologies to use, please send us a note via the “Contact Us” form or email info@rfidgs.com. We can develop a customized solution for your business’ needs.