A cost effective solution to location tracking
Author : John Hartley, Extronics
31 January 2023
As companies operating in the process industries are progressing with their new digitalisation strategies, an increasing number of Wi-Fi based use-cases and initiatives are being deployed. The layout of the Wi-Fi infrastructure will generally be optimised for device connectivity, to cover the largest area with the fewest Access Points (AP), bandwidth requirements permitting.
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When deploying Wi-Fi for the purposes of Real Time Location Systems (RTLS) in hazardous areas, an optimum number of wireless access points far outweigh the number required for general device connectivity.
In indoor areas, the number of Wi-Fi APs required could be 2-3x more in a given area to provide sub 15m location information accuracy. The cost will increase further in areas where power is not readily available. In outdoor areas for example, it can be extremely costly to run power and data cables to install APs, especially if it is only to support RTLS applications. Often the return on investment is difficult to justify in these scenarios.
Bluetooth Low Energy (BLE) offers a solution
One option to consider is a BLE based location solution. Wirepas is an example of a BLE technology that uses RSS (Received Signal Strength) to approximate the location of a tag. It is similar to Wi-Fi in this way, however the location anchors used in a Wirepas system are battery powered, require no external cabling and form their own self-healing, scalable mesh infrastructure.
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Network management is handled by each device in a Wirepas network. The devices self-negotiate the best way to offload the RSS data to the positioning server. This ensures there are no single points of failure if one anchor should fail.
Another option for BLE based positioning would be to use Quuppa technology. Quuppa uses Angle of Arrival (AoA) location where the receiver is mounted on a ceiling above where the tags are located and can achieve a sub 1 metre, even 0.5 metre location accuracy in some cases.
AoA measures the angle or direction a BLE transmitted signal approaches a Bluetooth receiver. A hybrid location technology solution could be another option. A hybrid solution uses multiple methods within the same hardware to achieve the best accuracy in a given area while reducing the total cost of ownership.
For example, in indoor applications a hybrid technology location tracking tag can leverage communication with BLE beacons to give a more accurate location. The tag measures the signal strength of nearby BLE beacons and transmits this data over the existing Wi-Fi network. Only one Wi-Fi AP needs to be in range to do this, so a connectivity-based Wi-Fi infrastructure is ideal.
Optimised for device connectivity (left) and optimised for RTLS (right) - Image: Extronics
Cost saving example: Hybrid BLE RTLS vs Wi-Fi only RTLS
The benefit of using BLE beacons to trilaterate a tags location vs Wi-Fi only is the cost savings that come with it. BLE beacons are battery powered and so can be installed in minutes. An Ex-certified BLE beacon will typically be ~2% of the total installed cost of an Ex-certified Wi-Fi access point.
For hazardous area RTLS, battery powered Ex BLE beacons installed in place of Wi-Fi APs at a similar density can achieve the equivalent location accuracy. As with most radio technologies, other factors in the area of deployment may impact the number of BLE beacons required to maintain the intended accuracy levels, so it is important to survey your site and plan for the most optimised layout based on your goals.
The cost savings of using BLE beacons to improve location accuracy, when compared to installing more Wi-Fi APs, is justification for its use as an RTLS technology.
John Hartley, Extronics
For outdoor applications, a hybrid location technology tag could be equipped with a GPS receiver and will transmit its coordinates, over the Wi-Fi network, back to the positioning server. A single Wi-Fi AP within ~250m (line of sight) is all that is required to get GPS level accuracy in outdoor areas.
Conclusion
If considering a hazardous areas RTLS as part of your digitalisation roadmap, it is worth considering BLE hardware as part of a standalone BLE tracking solution, such as Wirepas or Quuppa. Hybrid technology tags offer a flexible solution that can reduce the amount of Wi-Fi needed in hazardous areas of sites. Furthermore, BLE anchors can be used with worker safety tags in hazardous areas, meaning you can extend your tracking visibility, at a reduced cost of ownership with no need to sacrifice location accuracy.
About the author:
John Hartley founded Extronics back in 1992 after cutting his teeth at Siemens. John is passionate about innovation and truly believes that the future of the process industries lies in their adoption of modern technologies.
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