Understanding the Three Levels of Location: Presence, Proximity and Positioning

To maximize ROI when utilizing the Internet of Things, invest in an RTLS solution that covers all levels of accuracy and multiple use cases, and that will be scalable for future growth.
Published: September 4, 2019

Organizations across a wide range of industries are finding significant value in determining the precise location of a person or object as part of their Internet of Things (IoT) implementations. While all organizations want their IoT solutions to be able to provide an accurate location, what does that really mean? Is location within a meter considered accurate enough? For some use cases, yes. Others require much more precise levels of accuracy, perhaps even down to 10 centimeters.

There are a few different levels of accuracy, and several different ways in which to achieve each level. Finding which solution is the best fit—in terms of both accuracy and total cost of ownership (TCO)—depends on the requirements of the specific use case at hand. Location is important for many industries, but looking at one environment—a warehouse—makes it easy to understand the benefits and use cases the three different levels of location can enable:

Presence detection is the simplest location-based solution—and the least accurate. The goal with presence is simply to determine whether an item is present or not. A common use for presence detection in a warehouse is to determine whether or not an item or a pallet has arrived. Using an advanced location system utilizing Bluetooth technology and the angle-of-arrival (AoA) methodology, a locator at the entrance of the warehouse can act as a “gate” through which tagged items pass.

The locator identifies the tag based on its unique ID, measures the AoA of the tag’s signal, calculates the direction of motion for the tag, and determines whether it is entering or exiting the warehouse. Some real-time location systems (RTLS) can further determine presence and provide real-time information within the warehouse because of their long communications range.

Radio frequency identification technology is another choice for presence detection, but RFID has limitations. For example, it requires multiple locators to calculate the direction of motion of tracked items, which can increase infrastructure costs. Also, RFID technology cannot automatically detect if an item has already passed the gate, so there is no way to know if it is still present in the warehouse.

With proximity, the goal is to identify both the presence and location of items, and so proximity solutions typically use a combination of high-accuracy positioning in key areas and low-accuracy presence detection in others. For this reason, proximity solutions are ideal for use cases in which the end customer does not need uniformly accurate coverage throughout the deployment area.

Using the warehouse example, approximate location information may be adequate. With the Bluetooth/AoA system, locators can be placed in strategic areas within the warehouse to identify tracked items as they enter certain areas, generating real-time location information by zone. In a well-designed deployment, where locators are positioned at strategic choke points, basic movement tracking also becomes available. Optimizing the infrastructure deployment and locator density to enable higher location accuracy only where needed helps with budget concerns without limiting potential use cases.

Other technologies commonly used for proximity-level location accuracy are Wi-Fi and Bluetooth received signal strength indication (RSSI)-based beaconing, but their weakness lies in their inflexibility to allow for deployments with a non-uniform locator density for optimizing the accuracy across the different zones.

Positioning is the highest level of location accuracy, for which the goal is to reliably locate and track an item’s exact position in real time. This level of accuracy unlocks the full potential of location-based solutions. In a warehouse environment, it is often critical to know the precise and real-time location of items. Common warehousing applications, such as worker safety, collision avoidance, inventory management and advanced workflow optimization, all require precise location information. With the Bluetooth/AoA system, the strategy is to uniformly cover the area of interest with locators so that the system can reliably calculate the accurate locations of tags in real time. Investing in high-accuracy positioning infrastructure not only covers the use cases mentioned previously, but also opens the door to a host of new potential use cases.

Ultra-wideband (UWB) is also being used for use cases requiring this high level of location accuracy. However, UWB cannot be adapted to also cover both proximity and positioning requirements, limiting its effectiveness as a solution that covers all use cases. The high cost of tags and the limits to radio certifications across different geographical areas also limit UWB’s usability as a positioning solution.

As seen with the warehouse example, organizations of all types and sizes—ranging from manufacturing and supply chain and logistics to health care and retail—have a wide variety of use cases in which knowing the location of an object or person provides tremendous value. The level of accuracy, however, depends on the specific use cases currently in use, as well as those that might be considered in the future. Investing in an RTLS solution that covers all levels of accuracy and multiple use cases, and that is scalable for future growth, can help organizations minimize TCO and maximize their return on investment (ROI).

Fabio Belloni is the chief customer officer and cofounder of Quuppa, which is focused on accelerating the success of its partner companies. He is a frequent contributor and the author or co-author of numerous academic papers, and has several granted patents and pending patent applications.