Get started Bring yourself up to speed with our introductory content.

The 3 Ps of location accuracy: Presence, proximity and positioning

Location has become a critical component across a wide variety of organizations as part of their ever-expanding IoT implementations. As companies get more sophisticated in their knowledge of what IoT can do for their business, they’re moving beyond basic applications to use IoT to better manage key business processes.

Knowing the precise location of a person — or object — by itself, and in relation to other people and objects helps organizations better understand business processes such as inventory control in a warehouse environment as well as generating advanced player statistics in a sports environment.

While accurate location capabilities are on every company’s wish list, each has a different idea of what location accuracy means. Is location within a meter accurate enough? For some use cases and applications, it is perfectly sufficient. However, other use cases may demand much more precise levels of accuracy, perhaps even as accurate as 10 centimeters.

There are a few distinct levels of accuracy, and several technologies and methodologies by which to achieve each level. The gating factor is the use case for which location capabilities are required. Understanding what the short-term and longer-term needs are for location — and taking into consideration total cost of ownership (TCO) of the solution — will be critical to making the correct choice.

While location capabilities are important for many types of organizations, looking at the need for location services in a single environment, such as a warehouse, makes it easy to understand both the benefits and the use cases the different levels of location can enable. There are three general levels.


Detecting the presence of a person or object is the simplest location-based solution designed to answer the question: Is it present or not? Unfortunately, it’s also the least accurate location level. Presence detection is commonly used in a warehouse to determine whether an item or a pallet has arrived. Using an advanced location system using Bluetooth technology and the angle of arrival methodology, a locator is placed at the entrance of the warehouse to act as a gate through which each tagged item passes. The locator identifies the tag based on its unique ID, measures the angle of the tag’s signal and calculates the direction of motion for the tag, thereby determining whether it’s entering or exiting the warehouse. Some real-time location systems (RTLS) can determine presence, and provide real-time information within the warehouse because of their long communications range. However many are limited by unsophisticated solutions that work well outside or inside, but not both.

RFID technology can be used for presence detection by tracking objects transiting through the gates. However, scaling beyond this use case may be limited by the cost of architecting a solution using multiple gateway readers. Its inability to track items that are already inside the warehouse once the system is installed can also negatively impacting both the cost-effectiveness and usefulness as a location solution.


Proximity-based solutions are designed to identify both the presence and location of items. Proximity detection typically uses a combination of high-accuracy positioning in areas where the use case demands it, and low-accuracy presence detection in areas where precision is less of a requirement. These solutions are ideal when uniformly accurate coverage is not needed.

This is often the case in the warehouse example, where approximate location information may be adequate for many use cases. With an RTLS that utilizes Bluetooth technology and the angle of arrival methodology, locators can be placed strategically within the warehouse, creating zones that track items in real time as they enter or leave each zone. In some deployments, locators can be positioned at strategic choke points, providing basic movement tracking. Optimizing the deployment and density of locators to enable higher location accuracy only where it’s needed provides a strong TCO without limiting potential use cases.

Other technologies that are commonly used for proximity-level location accuracy include Wi-Fi and Bluetooth Received Signal Strength Indication-based beaconing. However, they are each too inflexible to allow for deployments with non-uniform locator density. This makes it difficult to manage costs and deliver the right level of accuracy for each use case that is supported.


Solutions based on Positioning, which is the highest level of location accuracy, are designed to reliably locate the exact position of a tracked item in real time, both inside a warehouse and nearby, such as in a storage yard. Positioning unlocks the full potential of location-based solutions because of its flexibility and very precise levels of accuracy.

In warehouses, companies often need to know the precise and real-time location of items, both stationary and in motion. Common warehousing applications such as worker safety, collision avoidance, inventory management and advanced workflow optimization all require knowing the precise location of people and objects. With an RTLS that utilizes Bluetooth technology and the angle of arrival methodology, businesses can uniformly cover the area of interest with locators, so that the system can reliably calculate the accurate location of tags in real time.

Having this level of accuracy, and the flexibility to also support presence and proximity, satisfies nearly all of today’s use cases as well as many potential new ones; some of which may not have been thought of yet because of the limitations of location technology and cost considerations.

An additional technology being used for use cases that demand high levels of location accuracy is Ultra-wideband (UWB). However, UWB is only useful for high-accuracy use cases. This is because it cannot be scaled down technology-wise, or even cost-wise to cover 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.

The warehouse example showcases the reach, flexibility and accuracy of the different types of solutions available for determining location. Organizations of all types and sizes, from manufacturing and supply chain and logistics to healthcare and retail, have already established a wide variety of use cases where knowing the location of an object — or person — provides tremendous business value. The specific level of accuracy they need depends on the use case — or use cases — they need to support across the business; today and in the future. An RTLS that covers all levels of accuracy, multiple use cases, and is scalable for future growth provides the most attractive TCO and best return on investment.

All IoT Agenda network contributors are responsible for the content and accuracy of their posts. Opinions are of the writers and do not necessarily convey the thoughts of IoT Agenda.

Data Center
Data Management