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The Basics

What Are Real-time Locating Systems (RTLS) and How Are They Used?

February 21, 2023
What Are Real-time Locating Systems (RTLS) and How Are They Used?
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What Are Real-time Locating Systems (RTLS) and How Are They Used?

Real-time locating systems (RTLS) track and manage assets, items or inventory. These tracking systems can be indoors or outdoors. Global position Systems (GPS) like those used in most modern cars, are one type of outdoor system. Indoor systems can furnish the same type of location information in real-time as well as providing a tracking history. Indoor systems are frequently referred to simply as RTLS. RTLS solutions make use of multiple types of technologies and have many applications in business and industry.

Main Components of an RTLS System

A real-time locating system is built using three main components.

Transponders or transmitters

The most basic element of an RTLS is a transponder or transmitter that is embedded in or attached to an item or person. These transponders are also called tags. Each transponder has a unique id that is used to identify the entity to which it is attached. In some cases, the transponder can respond to a signal from a receiver as well as broadcast signals if it is self-powered. A wide variety of devices can be used as transponders including:

  • Bluetooth beacons

  • Radio-frequency identification (RFID) tags

  • Wi-Fi tags

  • Ultra-Wide Band (UWB) tags

  • Infrared or ultrasound tags

  • Global Navigation Satellite System (GNSS) or Global Positioning System (GPS) tags

  • Smart devices


The receivers in a real-time locating system are powered hardware devices that communicate with transponders or tags. A receiver collects information from transponders and delivers it to the software that manages the system. Receivers can be various types of hardware including:

  • Dedicated readers

  • Smart devices with the appropriate app

  • Access points

  • Location sensors (sometimes called ‘anchors’)

Management software

Centralized management software is used to consolidate the data sent from receivers and provide the system’s functionality. Most RTLS implementations can determine the location of an object or individual, to which a tag or transponder has been attached, and perform some type of logging of the entity’s activity. An RTLS can be constructed to implement geofencing and identify when a person or item leaves a defined area.

RTLS Coverage

Different RTLS ranges and coverage options are available based on the locating technologies in use and the system’s objectives. Coverage is dependent on the hardware used and the underlying RTLS technologies which we will look at more closely. Coverage options include:

  • Wide area coverage - This type of coverage is used to locate an entity using global coordinates such as identifying specific shipping containers.

  • Local area coverage - Local coverage can locate an object or person inside a structure such as an office complex, store or warehouse or large interior space. Zonal coverage - Hardware positioning is used to implement zonal coverage that can identify where critical equipment is stored within an office or manufacturing plant.

  • Choke points - A choke point can be a hallway, doorway, or entrance that is used in normal business operations. An application for choke points would be to track the location of medical equipment when it has entered or exited a building or entered or exited a floor in a multi-story building.

Choosing the Right RTLS Technology

Various types of wireless communication standards are used as the foundation for locating technologies. Each one has strengths and weaknesses that may make it an appropriate choice for specific implementations.

Passive Radio-frequency identification (RFID)

Passive RFID, sometimes just called RFID, can be used for choke-point detection, as referenced above. Passive RFID tags are inexpensive and do not contain a power source. They are powered wirelessly when an energy source, usually called a passive RFID reader (because it both energizes the passive RFID tag and ‘reads’ the resulting signal that the RFID tag transmits) receiver is near the tag. They are best used in short-range implementations or choke point applications. Passive RFID readers are usually large stationary devices (dock doors, entryways, elevator lobbies, etc.) but handheld models are also available to manually scan/waive them near passive tags attached to stacked or shelved items. One of the principal disadvantages of RFID is that the infrastructure required to read the tags, which are relatively low in cost, is quite expensive. This limits the deployment of readers and hence the visibility of the assets.

Bluetooth Low Energy (BLE)

Bluetooth Low Energy tags or beacons communicate via a variation of classic Bluetooth technology. Tags can be configured to continuously broadcast signals or to send information. The tags are typically powered by a battery.

An advantage of using Bluetooth Low Energy is that the majority of portable electronic devices such as smartphones have a Bluetooth antenna. This allows them to act as readers to transfer signals from the beacons to the software application powering the RTLS implementation. Thus infrastructure costs can be low to negligible, but the tags which generally require batteries are more expensive than RFID. Wiliot’s IoT Pixels offer an innovative take on Bluetooth Low Energy tags with the ability to harvest source energy from surrounding ambient radio waves. These Pixels are postage-stamp sized stickers which contain a computer and transmit encrypted Bluetooth data packets. They have the advantage of both low cost infrastructure and low cost tags.

Infrared (IR)

Infrared signals usually require a line of sight between the transponder and a receiver, limiting their usefulness. If properly located in each room, they can work as an economical method of determining information such as in which room an asset is currently located. In this case the limiting requirement of line of sight can be an advantage, giving dependable isolation of assets in one room or curtained off area from another. Bluetooth beacons by contrast have signals that penetrate walls and so it is harder to get room level accuracy when rooms are in close proximity such as in a hospital.


Ultrasound is another technology that can be used in limited RTLS implementations. Solid surfaces block the sound waves and excessive interference can be experienced in noisy environments. If properly located in each room, they can work as an economical method of determining information such as in which room an asset is currently located.

Ultra-wideband (UWB)

RTLS solutions built on UWB technology deliver very precise location information using a range of frequencies. UWB RTLSs are typically more expensive than alternatives and can be challenging to configure and generally require a high density of single-purpose receivers to achieve high accuracy. They are most appropriate for minimizing high-risk security breaches of expensive assets.

Apple’s Air Tag uses a combination of Bluetooth technology (low power) and UWB (precise location) to allow for rapid location of assets relative to the position of their phones.
Business Uses of RTLS Solutions

The use of RTLS tags to identify the precise location of objects or personnel has many applications in the worlds of business and industry. Following are a few of the ways an RTLS solution can provide benefits to an organization.

Optimizing supply chains can be accomplished by understanding product movement and conditions to ensure regulatory compliance and the delivery of fresh goods. A prime example of this is the FDA’s Food Safety Modernization Act which requires precise traceability of the source for perishable products such as leafy greens by supermarkets by 2026. Enhanced customer satisfaction and cost reduction is provided by increasing product availability and eliminating empty shelves while reducing slack and waste in the supply chain.

Inventory reconciliation can be an expensive undertaking that is prone to human error. An RTLS solution eliminates potential errors and offers a simplified method of verifying inventory at any step in the manufacturing process. Automating inventory and supply chain management allows companies to quickly address trends in customer expectations.

Recent technology advances in significantly decreasing the cost of tags and receivers, have enabled the tracking of reusable transport packaging like pallets and shipping containers. This enables reusable containers (eliminating waste of single-use containers/pallets) which can be reused for better ROI, as well as real time knowledge of where/when something is located anywhere through its supply chain (shipping warehouse, distribution center, store, pallet/container cleaning, etc.) An understanding of where every asset is located at any time provides a huge competitive advantage over companies without that capacity.

Innovative Bluetooth Real-time Locating Systems

Wiliot’s IoT Pixels offer companies two variations of flexible Bluetooth Low Energy beacons that can be attached or embedded into virtually anything. These small devices are distributed on reels of paper for easy application and are available as radio-frequency energy harvesting self-powered models or sustainable printed battery-powered Pixels. The self-powered IoT Pixels obtain power by harnessing ambient radio waves and have an effectively limitless lifetime. Battery-powered IoT Pixels have a lifetime of approximately four years.

IoT Pixels communicate through dedicated apps on a Bluetooth enabled mobile device which in turn sends encrypted data to theWiliot Cloud. Here, the raw data collected from the IoT Pixels is decrypted, processed and used to trigger actions via the Wiliot cloud’s APIs. This can enable better asset management, enhanced supply chain visibility, enhanced business efficiency and a lower, quantifiable carbon footprint. The versatility of IoT Pixels make them suitable for a wide range of RTLS solutions that provide decision-makers with the information they need to run their companies efficiently.