Real-time location systems (RTLS) enable you to digitally track the real-time location and movements of physical things throughout large indoor facilities. As a type of indoor positioning system, RTLS primarily leverage radio-frequency (RF) technologies like UWB, BLE and Chirp, as well as wireless devices, such as tracking tags and smartphones, alongside other integrated components, to continuously determine the position of people and objects in areas GPS is not able to reach. This delivers actionable location data that can be used to visualize the location of key personnel, assets, vital equipment and more on a live, indoor map or integrated into automated workflows and systems such as IoT-enabled safety applications, asset & supply chain management solutions and more.
It’s been estimated that GPS technology has created over $1.4 trillion dollars (RTI International) in value for U.S. private sector industries since it was made accessible in the 1980s. RTLS seek to unlock the same location-aware value that GPS has created in our outdoor world for indoor spaces and localized areas where GPS isn’t effective. A key foundation of digital innovation, digital twin technology, IoT, and Industry 4.0, real-time location systems are helping organizations in healthcare, manufacturing, warehouses, and more transform physical operations by improving safety, boosting efficiency and driving business results.
The specific ways real-time location systems operate can vary greatly from system to system, but all RTLS leverage a network of connected hardware and software components that track the location of people and objects within a defined area. To enable indoor positioning, real-time location systems primarily rely on RF technologies such as UWB, Bluetooth, Wi-Fi and chirp that enable wireless communication between a group of transmitting, receiving, or dual-purpose transceiving devices to determine the location of the targeted object. The transmitting device, such as a RF tracking tag or smartphone will send out data encoded RF transmissions, or location “blinks”, at a continuous interval. RTLS receivers (anchors or readers) deployed in fixed positions, such as mounted on walls and within the communication range will receive and read the received signals from the transmitting device. The location data, and in certain applications, accompanying IoT data (temperature, battery, etc.) received by the anchors, is then forwarded to location engine software to calculate the device’s position.
In different RTLS technologies, the technique used to determine location can differ. Some use distance-based calculations such as time difference of arrival, which tends to deliver more accurate results than Received Signal Strength Indicator (RSSI) among other positioning methods. Enterprise-grade RTLS can include thousands of tracked assets, so a location engine will process this information concurrently for real-time location tracking of numerous targets at the same time. Derived location data can then be used to display the location of tracked items on a map or integrated into various enterprise applications to enable a multitude of location-aware use cases.
Some real-time location systems rely on fixed transmitting devices, such as Bluetooth beacons, which broadcast signals at regular intervals that can be detected by other BLE-enabled devices like smartphones. Location data from the beacons are then collected by those BLE-enabled devices and forwarded to the indoor positioning application to determine the device’s position and trigger specific actions.
In addition to real-time location tracking applications, RTLS components can also enable ranging applications in which communication between two devices, such as two transceiver tags that can be used to determine the relative distance between them, enabling proximity-based applications.
TDoA utilizes UWB or Chirp anchors that are deployed in a fixed position throughout an indoor space. These anchors then detect and locate a transmitting device, such as a tracking tag. To work properly, the fixed anchors need to be accurately synchronized to run on the same clock. The tag, or other device, will transmit signals in regular intervals. These signals will be received by any anchors in the communication range and time-stamped by the anchors. All the time-stamped data is then sent to the central IPS or RTLS.
The location engine will analyze each anchor’s data and the differences in arrival times to each anchor and use multilateration to calculate the tag’s coordinates. Those coordinates can be used to visualize the location of the device on an indoor map of your space or leveraged for other uses depending on the specific application.
While in TDoA multiple fixed anchors work together to determine the location of a mobile object, Two-Way Ranging primarily uses two-way communication between two devices, such as smartphones or vehicle tags, to sense the distance between them. This means that an autonomous collision awareness system can be created without any additional infrastructure. With TWR, when a device is in close proximity to another, the two devices will start ranging with each other to determine their distance, even as they communicate. The time it takes a signal to travel between them is then multiplied by the speed of light and used to determine their relative positions, frequently, to enable location-aware communication.
AoA is an advanced positioning method which can deliver with enhanced accuracy compared to more traditional techniques like fingerprinting and RSSI. This is possible due to Multiple Input Multiple Output (MIMO) interfaces. To be able to find direction, a mobile asset, such as a tag or beacon with a single antenna, transmits to a fixed RTLS sensor with a multi-antenna array. The phase shift of the multiple antennas, as a result of receiving the signal, is measured and calculated to determine the angle of the transmitting mobile device and create an area of certainty of the object to be located.
One advantage of an AoA approach is that it reduces the number of necessary reference points. Instead of a minimum of three sensors as required for any multilateration approach, you only need two to create an unambiguous determination of position. Additional reference points add to the accuracy and reliability of the calculated positions. While indoor positioning via AoA is more accurate than signal strength approaches, solutions that leverage this technique are only just entering the market.
In RSSI-based applications, multiple existing RTLS sensors deployed in a fixed position will detect transmitting devices and the received signal strength of the signal from the device. This location data collected by the sensors is sent to the location engine. The location engine analyzes the data and uses multilateration algorithms to estimate the location of transmitting devices. Alternatively, the signal strength of nearby sensors relative to a wireless device can be used to determine the device’s location.
Using an RSSI-based method with multilateration is the most easily activated and low-cost option for indoor positioning. However, it doesn't deliver a high degree of positional accuracy because it is subject to signal attenuation, absorption, reflection and interference.
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IoT Evolution Asset Tracking Award
Inpixon RTLS has been recognized with a 2022 IoT Evolution Asset Tracking Award, which highlights excellence and innovation in IoT solutions that enable asset tracking to optimize operations.
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