RTLS Hybridization is Here to Enable Seamless Indoor and Outdoor Location Visibility

Many location-based enterprise services involve scenarios where assets or people transition between indoor and outdoor spaces typically requiring multiple location systems, each utilized for their individual benefits and complementary operating coverage. Whether tracking goods in a supply chain or material flow analysis, guarding employees and equipment on a construction site, or navigating guest and staff on a complex campus, seamless and effective location visibility requires the use of Real Time Locating Systems (RTLS) supplemented by additional technologies for a comprehensive system. Where RTLS, utilizing short range radio communications such as Bluetooth LE, Ultra-Wideband (UWB), and Active Radio Frequency Identification (RFID), can effectively provide precise indoor positioning, location-based services it can introduce additional location systems for other cases such as: Global Navigation Satellite Systems (GNSS), GPS, or Automatic Identification Systems (AIS) for outdoor location, and barcode or passive RFID for lower-cost item level tracking. Where traditionally location-based services, would operate “technology-agnostic” systems to collate information from multiple location technologies in software, RTLS vendors are increasingly finding ways to include their technology and services at a more integrated, hardware level.

Consolidating location technologies at a hardware level presents the immediate benefit of reducing hardware and infrastructure costs by being able to halve the number of tags, anchors, or gateways used for a system that would employ RTLS and outdoor location. Most commonly, employing hybrid tags has been the solution opted for by RTLS vendors, and for good reason, as tag costs are a large contributor to overall system costs due to their large volumes, especially in use-cases where indoor/outdoor tracking will be common such as supply chain visibly. Additionally, infrastructure for indoor and outdoor location systems vary significantly so it would be practical to integrate them both at the tag level. RTLS primarily leverages short range standards, i.e., Bluetooth LE, UWB, and RFID for both positioning and communication to a nearby anchor, whereas GNSS uses satellite signals for positioning as well as a low-power wide-area network such as LoRa or Sigfox to transmit the data to a receiver over a much further distance. Several examples of these systems exist: Quuppa and Actility announced their partnership in April 2021, integrating support for precise Bluetooth LE positioning in to Actility’s Abeeway line of multi-mode trackers and IoT modules which, along with Bluetooth positioning, support GPS, low power GPS, Wi-Fi sniffing, and leverages LoRa for connectivity. Inpixon’s RTLS solution, coming from their acquisition of Nanotron in October of 2020, leverages two different RTLS radio technologies: UWB and their proprietary Chirp Spread Spectrum (CSS). Where UWB can achieve notably high precision (around 30 cm in practice), it operates most effectively at a range of about 50 m. For positioning where a longer range is required, Inpixon employs their CSS technology at up to 1000 m. Extronics leverages a hybrid RTLS solution for worker tracking on worksites such as factories and construction sites which incorporate indoor and outdoor environments, employing a mix of RFID, WI-FI GPS, Bluetooth LE, and UWB on a case by case basis. Worker tracking can be used to track the productivity and compliance of workers as well as for safety applications, warning workers about specific nearby safety hazards, especially important for lone workers.

As an alternative to including indoor and outdoor location and connectivity to tags, companies such as Link Labs and UWINLOC have engineered systems where cheaper single-technology tags can be used in indoor and outdoor scenarios using clever anchor or gateway implementations. Link Labs’ new SuperTag hub acts as a portable anchor and gateway device, where the device tracks its own location in outdoor scenarios using GNSS then scans for nearby Bluetooth LE tags, recording information about their position as well as itself to be backhauled to the cloud via satellite internet. The SuperTag hub approach has many benefits for assets that use RTLS but are in transit. For example, pallets being transported between distribution centers or specialty medical equipment sent between healthcare institutions are commonly Bluetooth tagged and can benefit from the additional location visibility to prevent loss and theft while on the road. While not providing the same level of accuracy while on the road, pinpointing the vehicle is an asset that is attainable and would be the level of accuracy required for an in-transit tracking application. Offloading location to the anchor/gateway in this system comes with a series of benefits, mainly in the use of standard Bluetooth LE tags. Simple Bluetooth LE tags are much cheaper than their hybrid counterparts, as not only are additional chipsets and antennae needed for GNSS but also but much higher battery requirements. Standalone (SA) Bluetooth tags are also much more common, allowing for much wider compatibility and vendor choice when designing an RTLS deployment.

ABI research estimates that by 2025, there will be 150 million RTLS tags for asset, material, and product flow tracking as well as around 130 million tags in use for tool and equipment tracking (MD-RTLS-103). Instead of utilizing specialized indoor/outdoor tag technology, shifting deployment costs away to external infrastructure can prevent adding too many additional technologies to an already fragmented market and is key for scaling systems which are introducing tens of thousands, or even more, tags. Leveraging the existing base of RTLS tags is especially convenient in an industry where standardized communication and democratized hardware is becoming common practice with systems based on Bluetooth 5.1 and UWB with FiRa verification or the IEEE 802.15.4z specification. Vendors can consider anchors and gateways as a point to add flexibility in deployment and functionality, expanding the coverage possible for RTLS to cater for specific use-cases, as seen with Link Labs solution for tracking RTLS tags on the road or Abeeway’s solution for full supply chain visibility.

The future of cellular positioning using 5G may pose a different solution for joint indoor and outdoor tracking solutions. 3GPP release 16 and upcoming releases 17 and 18 give focus to indoor positioning and target indoor positioning accuracies competitive with existing high-precision RTLS (3 m, 0.5 m, and 0.2 m for R16, R17, and R18 respectively) while also being viable for outdoor positioning, further consolidating location technology. Ultimately, the RTLS ecosystem as it exists now remains highly fragmented with many competing location technologies with their own accuracy, reliability, and value propositions. Location platforms which provide seamless indoor and outdoor positioning at all levels can benefit greatly from further interoperability to consolidate coverage and adapt existing location infrastructure.