An indoor positioning system (IPS) is an alternative to a global navigation satellite system (GNSS) that is ineffective indoors. Depending on the technology and methods used, an IPS can locate objects inside buildings with varying levels of accuracy. In this post, we’ll summarize IPS technologies and elaborate on Bluetooth, which is one of the most common choices for indoor positioning.
Indoor Positioning Technologies
An IPS comprises two types of devices: transmitters and receivers. The former are beacons or tags attached to people and objects. Their signals propagate to a receiver module that can sit inside a mobile phone or another electronic device. A software application processes the signals and converts them to beacon location data.
In some systems, signals are transmitted and received by one and the same device, for example, in a Radio Detection and Ranging (RADAR) system. Indoor positioning technologies mostly depend on the type of signal that propagates within the network of devices and include the following categories:
- IPS based on radio propagation (RFID, Wi-Fi, Bluetooth, RADAR).
- IPS based on sound propagation (Sound Navigation and Ranging (SONAR)).
- IPS based on light propagation (Light Detection and Ranging (LiDAR), infrared systems, and computer vision systems).
Some indoor positioning systems rely on inertial navigation. Inertial measurement units (IMUs) use sensor data to detect and track objects in a three-dimensional coordinate system.
IPS technologies vary in their positioning methods, application areas, and levels of performance. Bluetooth is not an absolute leader on this list, however, it has certain advantages that make it a strong contender.
Advantages of Bluetooth Indoor Positioning Technology
Bluetooth, or rather Bluetooth Low Energy (BLE) is an extremely power-efficient technology that reduces the size and cost of the network devices and extends their lifetime. So, a BLE-based IPS is second to none when it comes to power consumption.
Availability is an important factor that simplifies the implementation of an IPS, and it’s another advantage of Bluetooth technology. All major electronics manufacturers, such as Texas Instruments, Silicon Labs, STMicroelectronics, Qualcomm, and many others, integrate it into their products. There are millions of BLE-enabled devices worldwide, your smartphone included.
In addition, Bluetooth indoor positioning systems have high scalability and a sufficient range of data transfer. From a developer’s perspective, the technology is easy to use and customize. Depending on the Core Specification version, Bluetooth offers different positioning methods that provide accuracy ranging from several meters down to 1 centimeter.
Bluetooth Indoor Positioning Methods
The simplest method used in Bluetooth indoor location systems is received signal strength indication (RSSI). It allows users to estimate the distance between the network nodes by the intensity of the transmitter’s signal. The stronger the signal, the closer the transmitter or BLE beacon to the receiver. This method is available in all Bluetooth versions, but it provides low positioning accuracy.
For more accurate detection, you can install more beacons in the room or support RSSI with trilateration if you have at least three devices or multilateration for networks with multiple nodes. Mathematical modeling and calculations can increase the accuracy, but even in the best-case scenario, it won’t be less than a meter.
Bluetooth version 5.1 provides an advanced positioning technique or the so-called direction finding feature. It defines the angle of signal propagation by measuring the angle of arrival (AoA) and angle of departure (AoD).
By using the AoA and AoD methods, you can locate objects with high accuracy. To confirm the position measurements, you can use triangulation as an additional method based on mathematical models. Applying as many methods as possible provides greater results in indoor positioning.
Applications of Bluetooth Indoor Positioning
Bluetooth indoor positioning has specific use cases in various industries. For example, staff can monitor the process of material handling and goods manufacturing at large enterprises or factories. Using a Bluetooth IPS at a warehouse, you can see how the goods are stored, handled, and secured.
People’s safety is another important thing that an IPS can ensure. This is a high-priority task for hazardous working environments, such as mines. Using Bluetooth tags, you can track employees and improve their safety underground.
A BLE-based IPS can perform a life-critical function in healthcare. Tracking patients and personnel with tags and beacons at hospitals can guarantee timely aid.
An IPS integrated into museums, galleries, or tourist attractions can offer an item finding feature and provide visitors with points of interest (POI) information. By downloading an app on their smartphones, users can easily find the right item and receive information about it.
Installed in shopping malls, a BLE-based solution allows business owners to promote their products and services. The IPS will send messages to the app users once they approach the specific stores.
Bluetooth indoor positioning technology gives an opportunity for implementing wayfinding solutions at a variety of public places. An IPS can help people navigate through airports, railway stations, parks, college campuses, sports facilities, and office buildings.
Bluetooth is a radio signal-based technology widely used for indoor positioning and tracking. It is a viable solution that offers several advantages, including availability, energy efficiency, and easy implementation. BLE-based systems find application in diverse areas that comprise logistics, healthcare, retail business, production industries, and many others.
Different Bluetooth versions provide different positioning methods and accuracy levels. Implementing a BLE IPS has certain peculiarities and involves some challenges. You can learn more about them in our Bluetooth indoor positioning system guide based on our personal experience and case studies.