The IoT technology is constantly updated and iterated, and the indoor positioning technology has also undergone earth-shaking changes. From room-level positioning, decimeter-level positioning to high-precision centimeter positioning, the evolution of technology is always unexpected! Various positioning technologies of indoor positioning solutions appear in turn. Which technology is most suitable for indoor positioning? Let’s take a comprehensive perspective to understand the Bluetooth indoor positioning solution.

Overview of Beacon Indoor Positioning Technology

There are two Beacon indoor positioning technologies:

1. Passive location: Use the Bluetooth gateway to capture the broadcast data transmitted by the beacon on the person/object. The gateway is deployed and installed in the environment. And the gateway will return the collected beacon data to the server through the network. The server obtains the real-time position coordinates of the beacon through a positioning algorithm based on the coordinates known by the gateway.

2. Active position: Use the APP on a mobile device to get the Beacon broadcast data. The APP will have a positioning algorithm. Based on Beacon broadcast data, we can know the person's location who holds the mobile device. The location and navigation in the room are realized through APP or Applet, which is suitable for shopping malls, parking lots, and hospitals.

Features of Beacon Indoor Positioning Technology

Compared with Wi-Fi positioning technology, Beacon technology suffers less environmental interference. Beacon product is based on the battery power supply. With the advantages of Bluetooth low energy consumption, long service life, small size, and the high penetration rate of Beacon devices, Bluetooth positioning is the most commonly used technology in indoor positioning technology.

In daily life, smartphones and smart speakers support Bluetooth. The popularity and mass use of Bluetooth makes Bluetooth chips at a low price. And the BLE price is lower than traditional UWB/RFID solutions.

How does Bluetooth realize indoor positioning?

The Bluetooth working frequency is 2400 MHz ~ 2483.5 MHz. When Bluetooth initiates a broadcast, in addition to its own MAC address, the strength of the Bluetooth signal will also be broadcasted, namely RSSI information. The RSSI reflects the signal strength of the broadcast data packet. According to the RSSI, when the Bluetooth receiver is closer to the transmitter, the signal strength is stronger, on the contrary, will be weaker. The relationship between the signal strength and the distance from the transmitter can be found through the transformation of signal strength.

By deploying a Bluetooth transmitter in the room, namely a beacon, the Bluetooth receiver can determine its indoor location after receiving the RSSI signal broadcasted by the transmitter. This positioning method is called active positioning, and the positioning accuracy is 3 meters to 4 meters.

Through a reasonable algorithm, the RSSI transmitted by a beacon can backward deduce the distance between the beacon and the receiving device.

However, the RSSI value of the beacon is a reference. To calculate the distance of the beacon, you must also know the TX power value of the beacon device.

TX power refers to the RSSI value when it is 1m away from the beacon. Different equipment, working conditions, and site environments will affect the TX power value.

The three variables A, B, and C in the formula are empirical values, which need to be accurately adjusted according to the mobile phone system or hardware model. They rely on hardware adjustment and will be difficult to use if without data reserve.

Power supply issue of Beacon device

There is no need to lay cables in the room. Beacons are generally powered by batteries. When the TX power is 0 dBm and the broadcasting distance is 20 m, two AA dry batteries are used and can last for 5 to 7 years.

Bluetooth gateway

In some special environments, such as nursing homes, prisons, detention centers, mobile phone positioning cannot meet the needs of personnel management. To achieve accurate control of personnel, active beacon positioning is no longer suitable. To meet the positioning technology of this kind of environment, a Bluetooth gateway for scanning and receiving Bluetooth signals is developed. Bluetooth communication is carried out through the Bluetooth gateway with the person wearing the smart bracelet. The Bluetooth gateway is laid in the room to scan and collect the Bluetooth signal broadcast of the smart bracelet. The function of real-time positioning can also be realized, and the positioning accuracy can also reach 3 to 4 meters.

The Bluetooth gateway is 3 to 5 meters high in the room, and the Bluetooth signal coverage is about 10 meters. Considering the signal attenuation, when Bluetooth positioning is adopted, the Bluetooth gateway is best within 5 m from the Bluetooth transmission point. When positioning, the algorithm program must collect at least 3 Bluetooth gateway signals related to the Bluetooth transmission point to realize positioning. Compared with Wi-Fi positioning, the Bluetooth signal is more stable and positioning accuracy is higher.

Many Bluetooth gateways adopt a PoE power supply, which greatly reduces the maintenance cost! Bluetooth gateways are usually combined with smart bracelets. Smart bracelets are designed differently according to the needs of different scenes. For example, students need a fashionable appearance. The prison bracelet, which needs to be disassembled and has IP68 waterproof requirements to meet the needs of a daily shower.

The Bluetooth indoor positioning solution has been applied everywhere in the market, and various technical information about Beacon can be searched on the Internet. Whether domestic market or abroad, the strong demands of Beacon technology have attracted more and more manufacturers to invest in R&D. As a leading company in the IoT industry, RF-star Technology has played a role as a pioneer. The Beacon RF-B-AR1, RF-B-AR4 launched by RF-star are simple to operate, complete supporting tools, visual configuration parameters, and extremely low use thresholds to help customers shorten the project construction cycle and help customers’ products to land quickly. And there are many Beacon application scenarios in China. At present, the domestic Beacon application is becoming more mature, and the Bluetooth indoor positioning chain is beginning to take shape. Relying on the Beacon products’ advantages of low-power and low-cost, RF-star Technology has opened a broad prospect for the application of Bluetooth indoor positioning.