Working principle of Bluetooth beacon

At the moment when the Internet of Things and intelligent positioning technology are developing rapidly, Bluetooth beacon, as a key technology, is being widely used in many fields such as indoor navigation, personnel positioning, and material tracking. With its unique working principle, it provides accurate and convenient location information services for various intelligent applications.

Basic characteristics of Bluetooth beacon

A Bluetooth beacon is a wireless electronic device based on low-power Bluetooth (BLE) technology, usually powered by a battery. It sends data in an advertising packet in a standard format and operates in transmit-only mode, which means that it is only responsible for broadcasting data to the surrounding without establishing a connection with the terminal device. Its core function is to transmit data packets through short-range radio frequencies. These data packets can contain a variety of information and are designed to trigger corresponding actions on the receiving device.

Working process of Bluetooth beacon

A Bluetooth beacon broadcasts a data packet every certain interval, and the Bluetooth host (such as a mobile phone) performs a scanning action to receive the data packets broadcast by the beacon at intervals. The broadcast packet contains the MAC address of the broadcasting device, which can be used for device calibration. The host also calculates the signal strength, that is, the RSSI value, through the reverse channel reception mechanism, which can be used for distance measurement.

These data packets usually contain UUID, broadcast name, MAC address, major, minor, power information, etc. For example, in indoor navigation applications, UUID can be used to identify a specific navigation area, and major and minor can further subdivide different location points. When the host (such as a mobile phone) is installed with an app that adapts to the Beacon function, the corresponding action can be enabled according to the received ID, such as enabling the reception of broadcast information, enabling positioning and ranging, and enabling push programs.

Bluetooth beacon positioning principle

RSSI positioning principle

Bluetooth RSSI positioning refers to a positioning method based on Bluetooth 4.0 and above protocols, which uses the correlation between Bluetooth RSSI signal attenuation and distance to calculate the location of the Bluetooth terminal. In actual application, the transmitter is usually a Bluetooth beacon and the receiver is usually a smartphone. In the broadcast of a Bluetooth device, the farther the signal receiving end is from the transmitter, the weaker the received RSSI field strength value; the closer the signal receiving end is to the transmitter, the stronger the received RSSI field strength value. The dBm of the wireless signal received by the receiver is generally a negative value. The larger the signal value, the stronger the signal. The RSSI signal range is between 0 and 100. 0 is an ideal situation, which does not exist in actual applications.

Triangulation positioning principle

The triangulation positioning principle is an important method in Bluetooth RSSI positioning. The position of the transmitter is fixed. For example, there are 3 transmitters in an area, that is, three Bluetooth beacons are laid, which are recorded as BS1 (x1, y1), BS2 (x2, y2) and BS3 (x3, y3). Point E receives the signals sent by BS1, BS2, and BS3, and obtains the RSSI of different points. The triangulation positioning algorithm infers the coordinates of point E through the three known coordinates. The coordinates of the three transmitters (BS1, BS2, BS3) are fixed. The position of the receiver can be approximately calculated using the three-point positioning principle, that is, the signal of the transmitter diffuses 360 degrees outward to form the intersection of the sphere, and then the position of E (x, y) is calculated. However, in actual applications, the algorithm is not so simple. It is also necessary to consider the different attenuation factors of different environments and use filtering algorithms to filter signal interference to make the positioning point more stable. In some positioning algorithms, inertial navigation algorithms are also added. Even so, the position calculated using the Bluetooth RSSI field strength is still an approximate position.

Bluetooth beacon application case

Personnel positioning

In the chemical, electric power and other industries, the explosion-proof positioning beacon independently developed by Xinrui Kechuang is based on the ultra-low power Bluetooth BLE module. It has the characteristics of high performance, ultra-low power consumption and low cost, and has passed the inspection and certification of authoritative institutions. The explosion-proof mark is Ex ia IIC T6 Ga/ Ex ia IIIC T80℃ Da, the protection level reaches IP68, explosion-proof and waterproof, and adapts to various harsh environments such as high temperature. Fix the Bluetooth beacon and Bluetooth gateway in a specific position, and the personnel wear a positioning card (bracelet). The personnel positioning card can scan the broadcast data of the Bluetooth beacon, and then forward it to the Bluetooth gateway, and then transmit it to the cloud to achieve personnel positioning.

Indoor navigation

In indoor environments such as exhibitions, museums, airports, campuses, hospitals, shopping malls, and exhibition halls, Bluetooth beacons are deployed at appropriate locations, generally one every 5-8 meters (depending on the complexity of the indoor environment). Based on the Bluetooth RSSI value positioning algorithm, an indoor map is constructed, and the latitude and longitude coordinates of these hardware beacons are marked on the map. Based on a set of indoor positioning algorithms, an APP is made or integrated into a WeChat applet. When a person carries a mobile phone into the broadcast range of the Bluetooth beacon, after RSSI value measurement and MAC address resolution, based on the Bluetooth indoor positioning algorithm, the latitude and longitude coordinates of the smartphone can be marked on the map, thereby realizing the positioning of people in indoor environments and indoor navigation planning.

Reverse car search

Bluetooth beacons are used for reverse car search in parking lots, and can easily connect to traditional parking lot management systems. After the customer parks the car, open the mobile phone APP customized for the parking lot and press the "parking" button. At this time, the parking location is displayed, prompting that the parking location has been successfully recorded; when you want to pick up the car, press the "find car" button to display your current location, parking location, and navigation route.

Bluetooth beacons play an important role in the field of the Internet of Things with their unique working principle. It not only provides accurate location information services for various smart applications, but also promotes the development of indoor navigation, personnel positioning, material tracking and other technologies. With the continuous advancement of technology, the application prospects of Bluetooth beacons will be broader.