Current commonly used indoor positioning technologies include ultrasonic technology, infrared technology, ultra-wideband (UWB), radio frequency identification (RFID), Zig-Bee, Wlan, optical tracking and positioning, mobile communication positioning, Bluetooth positioning, and geomagnetic positioning.
Ultrasound positioning
Ultrasound positioning accuracy can reach centimeters, but ultrasonic attenuation is significant, affecting the effective range of positioning.
Infrared positioning
Infrared positioning accuracy can reach 5 ~ 10 m. However, infrared light is easily blocked by objects or walls in the transmission process, and the transmission distance is short. The positioning system has a high degree of complexity and the effectiveness and practicality are still different from other technologies.
UWB positioning
UWB positioning, the accuracy is usually not more than 15 cm. However, it is not yet mature. The main problem is that the UWB system occupies high bandwidth and may interfere with other existing wireless communication systems.
RFID indoor positioning
The RFID indoor positioning accuracy is 1 to 3 m. Disadvantages are: the identification volume is relatively small, requires a specific identification device, the role of distance, does not have communication capabilities, and is not easy to integrate into other systems.
Zigbee positioning
Zigbee technology positioning accuracy can reach meters. Due to the complex indoor environment, it is very difficult to establish an accurate propagation model. Therefore, the positioning accuracy of ZigBee positioning technology is greatly limited.
WLAN positioning
The WLAN positioning accuracy can reach 5 to 10 m. WiFi positioning system has disadvantages such as high installation cost and large power consumption, which hinders the commercialization of indoor positioning technology. The general positioning accuracy of light tracking positioning is 2 to 5 m. However, due to its own characteristics, to achieve high-precision optical positioning technology, it must be equipped with optical sensors, and the sensor's directivity is higher. Mobile communication positioning accuracy is not high, and its accuracy depends on the distribution of mobile base stations and the size of coverage.
The positioning accuracy of geomagnetic positioning is better than 30 m. Magnetic sensors are the key factors determining geomagnetic navigation and positioning. Accurate environmental magnetic field reference maps and reliable magnetic information matching algorithms are also very important. The high cost of high-precision geomagnetic sensors hinders the popularization of geomagnetic positioning.
Bluetooth positioning
Bluetooth positioning technology is suitable for measuring short distances and low power consumption. It is mainly applied in small-range positioning with an accuracy of 1 to 3 m, and has moderate security and reliability. Bluetooth devices are small in size and easy to integrate into PDAs, PCs, and mobile phones, so they are easily popularized. For customers who have integrated Bluetooth-enabled mobile devices, as long as the Bluetooth function of the device is enabled, the Bluetooth indoor positioning system can determine the location. When using this technology for indoor short-distance positioning, it is easy to discover the device and the signal transmission is not affected by the line-of-sight. Compared to several other popular indoor positioning methods, using low-power Bluetooth 4. 0 The standard indoor positioning method has the features of low cost, simple deployment scheme, fast response and other technical features, plus mobile device manufacturers for Bluetooth 4. 0 The promotion of the standard specification has led to better development prospects.
Since the promulgation of the Bluetooth 1 standard, there have been a variety of methods based on Bluetooth technology for indoor positioning, including the method based on range detection, the method based on the signal propagation model, and the method based on the field fingerprint matching. The method based on range detection has low positioning accuracy and the positioning accuracy is 5~10 m, and the location precision is about 3 m based on the signal propagation model, and the location accuracy based on the field intensity fingerprint matching is 2~3 m.
Beacon positioning
iBeacons are based on Bluetooth 4.0 BLE (Bluetooth Low Energy). With the release of BLE technology in Bluetooth 4.0 and Apple's strong derivation, iBeacons applications have become the hottest technology. Nowadays, many smart hardwares have begun to support the application of BLE, especially for newly-listed mobile phones, and BLE has become the standard configuration. Therefore, the use of BLE technology for indoor positioning of mobile phones has become a hot spot for indoor LBS applications. In the Bluetooth positioning method, the method based on field strength fingerprint matching has the highest accuracy and is widely used.
