# Secure Indoor Localization Based on Extracting Trusted Fingerprint  
[PERSON]  
1 School of Information Science and Engineering, Hunan University, Changsha 410012, China; [EMAIL_ADDRESS] (X.Y. ); [EMAIL_ADDRESS] (Y.Z. ); [EMAIL_ADDRESS] (C.W. )1 School of Information Science and Engineering, Hunan University, Changsha 410012, China; [EMAIL_ADDRESS] (X.Y. ); [EMAIL_ADDRESS] (Y.Z. ); [EMAIL_ADDRESS] (C.W. )1 School of Information Science and Engineering, Hunan University, Changsha 410012,  
ToF mainly estimates the distance by measuring the signal transmission time between nodes. However, this technique has some drawbacks. The transmission of an ultra-wide band signal requires relatively large energy consumption, and the effective measurement distance is short. The distance measured by ultrasonic technology can reach the precision of centimeters. Ultrasonic technology can make the structure of the system relatively simple, and the light does not interfere with the ultrasonic. The disadvantage is that the ultrasonic signal attenuates in the air, and the small ultrasonic probe can only reach the meter level. If the reflection range is adopted, it will also be affected by the multi-path effect, and the ultrasonic wave is the method of line-of-sight propagation, so it is not suitable for large-scale occasions. In addition, the transmitting nodes with ultrasonic sensors usually need to continuously broadcast the acoustic signal, which is a significant expense for the whole network, which increases the cost of the hardware facilities. The tracking and locating of equipment based on the principle of MG [8] is characterized by its portability, simple operation and low cost. However, the system also has many shortcomings as follows: The MG transmitting device needs to continuously emit MG signals with high power consumption and high requirements on the power supply system. In the tracking and positioning, the technology is seriously disrupted by the external MG interference; the operation is cumbersome; the error is large; and the requirements of the monitoring personnel are high. Technologies based on existing infrastructure include WiFi [9], ZigBee, Bluetooth, UWB and RFID [10]. To estimate the position, we need to measure some signal characteristics. Common signal features include arrival time (TOA), arrival time difference (TDOA), receiving signal strength indication (RSSI), etc. [11]. Among many RSSI-based indoor positioning technologies, the more popular positioning technology is based on WiFi wireless signals since the IEEE802.11 APs were deployed as wireless local area networks (WLANs). Prior to the widespread adoption of WiFi technology, radio frequency (RF)-based [7] RADAR systems have been proposed that determine a user's location by recording and processing signal strength information from multiple base stations. In the meantime, some researchers have proposed hybrid indoor positioning methods such as using 2D markers to supplement WiFi intensity or using different wireless technologies such as cellular GSM, DVB, FMand WLAN to locate users. However, network access points with higher radio coverage, such as GSM and FM base stations, contribute less to indoor positioning. Some researchers have tried to build indoor positioning systems such as RFID and ZigBee in combination with other low-power technologies. However, these technologies require a large number of low-power devices to support the positioning process. Some researchers are also working on multi-source data combination positioning technology, which can improve the positioning accuracy, but the system cost will be greatly increased. WiFi is very popular and is one of the most commonly-used wireless technologies in the room. It is often used for wireless Internet connections in many buildings, such as shopping malls, factories and other public places. One great advantage of this technology is that it is widely used in a variety of devices, such as mobile phones, laptops and tablets, which users usually use [12].