An Indoor Positioning and Tracking Algorithm Based on Angle-of-Arrival Using a Dual-Channel Array Antenna  
[PERSON]  
1 School of Geomatics, Liaoning Technical University (LNTU), Fuxin 123000, China; [EMAIL_ADDRESS] (C.L. ); [EMAIL_ADDRESS] (K.C. ); [EMAIL_ADDRESS] (A.X. ); zhu  
studies have demonstrated that most of people's activity areas are indoors. Different indoor environments, such as large shopping malls, airports, and stations, require efficient flow monitoring and dynamic analysis means. Also, many special types of work, such as mines and high-rise buildings, need to locate internal personnel accurately in real-time, especially in an emergency. Furthermore, medical and nursing institutions require locating nursing objects in real-time to maximize the rescue time to provide the most timely medical services. In recent years, there have been numerous efforts to use the basic features of acoustics [3], light [4], electricity [5; 6; 7; 8; 9], magnetic field [10], and force [11] in different fields, including detection, to obtain the parameters associated with indoor positioning. However, due to the indoor environment's complexity, the proposed indoor positioning technology and methods have not been enough mature and perfect [12], lacking the performance of high precision, low cost, and easy deployment of an indoor positioning environment. An indoor positioning method of low cost, wide coverage, low power consumption, high precision, and easy deployment is urgently needed. Wireless signal indoor positioning technology can be divided into categories of signal feature matching, time measurement, and angle measurement according to signal parameter measurement methods. Signal feature matching is mainly based on using the measured signal strength or channel status information (i.e., RSS or CSI) to establish a feature fingerprint database to obtain matching location. Time distance measurement includes measuring the signal's time of arrival, time difference, or time of flight (i.e., TOA, TDOA, or TOF). Angle measurement includes measuring the signal's arrival angle or direction of arrival (i.e., AOA or DOA) [13; 14; 15; 16; 17]. The radio direction finding, angle measuring, and positioning have been applied in many fields. A radar system using an array antenna can perform high-resolution direction finding. The 5G system equipped with a large-scale antenna array makes high-precision ranging and angle measuring possible. The Bluetooth Special Interest Group (Bluetooth SIG) has added the directional finding to the Bluetooth 5.1 standard, which was released in 2019 [18]. Compared with the positioning method based on measuring time and distance using multiple base stations, single-base station high-precision angular positioning technology based on using an antenna array requires fewer base stations, has lower cost, and avoids the problems of time synchronization and joint calculation between base stations [19]. In [19], a dual-channel switch switching and dual-polarization wheel antenna array was proposed, and the phase-specific angle measurement method of the antenna was introduced to eliminate the frequency estimation error caused by the antenna switching. Combined with the super-resolution estimation algorithm of angle and pole decoupling, the high-precision positioning of a single base station was realized. In this paper, the method is modified. The switching wheels of the dual-polarization antenna array are collected in turn in channel 1, the fast Fourier transform (FFT) is applied to the data of channel 2 to estimate the frequency offset, and the phase of the data is compensated, without eliminating the frequency estimation error through phase comparison. It can also achieve high precision positioning within the coverage area of a single base station. However, in the non-line-of-sight (NLOS) environment with signal occlusion, multipath, and other interfering factors, the dynamic positioning accuracy of the proposed Bluetooth array angular measurement and positioning system decreases sharply.