DoA-LF: A Location Fingerprint Positioning Algorithm With Millimeter-Wave

Location fingerprint (LF) has been widely applied in indoor positioning. However, the existing studies on LF mostly focus on the fingerprint of Wi-Fi below 6 GHz, bluetooth, ultra wideband, and so on. The LF with millimeter-wave (mmWave) was rarely addressed. Since mmWave has the characteristics of narrow beam, fast signal attenuation, and wide bandwidth, and so on, the positioning error can be reduced. In this paper, an LF positioning method with mmWave is proposed, which is named direction of arrival (DoA)-LF. Besides received signal strength indicator of access points (APs), the fingerprint database contains DoA information of APs, which is obtained via DoA estimation. Then the impact of the number of APs, the interval of reference points, the channel model of mmWave and the error of DoA estimation algorithm on positioning error is analyzed with Cramer-Rao lower bound. Finally, the proposed DoA-LF algorithm with mmWave is verified through simulations. The simulation results have proved that mmWave can reduce the positioning error due to the fact that mmWave has larger path loss exponent and smaller variance of shadow fading compared with low frequency signals. Besides, accurate DoA estimation can reduce the positioning error.