Research on LOS/NLOS Identification Technology Based on WIFI Signal Space-Frequency Domain Information

WIFI signal is met with an extensive application in the context of indoor wireless positioning. Nonetheless, the major challenge confronting indoor positioning systems based on ranging is the interference caused by multi-path and non-line-of-sight environments under the indoor context. Owning to the limitations on bandwidth and multipath resolution, it’s difficult for commercial WIFI devices to be effective in identifying LOS/NLOS scenarios. The application and expansion of the IEEE 802.11n protocol makes it much easier for commercial WIFI devices to obtain spatial information of subcarriers and MIMO systems. The channel state information of Space-Frequency domain is applied in this paper to establish the joint distribution of WIFI signal arrival angle and flight time, and extracts features from its estimated clustering results to complete non-line-of-sight identification. The results from conducting experiment indicate that the proposed method exhibits an excellent detection rate and robustness to LOS and NLOS environments in static scenarios.