Radio Map Noise Reduction Method Using Hankel Matrix for WLAN Indoor Positioning System

WLAN indoor positioning system has a wide application prospect because it is entirely based on the network infrastructure and mobile terminals which are both prevalent in our daily life without the need of additional equipment. However, indoor multipath channel, signal randomly blocking, unstable transmission power would no doubt cause interference to the propagation of signal, which introduces noise to the radio map built in the offline phase, and further degrades the positioning accuracy. Therefore, in this paper, we propose a radio map noise reduction method by using Hankel matrix. Based on the special structure of Hankel matrix, we could effectively separate the noise from the signal. We perform the noise reduction separately on each Hankel matrix coming from different signal vectors but not the entire radio map. The experiment results indicate that the proposed method could achieve better noise reduction on the radio map and contribute good positioning performance.