Speed Estimation Using Commercial Wi-Fi Device in Smart Home

Abstract: With the development of Internet of Things (IoT), the speed estimation technology has attracted significant attention in the field of indoor security, intelligent home and personalized service. Due to the indoor multipath propagation, the speed information is implicit in the motion-induced reflected signal. Thus, the wireless signal can be leveraged to measure the speed of moving target. Among existing speed estimation approaches, users need to either carry a specialized device or walk in a predefined route. Wi-Fi based approaches provide an alternative solution in a device-free way. In this paper, we propose a direction independent indoor speed estimation system in terms of Electromagnetic (EM) wave statistical theory. Based on the statistical characteristics of EM waves, we establish the deterministic relationship between the Autocorrelation Function (ACF) of Channel State Information (CSI) and the speed of a moving target. Extensive experiments show that the system achieves a median error of 0.18 m/s for device-free single target walking speed estimation.

Keywords: CSI; speed estimation; electromagnetic wave; direction-independent; autocorrelation function