Localization for a Mobile Node Based on Chrip Spread Spectrum Ranging

In this paper, we propose a localization algorithm for a mobile node based on the IEEE 802.15.4a chirp spread spectrum (CSS). IEEE 802.15.4a is an alternative PHY for IEEE 802.15.4, which is used for wireless sensor networks, and it can be applied to ranging applications. Through CSS ranging, the coordinate of a CSS node can be calculated by using trilateration. This approach is usually used for mobile robot localization. In the case of mobile robot localization, the dynamics of a mobile robot can be modeled as a state-space equation because a robot is an artificial object manufactured by designers. Therefore, the coordinate of a mobile robot can be estimated by using the Kalman filter. However, in the case of localization of a mobile node whose movement cannot be predicted, the dynamics of the mobile node are difficult to model. Therefore, we propose a strategy that regards the un-modeled dynamics as the process noise of the state-space equation. Further, we propose a method for determining the statics of the process noise based on some reasonable assumptions. Through the localization experiment, we verify the proposed method and discuss the results.