Time of flight error compensation for in-tunnel vehicle localization

Vehicle localization systems rely on measuring distances between a given target and a set of reference points. The accuracy of a localization system strictly depends on the exactness of these measurements. However, the estimation of distances via wireless signals is affected by errors due to factors such as channel noise and multipath propagation. Precise localization is very important for emergency management, especially in tunnels where accidents such as fire typically cause more damage due to difficult evacuation. In this paper we analysed the characteristics of time of flight based ranging in tunnel environment from the error stand point with the aim of designing an error compensation unit. We integrated such a compensation unit within an existing vehicle localization system to improve the localization accuracy. We designed and validated our solution by performing real experiments in a tunnel located in Lugano, Switzerland.