A Trajectory Model to Deal with Transmission Failures

A trajectory records the evolution of the position of a moving object in a space during a time interval. In Spaccapietra's trajectory model, trajectories are segmented in subintervals called stops and moves. On the other hand, during some periods failures can occur in the transmission of data of the trajectory causing missings of information. In this paper, we extend Spaccapietra's model by incorporating the missing information as a component of a trajectory. We consider this issue not only with regard to the object position but also with regard to other attributes of the trajectory (complementary attributes). We propose a classification for these attributes, depending on whether they are constant or variable during the stops and the moves. We also propose two algorithms: i) to convert a sequence of observations of a trajectory into stops, moves and missings. ii) to check that the data recorded for the attributes whose value must be constant is consistent.