Evaluation of a Cooperative Positioning Algorithm by Tight GPS/DSRC Integration for Vehicular Networks

GNSS alone is not a reliable source for DSRC safety applications. Cooperative Positioning (CP) in VANET refers to a technique based on communication via a DSRC channel and information fusion. CP combines the information gathered from several road users to refine self-position. CP can require range measurement between vehicles by some radio ranging technique. Two types of CP are introduced in this paper, loose and tight GPS/DSRC integration, which differ in the type of data being communicated. For loose CP, the position, velocity and measured ranges are broadcast to all neighbouring vehicles. For tight CP, the pseudo-ranges are communicated, instead of the positions. The two algorithms are compared using a Cramar Rao Lower Bound (CRLB) analysis and their effectiveness is evaluated. Tight integration proves to perform better, as might be expected.