  Accurate vehicular localization is important for various cooperative vehicle
safety (CVS) applications such as collision avoidance, turning assistant, etc.
In this paper, we propose a cooperative vehicular distance measurement
technique based on the sharing of GPS pseudorange measurements and a weighted
least squares method. The classic double difference pseudorange solution, which
was originally designed for high-end survey level GPS systems, is adapted to
low-end navigation level GPS receivers for its wide availability in ground
vehicles. The Carrier to Noise Ratio (CNR) of raw pseudorange measurements are
taken into account for noise mitigation. We present a Dedicated Short Range
Communications (DSRC) based mechanism to implement the exchange of pseudorange
information among neighboring vehicles. As demonstrated in field tests, our
proposed technique increases the accuracy of the distance measurement
significantly compared with the distance obtained from the GPS fixes.
