A method including determining a direct distance between the vehicle position and a position of the roadside unit and a planar distance between the vehicle position in a horizontal plane containing the vehicle position, and a projection of the position of the roadside unit onto the plane. The method further includes calculating a height of a roadside unit relative to the vehicle position using the direct distance and the planar distance determined for the vehicle position. The method also includes setting a value indicative of the height of the roadside unit relative to the vehicle position as a height correction value and storing the height correction value of the vehicle position in association with information indicative of the vehicle position as the height correction function.