Over the past few years, many applications of satellite navigation systems have been developed. Among the wide range of applications of such systems, transportation in urban environment seems to be one of the most prominent. Hence it is important to fully and accurately characterize the receiver performance for this application.The urban environment is characterized by high masking angles and the presence of a great number of obstacles which produce multipath. Investigating the receiver performance in this medium requires a model of the wave propagation. In this paper, a ray launching simulation tool is used to characterize different environments and the receiver errors due to multipath and the receiver performance with and without augmentation are evaluated.