The emergence of the LBS services (location based services) creates the need for indoor and outdoor positioning. Indoor environments refer to environments inside buildings, and outdoor environments refer to urban environments (streets). Indoor localization poses a true challenge for classical positioning systems. Indeed, radio propagation in indoor environments is affected by several factors particularly multipath, shadowing, cross-correlations, receiver mobility, interference. Urban environments are also challenging environments where multipaths problems are even more pronounced. This paper aims at analyzing such environments in the frame of a state of the art of the GPS acquisition environment.