Time keeping is at the core of any Global Positioning System (GPS.) Effects that are related to clocks' rate and synchronization must be considered in the designing of such systems. Between them are relativistic effects on clock's rate. From the very beginning in the life of GPS, It becomes clear that we need to consider the predictions of Special and General Relativity for the system to work properly. For example, at today's accuracy of position determination, we have to deal with the relativistic Doppler shift and the gravitational shift. If we wish to improve the accuracy in the position then we have to take in account relativistic effects of higher order. A possible way to deal with the torrent of corrections is to build an intrinsically relativistic GPS. For the relativistic system we don't have to look for new unknown corrections each time we upgrade the precision of the clocks. Here, we present a discussion about different schemata that can be used for a fully relativistic GPS.