Why don't we use free 868 MHz band for geolocation?

Geolocation with ultra wide band signals has seen much progress in recent years. Nevertheless, the use of narrow band signals hasn't been studied rigorously despite its advantages that we present in this paper. We study the case of using low power carrier signal from the ISM [Industrial, Scientific & Medical] radio bands, where each user that have to be geolocated accesses to a statistical frequency from the band [868, 870 MHz]. The modulating signal is a square of 100Hz frequency and the Method used for geolocation is TDOA.