The growing rate of positioning related applications such as car and pedestrian navigation has led to a desire to have access to Global Navigation Satellite Systems (GNSS) everywhere. This wish has been moderated by GNSS availability and coverage (and sometimes also accuracy) for numerous applications where signals are obstructed. Alternative or complementary positioning systems have to be found in order to develop the global domain of location-based applications. Current efforts are being carried out to broaden the spectrum of positioning systems such as hybridization between GNSS and inertial sensors, GSM/UMTS, WLAN, UWB, pseudolites and other radio beacons, etc. Thus, indoor positioning is a very important topic, mainly in terms of continuity of services, but is far from being the only one. The future developments of GNSS are likely to be the source of interference problems, either within the GNSS spectrum or with other systems. System interoperability must be carefully addressed, once again within GNSS and with other RF positioning systems. Among the proposed solutions, telecommunication networks are seen as potentially valuable candidates. Much works throughout the world is being carried out in the field of mobile networks and wireless local area networks, ranging from GSM to UWB. Furthermore, improvements in GNSS receivers are also needed in order to meet future integration and performance requirements. Thus, many activities are still ongoing and the forthcoming availability of the European Galileo, the Chinese Compass, the enhanced Russian Glonass, makes the competition towards the ultimate solution even more exciting. This special issue features six papers focusing on both GNSS and telecommunication networks. The main purpose is to find new approaches in order to improve current GNSS capabilities, either through GNSS developments or network-based methods. A brief overview of each of the papers is provided below