# Preparations for Galileo PRS in Poland
## 2 Galileo Services and Signal Plan  
Galileo is the European Global Navigation Satellite System (GNSS), providing worldwide radio signals for position, navigation and timing purposes. The European Commission is responsible for the Galileo program, and the European Union Agency for the Space Programme (EUSPA) is responsible for deploying the system and providing technical support for operational tasks. Galileo's performance is gradually improving as the system's space segment is getting close to its target parameters. When the system reaches the Full Operational Capability (FOC) phase, it will offer four high-performance services [1]:  
* Open Service (OS), free of charge open service providing initial signals for positioning and timing purposes. * High Accuracy Service (HAS), complementing the OS service and providing additional navigation signals and added-value services in a different frequency band. * Public Regulated Service (PRS), restricted to government-authorized users and dedicated for sensitive applications requiring a high level of service continuity. * Search and Rescue Service (SAR), Europe's contribution to the international satellite-based search and rescue distress alert detection system COSPAS-SARSAT. In order to facilitate the future improvement of the Galileo services' quality, it is also planned that Galileo Open Service will provide Navigation Message Authentication, allowing users to utilize the authenticated data extracted from navigation messages. The HAS and PRS signals will be encrypted in order to restrict the access only to authorized and governmental users. PRS is primarily intended for use by European units, such as fire brigades, health services (ambulance), humanitarian aid, search and rescue, police, coastguard, border control, customs and civil protection units. Access to the PRS is controlled through operational and technical means, including governmental-grade encryption. Users not granted access to the service will be unable to extract any information from the signal. Moreover, the PRS service will be more resilient and more robust than the initial open services of Galileo and other GNSS systems. The PRS will ensure better continuity of service to authorized users when access to other navigation services may be degraded (resilience), and in cases of malicious interference, PRS will increase the likelihood of the continuous availability of the Signal-in-Space (robustness). The service's end-to-end design ensures the protection and availability of the signal and its associated data flows. Due to the signal and system design, the PRS service will also be more resistant to typical spoofing and jamming attacks. Galileo satellites permanently transmit three independent CDMA and Right-Hand Circularly Polarized (RHCP) signals, denoted E1, E5 (sub-divided into E5a and E5b) and E6 [2]. These signals are transmitted on four frequency carriers: E1-1575.420 MHz, E6-1278.750 MHz, E5a-1176.450 MHz and E5b-1207.140 MHz (see Figure 1). Each of those occupies a different bandwidth: E1-24.552 MHz, E6-40.920 MHz, E5a and E5b-20.460 MHz, respectively. The Galileo frequency bands are allocated for Radio Navigation Satellite Services (RNSS), and in addition to that, the E5a, E5b and E1 bands are also allocated for Aeronautical Radio Navigation Services (ARNS), employed by civil aviation users for dedicated safety-critical applications. Figure 1: Galileo Frequency Plan [2]. The technical characteristics of specific Galileo service signals are well known, but some parameters, especially for the PRS, for obvious reasons, are classified or even restricted [2]. All the signals are transmitted in the same bands, but with different modulation schemes, so that they can be distinguished.