Space communications is an ideal candidate to handle critical and emergency situations arising on a regional to global scale, provided there is effective integration among them. The article presents a review of solutions offered by space communication systems for early warning and emergency communication services. It includes an up-to-date review of public research and standardization activity in the field, with a specific focus on mass alert. The main technical issues and challenges are also discussed along with the cutting-edge research from the scientific community.

Restoring the connectivity in the emergency areas and providing NAV/COM services able to support and coordinate the rescue teams represent two of the main telecommunication needs for efficient emergency situation management. The SALICE (Satellite-Assisted LocalIzation and Communication system for Emergency services) Project aimed at identifying the system architecture and the most suitable solutions to be adopted in the future integrated reconfigurable NAV/COM systems and to analyze their feasibility in realistic emergency scenarios. The article analyzes the proposed strategies and the most significant project results in pursuing both the global coverage of the emergency areas and the development of a reconfigurable and cooperative NAV/COM system.

Security is a crucial feature of current (5G) and even more for future (6G) communication networks. While the innate nature of the wireless channel is an issue for guaranteeing security, its physical characteristics can be exploited for protecting confidential data. Physical-layer Security (PLS) mechanisms take advantage of unique features of the transmission media or of the user equipment to introduce an additional level of data protection. The physical-layer security (PLS) can be seen as the first level of defense. The noise-loop (NL) modulation is a PLS technique that intrinsically provides confidentiality. In this paper, we first provide the theoretical analysis to evaluate the reliability and security in multipath fading channels, and then the theoretical results are evaluated by experimentation. A Software Defined Radio (SDR) testbed that exploits the NL secure modulation was implemented and a measurement campaign has been carried out in an indoor environment, with passive and active malicious nodes. An evaluation of the complexity of the proposed system is also reported, showing that the NL has low hardware resource occupancy and low computational cost. These fundamental characteristics make the NL modulation a valid PLS technique for providing a security solution for beyond 5G and 6G networks.