Public Protection and Disaster Relief (PPDR) agencies in EC member states are relying on digital Private Mobile Radio (PMR) networks for mission-critical voice and data communication. These networks are highly resilient and properly dimensioned to cope with crisis and emergency handling, and are well protected against monitoring and intrusion by means of encryption, authentication and integrity. The two main standards for digital PMR networks in Europe are TETRA (TErrestrial Trunked RAdio) and TETRAPOL. The majority of these networks are based on mature technology, requiring old-fashion synchronous links (backbone), and using proprietary hardware solutions that eventually become obsolete. These networks also provide limited inter-technology coverage providing very ineffective management of emergency events, both at the national level and in cross-border regions. The main goal of SALUS is to design, implement and evaluate a next generation communication network for Public Protection and Disaster Relief (PPDR) agencies, supported by network operators and industry, which will provide security, privacy, seamless mobility, QoS and reliability support for mission-critical PMR voice and broadband data services. The project covers the full techno-economic scope regarding development and deployment of the next generation PPDR networks by focusing on the integration with / migration to 4G wireless communications developments targeting three critical scenarios 1) city security, 2) disaster recovery, and 3) temporary protection. Salus will address key research challenges such as enterprise architectures, economic and business analysis, and a number of technical aspects concerning QoS, resilience, inter-systems handover (secure, seamless and fast), enhanced security, privacy mechanisms in heterogeneous network infrastructure, and multicast broadband PPDR services.