The aim of my thesis is to propose a security framework for the 5G next-generation telecommunication network’s architecture solution able to mitigate arising security threats and vulnerabilities. The solution suggested in my diploma work provides an appropriate network security framework that is in line with the next generation mobile network security requirements. For this framework to assume flawless protection it is paramount to have comprehensive understanding of the network in question. Due to this I present the business models and the expected development direction – layed out by standardization organisations, verticals and researchers – of the pervasive and ubiquitous 5G telecommunications networks. I demonstrate the use cases, the capabilities and requirements proposed for them, and the technology solutions able to satisfy these requirements. I showcase the mobile network architecture likely to be applied in the near future with particular regard to solutions based on virtualization and cloud technologies. Based on this, I present the security requirements and security aspects of 5G networks, paying particular attention to issues caused by architectural changes. Being aware of the expected direction of future developments, the use cases, the requirements, the new architecture, the risks, the threats and vulnerabilities, I suggest a complex, composite and detailed network security system to protect 5G mobile networks.