# Security Awareness in Software-Defined Multi-Domain 5G Networks
## 2 Related Work
### Fifth Generation Security  
Fifth generation standards are advancing mobile communication systems in several areas. For the end-users, the evolution of access interfaces will advance the service quality--with increased bandwidth, lower latency, higher availability--and make the connectivity available to billions of new kinds of devices and applications, including IoT [3]. For operators, 5G systems provide lower operating expenses, as new management approaches and virtualization technologies will improve cooperation between different parties and ease service customization.  
Fifth generation security architecture is an evolution of third and fourth generation (3G/4G) security standards and architecture defined by Third Generation Partnership Project (3 GPP) [4; 5; 6; 7; 8]. These specifications focus on the authentication between subscriber's terminals and networks as well as on protection of access and core network communication against external threats. Fifth generation security approaches address these requirements but also new threats arising from new technologies and applications. The requirements for security mechanisms include:  
* Scalability and performance--Solutions for new and legacy threats must support high traffic volumes and large device numbers with new emerging applications. Security solutions must be scalable in a horizontal manner (more connected devices) and in a vertical manner (support different applications with diverse requirements).
* Insider threat protection--Increased cooperation between different parties as well as complicated security demands of emerging applications are new challenges. They force 5G security to focus more on threats, which originate e.g., from weakly protected partner networks or from mobile botnets [9; 10].  
The security architecture provides a holistic security perspective to mechanisms and interactions in the 5G systems. Figure 2 illustrates a domain model of the security architecture [11; 12] that was developed in the 5G-ENSURE project. It illustrates domains with trust relationships. The model divides 5G horizontally into infrastructure and tenant domains--due to emerging virtualization of devices and hardware--and vertically into user equipment, operator, and external network domains. These domains are divided, respectively, into user subscriber identity module (USIM), identity management (IM), and mobile equipment (ME) domains; to access network with different Radio Access Technologies (RATs), serving network, transport network, and home network domains; and to third party and Internet Protocol (IP) service provider domains. Slice domains illustrate the potential of 5G for customization--dedicating separate logical resources for different applications or users. Management  
Figure 1: Evolution of security monitoring from fourth generation (4G) to fifth generation (5G) of mobile networks. The foci of our investigation—software-defined and big data analytic means to customize monitoring, machine learning, and control of virtualized 5G networks as well as means to share trust-relevant knowledge across domains—are highlighted in green.  
domains, where security monitoring solutions lie, are presented separately to emphasize 5G's focus on efficiency and operability of networks.