In mobile networks, the mobile core plays a crucial role in providing connectivity between mobile user devices and external packet data networks such as the Internet. Through the years, along with the dramatical changes in radio access networks, the mobile core has also been evolved from being a circuit-based analog telephony system in its first generation (1G) to become a purely packet-based network called the Evolved Packet Core (EPC) in the current generation (4G). In recent years, the explosion of mobile data traffic and devices and the advent of new services have led to the investigation of the next generation of mobile networks, i.e., 5G. A wide range of technologies has been proposed as candidates for the development of 5G. Among other technology candidates, Software Defined Networking (SDN) and Network Function Virtualization (NFV) have been widely considered to be key enablers for the network architecture of 5G, especially the mobile packet core (MPC) network. This thesis aims at identifying benefits and challenges of introducing SDN and NFV to re-achitect the current MPC network architecture towards 5G and addressing some of the challenges. To this end, we conduct a comprehensive literature review of the state-of-the-art work leveraging SDN and NFV to re-design the 4G EPC architecture. Through this survey work, several research questions for future work have been identified and we contribute to address two of them in this thesis. Firstly, since most of the current works focus on unicast services, we propose an SDN/NFV-based MPC architecture for providing multicast and broadcast services. Our numerical results show that the proposed architecture can reduce the total signaling cost compared to the traditional architecture. Secondly, we address the question regarding the scalability of the control plane. We take the Mobility Management Entity (MME) - one of the EPC key control plane entities - as a case study. In our work, the MME is deployed as a cluster of multiple virtual instances (vMMEs) and a front-end load balancer. We focus on investigating different approaches to achieve better load balancing among these vMMEs, which in turn improves scalability. Our experimental results suggest that carefully selected load balancing algorithms can significantly reduce the control plane latency. / In mobile networks, the mobile core plays a crucial role in providing connectivity between mobile user devices and external packet data networks such as the Internet. After more than three decades, the mobile core has been gradually evolved through four generations and is called the Evolved Packet Core (EPC) in the current generation (4G). In recent years, the explosion of mobile data traffic and devices and the advent of new services have led to the investigation of the next generation of mobile networks, i.e., 5G. Among other technology candidates, Software Defined Networking (SDN) and Network Function Virtualization (NFV) have been widely considered to be key enablers for the network architecture of 5G, especially the mobile packet core (MPC) network. This thesis aims at identifying benefits and challenges of introducing SDN and NFV to re-achitect the current MPC architecture towards 5G and addressing some of the challenges. To this end, we conduct a comprehensive survey of the existing SDN/NFV-based MPC architectures. Through this survey work, several research questions for future work have been identified and we contribute to address two of the research questions. Firstly, we propose an SDN/NFV-based MPC architecture for providing multicast and broadcast services. Secondly, we tackle the scalability problem of the Mobility Management Entity (MME) - one of the EPC key control plane entities. In particular, we investigate different approaches to achieve better load balancing among virtual MMEs in a virtual and distributed MME design, which in turn improves scalability. / HITS, 4707