The mobile network operators are now facing several challenges such as a huge traffic demand with more sophisticated services (thus, posing different connectivity requirements), the need for seamless delivery services across different technologies, and a rapid changing of business environment. Thus, the operators are seeking innovative solutions to improve their network performance and efficiency, as well as to reduce the costs expended on network operation, maintenance, and new service deployment. Considering the deployment of heterogeneous 5G networks, including a mix of femto and pico cells of different technologies, simplifying the network architecture and optimizing the data transmission costs are driving 5G networks to evolve toward flat architectures.
In line with this trend, the 3rd Generation Partnership Project (3GPP) proposed such flat optimization techniques as Local IP Access/Selected IP Traffic Offload (LIPA/SIPTO) and IP Flow Mobility (IFOM). Following the same idea, the Internet Engineering Task Force (IETF) has recently chartered the Distributed Mobility Management (DMM) Working Group, which specifies flat IP mobility management architecture separating data and control planes to address the limitations of current centralized mobility management such as sub-optimal routing, scalability and reliability issues. Flat architectures are designed to improve the data plane yet at the cost of an increased complexity at the control plane.
On the other hand, Software-Defined Networking (SDN) together with Network Function Virtualization (NFV) are transforming the telecommunication ecosystems. SDN allows the network operators to easily and quickly introduce new services and flexibly adapt to their requirements, while simplifying the network management to reduce the cost expended on network operation, maintenance and service deployment. NFV leverages on virtualization techniques to separate software instance from hardware platform, and decouple the network functionalities from location. Accordingly, network functions are fully defined by software, thus minimizing dependence on hardware constraints and improving the flexibility of network service provisioning and reducing the time to market of new service. Since DMM and SDN/NFV have complementarity assets and share the same decoupled data and control plane paradigm, DMM based on SDN and NFV can be considered as a promising candidate for mobility management in 5G networks.
Long Term Evolution (LTE), with its wide-scale commercial deployment and the ability to support a wide variety of services from high bandwidth data to real-time communication, has been selected as a technology for mission critical mobile broadband communications and public safety by majors' public safety organizations. To improve the resilience and coverage, the public safety network (PSN) can rely on the current narrowband networks together with the public safety network built on top of the commercial LTE. The ability to move seamlessly across networks using different access technologies therefore plays a crucial role. Additionally, PS users and first responders encounter a wide range of operational conditions and missions in many situations, for example, natural disaster occurring at the scene outside wide area network coverage and terrorist attack in the city center. Accordingly, different scenarios should be taken into account for example under full backhaul connectivity,
and with limited/without backhaul access.