The emergence of two new technologies, namely, software defined networking (SDN) and network function virtualization (NFV), have radically changed the development of network functions and the evolution of network architectures. These two technologies bring to mobile operators the promises of reducing costs, enhancing network flexibility and scalability, and shortening the time-to-market of new applications and services. With the advent of SDN and NFV and their offered benefits, the mobile operators are gradually changing the way how they architect their mobile networks to cope with ever-increasing growth of data traffic, massive number of new devices and network accesses, and to pave the way toward the upcoming fifth generation networking. This survey aims at providing a comprehensive survey of state-of-the-art research work, which leverages SDN and NFV into the most recent mobile packet core network architecture, evolved packet core. The research work is categorized into smaller groups according to a proposed four-dimensional taxonomy reflecting the: 1) architectural approach, 2) technology adoption, 3) functional implementation, and 4) deployment strategy. Thereafter, the research work is exhaustively compared based on the proposed taxonomy and some added attributes and criteria. Finally, this survey identifies and discusses some major challenges and open issues, such as scalability and reliability, optimal resource scheduling and allocation, management and orchestration, and network sharing and slicing that raise from the taxonomy and comparison tables that need to be further investigated and explored.

Software-defined networking (SDN) features the decoupling of the control plane and data plane, a programmable network and virtualization, which enables network infrastructure sharing and the ''softwarization'' of the network functions. Recently, many research works have tried to redesign the traditional mobile network using two of these concepts in order to deal with the challenges faced by mobile operators, such as the rapid growth of mobile traffic and new services. In this paper, we first provide an overview of SDN, network virtualization, and network function virtualization, and then describe the current LTE mobile network architecture as well as its challenges and issues. By analyzing and categorizing a wide range of the latest research works on SDN and virtualization in LTE mobile networks, we present a general architecture for SDN and virtualization in mobile networks (called SDVMN) and then propose a hierarchical taxonomy based on the different levels of the carrier network. We also present an in-depth analysis about changes related to protocol operation and architecture when adopting SDN and virtualization in mobile networks. In addition, we list specific use cases and applications that benefit from SDVMN. Last but not least, we discuss the open issues and future research directions of SDVMN.

Recently, several researchers have proposed adopting software-defined networking (SDN) concepts for mobile network architectures, particularly for LTE-evolved packet core (LTE/EPC). Although several new designs have been introduced for architectures based on SDN or its concrete realization, Openflow, few studies have presented in-depth discussions of real procedures that are relevant to such architectures. To this end, this paper first surveys the current approaches and solutions for adopting SDN/Openflow in LTE/EPC architectures and then introduces a new Openflow-enabled EPC (OEPC) architecture. This work provides detailed analyses of five procedures that commonly occur in LTE/EPC architectures, and the analyses are further elaborated with the separation of the control and data planes and the support of extended Openflow protocol. The analysis shows that the data management of these procedures is simpler relative to traditional LTE/EPC. In addition, in order to prove that efficient data management takes place for these procedures relative to a traditional LTE/EPC architecture, the numbers of signalling messages that are processed by control entities (i.e., the MME and the controller) are taken into account as a metric to evaluate the OEPC architecture. Moreover, the results of a numerical evaluation also show the benefits of this proposal relative to another Openflow-based LTE/EPC architecture.

In this paper, we propose a new architecture for LTE/EPC network by leveraging the Openflow technology. We focus on making detail procedures for initial attach and default bearer setup in Openflow-enabled LTE/EPC network. By numerical analysis, we show the reduction of the signaling load of this procedure in our architecture compared to that in the traditional LTE/EPC architecture.

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