OpenFlow Protocol Extension And SGW Selection Algorithm In SDN-SAE Architecture

The network architecture of traditional System Architecture Evolution(SAE) combines control logic with data forwarding into the same network equipment, resulting in the limitations of network management and architecture flexibility under the current architecture. The Software Defined Network(SDN) decouples the network control function from forwarding function, making the network equipment a simple forwarding element, and implementing the network control functions on the upper layer of an SDN controller in the form of software. The control function software can be customized flexibly according to the different needs of network operators or users, thus enhancing the ease of network control and increasing the network resource utilization. However, the SDN architecture does not support the GTP(GPRS Tunneling Protocol) tunnel processing used in the current mobile communication networks yet, and that is one of the main reasons why SDN technology has not been applied practically in the LTE/SAE network. The advantages of SDN technology can be taken to optimize the realization of the SAE network functions. Thus, SDN brings both opportunities and challenges to the mobile communication networks. This thesis studies the two aspects of Open Flow protocol extension and Serving Gate Way(SGW) in SDN-SAE architecture, and expects to provide some references for the practical application of SDN technology in mobile communication networks.The study background and the related research status are introduced, and a description of the LTE/SAE network architecture and the fundamentals of SDN technology is presented. Then the thesis makes a brief analysis on the superiority of LTE/SAE architecture improved with SDN technology. The main contributions of this thesis include the following two parts:(1) A summary of the solutions integrating SDN with LTE/SAE network is given in this thesis. To address the issue that SDN does not support user data transmission based on the GTP tunnel, an extension scheme of Open Flow v1.5.1 protocol is proposed. This extension allows the user plane to get GTP parameters from the control plane by using the Open Flow protocol and to implement the capability of GTP tunnel transmission. In addition, the processes to handle user GTP packets with flow table in SGW and PDN Gate Way(PGW) and the processes to manage bearer based on the extensional Open Flow protocol arestudied.(2) Network elements selection is one of the important control plane functions in SAE networks. Currently, the study of SAE network elements selection mainly focuses on the network elements themselves and especially on the increment of the load balance extent of network elements, but the selection of network elements based on their load condition solely could not provide a reliable Quality of Service(Qo S) guarantees for users. Therefore, a Novel SGW Selection Algorithm(NSSA) for the SDN-based SAE network is proposed. By taking the advantages that the control plane has the view of the entire network, and considering both the real-time load state of SGWs and real-time network state, NSSA realizes the SGW load balancing and provides users with a traffic transmission path to guarantee the Qo S. Moreover, the performance evaluation program of the proposed NSSA algorithm in this thesis is implemented via C/C++ programming language and the proposed algorithm is simulated in several scenarios. A comparison of the simulation results between the proposed algorithm and other existing algorithms is given to verify the feasibility and the effectiveness of the proposed NSSA. The result shows that the proposed algorithm in this thesis has some superiorities in reducing the blocking probability, optimizing traffic path and balancing SGWs load.