[1] [1] Benzekk K, Fergougui A E, Elalaoui A E, et al. Software-Defined Networking (SDN): A Survey[J]. Security and Communication Networks, 2017, 9(18): 1737.

[2] [2] Li Y, Chen M. Software-Defined Network Function Virtualization: A Survey[J]. IEEE Access, 2015, 3: 2542-2553.

[3] [3] Ameigeiras P, Ramos-munoz J J, Schumacher L, et al. Link-Level Access Cloud Architecture Design based on SDN for 5G Networks[J]. IEEE Network , 2015, 29(2): 24-31.

[4] [4] Costa-Requena J, Santos J L, Guasch V F, et al.. SDN and NFV Integration in Generalized Mobile Network Architecture[C]// 2015 European Conference on Networks and Communications (EuCNC). Paris, France: IEEE, 2015: 154-158.

[5] [5] Taleb T, Corici M, Parada C, et al. EASE: EPC as a Service to Ease Mobile Core Network Deployment over Cloud[J]. IEEE Network, 2015, 29(2): 78-88.

[6] [6] Kyung Y, Nguyen T M, Hong K, et al. Software Defined Service Migration through Legacy Service Integration into 4G Networks and Future Evolutions[J]. IEEE Communications Magazine, 2015, 53(9): 108-114.

[7] [7] Wasserman M, Hartman S. OpenFlow Swicth Specification, version 1.4.0, Open Networking Foundation (ONF) TS-012[DB/OL]. (2013-04-17)[2011-11-30]. https: //tools.ietf.org/html/draft-mrw-sdnsec-openflow-analysis-02.

[8] [8] Prados-Garzon J, Adamuz-Hinojosa O, Ameigeiras P, et al. Handover Implementation in a 5G SDN-based Mobile Network Architecture[C]// 2016 IEEE 27th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC). Valencia, Spain: IEEE, 2016: 7794936.

[9] [9] Banik J, Luo Y, Seawright J, et al. A Software Defined Semi Distributed Mobility Management System based on Layer 2 Backhaul Network[C]// 2015 IEEE 82nd Vehicular Technology Conference (VTC2015-Fall). Boston, MA, USA: IEEE, 2015: 7390819.

[10] [10] Contreras L M, Cominardi L, Qian H, et al. Software-defined Mobility Management: Architecture Proposal and Future Directions[J]. Mobile Networks and Applications, 2016, 21(2): 663-670.

[11] [11] Zeng Q A, Mukumoto K, Fukuda A. Performance Analysis of Mobile Cellular Radio System with Priority Reservation Handoff Procedures.[C]// IEEE Vehicular Technology Conference. Stockholm, Sweden: IEEE, 1994: 345415.