Resource Allocation In SDN-based C-RAN System

With mobile service development,it gets more difficult for conventional communication systems to meet users' demands,and problems such as rigid network structure and growing maintaining expenses become more outstanding.5G(5th Generation Mobile Communications System)is proposed for 2020 and beyond,to improve spectrum efficiency,energy efficiency,reliability and scalability.Compared to wide used LTE(Long Term Evolution),it is tended to provide higher transmission rate,lower delay,more flexible network structure,and more convenient maintenance and upgrade.C-RAN(Cloud Radio Access Network),SDN(Software Defined Networks)and NFV(Network Function Virtualization)have been proposed to promote 5G performance.Multiple network architectures and schemes have been submitted.One of these proposals is C-RAN architecture combined with SDN/NFV.It is feasible to decouple network functions and equipment,deploy network devices as needed,and extend the flexibility and scalability of network maintenance and upgrade.Resource scheduling is significant researching direction in mobile communication systems,which is important to improve throughput,resource utility and scalability.Based on SDN/NFV principles and network characteristics,this thesis delves into SD-resource allocation applicable to C-RAN systems,and proposes multiple-service QoS(Quality of Service)guaranteed radio resource allocation method and SDN orchestration-based C-RAN system abstraction and configuration.The main work of this thesis includes:(1)SDN architecture.Summarize existing problems in currently SDN-applicable mobile communications systems;introduces standard SDN,software defined radio network and key technologies of SDN.NFV principle and multiple virtualization schemes in mobile communication systems are also presented and compared.(2)Compare C-RAN architecture with traditional base station model.On downlink accessing process in C-RAN and radio resource allocation basics,the thesis proposes a bandwidth allocation algorithm for multiple services.The algorithm guarantees system throughout and takes user QoS into account.By joining conditions like available bandwidth,service priority and rate requirement,the method sets varied weight coefficients for different services and adjusts their values during allocation for multiple users.Simulation shows average rates of services differentiate and throughput is high.(3)Based on abstraction and virtualization of SDN/NFV,propose two dynamic mapping methods between C-RAN data processing center and radio parts.The methods view BBUs and radio modules as virtual ports without device information to perform centralized resource allocation with orchestrator scheduling in higher network layer,then configuration results and updated network state are sent to the network controller to validate physical links.Simulation results show,compared to traditional fixed links,both methods deduce user request blockage rate,improve resource utility and adapts well to different configurations.