Investigations On Key Technologies For Wireless Network Virtualization

Recently,with the growing popularity of smartphones,notepads and other wireless devices,the demand of mobile data keeps increasing rapidly.To meet the anticipated traffic demand,Mobile Network Operators(MNOs)are exploring many techniques but lead to increase in the capital and operating expenditures and complexity of the network.Alternatively,increasing capacity by acquiring additional resource in terms of new static-licensing spectrum also requires large upfront investment.Wireless Network Virtualization(WNV)where multiple MNOs can share the infrastructure and physical resources with each other is an emerging technique and will result in improvement of system performance and reduction of overall costs,which becomes the core technology of next-generation wireless network.Firstly,a framework for inter-operator resource sharing through WNV is proposed.A Software Defined Network(SDN)based network architecture is proposed for centalized control of WNV.The network is divided into two logical planes:Control Plane and Data Plane.A Network Virtualization(NV)component is embedded in the control plane for computing NV triggering conditions and SDN controllers of MNOs is responsible for offloading users if NV is triggered.Data Plane is composed of Heterogeneous Network(HetNet)Base Stations(BSs)but only responsible for forwarding and collecting information.Based on this architecture,algorithms for inter-operator resource sharing through WNV in two scenarios where operators have imbalanced load or balanced non-heavy load are proposed.Users measure Signal to Interference plus Noise Ratios(SINRs)both in cell of their own MNO and cells of other MNOs and then report them to the Control Plane,at the same time non-heavy loaded cells report numbers of spare Physical Resource Blocks(PRBs)to the Control Plane.The network virtualization component calculates and determines whether virtualization trigger conditions are met according to reported data,and sends signals to controllers of MNOs and base stations if conditions are met.In this case,virtualization is triggered and users are offloaded to virtualized base stations of other MNOs.Simulation results show that algorithms for inter-operator resource sharing through WNV proposed in this paper can significantly improve the system throughput and resource utilization,and operators can set different virtualization triggering conditions to make tradeoff between throughput and cost.Inter-operator resource sharing for mixed traffic based on WNV is investigated.For case without virtualization,a low complexity algorithm is proposed for allocating PRBs with mixed traffic.Firstly,Hard Quality of Service(QoS)users are allocated resources,and then leftover PRBs are allocated to Soft QoS and Best Effort users using greedy algorithm.With virtualization,MNOs can pool their spectrum together in one common BS to share with each other.A network utility maximization problem is formulated and an algorithm for assigning resources among operators is proposed accordingly.Users whose utilities are not zero without virtualization are allocated resource firstly,assigning of PRBs stops until their utilities are not less than utilities without virtualization.Then leftover PRBs are allocated to users according to PRBs allocating algorithm without virtualization.Simulation results show that algorithm for inter-operator resource sharing for mixed traffic through WNV proposed in this paper can achieve significant gains in terms of aggregate system utility and system throughput,and the fairness of system gains of different operators is guaranteed.