s the operators to create service-customized (logical) networks in order to provide optimized solutions for different services which have diverse requirements in terms of functionality, performance, and isolation. The fundamental assumption in this solution is that slicing of an operator's network should be transparent to the UEs at the radio interface level. A network slice is a logical network that includes a set of network functions, which may be virtual network functions (VNFs) or physical network functions, and corresponding resources, such as compute, storage, and networking resources. A slice can also be seen as a unique profile for an application, defined as a set of services within the network to support a given use case, traffic type, or a customer. A slice may serve a particular purpose or a specific category of services (e.g., a specific use case or a specific traffic type) or even individual customers, in which case it may be created on- demand using a network-as-a-service (NaaS) approach. Each network slice exists within an SDN overlay. Within the slice, a collection of network functions are chained together according to the requirements of the service using the slice. Each slice sharing the same underlying physical infrastructure is a logically separated and isolated system that can be designed with different network architecture, hardware/software and network provisioning. In some cases, network slices can share functional components. To implement network slices, the NFV is a prerequisite. The main idea of NFV is to imple- ment network functions in software (i.e., packet core and selective radio access functions) mapped virtual machines (VMs) that are run on commercial server platforms as opposed to processing over dedicated network equipment. In this case, the access network works as NaaS is a business model for delivering network services virtually over the Internet on a pay-per-use or sub- scription basis. A VM is an operating system or application environment that is installed on software, whi