ces SO that the intended QoS can be provided. There is no point, for example, reserving some dedicated piece of spectrum for a particular slice; rather, the scheduler should always be allowed to select the most suitable resource taking into account the situation for the whole band (or set of fre- quency bands) that is available at the gNB. The configuration of radio parameters may be different for each slice (but does not have to be). If a particular part of spectrum is 5 5G Architecture Local low latency service User Plane 5G-RAN Function at UE with local low latency Access service and Internet no mobility User Plane 5G-RAN Function at Core site UE with MBB service with mobility Figure 5.13 Example network slicing use case. Configuration of slices (S-NSSAI) Slice selection control by AMF 5G gNB Slice 1 5G UE Slice 2 PDU session setup with NSSAI Figure 5.14 Setting up a slice for UE. used for a specific slice, the tolerance for interference would decrease and the frequency domain scheduling benefits would be degraded. The example in Figure 5.13 shows the different handling for two slices with different types of service requirements. The service requiring very low latency is handled with more local UPF resources compared to the "regular" mobile broadband service. With slicing, it is possible to consider the customers needing different level of service. The NSSAI has one or more S-NSSAIs (Single NSSAI). The S-NSSAI identifies each slice configured for the UE. An example of signaling flow for setting up the slicing operation is shown in Figure 5.14 with NAS signaling being used to provide slide information for the UE 5.5.1 Interworking with LTE The focus on the any work related to interworking has been on interworking with LTE. Release 15 contains the methods that enable interworking between LTE and 5G for both 5.5 Network Slicing Figure 5.15 Reselection from 5G to LTE. Tracking area update UE context transfer 5G/LTE UE 5G Core idle and active modes of connection. When losing the coverage of the 5G signal (when conn