ther RAN sub-system 1. Slice-customized protocol adaptation: The RAN can tailor the slice-specific protocol layer and protocol functionalities to adapt to slice-specific requirements. The following gives several illustrative examples. 12 Service-Oriented RAN Support of Network Slicing ((i||)) Different data paths for different subsystems Figure 12.12 Single-connectivity with different RAN subsystems. The UE is configured with full data link layer protocol stack and all functionalities for eMBB slices. - To support URLLC slices, the UE in carrier aggregation/dual connectivity (CA/DC) case is configured with data link layer and short TTI numerology mapping. - mMTC slices may not be configured with ciphering function or even without packet data convergence protocol (PDCP) sublayer. Slice-separated resource allocation: The RAN can also allocate isolated resources for different RAN subsystems. For example, dedicated frequency bands can be used for particular slices. Even within the single band, the separated radio resources can be allocated, which could be used for public safety, vertical applications with stringent isolation requirements, etc. Slice-separated security: Owing to the different service requirements, when one UE supports multiple network slices simultaneously, the RAN may support slice-specific keys for user plane (UP) pro- tection between the UE and the RAN. In addition, RAN may use different cryptographic algorithms or key length for different slices. 12.4.3 Mission-Driven Resource Utilization, Sharing, and Aggregation When the UE simultaneously supports multiple slices via different RAN subsystems, the RAN can provide efficient resource utilization to meet the requirements of these slices with high spectrum efficiency. The following analyzes single connectivity and dual connectivity respectively. Resource allocation in single-connectivity: When the RAN node identifies UE-supported slices, it can enable the UE to have mul- tiple data paths for various services toward RAN subsystems based SLA requiremen