3GPP 23.501 v20.2.0 — the document's own text
5.3.4.3.2 Preferred band(s) per data radio bearer(s)
Taught in 9. Registration, reachability and paging (The 5G system architecture, in depth).
The NG-RAN may prefer to use specific radio resources per data radio bearer(s), e.g. depending on the Network Slices associated to the data radio bearer used by the UE. The UE idle mode mobility control and priority-based reselection mechanism operates as described in clause 5.3.4.3.1 and when UP resources are activated e.g. for a specific S-NSSAI the NG-RAN can use local policies to decide on what specific radio resources to use for the associated data radio bearer(s). A UE may be served by a set of data radio bearers which may be served by cells in different bands, selected based on RRM policies.