Assistance information for SPCell selection

A central unit (CU) of a base station, configured to select a special cell (SpCell) to be used by a first distributed unit (DU) of the base station for serving a user equipment (UE), the CU comprising:

• a non-transitory memory storing computer-executable instructions;
• and
• processing circuitry coupled to the non-transitory memory and configured to execute the stored instructions, wherein execution of the stored instructions causes the CU to:
• send, to the first DU, a first request comprising:
• an identity of a first cell served by the first DU, as a preferred SpCell for the UE;
• and
• identities of one or more second cells served by the first DU, as candidate SpCells for the UE;
• and
• receive, from the first DU, a first response comprising:
• a first indication that the first DU cannot configure the first cell as an SpCell for the UE;
• and
• a second indication of which of the second cells that the first DU can configure as an SpCell for the UE.

A non-transitory computer-readable medium storing computer-executable instructions that, when executed by processing circuitry comprising a central unit (CU) of a base station, configure the CU to:

• send, to a first distributed unit (DU), a first request comprising:
• an identity of a first cell served by the first DU, as a preferred special cell (SpCell) for the UE;
• and
• identities of one or more second cells served by the first DU, as candidate SpCells for the UE;
• and
• receive, from the first DU, a first response comprising:
• a first indication that the first DU cannot configure the first cell as an SpCell for the UE;
• and
• a second indication of which of the second cells that the first DU can configure as an SpCell for the UE.