6.2.16 Procedure for UE to use provisioned radio resources for 5G ProSe direct discovery

24.5543GPPProximity-services (ProSe) in 5G System (5GS) protocol aspectsRelease 17Stage 3TS

When the UE is not served by NG-RAN for 5G ProSe direct discovery and is authorized to use 5G ProSe direct discovery, the UE shall select the corresponding radio parameters to be used for 5G ProSe direct discovery as follows:

a) if the UE can determine itself located in a geographical area and the UE is provisioned with radio parameters for the geographical area, the UE shall select the radio parameters associated with that geographical area; or

b) in all other cases, the UE shall not initiate 5G ProSe direct discovery over PC5.

If the UE intends to use "non-operator managed" radio parameters as specified in clause 5.2.3, the UE shall initiate 5G ProSe direct discovery with the selected radio parameters.

If the UE intends to use "operator managed" radio parameters as specified in clause 5.2.3, before initiating 5G ProSe direct discovery, the UE shall check with lower layers whether the selected radio parameters can be used in the current location without causing interference to other cells as specified in 3GPP TS 38.331 [13]; and:

a) if the lower layers indicate that the usage would not cause any interference, the UE shall initiate 5G ProSe direct discovery; or

NOTE: If the lower layers find that there exists a cell operating the provisioned radio resources (i.e., carrier frequency) and the cell belongs to the registered PLMN or a PLMN equivalent to the registered PLMN and the UE is authorized for 5G ProSe direct discovery in this PLMN, the UE can use the radio parameters indicated by the cell as specified in 3GPP TS 38.331 [13].

b) else if the lower layers report that one or more PLMNs operate in the provisioned radio resources (i.e., carrier frequency) then:

1) if the following conditions are met:

i) none of the PLMNs reported by the lower layers is the registered PLMN or equivalent to the registered PLMN;

ii) at least one of the PLMNs reported by the lower layers is in the list of authorized PLMNs for 5G ProSe direct discovery and provides radio resources for 5G ProSe direct discovery as specified in 3GPP TS 38.331 [13]; and

iii) the UE does not have an emergency PDU session;

then the UE shall:

i) if in 5GMM-IDLE mode, perform PLMN selection triggered by 5G ProSe direct discovery as specified in 3GPP TS 23.122 [14]; or

ii) else if in 5GMM-CONNECTED mode, either:

A) perform a De-registration procedure as specified in 3GPP TS 24.501 [11] and then perform PLMN selection triggered by 5G ProSe direct discovery as specified in 3GPP TS 23.122 [14]; or

B) not initiate 5G ProSe direct discovery.

Whether the UE performs i) or ii) above is left up to UE implementation; or

2) else the UE shall not initiate 5G ProSe direct discovery.

If the registration to the selected PLMN is successful, the UE shall proceed with the procedure to initiate 5G ProSe direct discovery as specified in clause 6.2.14 and clause 6.2.15.

If the UE is performing 5G ProSe direct discovery using radio parameters associated with a geographical area and moves out of that geographical area, the UE shall stop performing 5G ProSe direct discovery and then if the UE is not served by NG-RAN for 5G ProSe direct discovery, the UE shall select appropriate radio parameters for the new geographical area as specified above.