5.6 UE capabilities

38.3313GPPNRProtocol specificationRadio Resource Control (RRC)Release 15TS

5.6.1 UE capability transfer

5.6.1.1 General

This clause describes how the UE compiles and transfers its UE capability information upon receiving a UECapabilityEnquiry from the network.

Figure 5.6.1.1-1: UE capability transfer

5.6.1.2 Initiation

The network initiates the procedure to a UE in RRC_CONNECTED when it needs (additional) UE radio access capability information. The network should retrieve UE capabilities only after AS security activation. Network does not forward UE capabilities that were retrieved before AS security activation to the CN.

5.6.1.3 Reception of the UECapabilityEnquiry by the UE

The UE shall set the contents of UECapabilityInformation message as follows:

1> if the ue-CapabilityRAT-RequestList contains a UE-CapabilityRAT-Request with rat-Type set to nr:

2> include in the ue-CapabilityRAT-ContainerList a UE-CapabilityRAT-Container of the type UE-NR-Capability and with the rat-Type set to nr;

2> include the supportedBandCombinationList, featureSets and featureSetCombinations as specified in clause 5.6.1.4;

1> if the ue-CapabilityRAT-RequestList contains a UE-CapabilityRAT-Request with rat-Type set to eutra-nr:

2> if the UE supports (NG)EN-DC or NE-DC:

3> include in the ue-CapabilityRAT-ContainerList a UE-CapabilityRAT-Container of the type UE-MRDC-Capability and with the rat-Type set to eutra-nr;

3> include the supportedBandCombinationList and featureSetCombinations as specified in clause 5.6.1.4;

1> if the ue-CapabilityRAT-RequestList contains a UE-CapabilityRAT-Request with rat-Type set to eutra:

2> if the UE supports E-UTRA:

3> include in the ue-CapabilityRAT-ContainerList a ue-CapabilityRAT-Container of the type UE-EUTRA-Capability and with the rat-Type set to eutra as specified in TS 36.331 [10], clause 5.6.3.3, according to the capabilityRequestFilter, if received;

1> submit the UECapabilityInformation message to lower layers for transmission, upon which the procedure ends.

5.6.1.4 Setting band combinations, feature set combinations and feature sets supported by the UE

The UE invokes the procedures in this clause if the NR or E-UTRA network requests UE capabilities for nr, eutra-nr or eutra. This procedure is invoked once per requested rat-Type (see clause 5.6.1.3 for capability enquiry by the NR network; see TS 36.331 [10], clause 5.6.3.3 for capability enquiry by the E-UTRA network). The UE shall ensure that the feature set IDs are consistent across feature sets, feature set combinations and band combinations in all three UE capability containers that the network queries with the same fields with the same values, i.e. UE-CapabilityRequestFilterNR, UE-CapabilityRequestFilterCommon and fields in UECapabilityEnquiry message (i.e. requestedFreqBandsNR-MRDC, requestedCapabilityNR, eutra-nr-only flag, and requestedCapabilityCommon) as defined in TS 36.331, where applicable.

NOTE 1: Capability enquiry without frequencyBandListFilter is not supported.

NOTE 2: In EN-DC, the gNB needs the capabilities for RAT types nr and eutra-nr and it uses the featureSets in the UE-NR-Capability together with the featureSetCombinations in the UE-MRDC-Capability to determine the NR UE capabilities for the supported MRDC band combinations. Similarly, the eNB needs the capabilities for RAT types eutra and eutra-nr and it uses the featureSetsEUTRA in the UE-EUTRA-Capability together with the featureSetCombinations in the UE-MRDC-Capability to determine the E-UTRA UE capabilities for the supported MRDC band combinations. Hence, the IDs used in the featureSets must match the IDs referred to in featureSetCombinations across all three containers. The requirement on consistency implies that there are no undefined feature sets and feature set combinations.

NOTE 3: If the UE cannot include all feature sets and feature set combinations due to message size or list size constraints, it is up to UE implementation which feature sets and feature set combinations it prioritizes.

The UE shall:

1> compile a list of "candidate band combinations" according to the filter criteria in capabilityRequestFilterCommon (if included), only consisting of bands included in frequencyBandListFilter, and prioritized in the order of frequencyBandListFilter (i.e. first include band combinations containing the first-listed band, then include remaining band combinations containing the second-listed band, and so on), where for each band in the band combination, the parameters of the band do not exceed maxBandwidthRequestedDL, maxBandwidthRequestedUL, maxCarriersRequestedDL, maxCarriersRequestedUL, ca-BandwidthClassDL-EUTRA or ca-BandwidthClassUL-EUTRA, whichever are received;

1> for each band combination included in the list of "candidate band combinations":

2> if the network (E-UTRA) included the eutra-nr-only field, or

2> if the requested rat-Type is eutra:

3> remove the NR-only band combination from the list of "candidate band combinations";

NOTE 4: The (E-UTRA) network may request capabilities for nr but indicate with the eutra-nr-only flag that the UE shall not include any NR band combinations in the UE-NR-Capability. In this case the procedural text above removes all NR-only band combinations from the candidate list and thereby also avoids inclusion of corresponding feature set combinations and feature sets below.

2> if it is regarded as a fallback band combination with the same capabilities of another band combination included in the list of "candidate band combinations", and

2> if this fallback band combination is generated by releasing at least one SCell or uplink configuration of SCell or SUL according to TS 38.306 [26]:

3> remove the band combination from the list of "candidate band combinations";

NOTE 5: Even if the network requests (only) capabilities for nr, it may include E-UTRA band numbers in the frequencyBandListFilter to ensure that the UE includes all necessary feature sets needed for subsequently requested eutra-nr capabilities. At this point of the procedure the list of "candidate band combinations" contains all NR- and/or E-UTRA-NR band combinations that match the filter (frequencyBandListFilter) provided by the NW and that match the eutra-nr-only flag (if RAT-Type nr is requested by E-UTRA). In the following, this candidate list is used to derive the band combinations, feature set combinations and feature sets to be reported in the requested capability container.

1> if the requested rat-Type is nr:

2> include into supportedBandCombinationList as many NR-only band combinations as possible from the list of "candidate band combinations", starting from the first entry;

3> if srs-SwitchingTimeRequest is received:

4> if SRS carrier switching is supported;

5> include srs-SwitchingTimesListNR for each band combination;

4> set srs-SwitchingTimeRequested to true;

2> include, into featureSetCombinations, the feature set combinations referenced from the supported band combinations as included in supportedBandCombinationList according to the previous;

2> compile a list of "candidate feature set combinations" referenced from the list of "candidate band combinations" excluding entries (rows in feature set combinations) with same or lower capabilities;

NOTE 6: This list of "candidate feature set combinations" contains the feature set combinations used for NR-only as well as E-UTRA-NR band combinations. It is used to derive a list of NR feature sets referred to from the feature set combinations in the UE-NR-Capability and from the feature set combinations in a UE-MRDC-Capability container.

2> include into featureSets the feature sets referenced from the "candidate feature set combinations" and may exclude the feature sets with the parameters that exceed any of maxBandwidthRequestedDL, maxBandwidthRequestedUL, maxCarriersRequestedDL or maxCarriersRequestedUL, whichever are received;

1> else, if the requested rat-Type is eutra-nr:

2> include into supportedBandCombinationList and/or supportedBandCombinationListNEDC-Only as many E-UTRA-NR band combinations as possible from the list of "candidate band combinations", starting from the first entry;

3> if srs-SwitchingTimeRequest is received:

4> if SRS carrier switching is supported;

5> include srs-SwitchingTimesListNR and srs-SwitchingTimesListEUTRA for each band combination;

4> set srs-SwitchingTimeRequested to true;

2> include, into featureSetCombinations, the feature set combinations referenced from the supported band combinations as included in supportedBandCombinationList according to the previous;

1> else (if the requested rat-Type is eutra):

2> compile a list of "candidate feature set combinations" referenced from the list of "candidate band combinations" excluding entries (rows in feature set combinations) with same or lower capabilities;

NOTE 7: This list of "candidate feature set combinations" contains the feature set combinations used for E-UTRA-NR band combinations. It is used to derive a list of E-UTRA feature sets referred to from the feature set combinations in a UE-MRDC-Capability container.

2> include into featureSetsEUTRA (in the UE-EUTRA-Capability) the feature sets referenced from the "candidate feature set combinations" and may exclude the feature sets with the parameters that exceed ca-BandwidthClassDL-EUTRA or ca-BandwidthClassUL-EUTRA, whichever are received;

1> include the received frequencyBandListFilter in the field appliedFreqBandListFilter of the requested UE capability, except if the requested rat-Type is nr and the network included the eutra-nr-only field;

1> if the network included ue-CapabilityEnquiryExt:

2> include the received ue-CapabilityEnquiryExt in the field receivedFilters;

5.6.1.5 Void