NTN-Config (NTN-Config-r17)

RRC IE · TS 38.331 v19.4.0 (2026-09) · clause 6.3.2

NTN-Config-r17 is an RRC information element of 3GPP TS 38.331 (38331), the 5G NR Radio Resource Control (RRC) protocol.

First seen v17.0.0 (2022-04) · Last changed v19.3.0 (2026-06)

Definition

The IE NTN-Config provides parameters needed for the UE to access NR via NTN access.

NTN-Config-r17 ::=             SEQUENCE {
    epochTime-r17                  EpochTime-r17                                                            OPTIONAL,  -- Need R
    ntn-UlSyncValidityDuration-r17 ENUMERATED{ s5, s10, s15, s20, s25, s30, s35,
        s40, s45, s50, s55, s60, s120, s180, s240, s900}              OPTIONAL,  -- Cond SIB19
    cellSpecificKoffset-r17        INTEGER(1..1023)                                                         OPTIONAL,  -- Need R
    kmac-r17                       INTEGER(1..512)                                                          OPTIONAL,  -- Need R
    ta-Info-r17                    TA-Info-r17                                                              OPTIONAL,  -- Need R
    ntn-PolarizationDL-r17         ENUMERATED {rhcp,lhcp,linear}                                            OPTIONAL,  -- Need R
    ntn-PolarizationUL-r17         ENUMERATED {rhcp,lhcp,linear}                                            OPTIONAL,  -- Need S
    ephemerisInfo-r17              EphemerisInfo-r17                                                        OPTIONAL,  -- Need R
    ta-Report-r17                  ENUMERATED {enabled}                                                     OPTIONAL,  -- Need R
    ...,
    [[
        ntn-LinearPolarizationDL-r19   ENUMERATED {xlp,ylp}                                                     OPTIONAL,  -- Need R
        ntn-LinearPolarizationUL-r19   ENUMERATED {xlp,ylp}                                                     OPTIONAL   -- Need S
    ]]
}

Candidate change requests of v19.3.0

The CRs whose title or cover names this change, strong and likely matches only.

CR 5603 r3 (likely): Linear polarization orientation RRC signalling for NR NTN
CR 5773 r3 (likely): Correction to NTN-NTN redirection

Fields (11)

Field	Description
epochTime-r17 EpochTime-r17 · OPTIONAL Need R	If this field is absent for the NTN serving cell, the epoch time is the end of SI window where this SIB19 or SIB28 is scheduled. This field is mandatory present when ntn-Config is provided in dedicated configuration. If this field is absent in ntn-Config provided via NTN-NeighCellConfig or SatSwitchWithReSync or NTN-NeighCellConfigIoT in an NTN cell, the UE uses epoch time of the serving cell, otherwise the field is based on the timing of the serving cell, i.e. the SFN and sub-frame number indicated in this field refers to the SFN and sub-frame of the serving cell. If this field is absent in ntn-Config provided via NTN-NeighCellConfig in a TN cell, the epoch time is the end of SI window where this SIB19 is scheduled. In case of satellite switch with resynchronization, this field is based on the timing of the cell served by the source satellite. This field is excluded when determining changes in system information, i.e. changes to epochTime should neither result in system information change notifications nor in a modification of valueTag in SIB1 .
ntn-UlSyncValidityDuration-r17 ENUMERATED{ s5, s10, s15, s20, s25, s30, s35, s40, s45, s50, s55, s60, s120, s180, s240, s900} · OPTIONAL Cond SIB19	A validity duration configured by the network for assistance information (i.e. Serving and/or neighbour satellite ephemeris and Common TA parameters) which indicates the maximum time duration (from epochTime ) during which the UE can apply assistance information without having acquired new assistance information. The unit of ntn-UlSyncValidityDuration is second. Value s5 corresponds to 5 s, value s10 indicate 10 s and so on. If this field is absent in ntn-Config provided via NTN-NeighCellConfig, SatSwitchWithReSync, or NTN-NeighCellConfigIoT in an NTN cell , the UE uses validity duration from the serving cell assistance information. If this field is absent in ntn-Config provided via NTN-NeighCellConfig in a TN cell, how the UE sets the validity duration is left to UE implementation. This field is excluded when determining changes in system information, i.e. changes of ntn-UlSyncValidityDuration should neither result in system information change notifications nor in a modification of valueTag in SIB1 . ntn-UlSyncValidityDuration is only updated when at least one of epochTime , ta-Info , ephemerisInfo is updated.
cellSpecificKoffset-r17 INTEGER(1..1023) · OPTIONAL Need R	Scheduling offset used for the timing relationships that are modified for NTN (see TS 38.213 [13]). The unit of the field K_offset is number of slots for a given subcarrier spacing of 15 kHz. If the field is absent UE assumes value 0.
kmac-r17 INTEGER(1..512) · OPTIONAL Need R	Scheduling offset provided by network if downlink and uplink frame timing are not aligned at gNB. If the field is absent UE assumes value 0. The unit of kmac is number of slots for a given subcarrier spacing of 15 kHz.
ta-Info-r17 TA-Info-r17 · OPTIONAL Need R	Indicate network-controlled common timing advanced related information. ta-InfoIoT is used for access to IoT via NTN. ta-InfoIoT is only included in SIB28 .
ntn-PolarizationDL-r17 ENUMERATED {rhcp,lhcp,linear} · OPTIONAL Need R	If present, this parameter indicates polarization information for downlink transmission on service link: including Right hand, Left hand circular polarizations (RHCP, LHCP) and Linear polarization.
ntn-PolarizationUL-r17 ENUMERATED {rhcp,lhcp,linear} · OPTIONAL Need S	If present, this parameter indicates Polarization information for uplink service link. If not present and ntn-PolarizationDL is present, UE assumes the same polarization for UL and DL. If both ntn-PolarizationUL and ntn-PolarizationDL are not present, the UE releases any stored value.
ephemerisInfo-r17 EphemerisInfo-r17 · OPTIONAL Need R	This field provides satellite ephemeris either in format of position and velocity state vector or in format of orbital parameters. This field is excluded when determining changes in system information, i.e. changes to ephemerisInfo should neither result in system information change notifications nor in a modification of valueTag in SIB1 .
ta-Report-r17 ENUMERATED {enabled} · OPTIONAL Need R since v17.1.0	When this field is included in SIB19 , it indicates reporting of timing advance is enabled during Random Access due to RRC connection establishment or RRC connection resume, and during RRC connection reestablishment. When configured, the UE may include TA report during the SDT procedure for CG-SDT. When this field is included in ServingCellConfigCommon within dedicated signalling, it indicates TA reporting is enabled during reconfiguration with sync (see TS 38.321 [3], clause 5.4.8).
ntn-LinearPolarizationDL-r19 ENUMERATED {xlp,ylp} · OPTIONAL Need R since v19.3.0	If present, this parameter indicates linear polarization information used by the network for the downlink transmission on the service link, i.e. X-plane (horizontal) linear polarization (xlp) or Y-plane (vertical) linear polarization (ylp).
ntn-LinearPolarizationUL-r19 ENUMERATED {xlp,ylp} · OPTIONAL Need S since v19.3.0	If present, this parameter indicates linear polarization information to be used by the UE on the uplink service link. If not present and ntn-LinearPolarizationDL is present, UE assumes the same linear polarization information for UL and DL. If none of ntn-LinearPolarizationUL and ntn-LinearPolarizationDL is present, the UE releases any stored value. If ntn-PolarizationUL indicates non-linear polarization, this field is not applicable.

NTN-Config (NTN-Config-r17)

Definition

Candidate change requests of v19.3.0

Fields (11)

Used by (5)

Uses (3)

In the viewer