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5G NR RNTI: Usage and Values Explained

5g nr rnti ue identifier

This document explains 5G NR RNTI (Radio Network Temporary Identifier), detailing its usage as UE identities, network identifiers, and the specific purposes they serve within the 5G NR system. RNTI is a crucial component for managing radio resources and identifying devices within the network.

  • It’s similar in concept to LTE RNTI.
  • Definitions are found in 3GPP TS 38.202 and 38.321 specifications.

The following tables illustrate the possible combinations of physical channels received simultaneously by a UE in the downlink.

RNTI Downlink Reception Types 5G NR RNTI Downlink Reception Types 5G NR

Table 1: RNTI for downlink reception types

RNTI Downlink Reception Type Combinations 5G NR RNTI Downlink Reception Type Combinations 5G NR

Table 2: Downlink Reception Type Combinations

Usage and Values of 5G NR RNTI

Table 3 shows RNTI values used to distinguish different types of RNTIs in 5G NR, while Table 4 outlines their usage.

RNTI Values RNTI Values

Table 3: RNTI Values

RNTI Usage RNTI Usage

Table 4: RNTI Usage

5G NR UE Identifiers

Table 5 defines the various types of 5G NR UE identifiers.

  • C-RNTI, CS-RNTI, INT-RNTI, P-RNTI, SI-RNTI, and SP-CSI-RNTI are used for scheduling at the cell level.
  • SFI-RNTI, TPC-PUCCH-RNTI, TPC-PUSCH-RNTI, and TPC-SRS-RNTI are used for power and slot format control.
  • RA-RNTI and Temporary C-RNTI are used during the random access procedure.
  • I-RNTI is used for NR connected to 5GC at the NG-RAN level.
UE IdentitiesDescription
C-RNTIUnique UE identification used as an identifier of the RRC Connection and for scheduling
CS-RNTIUnique UE identification used for Semi-Persistent Scheduling in the downlink
INT-RNTIIdentification of pre-emption in the downlink
P-RNTIIdentification of Paging and System Information change notification in the downlink
SI-RNTIIdentification of Broadcast and System Information in the downlink
SP-CSI-RNTIUnique UE identification used for semi-persistent CSI reporting on PUSCH
SFI-RNTIIdentification of slot format
TPC-PUCCH-RNTIUnique UE identification to control the power of PUCCH
TPC-PUSCH-RNTIUnique UE identification to control the power of PUSCH
TPC-SRS-RNTIUnique UE identification to control the power of SRS
RA-RNTI
  • Identification of the Random Access Response in the downlink
  • It is used during the random access procedure.
Temporary C-RNTI
  • UE identification temporarily used for scheduling during the random access procedure.
  • It is used during the random access procedure.
I-RNTIIt is used to identify the UE context in RRC_INACTIVE.

Table 5: 5G NR UE Identifiers

5G NR Network Identifiers

Table 6 defines different types of 5G NR Network identifiers.

Network IdentitiesDescription
AMF NameIt is used to identify an AMF.
NCGI (NR Cell Global Identifier)It is used to identify NR cells globally. The NCGI is constructed from the PLMN identity the cell belongs to and the NR Cell Identity (NCI) of the cell.
gNB IDIt is used to identify gNBs within a PLMN. The gNB ID is contained within the NCI of its cells.
Global gNB IDIt is used to identify gNBs globally. The Global gNB ID is constructed from the PLMN identity the gNB belongs to and the gNB ID. The MCC and MNC are the same as included in the NCGI.
TAI (Tracking Area identity)It is used to identify tracking areas. The TAI is constructed from the PLMN identity the tracking area belongs to and the TAC (Tracking Area Code) of the Tracking Area.
S-NSSAIIt stands for Single Network Slice Selection Assistance information. It identifies a network slice.

Table 6: 5G NR Network Identifiers

References

  • 3GPP TS 38.202
  • 3GPP TS 38.300
  • 3GPP TS 38.321