Radio Network Temporary Identifier (RNTI) are used in LTE to
RA-RNTI: The Random Access RNTI is used on the PDCCH when Random Access Response messages are transmitted. It unambiguously identifies which time-frequency resource was utilized by the UE to transmit the Random Access preamble.
References:
[1] 36.421
[2] 36.211
- Associate the data in UL and DL with a Transport channel: Like the P-RNTI and SI-RNTI identify the Paging and the System Information Channels
- address a particular UE on a shared Transport Channel; like the C-RNTI identifies the data for a UE on the DL-SCH channel
On the shared channels, the UL-SCH and the DL-SCH, the C-RNTI is used to initialise the scrambling code that is used to scramble the data stream before modulation. This allows the data to be multiplexed on the shared transport channel. The intended UE can un-scramble the data using the C-RNTI assigned to it and receive the data.
LTE simplifies the use of RNTI as there is no need to define URNTI, ERNTI, HRNTI, SRNTI in LTE, since there is only one shared MAC entity.
LTE simplifies the use of RNTI as there is no need to define URNTI, ERNTI, HRNTI, SRNTI in LTE, since there is only one shared MAC entity.
RNTI values
Value (hexa-decimal)
|
RNTI
|
0000
|
N/A
|
0001-003C
|
RA-RNTI, C-RNTI, Semi-Persistent Scheduling
C-RNTI, Temporary C-RNTI, TPC-PUCCH-RNTI and TPC-PUSCH-RNTI (see note)
|
003D-FFF3
|
C-RNTI, Semi-Persistent Scheduling C-RNTI,
Temporary C-RNTI, TPC-PUCCH-RNTI and TPC-PUSCH-RNTI
|
FFF4-FFFD
|
Reserved for future use
|
FFFE
|
P-RNTI
|
FFFF
|
SI-RNTI
|
NOTE: The
values corresponding to the RA-RNTI values of a cell’s PRACH configuration are
not used in the cell for any other RNTI (C-RNTI, Semi-Persistent Scheduling
C-RNTI, Temporary C-RNTI, TPC-PUCCH-RNTI or TPC-PUSCH-RNTI).
The table below gives the usage of the RNTIs in LTE.
RNTI usage
RNTI
|
Usage
|
Transport Channel
|
Logical Channel
|
P-RNTI
|
Paging and System Information change notification
|
PCH
|
PCCH
|
SI-RNTI
|
Broadcast of System Information
|
DL-SCH
|
BCCH
|
RA-RNTI
|
Random Access Response
|
DL-SCH
|
N/A
|
Temporary C-RNTI
|
Contention Resolution
(when no valid C-RNTI is available) |
DL-SCH
|
CCCH
|
Temporary C-RNTI
|
Msg3 transmission
|
UL-SCH
|
CCCH, DCCH, DTCH
|
C-RNTI
|
Dynamically scheduled unicast transmission
|
UL-SCH
|
DCCH, DTCH
|
C-RNTI
|
Dynamically scheduled unicast transmission
|
DL-SCH
|
CCCH, DCCH, DTCH
|
C-RNTI
|
Triggering of PDCCH ordered random access
|
N/A
|
N/A
|
Semi-Persistent
Scheduling C-RNTI
|
Semi-Persistently scheduled unicast transmission
(activation, reactivation and retransmission)
|
DL-SCH, UL-SCH
|
DCCH, DTCH
|
Semi-Persistent
Scheduling C-RNTI
|
Semi-Persistently scheduled unicast transmission
(deactivation)
|
N/A
|
N/A
|
TPC-PUCCH-RNTI
|
Physical layer Uplink power control
|
N/A
|
N/A
|
TPC-PUSCH-RNTI
|
Physical layer Uplink power control
|
N/A
|
N/A
|
RA-RNTI: The Random Access RNTI is used on the PDCCH when Random Access Response messages are transmitted. It unambiguously identifies which time-frequency resource was utilized by the UE to transmit the Random Access preamble.
References:
[1] 36.421
[2] 36.211