- RNTI,Radio Network Temporary Identifier,是一种标识,两类用途:用于加扰DCI的CRC,UE只有使用正确的RNTI才能对接收到的消息解码;基站用于识别UE,UE发送的RRC message会携带自己专用的RNTI值。
- 5G中有多种类型的RNTI,可分为公共的和专用的两类:公共的RNTI取值是固定的,所有UE都一样(SI-RNTI,P-RNTI),专用的RNTI取值不是固定的,UE需要根据基站指示或者通过相关状态计算得到(如RA-RNTI是通过UE发送Preambles的RACH Occasion计算的)
RNTI的取值
为16bit,取值范围如下:
TS38.321 Table 7.1-1: RNTI values.
|
Value (hexa-decimal) |
RNTI |
- |
0000 |
N/A |
专用的 |
0001–FFF2 (1~65522) |
RA-RNTI, MSGB-RNTI, Temporary C-RNTI, C-RNTI, CI-RNTI, MCS-C-RNTI, CS-RNTI, TPC-PUCCH-RNTI, TPC-PUSCH-RNTI, TPC-SRS-RNTI, INT-RNTI, SFI-RNTI, SP-CSI-RNTI, PS-RNTI, SL-RNTI, SLCS-RNTI SL Semi-Persistent Scheduling V-RNTI, and AI-RNTI |
- |
FFF3–FFFD (65523~65533) |
Reserved |
公共的 |
FFFE(65534) |
P-RNTI |
FFFF(65535) |
SI-RNTI |
RNTI的用途以及与信道的映射关系
TS38.321 Table 7.1-2: 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 |
MSGB-RNTI |
Random Access Response for 2-step RA type |
DL-SCH |
CCCH, DCCH |
Temporary C-RNTI |
Contention Resolution |
DL-SCH |
CCCH, DCCH |
Temporary C-RNTI |
Msg3 transmission |
UL-SCH |
CCCH, DCCH, DTCH |
C-RNTI, MCS-C-RNTI |
Dynamically scheduled unicast transmission |
UL-SCH |
DCCH, DTCH |
C-RNTI |
Dynamically scheduled unicast transmission |
DL-SCH |
CCCH, DCCH, DTCH |
MCS-C-RNTI |
Dynamically scheduled unicast transmission |
DL-SCH |
DCCH, DTCH |
C-RNTI |
Triggering of PDCCH ordered random access |
N/A |
N/A |
CS-RNTI |
Configured scheduled unicast transmission |
DL-SCH, UL-SCH |
DCCH, DTCH |
CS-RNTI |
Configured scheduled unicast transmission |
N/A |
N/A |
TPC-PUCCH-RNTI |
PUCCH power control |
N/A |
N/A |
TPC-PUSCH-RNTI |
PUSCH power control |
N/A |
N/A |
TPC-SRS-RNTI |
SRS trigger and power control |
N/A |
N/A |
INT-RNTI |
Indication pre-emption in DL |
N/A |
N/A |
SFI-RNTI |
Slot Format Indication on the given cell |
N/A |
N/A |
SP-CSI-RNTI |
Activation of Semi-persistent CSI reporting on PUSCH |
N/A |
N/A |
CI-RNTI |
Cancellation indication in UL |
N/A |
N/A |
PS-RNTI |
DCP to indicate whether to start drx-onDurationTimer for associated DRX cycle |
N/A |
N/A |
SL-RNTI |
Dynamically scheduled sidelink transmission |
SL-SCH |
SCCH, STCH |
SLCS-RNTI |
Configured scheduled sidelink transmission |
SL-SCH |
SCCH, STCH |
SLCS-RNTI |
Configured scheduled sidelink transmission |
N/A |
N/A |
SL Semi-Persistent Scheduling V-RNTI (NOTE 2) |
Semi-Persistently scheduled sidelink transmission for V2X sidelink communication (activation, reactivation and retransmission) |
SL-SCH |
STCH |
SL Semi-Persistent Scheduling V-RNTI (NOTE 2) |
Semi-Persistently scheduled sidelink transmission for V2X sidelink communication (deactivation) |
N/A |
N/A |
AI-RNTI |
Availability indication on the given cell |
N/A |
N/A |
NOTE 1: The usage of MCS-C-RNTI is equivalent to that of C-RNTI in MAC procedures (except for the C-RNTI MAC CE). NOTE 2: The MAC entity uses SL Semi-Persistent Scheduling V-RNTI to control semi-persistently scheduled sidelink transmission on SL-SCH for V2X sidelink communication as specified in clause 5.14.1.1 of TS 36.321 [22]. |
专用RNTI中,RA-RNTI以及TC-RNTI,C-RNTI的确定
-RA-RNTI:
RA-RNTI = 1 + s_id + 14 × t_id + 14 × 80 × f_id + 14 × 80 × 8 × ul_carrier_id
<38.321, 5.1.3> where s_id is the index of the first OFDM symbol of the PRACH occasion (0 ≤ s_id < 14), t_id is the index of the first slot of the PRACH occasion in a system frame (0 ≤ t_id < 80), where the subcarrier spacing to determine t_id is based on the value of μ specified in clause 5.3.2 in TS 38.211 [8], f_id is the index of the PRACH occasion in the frequency domain (0 ≤ f_id < 8), and ul_carrier_id is the UL carrier used for Random Access Preamble transmission (0 for NUL carrier, and 1 for SUL carrier). |
- TC-RNTI:
UE由Msg2中获得TC-RNTI,位于MAC RAR中,UE获取到TC-RNTI后,用于发送Msg3和接收Msg4。
TS38.321,Figure 6.2.3-1: MAC RAR
-C- RNTI
UE接收到Msg4后,随机接入竞争解决成功,则UE将TC-RNTI升级为C-RNTI。