En DC
September 4, 2024 | Author: Anonymous | Category: N/A
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Description
EN-DC Call Flow
July 23, 2020
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EN-DC Call Setup
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EN-DC Call Setup MeNB
UE
SgNB
P-GW
S-GW
MME
S1AP:Initial UE Message GTP:Create Session Request GTP:Create Session Request
UE Capability Enquiry, SMC, RRC Connection Reconfiguration (SRB, DRB, B1 Configuration)
S1AP:Initial Context Setup Request
S1AP:Initial Context Setup Response
Measurement Report
RRC Connection Reconfiguration RRC Connection Reconfiguration Complete
GTP:Create Session Response
GTP:Modify Bearer Request
GTP:Modify Bearer Request
GTP:Modify Bearer Response
GTP:Modify Bearer Response
X2AP:SgNB Addition Request X2AP:SgNB Addition Request Acknowledge
X2AP:SgNB Reconfiguration Complete
5G Cell detection and Random Access over 5G
X2AP:SN Status Transfer DL data Forwarding S1AP:E-RAB Modification Indication S1AP:E-RAB Modification Confirm
GTP:Create Session Response
GTP:Modify Bearer Request GTP:Modify Bearer Response
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EN-DC Call Setup ① ue-capability Request • eutra/cdma2000-1XRTT/utra/nr/eutra-nr • UE to support EN-DC • UE to report at least one of SupportedBandCombination supported by eNB/gNB ② rrcConnectionReconfiguration • SRB2, DRB1,DRB2 • Non-GBR DRB to be eligible for EN-DC ③ rrcConnectionReconfiguration • B1 Configuration ④ measurementReport • UE reports B1 event if any candidate NR cell is above b1-ThresholdNR • SgNB addition procedure starts via X2 if there is proper neighbors configured and X2 links are available for reported PCIs • Radio resource to be prepared in SgNB ⑤ rrcConnectionReconfiguration • nr-config, A3/A2 Configuration ⑥ SS/PBCH Block detection and RACH to NR ⑦ Data forwarding and Path switch for S1-U ⑧ Dual Connectivity operation starts
① ②
②
③ ④ ⑤ ⑥
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EN-DC Call Setup – RRC Connection To LTE MeNB
UE
SgNB
P-GW
S-GW
MME
S1AP:Initial UE Message GTP:Create Session Request
GTP:Create Session Request
1. RRC Connection To LTE
UE Capability Enquiry, SMC, RRC Connection Reconfiguration (SRB, DRB, B1 Configuration)
S1AP:Initial Context Setup Request
S1AP:Initial Context Setup Response
Measurement Report
RRC Connection Reconfiguration RRC Connection Reconfiguration Complete
GTP:Create Session Response
GTP:Modify Bearer Request
GTP:Modify Bearer Request
GTP:Modify Bearer Response
GTP:Modify Bearer Response
X2AP:SgNB Addition Request X2AP:SgNB Addition Request Acknowledge
X2AP:SgNB Reconfiguration Complete
5G Cell detection and Random Access over 5G
X2AP:SN Status Transfer DL data Forwarding S1AP:E-RAB Modification Indication S1AP:E-RAB Modification Confirm
GTP:Create Session Response
GTP:Modify Bearer Request GTP:Modify Bearer Response
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RRC Connection To LTE – ueCapabilityEnquiry ➢ requestedFreqBandsNR-MRDC • Interpreted as FreqBandList IE • It concerns a list of NR and/ or E-UTRA frequency bands for which the UE is requested to provide its supported NR CA and/or MR-DC band combinations and feature sets corresponding to the MR-DC band combinations
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RRC Connection To LTE – uecapabilityInformation ➢ ueCapabilityRAT-Container • Container for the UE capabilities of the indicated RAT • For NR - The octet string contains the IE
UE-NR-Capability
• For EUTRA-NR - The octet string contains the IE UE-MRDC-Capability
➢ UE has to support EN-DC ➢ UE has to report at least one of SupportedBandCombination supported by eNB/gNB
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RRC Connection To LTE – B1 Configuration ➢ The typical value of b1-ThreshodNR is around -95dBm to -105dBm in KOREA ➢ The actual value of RSRP is [the field value -156] dBm, except the field value 127, in which case the actual value is infinity
① ②
③ ④
⑥ ⑤
⑦
① absoluteFrequencySSB ② The SSB configuration for measuring the set of SS blocks ③ The linear average of the power values of the, up to maxRS-IndexCellQual, best of the detected NR-SS beams exceeding threshRS-Index; ④ The maximum number of RS indices to be considered / averaged to derive the cell quality ⑤ The n-th element of quantityConfigNRList provided in MeasConfig ⑥ Max number of RS indices to include in the measurement report. ⑦ Indicates whether or not the UE shall report beam measurement result of NR in the measurement report
Paramter
Value
Periodicity
sf20
offset
5
ssb-Duration
sf1
T
2
SFN
0,2,4,…
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5
EN-DC Call Setup – SgNB Addition MeNB
UE
SgNB
P-GW
S-GW
MME
S1AP:Initial UE Message GTP:Create Session Request GTP:Create Session Request
UE Capability Enquiry, SMC, RRC Connection Reconfiguration (SRB, DRB, B1 Configuration)
S1AP:Initial Context Setup Request
S1AP:Initial Context Setup Response
Measurement Report
RRC Connection Reconfiguration RRC Connection Reconfiguration Complete 2. SgNB Addition
GTP:Create Session Response
GTP:Modify Bearer Request
GTP:Modify Bearer Request
GTP:Modify Bearer Response
GTP:Modify Bearer Response
X2AP:SgNB Addition Request X2AP:SgNB Addition Request Acknowledge
X2AP:SgNB Reconfiguration Complete
5G Cell detection and Random Access over 5G
X2AP:SN Status Transfer DL data Forwarding S1AP:E-RAB Modification Indication
S1AP:E-RAB Modification Confirm
GTP:Create Session Response
GTP:Modify Bearer Request
GTP:Modify Bearer Response
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SgNB Addition – SgNB addition Request ➢ The purpose of the SgNB Addition Preparation procedure is to request the en-gNB to allocate resources for EN-DC connectivity operation for a specific UE • The MeNB initiates the procedure by sending the SGNB ADDITION REQUEST message to the en-gNB. When the MeNB sends the SGNB ADDITION REQUEST message, it shall start the timer 𝑇𝐷𝐶𝑝𝑟𝑒𝑝 • Upon reception of the SGNB ADDITION REQUEST ACKNOWLEDGE message the MeNB shall stop the timer 𝑇𝐷𝐶𝑝𝑟𝑒𝑝 • Radio resource prepared and UE context established in SgNB once SgNB Addition Request is received
MeNB
UE
SgNB-CU
SgNB-DU
X2AP:SgNB Addition Request F1AP: UE Context Setup Request
𝑇𝐷𝐶𝑝𝑟𝑒𝑝
F1AP: UE Context Setup Response X2AP:SgNB Addition Request Acknowledge
RRC:RRC Connection Reconfiguration RRC:RRC Connection Reconfiguration Complete
𝑇𝐷𝐶𝑜𝑣𝑒𝑟𝑎𝑙𝑙 X2AP:SgNB Reconfiguration Complete
5G Cell detection and Random Access over 5G
X2AP:SN Status Transfer
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SgNB Addition – SgNB addition Request ➢ NR UE Security Capabilities • The supported algorithms by UE for encryption and Integrity protection • When MME receives UE Additional Security Capability from Attach/TAU, MME parses the UE Additional Security Capability and replays the same in the Security Mode command • MME includes or sends the NRUESecurityCapabilities IE over S1AP interface as part of the following messages ✓ INITIAL-CONTEXT-SETUP-REQUEST ✓ PATH-SWITCH-REQ-ACK
➢ SgNB Security Key
• The SgNB Security Key IE is used to apply security in the en-gNB
➢ SgNB UE Aggregate Maximum Bit Rate
• UE-AMBR is a bandwidth limitation applicable to the total accumulated bandwidth for all of the non GBR • The UE Aggregate Maximum Bit Rate is split into MeNB UE Aggregate Maximum Bit Rate and SgNB UE Aggregate Maximum Bit Rate which are enforced by MeNB and en-gNB respectively
IE/Group Name
Presence
IE type and reference
Message Type
M
9.2.13
MeNB UE X2AP ID
M
eNB UE X2AP ID 9.2.24
NR UE Security Capabilities
M
9.2.107
SgNB Security Key
M
9.2.101
SgNB UE Aggregate Maximum Bit Rate
M
Selected PLMN
O
Handover Restriction List
O
9.2.3
MeNB to SgNB Container
M
OCTET STRING (CG-ConfigInfo)
SgNB UE X2AP ID
O
en-gNB UE X2AP ID 9.2.100
Expected UE Behaviour
O
9.2.70
MeNB UE X2AP ID Extension
O
Extended eNB UE X2AP ID 9.2.86
Requested split SRBs
O
ENUMERATED (srb1, srb2, srb1&2, ...)
MeNB Resource Coordination Information
O
9.2.116
SGNB Addition Trigger Indication
O
ENUMERATED (SN change, inter-eNB HO, intra-eNB HO, ...)
Subscriber Profile ID for RAT/Frequency priority
O
9.2.25
MeNB Cell ID
M
ECGI 9.2.14
Desired Activity Notification Level
O
9.2.141
Trace Activation
O
9.2.2
Location Information at SgNB reporting
O
ENUMERATED (pscell, ...)
Masked IMEISV
O
9.2.69
UE Aggregate Maximum Bit Rate 9.2.12 PLMN Identity 9.2.4
E-RABs To Be Added List
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SgNB Addition – SgNB addition Request ➢ E-RABs To Be Added List
IE/Group Name
• E-RAB ID, DRB-ID, QoS Parameters, GTP-TEID
IE type and reference
Message Type
M
9.2.13
MeNB UE X2AP ID
M
eNB UE X2AP ID 9.2.24
NR UE Security Capabilities
M
9.2.107
SgNB Security Key
M
9.2.101
SgNB UE Aggregate Maximum Bit Rate
M
Selected PLMN
O
Handover Restriction List
O
9.2.3
MeNB to SgNB Container
M
OCTET STRING (CG-ConfigInfo)
SgNB UE X2AP ID
O
en-gNB UE X2AP ID 9.2.100
Expected UE Behaviour
O
9.2.70
MeNB UE X2AP ID Extension
O
Extended eNB UE X2AP ID 9.2.86
Requested split SRBs
O
ENUMERATED (srb1, srb2, srb1&2, ...)
MeNB Resource Coordination Information
O
9.2.116
SGNB Addition Trigger Indication
O
ENUMERATED (SN change, inter-eNB HO, intra-eNB HO, ...)
Subscriber Profile ID for RAT/Frequency priority
O
9.2.25
MeNB Cell ID
M
ECGI 9.2.14
Desired Activity Notification Level
O
9.2.141
Trace Activation
O
9.2.2
Location Information at SgNB reporting
O
ENUMERATED (pscell, ...)
Masked IMEISV
O
9.2.69
UE Aggregate Maximum Bit Rate 9.2.12 PLMN Identity 9.2.4
E-RABs To Be Added List
The EN-DC resource configuration for an ERAB, indicating the presence of PDCP at the en-gNB and Lower Layers at MCG and SCG.
Includes the E-RAB level QoS parameters as received on S1-MME
MeNB DL GTP Tunnel Endpoint at MCG MeNB endpoint of the X2-U transport bearer at MCG for delivery of DL PDCP PDUs S1 UL GTP Tunnel Endpoint - SGW endpoint of the S1-U transport bearer for delivery of UL PDUs from the en-gNB
Indicate the RLC mode at the MeNB for PDCP transfer to en-gNB
Presence
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SgNB Addition – SgNB addition Request ➢ MeNB to SgNB Container
• Includes the CG-ConfigInfo message • This message is used by master eNB or gNB to request the SgNB or SeNB to perform certain actions e.g. to establish, modify or release an SCG. The message may include additional information e.g. to assist the SgNB or SeNB to set the SCG configuration.
IE/Group Name
Presence
IE type and reference
Message Type
M
9.2.13
MeNB UE X2AP ID
M
eNB UE X2AP ID 9.2.24
NR UE Security Capabilities
M
9.2.107
SgNB Security Key
M
9.2.101
SgNB UE Aggregate Maximum Bit Rate
M
Selected PLMN
O
Handover Restriction List
O
9.2.3
MeNB to SgNB Container
M
OCTET STRING (CG-ConfigInfo)
SgNB UE X2AP ID
O
en-gNB UE X2AP ID 9.2.100
Expected UE Behaviour
O
9.2.70
MeNB UE X2AP ID Extension
O
Extended eNB UE X2AP ID 9.2.86
Requested split SRBs
O
ENUMERATED (srb1, srb2, srb1&2, ...)
MeNB Resource Coordination Information
O
9.2.116
SGNB Addition Trigger Indication
O
ENUMERATED (SN change, inter-eNB HO, intra-eNB HO, ...)
Subscriber Profile ID for RAT/Frequency priority
O
9.2.25
MeNB Cell ID
M
ECGI 9.2.14
Desired Activity Notification Level
O
9.2.141
Trace Activation
O
9.2.2
Location Information at SgNB reporting
O
ENUMERATED (pscell, ...)
Masked IMEISV
O
9.2.69
UE Aggregate Maximum Bit Rate 9.2.12 PLMN Identity 9.2.4
E-RABs To Be Added List A list of radio access technology specific capability containers which contain UE-NRCapability and UE-MRDC-Capability here
Band combinations from which SN is allowed to select the SCG band combination and FeatureSetCombination
Measurements on NR Frequency - Contains information regarding cells that the MN suggests the target gNB to consider configuring(ssbFrequency,PCI,MeasResult)
Range of serving cell indices that SN is allowed to configure for SCG serving cells
➢ MeNB Cell ID
• ECGI – Indicates the cell ID for PCell in MeNB
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SgNB Addition – SgNB addition Request Acknowledge ➢ SgNB addition Request Acknowledge is sent by the en-gNB to confirm the MeNB about the SgNB addition preparation
• If the en-gNB admits at least one E-RAB, the en-gNB shall start the timer 𝑇𝐷𝐶𝑜𝑣𝑒𝑟𝑎𝑙𝑙 when sending the SGNB ADDITION REQUEST ACKNOWLEDGE message to the MeNB. The reception of the SGNB RECONFIGURATION COMPLETE message shall stop the timer 𝑇𝐷𝐶𝑜𝑣𝑒𝑟𝑎𝑙𝑙
MeNB
UE
SgNB-CU
SgNB-DU
X2AP:SgNB Addition Request F1AP: UE Context Setup Request
𝑇𝐷𝐶𝑝𝑟𝑒𝑝
F1AP: UE Context Setup Response
X2AP:SgNB Addition Request Acknowledge RRC:RRC Connection Reconfiguration RRC:RRC Connection Reconfiguration Complete
𝑇𝐷𝐶𝑜𝑣𝑒𝑟𝑎𝑙𝑙 X2AP:SgNB Reconfiguration Complete
5G Cell detection and Random Access over 5G
X2AP:SN Status Transfer
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SgNB Addition – SgNB addition Request Acknowledge ➢ E-RABs To Be Added List • E-RAB ID, DRB-ID, QoS Parameters, GTP-TEID
IE/Group Name
The EN-DC resource configuration for an ERAB, indicating the presence of PDCP at the en-gNB and Lower Layers at MCG and SCG.
Presence
Message Type
M
MeNB UE X2AP ID
M
SgNB UE X2AP ID
M
IE type and reference 9.2.13
eNB UE X2AP ID 9.2.24 en-gNB UE X2AP ID 9.2.100
E-RABs Admitted To Be Added List
SgNB UL GTP Tunnel Endpoint at PDCP – en-gNB endpoint of the X2-U transport bearer at PDCP for delivery of UL PDCP PDUs
S1 DL GTP Tunnel Endpoint at the SgNB - en-gNB endpoint of the S1 transport bearer for delivery of DL PDUs
DL Forwarding GTP Tunnel Endpoint - Identifies the X2 transport bearer used for forwarding of DL PDUs Includes E-RAB level QoS parameters requested to be provided by the MCG
E-RAB List 9.2.28
E-RABs Not Admitted List
O
SgNB to MeNB Container
M
Criticality Diagnostics
O
MeNB UE X2AP ID Extension
O
Admitted split SRBs
O
SgNB Resource Coordination Information
O
9.2.117
RRC config indication
O
9.2.132
Location Information at SgNB
O
9.2.142
Information about UL Usage in the MeNB (no-data, shared, only)
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OCTET STRING (CG-Config) 9.2.7
Extended eNB UE X2AP ID 9.2.86 ENUMERATED (srb1, srb2, srb1&2, . ..)
SgNB Addition – SgNB addition Request Acknowledge ➢ SgNB to MeNB Container
• Includes the CG-Config which is used to transfer the SCG radio configuration as generated by the SgNB • scg-CellGroupConfig - Contains the RRCReconfiguration message (containing only secondaryCellGroup and/or measConfig)
IE/Group Name
Presence
Message Type
M
MeNB UE X2AP ID
M
SgNB UE X2AP ID
M
IE type and reference 9.2.13 eNB UE X2AP ID 9.2.24 en-gNB UE X2AP ID 9.2.100
E-RABs Admitted To Be Added List E-RAB List 9.2.28
E-RABs Not Admitted List
O
SgNB to MeNB Container
M
Criticality Diagnostics
O
MeNB UE X2AP ID Extension
O
Admitted split SRBs
O
SgNB Resource Coordination Information
O
9.2.117
RRC config indication
O
9.2.132
Location Information at SgNB
O
9.2.142
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OCTET STRING (CG-Config) 9.2.7 Extended eNB UE X2AP ID 9.2.86 ENUMERATED (srb1, srb2, srb1&2, . ..)
SgNB Addition – SgNB addition Request Acknowledge ➢ CG-Config scg-CellGroupConfig (RRCReconfiguration)
scg-RB-Config (RadioBearerConfig)
selectedBandCombination (BandCombinationInfoSN)
fr-InfoListSCG (FR-InfoList)
nonCriticalExtension (CG-Config-v1540-IEs)
secondaryCellGroup (CellGroupGonfig)
srb-ToAddModList
bandCombinationIndex
servCellIndex
pSCellFrequency
cellGroupId
srb-Identity
requestedFeatureSets
fr-Type
reportCGI-RequestNR
rlc-BearerToAddModList
reestablishPDCP
mac-CellGroupConfig
discardOnPDCP
physicalCellGroupConfig
pdcp-Config
spCellConfig
drb-ToAddModList
sCellToAddModList
cnAssociation
measConfig
drb-Identity
measObjectToAddModList
reestablishPDCP
reportConfigToAddModList
recoverPDCP
measIdToAddModList
pdcp-Config
s-MeasureConfig
securityConfig
quantityConfig
securityAlgorithmConfig
measGapConfig
keyToUse
measGapSharingConfig
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ph-InfoSCG
SgNB Addition – rrcConnectionReconfiguration ➢ After MeNB receives SgNB Addition Request Acknowledge, it starts the procedure for RRC Connection Reconfiguration to configure all the necessary information to switch to SCG bearer ➢ The RRCConnectionReconfiguration message is the command to modify an RRC connection. It may convey information for measurement configuration, mobility control, radio resource configuration
MeNB
UE
SgNB-CU
SgNB-DU
X2AP:SgNB Addition Request F1AP: UE Context Setup Request
𝑇𝐷𝐶𝑝𝑟𝑒𝑝
F1AP: UE Context Setup Response X2AP:SgNB Addition Request Acknowledge
RRC:RRC Connection Reconfiguration RRC:RRC Connection Reconfiguration Complete
𝑇𝐷𝐶𝑜𝑣𝑒𝑟𝑎𝑙𝑙 X2AP:SgNB Reconfiguration Complete
5G Cell detection and Random Access over 5G
X2AP:SN Status Transfer
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SgNB Addition – rrcConnectionReconfiguration ➢ RRCConnectinReconfiguration
• nr-Config includes the NR related configurations. This field is used to configure EN-DC configuration • nr-SecondaryCellGroupConfig includes the NR RRCReconfiguration message (only including fields secondaryCellGroup and/ or measConfig) secondaryCellGroup
measConfig
cellGroupId
measObjectToAddModList
rlc-BearerToAddModList
reportConfigToAddModList
mac-CellGroupConfig
measIdToAddModList
physicalCellGroupConfig
s-MeasureConfig
spCellConfig
quantityConfig
sCellToAddModList
measGapConfig measGapSharingConfig
• nr-RadioBearerConfig - Includes the NR RadioBearerConfig, i.e the configuration of RBs configured with NR PDCP srb-ToAddModList
drb-ToAddModList
securityConfig
srb-Identity
cnAssociation
securityAlgorithmConfig
reestablishPDCP
drb-Identity
keyToUse
discardOnPDCP
reestablishPDCP
pdcp-Config
recoverPDCP pdcp-Config
The maximum power available for LTE
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Update Location
SgNB Addition – rrcConnectionReconfigurationComplete ➢ The RRCConnectionReconfigurationComplete message is used to confirm the successful completion of an RRC connection reconfiguration ➢ SGNB RECONFIGURATION COMPLETE is sent by the MeNB to the en-gNB to indicate whether the configuration requested by the en-gNB was applied by the UE
MeNB
UE
SgNB-CU
SgNB-DU
X2AP:SgNB Addition Request F1AP: UE Context Setup Request
𝑇𝐷𝐶𝑝𝑟𝑒𝑝
F1AP: UE Context Setup Response
X2AP:SgNB Addition Request Acknowledge RRC:RRC Connection Reconfiguration
RRC:RRC Connection Reconfiguration Complete
𝑇𝐷𝐶𝑜𝑣𝑒𝑟𝑎𝑙𝑙
X2AP:SgNB Reconfiguration Complete 5G Cell detection and Random Access over 5G
X2AP:SN Status Transfer
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Update Location
SgNB Addition – rrcConnectionReconfigurationComplete ➢ RRC rrcConnectionReconfigurationComplete
• scg-ConfigResponseNR includes the NR RRCReconfigurationComplete message
➢ X2AP SgNB Reconfiguration Complete
• After the UE has successfully applied the configuration requested by the en-gNB, the MeNB also provides NR RRCReconfigurationComplete message in the MeNB to SgNB Container IE. IE/Group Name
Presence
IE type and reference
Message Type
M
9.2.13
MeNB UE X2AP ID
M
eNB UE X2AP ID 9.2.24
SgNB UE X2AP ID
M
en-gNB UE X2AP ID 9.2.100
Response Information
M
>CHOICE Response Type
M
>>Configuration successfully applied >>>MeNB to SgNB Container
O
OCTET STRING (NR RRCReconfigurationComplete message)
M
9.2.6
O
Extended eNB UE X2AP ID 9.2.86
>>Configuration rejected >>>Cause MeNB UE X2AP ID Extension
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SgNB Addition – RACH ➢ RACH Procedure is to obtain the resource for Msg3 and initialize L1 synchronization (Time and Power) ➢ The random access procedure takes two distinct forms: contention-based random access (CBRA) and contention-free random access (CFRA)
MeNB
UE
SgNB-CU
SgNB-DU
X2AP:SgNB Addition Request F1AP: UE Context Setup Request
𝑇𝐷𝐶𝑝𝑟𝑒𝑝
F1AP: UE Context Setup Response X2AP:SgNB Addition Request Acknowledge
RRC:RRC Connection Reconfiguration
𝑇𝐷𝐶𝑜𝑣𝑒𝑟𝑎𝑙𝑙
RRC:RRC Connection Reconfiguration Complete X2AP:SgNB Reconfiguration Complete
5G Cell detection and Random Access over 5G X2AP:SN Status Transfer
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SgNB Addition – RACH ➢ In case of CBRA-NSA no PDSCH carrying UE Contention Resolution Identity MAC CE is needed. A UL Grant for PUSCH functions is a kind of Contention Resolution • In response to a PUSCH transmission scheduled by a RAR UL grant when a UE has not been provided a C-RNTI, the UE attempts to detect a DCI format 1_0 with CRC scrambled by a corresponding TC-RNTI scheduling a PDSCH that includes a UE contention resolution identity • If the C-RNTI MAC CE was included in Msg3 and the PDCCH transmission is addressed to the C-RNTI and contains a UL grant for a new transmission then consider this Contention Resolution successful • If the CCCH SDU was included in Msg3 and the PDCCH transmission is addressed to its TC-RNTI and the MAC PDU contains a UE Contention Resolution Identity MAC CE and the UE Contention Resolution Identity in the MAC CE matches the CCCH SDU transmitted in Msg3 then consider this Contention Resolution successful • The UE Contention Resolution Identity MAC CE has a fixed 48-bit size and contains the UL CCCH SDU gNB
UE
CFRA gNB
UE
gNB
UE PRACH: Msg1
PRACH: Msg1
Random Access Preamble
Random Access Preamble
PDCCH – RAR Grant (RA-RNTI)
RAR Window
PDCCH – RAR Grant (RA-RNTI)
PDSCH: Msg2 RAR
PDSCH: Msg2 RAR
Random Access Response
Random Access Response
TC-RNTI, UL Grant, TA
TC-RNTI, UL Grant, TA
PUSCH: Msg3 (TC-RNTI)
PUSCH: Msg3 (TC-RNTI)
Scheduled Transmission
C-RNTI MAC CE
PDCCH (C-RNTI) Contention Resolution
UL Grant for a new transmission
MAC Contention Resolution Timer
RAR Window
PDCCH (TC-RNTI) PDSCH : Msg4
Contention Resolution
PRACH: Msg1 Random Access Preamble
PDCCH – RAR Grant (RA-RNTI)
PDSCH: Msg2 RAR
Scheduled Transmission
UE CRI MAC CE HARQ ACK
CBRA - NSA
RA Preamble assignment
Random Access Response
MAC Contention Resolution Timer
C-RNTI, UL Grant, TA
set the C-RNTI to the value of the TC-RNTI
CBRA - SA
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CFRA
RAR Window
SgNB Addition – SN Status Transfer ➢ The purpose of the SN Status Transfer procedure is to transfer the uplink PDCP SN and HFN receiver status and the downlink PDCP SN and HFN transmitter status either between MeNB and en-gNB involved in EN-DC
MeNB
UE
SgNB-CU
SgNB-DU
X2AP:SgNB Addition Request F1AP: UE Context Setup Request
𝑇𝐷𝐶𝑝𝑟𝑒𝑝
F1AP: UE Context Setup Response X2AP:SgNB Addition Request Acknowledge
RRC:RRC Connection Reconfiguration
𝑇𝐷𝐶𝑜𝑣𝑒𝑟𝑎𝑙𝑙
RRC:RRC Connection Reconfiguration Complete X2AP:SgNB Reconfiguration Complete 5G Cell detection and Random Access over 5G
X2AP:SN Status Transfer
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SgNB Addition – SN Status Transfer ➢ SgNB shall use DL COUNT Value IE to mark the first downlink packet for which there is no PDCP SN yet ➢ SgNB shall not deliver any uplink packet which has a PDCP SN lower than the value of UL COUNT Value IE
IE/Group Name
Presence
IE type and reference
Message Type
M
9.2.13
Old eNB UE X2AP ID
M
eNB UE X2AP ID 9.2.24
New eNB UE X2AP ID
M
eNB UE X2AP ID 9.2.24
>>E-RAB ID
M
9.2.23
>>Receive Status Of UL PDCP SDUs
O
BIT STRING (4096)
>>UL COUNT Value
M
COUNT Value 9.2.15
>>DL COUNT Value
M
COUNT Value 9.2.15
>>Receive Status Of UL PDCP SDUs Extended
O
BIT STRING (1..16384)
>>UL COUNT Value Extended
O
COUNT Value Extended 9.2.66
>>DL COUNT Value Extended
O
COUNT Value Extended 9.2.66
>>Receive Status Of UL PDCP SDUs for PDCP SN Length 18
O
BIT STRING (1..131072)
>>UL COUNT Value for PDCP SN Length 18
O
>>DL COUNT Value for PDCP SN Length 18
O
E-RABs Subject To Status Transfer List >E-RABs Subject To Status Transfer Item
PDCP-SN and Hyper Frame Number of the first missing UL SDU in case of 18 bit long PDCP-SN
PDCP-SN and Hyper Frame Number that the target eNB/en-gNB should assign for the next DL SDU not having an SN yet in case of 18 bit long PDCP-SN
COUNT Value for PDCP SN Length 18 9.2.82 COUNT Value for PDCP SN Length 18 9.2.82
Old eNB UE X2AP ID Extension
O
Extended eNB UE X2AP ID 9.2.86
New eNB UE X2AP ID Extension
O
Extended eNB UE X2AP ID 9.2.86
SgNB UE X2AP ID
O
en-gNB UE X2AP ID 9.2.100
※ HFN is timer at the next level to SFN. HFN range is between 0 and 1023 and the value increases by 1 when SFN reaches 1023 and reset to 0 ⓒ SK Telecom. All Rights Reserved. Confidential and Proprietary
EN-DC Call Setup – Path Update MeNB
UE
SgNB
P-GW
S-GW
MME
S1AP:Initial UE Message GTP:Create Session Request GTP:Create Session Request
UE Capability Enquiry, SMC, RRC Connection Reconfiguration (SRB, DRB, B1 Configuration)
S1AP:Initial Context Setup Request
S1AP:Initial Context Setup Response
Measurement Report
RRC Connection Reconfiguration RRC Connection Reconfiguration Complete
GTP:Create Session Response
GTP:Modify Bearer Request
GTP:Modify Bearer Request
GTP:Modify Bearer Response
GTP:Modify Bearer Response
X2AP:SgNB Addition Request X2AP:SgNB Addition Request Acknowledge
X2AP:SgNB Reconfiguration Complete
5G Cell detection and Random Access over 5G
X2AP:SN Status Transfer DL data Forwarding S1AP:E-RAB Modification Indication 3. Path Update
S1AP:E-RAB Modification Confirm
GTP:Create Session Response
GTP:Modify Bearer Request
GTP:Modify Bearer Response
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Path Update – E-RAB Modification Indication ➢ The purpose of the E-RAB Modification Indication procedure is to enable the eNB to request modifications of already established E-RABs for a given UE.
MeNB
SgNB
MME
S-GW
S1AP:E-RAB Modification Indication GTP:Modify Bearer Request GTP:Modify Bearer Response S1AP:E-RAB Modification Confirm
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Path Update – E-RAB Modification Indication ➢ transportLayerAddress and S1 dl-GTP-TEID MeNB received from SgNB via SgNB Addition Request Acknowledge is sent to S-GW and S1-U Path is switched to SgNB
IE/Group Name
Presence
IE type and reference
Message Type
M
9.2.1.1
MME UE S1AP ID
M
9.2.3.3
eNB UE S1AP ID
M
9.2.3.4
>>E-RAB ID
M
9.2.1.2
>>Transport Layer Address
M
9.2.2.1
>>DL GTP TEID
M
GTP-TEID 9.2.2.2
E-RAB to be Modified List >E-RAB to Be Modified Item IEs
S1 DL GTP Tunnel Endpoint at the SgNB - en-gNB endpoint of the S1 transport bearer for delivery of DL PDUs
SgNB Addition Request Acknowledge
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SgNB Release
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MeNB Initiated SgNB Release UE
MeNB
SgNB
S-GW
MME
X2AP:SgNB Release Request X2AP:SgNB Release Request Acknowledge RRC: RRC Connection Reconfiguration RRC: RRC Connection Reconfiguration Complete X2AP:SN Status Transfer
DL data Forwarding S1AP:E-RAB Modification Indication GTP:Modify Bearer Request Path Update
GTP:Modify Bearer Response S1AP:E-RAB Modification Confirm X2AP:UE Context Release
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P-GW
SgNB Initiated SgNB Release UE
MeNB
SgNB
S-GW
MME
X2AP:SgNB Release Required X2AP:SgNB Release Confirm
RRC: RRC Connection Reconfiguration RRC: RRC Connection Reconfiguration Complete X2AP:SN Status Transfer
DL data Forwarding S1AP:E-RAB Modification Indication GTP:Modify Bearer Request Path Update
GTP:Modify Bearer Response S1AP:E-RAB Modification Confirm X2AP:UE Context Release
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P-GW
UE Initiated RLF MeNB
UE
SgNB
S-GW
MME
RRC: SCGFailureInformation X2AP:SgNB Modification Request X2AP:SgNB Modification Request Acknowledge X2AP:SgNB Release Required (Cause – RNL Radio Connection With UE Lost) X2AP:SgNB Release Confirm
RRC: RRC Connection Reconfiguration RRC: RRC Connection Reconfiguration Complete X2AP:SN Status Transfer
DL data Forwarding
S1AP:E-RAB Modification Indication GTP:Modify Bearer Request Path Update
GTP:Modify Bearer Response
S1AP:E-RAB Modification Confirm X2AP:UE Context Release
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P-GW
UE Initiated RLF ➢ UE initiates transmission of the SCGFailureInformationNR message to MeNB with the failure types and the reasons as below • • • • • •
t310-Expiry - T310 expiry (t310) synchReconfigFailure-SCG - reconfiguration with sync failure for an SCG randomAccessProblem - random access problem (preambleTransMax) rlc-MaxNumRetx - the maximum number of RLC retransmissions has been reached (maxRetxThreshold) srb3-IntegrityFailure - SRB3 integrity check failure scg-reconfigFailure - Reconfiguration failure of NR RRC reconfiguration message
➢ MeNB transfers scgfailureinformation to SgNB via SgNB Modification request ➢ PSCell Change (SN initiated SN Modification) based on MeasResultSCG-failure in SgNB Modification Request
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UE Initiated RLF – SgNB Modification Request ➢ SgNB Modification Request is sent by the MeNB to the en-gNB to request the preparation to modify en-gNB resources for a specific UE, to query for the current SCG configuration, or to provide the S-RLF-related information to the en-gNB. IE/Group Name
Presence
IE type and reference
Message Type
M
9.2.13
MeNB UE X2AP ID
M
eNB UE X2AP ID 9.2.24
SgNB UE X2AP ID
M
en-gNB UE X2AP ID 9.2.100
Cause
M
9.2.6
Selected PLMN
O
PLMN Identity 9.2.4
Handover Restriction List
O
9.2.3
SCG Configuration Query
O
9.2.103
MeNB to SgNB Container
O
Includes the CG-ConfigInfo message
MeNB UE X2AP ID Extension
O
Extended eNB UE X2AP ID 9.2.86
MeNB Resource Coordination Information
O
9.2.116
Requested split SRBs
O
ENUMERATED (srb1, srb2, srb1&2, ...)
Requested split SRBs release
O
ENUMERATED (srb1, srb2, srb1&2, ...)
Desired Activity Notification Level
O
9.2.141
Location Information at SgNB reporting
O
ENUMERATED (pscell, ...)
MeNB Cell ID
O
ECGI 9.2.14
UE Context Information
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gNB Initiated RLF UE
MeNB
SgNB
S-GW
MME
X2AP:SgNB Release Required (Cause – RNL Radio Connection With UE Lost) X2AP:SgNB Release Confirm
RRC: RRC Connection Reconfiguration RRC: RRC Connection Reconfiguration Complete X2AP:SN Status Transfer
6PRB in case of ∆𝑓 𝑅𝐴 =15kHz 12PRB in case of ∆𝑓 𝑅𝐴 =30kHz
DL data Forwarding S1AP:E-RAB Modification Indication GTP:Modify Bearer Request
Path Update
GTP:Modify Bearer Response S1AP:E-RAB Modification Confirm X2AP:UE Context Release
gNB Initiated RLF is depending on vendor implementation as like triggered by the maximum number of RLC retransmissions, HARQ, CSI
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P-GW
UE Inactivity UE
MeNB
SgNB
S-GW
MME
InactivityTimer
SgNB will be released when there is no data received and no data in the buffer for Inactivity Timer
X2AP:SgNB Release Required
X2AP:SgNB Release Confirm
RRC: RRC Connection Reconfiguration
RRC: RRC Connection Reconfiguration Complete X2AP:SN Status Transfer
DL data Forwarding
S1AP:E-RAB Modification Indication GTP:Modify Bearer Request Path Update
GTP:Modify Bearer Response S1AP:E-RAB Modification Confirm
X2AP:UE Context Release
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P-GW
End of Document
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