5G Callflow_PMcounters and call flow decriptions

NR NSA option 3.x
L3 RRC Call Flow of procedures
&
PM counters triggering message
&
Impacting causes of scenarios
Ver. 3.6
Reza Khaniki (EREZKHA)

Contents
1. Architecture ....................................................................................................................................................................6
1.1 NSA interfaces.........................................................................................................................................................6
1.2 NSA ENDC bearers...................................................................................................................................................6
2. PM Counters in Call Flow ................................................................................................................................................8
2.1. Secondary Node Addition procedure – ENDC (Call flow) .......................................................................................8
2.1.1. NR Leg addition in eNB & gNB – Configuration Based (Call flow)...................................................................8
2.1.2. NR Leg addition in eNB – Measurement Based (Call flow).............................................................................9
2.1.3. Known problems – Configuration & Measurement based : .........................................................................10
2.1.4. Use case ........................................................................................................................................................10
2.1.5. Main PM counters.........................................................................................................................................10
2.1.6. NR NSA EN-DC Connection Setup - Addition Request initiated EN-DC connection setup (Call flow)
[additional]....................................................................................................................................................................11
2.1.7. Secondary Node Addition Procedure (Diagram)...........................................................................................12
2.2. NR RACH in gNB (Call flow) ...................................................................................................................................13
2.2.1. Known problems...........................................................................................................................................15
2.2.2. Use case ........................................................................................................................................................15
2.2.3. Main PM counters.........................................................................................................................................16
2.2.4. Contention Based Random Access (Flowchart) ............................................................................................16
2.2.5. Accessibility - Random Access - CBRA Scenario (Contention Based Random Access) (Flowchart) ..............19
2.2.6. Accessibility - Random Access - CFRA Scenario (Contention Free Random Access) (Flowchart) .................20
2.3. UE release into Idle mode in eNB & gNB (Call flow).............................................................................................21
2.3.1. Known problems...........................................................................................................................................23
2.3.2. Use case ........................................................................................................................................................23
2.3.3. Main PM counters.........................................................................................................................................23
2.4. NR Leg Release initiated in eNB (Call flow)...........................................................................................................24
2.4.1. SN Release procedure – MN initiated – ENDC (Call flow).............................................................................24
2.4.2. Master Node Initiated Secondary Node Release (Diagram).........................................................................25
2.4.3. Retainability - EN-DC connection release initiated by eNodeB (Flowchart).................................................26
2.4.4. Known problems...........................................................................................................................................26
2.4.5. Use case ........................................................................................................................................................27
2.4.6. Main PM counters.........................................................................................................................................27
2.5. NR Leg Release initiated in gNB (Call flow)...........................................................................................................27
2.5.1. SN Release procedure – SN initiated – ENDC (Call flow) ..............................................................................28
2.5.2. Secondary Node Initiated Secondary Node Release (Diagram)....................................................................29
2.5.3. Retainability - EN-DC connection release initiated by gNodeB (Call flow) ...................................................29
2.5.4. Known problems...........................................................................................................................................30

2.5.5. Use case ........................................................................................................................................................30
2.5.6. Main PM counters.........................................................................................................................................31
2.6. UL Leg Switching ...................................................................................................................................................31
2.6.1. Known problems...........................................................................................................................................32
2.6.2. Use case ........................................................................................................................................................33
2.6.3. Main PM counters.........................................................................................................................................33
2.6.4. Uplink MCG and SCG Resource Switching (Diagram)....................................................................................33
2.7. Packet Forwarding at SGNB Addition....................................................................................................................34
2.7.1. Known problems...........................................................................................................................................34
2.7.2. Use case ........................................................................................................................................................35
2.7.3. Main PM counters.........................................................................................................................................35
2.7.4. Downlink Session Packet Flow in EN-DC during Secondary Node Addition Procedure (Schema)................35
2.8. Intra-cell Handover ...............................................................................................................................................37
2.8.1. Known problems...........................................................................................................................................37
2.8.2. Use case ........................................................................................................................................................37
2.8.3. Main PM counters.........................................................................................................................................37
2.9. Intra-eNB Handover..............................................................................................................................................38
2.9.1. Known problems...........................................................................................................................................38
2.9.2. Use case ........................................................................................................................................................38
2.9.3. Main PM counters.........................................................................................................................................38
2.10. X2 Handover......................................................................................................................................................39
2.10.1. Known problems...........................................................................................................................................39
2.10.2. Use case ........................................................................................................................................................39
2.10.3. Main PM counters.........................................................................................................................................39
2.11. SN Modification procedure - MN initiated - ENDC ...........................................................................................40
2.11.1. Known problems...........................................................................................................................................40
2.11.2. Use case ........................................................................................................................................................41
2.11.3. Main PM counters.........................................................................................................................................41
2.11.4. Master Node Initiated Secondary Node Modification..................................................................................41
2.12. Master Node Based Handover in EN-DC...........................................................................................................41
2.12.1. Known problems...........................................................................................................................................42
2.12.2. Use case ........................................................................................................................................................42
2.12.3. Main PM counters.........................................................................................................................................42
3. Supplementary flowchart or call flow...........................................................................................................................43
3.1. SN Modification procedure - SN initiated with MN involvement – ENDC............................................................43
3.2. SN modification - SN initiated without MN involvement .....................................................................................44
3.3. Transfer of an NR RRC message to/from the UE - ENDC ......................................................................................45

3.4. SN Change – MN initiated – ENDC........................................................................................................................46
3.5. SN Change – SN initiated – ENDC..........................................................................................................................47
3.6. Inter-MN handover with/without MN initiated SN change..................................................................................48
3.7. Master Node to eNB Change procedure – ENDC..................................................................................................49
3.8. eNB to Master Node change – ENDC....................................................................................................................50
3.9. RRC Transfer procedure for the split SRB (DL operation) – ENDC........................................................................51
3.10. RRC Transfer procedure for the split SRB (UL operation) – ENDC....................................................................52
3.11. RRC Transfer procedure for NR measurement report or NR failure information – ENDC................................53
3.12. Secondary RAT data volume periodic reporting - EN-DC..................................................................................54
3.13. Support of Activity Notification in EN-DC .........................................................................................................55
3.14. NR NSA EN-DC Connection Setup - Modification Request Initiated EN-DC SCG connection setup .................56
3.15. RRC Connection Establishment for NR SA - RRC connection establishment ....................................................57
3.16. Mobility - NR NSA Intra-Frequency Intra-gNodeB PSCell Change.....................................................................58
3.17. Mobility - NR NSA Intra-Frequency Inter-gNodeB PSCell Change ....................................................................59
3.18. Mobility - NR SA Intra-gNodeB Mobility ...........................................................................................................60
3.19. Mobility - NR SA Inter-gNodeB Mobility...........................................................................................................61
3.20. Accessibility - Paging Scenario ..........................................................................................................................62
3.20.1. Help to read Flowchart .................................................................................................................................63
3.21. Accessibility - RRC Connection Setup................................................................................................................63
3.22. Accessibility - RRC Connection Reestablishment..............................................................................................66
3.23. Accessibility - Multi-target RRC Connection Reestablishment (& UE context fetch)........................................67
3.24. Accessibility - Signaling Connection Setup and E-RAB Establishment - E-RAB Establishment with Initial
Context Setup Procedure..................................................................................................................................................70
3.25. Accessibility - Signaling Connection Setup and E-RAB Establishment - E-RAB Establishment with E-RAB Setup
Procedure..........................................................................................................................................................................72
3.26. Retainability - UE Context Release - MME Triggered UE Context Release .......................................................73
3.27. Retainability - UE Context Release - RBS Triggered UE Context Release Scenario...........................................74
3.28. Retainability - E-RAB Release - E-RAB Release Scenario (MME-Triggered) ......................................................77
3.29. Retainability - E-RAB Release - E-RAB Release Scenario (RBS-Triggered).........................................................78
3.30. Retainability - E-RAB Modification....................................................................................................................83
3.31. Retainability - CS Fallback - CS Fallback Scenario..............................................................................................84
3.32. Retainability - CS Fallback - Enhanced CS Fallback to CDMA 1xRTT scenario...................................................86
3.33. Availability - Cell Downtime - Cell Downtime Procedure..................................................................................87
3.34. Integrity - Latency - PDCP level Latency measurements...................................................................................88
3.35. Integrity - PDCP Volume - PDCP Volume Measurements .................................................................................89
3.36. Integrity - RLC Acknowledged Mode (AM) Automatic Repeat request (ARQ) procedures - ARQ procedures.91
3.37. Mobility - Intra-frequency Handover - Intra-Frequency intra-LTE S1 Handover Scenario ...............................92

3.38. Mobility - Intra-Frequency intra-LTE X2 Handover Scenario ............................................................................94
3.39. Mobility - Inter-Frequency intra-LTE S1 Handover Scenario ............................................................................96
3.40. Mobility - Inter-Frequency intra-LTE X2 Handover Scenario ............................................................................99
3.41. Mobility - Coverage-triggered IRAT Handover - Coverage-Triggered IRAT Handover Scenario.....................102
3.42. Mobility - Inter-RAT Offload to UTRAN - Inter-RAT Offload to UTRAN Handover Scenario...........................103
3.43. Mobility - Incoming UTRAN IRAT Handover - Incoming UTRAN IRAT Handover Scenario .............................104
3.44. Mobility - UE Throughput-based Mobility to WiFi - WiFi AC requests LTE UE throughput value...................105
4. PM counters................................................................................................................................................................106
4.1. PM counters triggering Signals or Commands....................................................................................................106
4.2. PM counters definition .......................................................................................................................................108
5. KPI ...............................................................................................................................................................................109
5.1. NSA gNB NR KPIs.................................................................................................................................................109
5.2. NSA eNB LTE ENDC & Flex KPIs...........................................................................................................................110
6. References ..................................................................................................................................................................111

1. Architecture
1.1 NSA interfaces
The NSA interfaces are seen as below :
en-gNB
eNB
S1-U
S
1
S1
X
2
E-UTRAN
EPC
MME/S-GW
en-gNB
eNB
S1-U
S1
S
1
X
2
MME/S-GW
X2
X2-U
S1-U S1-U
MeNB
MME
en-gNB
S1-MME
X2-C
MeNB
S-GW
en-gNB
S1-U
X2-U
S1-U
1.2 NSA ENDC bearers
The Protocol layers in NSA option 3x are connected as below :

SN
NR RLC NR RLC
NR MAC
E-UTRA/
NR PDCP
E-UTRA
RLC
NR PDCP
E-UTRA
RLC
E-UTRA MAC
MCG
Bearer
Split
Bearer
EUTRA
RLC
X2
SCG
Bearer
NR PDCP NR PDCP NR PDCP NR PDCP
EUTRA
RLC
NR
RLC
NR
RLC
MN
MCG
Bearer
Split
Bearer
SCG
Bearer
Below diagram describes how the bearers (Secondary Node Terminated Split bearer, Master Node Terminated MCG Bearer,
Secondary Node Terminated MCG Bearer) are going between UE and EPC :

2. PM Counters in Call Flow
2.1. Secondary Node Addition procedure – ENDC (Call flow)
In NR NSA 3.x deployment , the Control Plane of the gNB is driven by eNB. While all L3 RRC signaling
(with UE like Core) goes through eNB / LTE node. Adding NR is possible after having a 4G stablished
connection. There are two way of stablishing NR : Configuration based which is called as well Blind as
the initial configured 5G cell is predefined by parameters. Measurement based (B1) for which adding NR
leg is after B1 event and selecting the appropriate NR leg only by measurement. Bouygues Telecom has
chosen the scenario measurement based. Both scenarios are similar in exception of initial NR cell
selection and configuration.
UE MN SN S-GW MME
1. SgNB Addition Request
2. SgNB Addition Request Acknowledge
3. RRCConnectionReconfiguration
4. RRCConnectionReconfigurationComplete
9. E-RAB Modification Indication
5. SgNB Reconfiguration Complete
12. E-RAB Modification Confirm
10. Bearer Modication
7. SN Status Transfer
8. Data Forwarding
6. Random Access Procedure
Path Update procedure
11. End Marker Packet
2.1.1. NR Leg addition in eNB & gNB – Configuration Based (Call flow)
While stablishing the 4G connection, the UE answers to MME (through eNB on S1) about its NR NSA ENDC
capability. If the UE is eligible for having NR, the eNB sends the Addition Request message to the gNB (X2). After
receiving the acknowledgement of the gNB addition, the eNB sends the RRC reconfiguration message to the UE
in order to receive the message RRC reconfiguration complete message (Air : Uu). This will initiate the message
SgNB Reconfiguration Complete from eNB to gNB through X2. Consequently eNB informs the MME for for
changing RAB by the message eRAB Modification Indication through S1 while and ENDC split bearer is stablished
and receives the confirmation from MME by the message eRAB Modification Confirmation. Configuration based
is used only for first connection of the UE. NR related RACH procedure in gNB starts anytime after receiving
RRC_Connection_Reconfiguration as soon as the UE send the message
RRC_Connection_Reconfiguration_Complete.

2.1.2. NR Leg addition in eNB – Measurement Based (Call flow)
The measurement based (B1 event measurement) secondary node addition is similar to the Configuration
based. All post initial secondary node addition (even if configuration based is configured) would be via B1.
If Configuration based is not configured, then B1 even would take both initial Secondary node addition as
well as next additions. In Measurement Based NR leg addition in ENDC (so called B1), the addition of the
NR leg follows triggering B1 event following to B1 measurements. The Measurement Reports which will
be sent from UE to the eNB (holding B1 measurement of the UE on NR cells) Is the main difference with
NR leg addition (Secondary node addition) in Configuration based.
< pmEndcSetupUeAtt >
< pmEndcSetupUeSucc >
< pmEndcSetupScgUeAtt >
< pmEndcSetupScgUeSucc>
< pmEndcCapableUe >
< pmEndcSetupScgUeAtt >
< pmEndcSetupScgUeSucc >

2.1.3. Known problems – Configuration & Measurement based :
i. Incompatibility or mal behaviour of the UE
ii. Wrong definition of X2’ relations between eNB and gNB
iii. NR Cell Edge coverage
iv. Bad selection of Configured Based NR cell for a LTE anchor cell
v. Misconnected eCPRI cables
vi. Problem in PLMN config
vii. Synchronization problem
viii. Bad threshold of B1
ix. Problem in the functionality of B1 Measurement in GAP (in compare with Gapless measurement)
x. Wrong SSB or central Frequency config in a cell
2.1.4. Use case
i. Adding NR leg (NR gNB / NR Cell) to UE after first connection of the UE to LTE eNB with ENDC enabled
ii. Adding NR leg (NR gNB / NR Cell) to UE after coming back to 5G coverage (while UE doesn’t have a
configured NR gNB added to its ongoing 4G session)
2.1.5. Main PM counters
i. pmEndcCapableUe
< pmMeasConfigB1Endc >
< pmB1MeasRepEndcConfig >
< pmEndcSetupFailNrRa >

ii. pmEndcSetupUeAtt
iii. pmEndcSetupUeSucc
iv. pmEndcSetupScgUeAtt
v. pmEndcSetupScgUeSucc
vi. pmB1MeasRepEndcConfig
2.1.6. NR NSA EN-DC Connection Setup - Addition Request initiated EN-DC connection setup
(Call flow) [additional]

2.1.7. Secondary Node Addition Procedure (Diagram)

2.2. NR RACH in gNB (Call flow)
The steps RACH access in gNB under NSA as below :
1. The UE sends a preamble to the gNodeB (Msg1).
2. The gNodeB sends the assigned resources through PDCCH and the random access response through PDSCH
(Msg2).
3. The UE sends the RRC connection request message through PUSCH (Msg3).
4. The gNodeB sends the contention resolution message.
This is a regular PDCCH transmission addressed to the UE C-RNTI. It contains an uplink grant for a new
transmission.
CBRA is applied to the following random access events : “Initial network access”. The CBRA process is initiated by the
UE when trying to gain access to the network. The UE randomly selects one random access preamble code from the

available list of codes. After its selection, the UE transmits the preamble code in the uplink through PRACH to gain
access to the network. Contention can occur if the following conditions apply. The CBRA process involves additional
signaling to resolve contention.
- Multiple UEs attempt to access the network through the same PRACH slot.
- The UEs attempting to access the network use the same preamble code.
Power Ramping :
The random access transmission process uses open-loop power control. The UE estimates the transmission power required
to achieve a specified reception power value for the first random access burst. Power ramping can be used for subsequent
retransmission bursts. The process continues until the following conditions occur:
- The UE successfully receives a response from the NR system.
- The maximum number of transmission attempts is reached.

2.2.1. Known problems
i. Wrong PCI planning
ii. Wrong Preamble format, CellRange, Rach Root SequencePlanning
iii. Conflict of RRS or remaining on default value
iv. Uplink coverage limitation (Cell Edge)
v. High noise or interference in uplink
vi. High load of UE present in the zone
vii. Synchronization problem between eNB and gNBs
viii. Product design : Minimum Power for consideration of Preamble
ix. Overshooting cell , Far distance UE
x. Synchronization problem
xi. T304
2.2.2. Use case
i. Random Access in NR NSA allows the UE to gain access to the NR network and to obtain uplink timing
synchronization.
ii. Obtaining access to the NR network when the SCG radio resources are added
iii. Gaining uplink time alignment
iv. Requesting an uplink grant without a dedicated scheduling request resource
< pmRadioRaCbPreambles >
< pmRadioRaCbAttMsg2 >
< pmRadioRaCbSuccMsg3 >

i. NRCellDU.pmRadioRaCbAttMsg2
ii. NRCellDU.pmRadioRaCbFailMsg1MaxMsg3Sched
iii. NRCellDU.pmRadioRaCbFailMsg1Ooc
iv. NRCellDU.pmRadioRaCbFailMsg2Disc
v. NRCellDU.pmRadioRaCbFailMsg3Crc
vi. NRCellDU.pmRadioRaCbFailMsg3Crnti
vii. NRCellDU.pmRadioRaCbFailMsg3Dtx
viii. NRCellDU.pmRadioRaCbPreambles
ix. NRCellDU.pmRadioRaCbSuccMsg3
x. NRCellDU.pmRadioRaAttTaDistr
2.2.4. Contention Based Random Access (Flowchart)

2.2.5. Accessibility - Random Access - CBRA Scenario (Contention Based Random Access)
(Flowchart)

2.2.6. Accessibility - Random Access - CFRA Scenario (Contention Free Random Access)
(Flowchart)

2.3. UE release into Idle mode in eNB & gNB (Call flow)
Releasing the UE into Idle mode under NSA configuration follows below procedure. In NSA, UEs in idle mode camp on
LTE and follow legacy LTE procedures, for example:
• PLMN Selection
• System information acquisition
• Cell selection and reselection (intra-frequency, inter-frequency and inter-RAT)
• Tracking area updates and paging
In NSA, UEs camp on LTE in idle mode, so they are not necessarily aware that the selected cell is EN-DC capable or that NR
coverage exists. The network can, however, advise UEs that 5G service is potentially available by broadcasting an “upper
layer indicator” in system information. This indicator is used by UEs when deciding whether to display a 5G status icon.
In NSA, the default idle mode reselection behavior of EN-DC capable UEs mirrors that of legacy LTE UEs. To obtain different
idle mode reselection behavior for EN-DC capable UEs, some features like “Capability-Aware Idle Mode Control (CAIMC)”
and “Subscriber Triggered Mobility (STM)” are available.
NSA-only NR cells do not provide idle mode services. UEs which are capable of NSA only do not reselect to the NR cells in
idle mode as they are not capable of doing so. Secondary Node Release, keeping the Master Node, is not triggered by
inactivity; inactivity causes release to idle mode.
UE release from connected mode to idle mode is triggered by either the MME or the eNodeB. Reasons for the eNodeB to
trigger a release are UE inactivity or LTE Radio Link Failure. For inactivity, the procedure depends on the bearers in use by
the UE. There are two cases:
• UE with only Master Node (MN) terminated bearers
• UE with one or more Secondary Node (SN) terminated bearers
In both cases the release decision is taken by the MN (eNodeB). However, when the UE has an SN terminated bearer, the
eNodeB obtains assistance from the SN. At release to idle mode, the feature Capability-Aware Idle Mode Control can be
used to alter the idle mode reselection behavior of UEs, for example to steer EN-DC capable UEs towards EN-DC capable
LTE carriers.
1. Inactivity Release – UE with only MN terminated bearers
If the UE has only MN terminated bearers (no SN terminated bearers), then the inactivity release is identical to that for
legacy LTE. The eNodeB releases the UE if no data has been sent in the uplink or the downlink on any DRB for a period of
at least Rcs.tInactivityTimer (set in the eNodeB) and no NAS message has been sent or received for at least 3 seconds. The
minimum settable value for tInactivityTimer is 10 seconds, and this setting is typically used.
2. Inactivity Release – UE with an SN terminated bearer
If the UE has one or more SN terminated bearers, then both the MN (eNodeB) and the SN (gNodeB) monitor UE activity.
The monitoring is performed at the PDCP layer. The MN monitors the activity of any MN terminated DRBs. The SN monitors
the activity of SN terminated DRBs and informs the eNodeB of the results over the X2-AP interface. The node responsible
for actually releasing a UE due to inactivity is the eNodeB. It releases the UE when all DRBs (both MN and SN terminated)
have been inactive for a period of at least Rcs.tInactivityTimer (set in the eNodeB) and no NAS message has been sent or
received for at least 3 seconds. To achieve this, the following processes are followed.
2.A. SN (gNodeB) Inactivity Monitoring
The SN considers a UE inactive if all SN terminated DRBs have been inactive in both the uplink and the downlink for a
period of at least 5 seconds (hardcoded). The SN informs the MN (eNodeB) of the UE inactivity by sending the notification
SGNB Activity Notification (inactive) over the X2-AP interface. The SN considers a UE active if any SN terminated DRB has
any activity in either the uplink or downlink. The SN informs the MN (eNodeB) of the UE activity by sending the notification

SGNB Activity Notification (active) over the X2-AP interface. The SN does not initiate release based on inactivity. It simply
notifies the eNodeB of the activity, and the eNodeB determines when to release the UE.
2.B. MN (eNodeB) Inactivity Monitoring
The UE is released to idle mode when the eNodeB decides that the DRBs (both MN and SN terminated) are inactive and
NAS signaling has not occurred for at least 3 seconds. The eNodeB uses the following rules to decide whether a DRB is
inactive:
• Any MN terminated DRB is considered inactive by the eNodeB when no data has been transmitted in either the
uplink or the downlink on that DRB for at least Rcs.tInactivityTimer.
• All SN terminated DRBs are considered inactive by the eNodeB when the notification SGNB Activity Notification
(inactive) is received by the eNodeB and a further time of Rcs.tInactivityTimer - 5 seconds expires without receiving
an active notification. Given that the SN requires 5 seconds of inactivity before notifying the eNodeB, the total
inactivity time required for SN terminated bearers is at least tInactivityTimer; same as for MN terminated bearers.
Note that the minimum configurable value for tInactivityTimer is 10 seconds, which is longer than the 5 second
timer in the SN.

i. inctivity timer
ii. MME causes
2.3.2. Use case
UE release from connected mode to idle mode is triggered by either the MME or the eNodeB. Reasons for the eNodeB
to trigger a release are UE inactivity or LTE Radio Link Failure. For inactivity, the procedure depends on the bearers in
use by the UE. There are two cases:
• UE with only Master Node (MN) terminated bearers
• UE with one or more Secondary Node (SN) terminated bearers
i. pmEndcRelUeNormal
ii. pmFlexErabRelMme
iii. pmFlexErabRelNormalEnb
iv. pmEndcRelUeAbnormalMenb
v. pmEndcRelUeAbnormalSgnb
vi. pmEndcRelUeAbnormalMenbAct
vii. pmEndcRelUeAbnormalSgnbAct
< pmEndcRelUeNormal >
pmFlexErabRelMme >
< pmFlexErabRelNormalEnb &

2.4. NR Leg Release initiated in eNB (Call flow)
Secondary Node Release, keeping the Master Node, can be initiated either by the Master Node or the Secondary Node.
When the SN is released, any SN terminated bearers are transitioned to MN Terminated MCG Bearers. The eNodeB then
configures a B1 measurement in the UE to detect NR coverage and, if a B1 report is received from the UE, the eNodeB
attempts SN addition. Secondary Node Release, keeping the Master Node, is not triggered by inactivity; inactivity causes
release to idle mode. The Master Node initiates a Secondary Node release in the following cases:
• MN receives SCGFailureInformationNR message from the UE, due to Radio Link Failure
• MN detects LTE mobility due to intra-cell, intra-frequency or inter-frequency
2.4.1. SN Release procedure – MN initiated – ENDC (Call flow)
< pmEndcRelMnMcgRelocAtt > < pmEndcRelUeNormal & pmEndcRelUeAbnormalMenb
& pmEndcRelUeAbnormalMenbAct >
< pmEndcRelMnMcgReallocSucc >

UE MN SN S-GW MME
6. Data Forwarding
8. Path Update procedure
1. SgNB Release Request
9. UE Context Release
7. Secondary RAT Data Usage Report
2. SgNB Release Request Acknowledge
2.4.2. Master Node Initiated Secondary Node Release (Diagram)

2.4.3. Retainability - EN-DC connection release initiated by eNodeB (Flowchart)
EN-DC connection release of type normal and abnormal scenarios. A normal release is a release with cause “Cell not
Available”, “User Inactivity”, “MCG Mobility” or “SCG Mobility”.
— EN-DC connection release initiated by eNodeB
— EN-DC connection release initiated by gNodeB
i. Bad NR radio conditions
ii. High noise or interference
iii. Radio Link Failure
iv. LTE mobility (intra-cell, intra-frequency or inter-frequency) for any LTE related reasons

v. internal cause (considered abnormal with precondition that EN-DC NR leg setup procedure must be completed)
vi. gNB Cell not Available
vii. User Inactivity
viii. connection gNB to eNodeB is lost
ix. Coverage related problems (tilt, power, azimuth, black hole, … ) causing loosing NR cell coverage
x. T310
2.4.5. Use case
The Master Node initiates a Secondary Node release in the following cases:
• MN receives SCGFailureInformationNR message from the UE, due to Radio Link Failure
• MN detects LTE mobility due to intra-cell, intra-frequency or inter-frequency
i. pmEndcRelMnMcgRelocAtt
ii. pmEndcRelMnMcgReallocSucc
iii. pmEndcRelUeAbnormalSgnb
iv. pmEndcRelUeAbnormalSgnbAct
v. pmEndcRelUeAbnormalMenb
vii. pmEndcRelUeNormal
2.5. NR Leg Release initiated in gNB (Call flow)
Secondary Node Release, keeping the Master Node, can be initiated either by the Master Node or the Secondary Node.
When the SN is released, any SN terminated bearers are transitioned to MN Terminated MCG Bearers. The eNodeB then
configures a B1 measurement in the UE to detect NR coverage and, if a B1 report is received from the UE, the eNodeB
attempts SN addition. Secondary Node Release, keeping the Master Node, is not triggered by inactivity; inactivity causes
release to idle mode. The Secondary Node initiates a Secondary Node release in the following cases:
• SN detects expiry of the Random Access Supervision Timer or failure in another part of the SCG Addition process
• SN detects that RLC exceeds its maximum downlink retransmission
• SN detects NR cell lock

2.5.1. SN Release procedure – SN initiated – ENDC (Call flow)
< pmEndcRelMnMcgRelocAtt > < pmEndcRelUeAbnormalSgnb &
pmEndcRelUeAbnormalSgnbAct >
< pmEndcRelMnMcgReallocSucc >

UE MN SN S-GW MME
1. SgNB Release Required
6. Data Forwarding
2. SgNB Release Confirm
7. Secondary RAT Data Usage report
2.5.2. Secondary Node Initiated Secondary Node Release (Diagram)
2.5.3. Retainability - EN-DC connection release initiated by gNodeB (Call flow)
EN-DC connection release of type normal and abnormal scenarios. A normal release is a release with cause “Cell not
Available”, “User Inactivity”, “MCG Mobility” or “SCG Mobility”.
— EN-DC connection release initiated by eNodeB
— EN-DC connection release initiated by gNodeB

i. Internal cause (considered abnormal)
ii. RACH procedure problems (expiry of the Random Access Supervision Timer)
iii. Bad NR radio conditions (RLC exceeds its maximum downlink retransmission)
iv. High noise or interference
v. NR cell lock
2.5.5. Use case
The Secondary Node initiates a Secondary Node release in the following cases:
• SN detects expiry of the Random Access Supervision Timer or failure in another part of the SCG Addition process
• SN detects that RLC exceeds its maximum downlink retransmission

• SN detects NR cell lock
i. pmEndcRelMnMcgRelocAtt
ii. pmEndcRelMnMcgReallocSucc
iii. pmEndcRelUeAbnormalSgnb
iv. pmEndcRelUeAbnormalSgnbAct
v. pmEndcRelUeAbnormalMenb
vii. pmEndcRelUeNormal
2.6. UL Leg Switching
Uplink user data for a split DRB is transmitted over the MCG or the SCG resource, which is controlled by the
endcUlLegSwitchEnabled MOM parameter. If the parameter is set to false, then the MCG resource is used by default and
it is not switchable. If the parameter is set to true, then the feature Switching of the uplink MCG and SCG Resources is
enabled, and the MCG or SCG radio resource used for the uplink user data switches depending on the NR connection
quality. The switch is triggered based on the measurement result of the uplink NR signal quality and the threshold set. The
configuration for the split DRB has an impact on the transport network dimensioning for S1 and X2.
The switching of uplink Master Cell Group (MCG) and Secondary Cell Group (SCG) resources allows uplink data
transmission to conform to the estimated radio quality of the NR link in the following way:
- When the estimated radio quality of the NR link is good, the uplink data transmission uses the SCG radio resources.
- When the estimated radio quality of the NR link is poor, the uplink data transmission uses the MCG radio
resources.
The switching of MCG and SCG resources in UL is slower than it is in DL because it involves the reconfiguration of the UE.
The radio quality of the NR link is defined by the configured threshold value of NRCellDU.endcUlNrLowQualThresh. If the
NR radio quality drops below the configured threshold value, the gNodeB switches to the MCG radio resources of the split
bearer. On low-band and mid-band, if the UE quickly moves out of the NR cell coverage, the detection of CRC failures and
discontinuous transmissions in uplink causes the gNodeB to switch to the MCG radio resources regardless of the estimated
radio quality of the NR link.
The NRCellDU.endcUlNrQualHyst parameter defines the hysteresis for switching back to the SCG radio resources. If the
radio quality of the NR link reaches the threshold, as well as the hysteresis value, the traffic is directed back to the SCG
radio resources again. The maximum value of the uplink SINR is estimated at every PUSCH reception. A filter smooths the
uplink SINR samples. The smoothing is needed to normalize the reaction time to temporary changes of the SINR. The
maximum uplink-normalized SINR value is checked against the value of the NRCellDU.endcUlNrLowQualThresh attribute.
The shortest possible period of successfully switching between MCG and SCG radio resources can be configured in the
GNBCUUPFunction.endcUlNrRetProhibTimer parameter, that serves as a prohibit timer. Enabling of UL leg switching is by
parameter endcUlLegSwitchEnabled; initial UL leg selection is byt parameter initialUplinkConf. Control of Leg switching
between gNB and eNB is by three parameters endcUlNrLowQualThresh, endcUlNrRetProhibTimer, endcUlNrQualHyst.

i. Ping pong between legs
ii. SN (gNB) deconfiguration instead of UL leg switching

2.6.2. Use case
i. When the estimated radio quality of the NR link is good, the uplink data transmission uses the SCG
radio resources.
ii. When the estimated radio quality of the NR link is poor, the uplink data transmission uses the MCG
radio resources.
i. ---
2.6.4. Uplink MCG and SCG Resource Switching (Diagram)

2.7. Packet Forwarding at SGNB Addition
Packet Forwarding at SGNB Addition is a procedure starting while adding Secondary gNB to an eNB with traffic
in buffer. This procedure permits to transfer the eNB in buffer packet data from eNB to gNB while adding the
Secondary gNB.
Downlink packet forwarding is supported in EN-DC during the Secondary Node Addition procedure. It is always
enabled and not controlled by MO configuration. Downlink packets are forwarded from the Master Node to the
Secondary Node using the X2-U interface. During the Secondary Node Addition procedure, bearer resources
allowed to be Secondary Node terminated Split DRBs are moved from the Master Node to the Secondary Node.
Downlink packets are sent from the SGW to old bearer resources in the Master Node. During the Secondary
Node Addition procedure, a packet forwarding tunnel between the two nodes is established over the X2-U
interface. Packet forwarding behavior between the old and the new bearer resources varies based on the
following conditions:
– In both RLC AM and UM, downlink packets that are not yet sent to the UE by the old bearer resources in
the Master Node are forwarded to the newly set up Split DRBs. The Split DRBs in the Secondary Node
send these packets to the UE.
– In RLC AM, downlink packets from the Master Node that are sent to, but not acknowledged by the UE,
are forwarded to the Secondary Node terminated Split DRB where they are dropped.
Packet forwarding between old and newly set up bearer resources ensures that packet loss is minimized during
the Secondary Node Addition procedure. Packet forwarding ends when the path switch is completed and the
SGW starts sending packets to the new bearer resources in the Secondary Node.
i. ---

2.7.2. Use case
i. While adding NR leg (Secondary gNB) to eNB NSA with traffic in buffer
i. ---
2.7.4. Downlink Session Packet Flow in EN-DC during Secondary Node Addition Procedure
(Schema)

2.8. Intra-cell Handover
eNB Intra-cell Handover is a LTE event which influence the NR NSA environment. eNB intra-Cell Handover
would be triggered in eNB (4G) which causing the release of gNB if it is already configured.
The Master Node initiates a Secondary Node release if MN detects LTE mobility due to intra-cell, intra-
frequency or inter-frequency. LTE intra-cell handover that is performed by EN-DC capable UEs when one of the
following events occurs:
– TTI bundling activation or deactivation
– E-RAB setup when there are no available DRB IDs on the same security key
– Security key change
The SN addition is typically either configuration-based or measurement-based, but may not be in the case of
LTE intra-cell handover.
i. ---
2.8.2. Use case
LTE intra-cell handover that is performed by EN-DC capable UEs when one of the following events
occurs:
ii. TTI bundling activation or deactivation
iii. E-RAB setup when there are no available DRB IDs on the same security key
iv. Security key change
i. ---

2.9. Intra-eNB Handover
4G Intra-eNB Handover is a LTE event which influence the NR NSA environment. 4G Intra-eNB Handover would
be triggered in eNB (4G) which causing the release of gNB if it is already configured.
i. ---
2.9.2. Use case
i. Handover in same eNB among belonging sectors.
i. ---

2.10. X2 Handover
eNB X2 Handover is a LTE event which influence the NR NSA environment. eNB X2 Handover would be
triggered in eNB (4G) which causing the release of gNB if it is already configured.
i. ---
2.10.2. Use case
i. Handover between 2 eNBs connected through X2 interface.
i. ---

2.11.SN Modification procedure - MN initiated - ENDC
The Master Node Initiated Secondary Node Modification procedure is initiated by the Master Node and has one of the
following purposes:
- SCG Removal : To remove the SCG resources and reconfigure the Secondary Node terminated split DRB(s) to
Secondary Node terminated MCG DRB(s), while keeping NR PDCP resources in the Secondary Node.
- SCG Addition : To set the SCG resources up and reconfigure the Secondary Node terminated MCG DRB(s) to
Secondary Node terminated split DRB(s).
The EN-DC band combination coordination function is triggered during the SCG Addition procedure to select the EN-DC
band combination.
(1) Secondary Node Modification Preparation
(1.A) The Master Node triggers the modification procedure, by sending the SGNB MODIFICATION REQUEST
message, when either of the following occurs:
- At E-RAB Setup
- At the reception of a B1 measurement report
The modification can contain either an SCG Addition or an SCG Removal procedure.
(1.B) The Secondary Node confirms the procedure by sending the SGNB MODIFICATION REQUEST ACKNOWLEDGE
message back.
(2) RRC Connection Reconfiguration
(2.A) The Master Node initiates RRC connection reconfiguration towards the UE by sending the
RRCConnectionReconfiguration message, including the NR RRC reconfiguration message received from the
Secondary Node, to it. The modification can contain either an SCG Addition or an SCG Removal procedure.
(2.B) The LTE Random Access procedure between the UE and the Master Node is performed.
(2.C) The UE applies the new configuration and replies to Master Node in the
RRCConnectionReconfigurationComplete message, including the NR RRC response message.
(3) The Master Node sends the SGNB RECONFIGURATION COMPLETE message to the Secondary Node indicating that the
reconfiguration procedure by the UE is completed.
(4) The NR Random Access procedure between the UE and the Secondary Node is only performed at SCG Addition.
UE MN SN S-GW MME
1. SgNB Modification Request
2. SgNB Modification Request Acknowledge
8. SNStatus Transfer
9. Data Forwarding
7. Random access procedure
10. Secondary RAT Data Volume Report
i. ---

2.11.2. Use case
The Master Node Initiated Secondary Node Modification procedure is initiated by the Master Node and has one of the
following purposes:
i. SCG Removal : To remove the SCG resources and reconfigure the Secondary Node terminated split DRB(s)
to Secondary Node terminated MCG DRB(s), while keeping NR PDCP resources in the Secondary Node.
ii. SCG Addition : To set the SCG resources up and reconfigure the Secondary Node terminated MCG DRB(s)
to Secondary Node terminated split DRB(s).
i. ---
2.11.4. Master Node Initiated Secondary Node Modification
2.12.Master Node Based Handover in EN-DC
The handover process for an EN-DC-capable UE is performed between two LTE nodes. During handover the Secondary
Node is released and following a successful handover it is added in the target node if all preconditions are met.
All handover types that are defined in LTE are supported for UEs with established EN-DC.
(1) The UE is connected to the network with established EN-DC.
(2) The handover procedure is initiated by the source Master Node.

During handover preparation the following happens:
- The source Master Node requests the preparation of resources at the target Master Node through the X2-C or
S1-C interfaces.
- After the target Master Node completes the preparation, it signals back to the source Master Node on the
corresponding interface.
(3) The source Master Node initiates the release of the source Secondary Node.
Note: During the release process the source Secondary Node stops data transmission towards the UE.
(4) During handover execution the following happens:
- The source Secondary Node is released.
- The source Master Node sends the handover command to the UE.
(5) During the capability fetch phase the target Master Node requests the UE for missing capability information.
After the request is received, the UE sends back the requested information including EN-DC capability.
(6) The target Master Node initiates the process to set up the target Secondary Node if all preconditions are met.
i. ---
2.12.2. Use case
i. ---
i. ---

3.Supplementary flowchart or call flow
3.1. SN Modification procedure - SN initiated with MN involvement –
ENDC
UE MN SN S-GW MME
1. SgNB Modification Required
6. SgNB Modification Confirm
8. SNStatus Transfer
9. Data Forwarding
3. SgNB Modification Request Acknowledge
2. SgNB Modification Request
For providing of Forwarding addresses, SgNB Security Key

3.2. SN modification - SN initiated without MN involvement
UE MN
SN
1. NR RRCConnectionReconfiguration
3. NR RRCConnectionReconfigurationComplete

3.3. Transfer of an NR RRC message to/from the UE - ENDC
UE MN SN S-GW MME
1. SgNB Modification Required
2. RRCReconfiguration
3. RRCReconfigurationComplete
4. SgNB Modification Confirm

3.4. SN Change – MN initiated – ENDC
UE MN S-SN S-GW MME
8a. SN Status Transfer
9. Data Forwarding
3a. SgNB Release Request
T-SN
12. Bearer Modification
14. New Path
8b. SN Status Transfer
3b. SgNB Release Request Acknowledge

3.5. SN Change – SN initiated – ENDC
UE MN S-SN S-GW MME
10. Data Forwarding
1. SgNB Change Required
T-SN
15. New Path
6. SgNB Change Confirm

3.6. Inter-MN handover with/without MN initiated SN change
UE
source
MN
(target)
SN
S-GW MME
target
MN
1. Handover Request
4. Handover Request Acknowledge
14. Path Switch Request
17. Path Swtich Request Acknowledge
3. SgNB Addition Request Ack
16a. New Path (MN terminated bearer)
13. Data Forwarding
(source)
SN
11a. Secondary RAT Data Usage Report
11b. Secondary RAT Data Usage Report
16b. New Path (SN terminated bearer)
12c. SN Status Transfer

3.7. Master Node to eNB Change procedure – ENDC
UE S-MN S-SN S-GW MME
8. Data Forwarding
T-eNB
1. Handover Request
11. Bearer Modication
13. New Path
9a. Secondary RAT Data Usage report
9b. Secondary RAT Data Usage Report

3.8. eNB to Master Node change – ENDC
UE S-eNB T-SN S-GW MME
T-MN
1. Handover Request
14b. New Path (SN terminated bearer)
3. SgNB Addition Request Ack
14a. New Path (MN terminated bearer)
11. Data Forwarding

3.9. RRC Transfer procedure for the split SRB (DL operation) – ENDC
UE MN SN S-GW MME
1. RRC Transfer
2. RLC SDU
3. RRC Transfer

3.10.RRC Transfer procedure for the split SRB (UL operation) – ENDC
UE MN SN S-GW MME
1. RLC SDU
2. RRC Transfer

3.11.RRC Transfer procedure for NR measurement report or NR failure
information – ENDC
UE MN SN S-GW MME
2. RRC Transfer
1. ULInformationTransferMRDC

3.12.Secondary RAT data volume periodic reporting - EN-DC
UE MN SN S-GW MME

3.13.Support of Activity Notification in EN-DC
UE MN SN S-GW MME
1. Activity Notification
(inactive)
3. Activity Notification
(re-activated)
2. MN decides to
keep SN resources

3.14.NR NSA EN-DC Connection Setup - Modification Request Initiated
EN-DC SCG connection setup

3.15.RRC Connection Establishment for NR SA - RRC connection
establishment

3.16.Mobility - NR NSA Intra-Frequency Intra-gNodeB PSCell Change

3.17.Mobility - NR NSA Intra-Frequency Inter-gNodeB PSCell Change

3.18.Mobility - NR SA Intra-gNodeB Mobility

3.19.Mobility - NR SA Inter-gNodeB Mobility

3.20.Accessibility - Paging Scenario

3.20.1. Help to read Flowchart
3.21.Accessibility - RRC Connection Setup
This traffic scenario describes both successful and unsuccessful attempts to set up a RRC connection for an originating or
terminating call.

3.22.Accessibility - RRC Connection Reestablishment
This traffic scenario describes both successful and unsuccessful attempts to reestablish a RRC connection.

3.23.Accessibility - Multi-target RRC Connection Reestablishment (& UE
context fetch)
Note: Counters related to RRC connection reestablishment which name begins with pmRrcConnReest are pegged in
target cell.
UE context fetch :
Note: Counters related to UE context fetch which name begins with pmUeCtxtFetch are pegged in source cell where the
previous UE context is stored.

3.24.Accessibility - Signaling Connection Setup and E-RAB
Establishment - E-RAB Establishment with Initial Context Setup
Procedure

3.25.Accessibility - Signaling Connection Setup and E-RAB
Establishment - E-RAB Establishment with E-RAB Setup Procedure

3.26.Retainability - UE Context Release - MME Triggered UE Context
Release

3.27.Retainability - UE Context Release - RBS Triggered UE Context
Release Scenario

3.28.Retainability - E-RAB Release - E-RAB Release Scenario (MME-
Triggered)

3.29.Retainability - E-RAB Release - E-RAB Release Scenario (RBS-
Triggered)

3.30.Retainability - E-RAB Modification

3.31.Retainability - CS Fallback - CS Fallback Scenario

3.32.Retainability - CS Fallback - Enhanced CS Fallback to CDMA 1xRTT
scenario

3.33.Availability - Cell Downtime - Cell Downtime Procedure
Note: The default setting for the delay timer is 0, which does not impact the cell restart time. If the delay timer is set to
be larger than 0, cell restart/unlock time duration is extended as a consequence of the number of TX updates taken
place during the lock/unlock procedure.

3.34.Integrity - Latency - PDCP level Latency measurements

3.35.Integrity - PDCP Volume - PDCP Volume Measurements

3.36.Integrity - RLC Acknowledged Mode (AM) Automatic Repeat request
(ARQ) procedures - ARQ procedures

3.37.Mobility - Intra-frequency Handover - Intra-Frequency intra-LTE S1
Handover Scenario

3.38.Mobility - Intra-Frequency intra-LTE X2 Handover Scenario

3.39.Mobility - Inter-Frequency intra-LTE S1 Handover Scenario

3.40.Mobility - Inter-Frequency intra-LTE X2 Handover Scenario

3.41.Mobility - Coverage-triggered IRAT Handover - Coverage-Triggered
IRAT Handover Scenario
The main counters for this scenario are the following. These counters exist in class UtranCellRelation for WCDMA and
TD-SCDMA handovers and in class GeranCellRelation for GERAN SRVCC handovers.

3.42.Mobility - Inter-RAT Offload to UTRAN - Inter-RAT Offload to UTRAN
Handover Scenario

3.43.Mobility - Incoming UTRAN IRAT Handover - Incoming UTRAN IRAT
Handover Scenario

3.44.Mobility - UE Throughput-based Mobility to WiFi - WiFi AC requests
LTE UE throughput value

4.PM counters
4.1. PM counters triggering Signals or Commands
Description of some PM counters and triggering message can be found in below:
Model.MO Class Name.Counter Description / Condition
ENodeBFunction. EUtranCellFDD.
pmB1MeasRepEndcConfig
Number of received B1 measurement report on NR frequency for EN-DC
Configuration.
Stepped at first received B1 measurement report on NR frequency for EN-DC
configuration.
pmEndcCapableUe
Total number of EN-DC capable UEs setup to the cell (at initial setup or when UE
capability is fetched or at handover or at re-establishment).
Stepped every time an EN-DC capable UE sets up connection to the cell if one of the
following conditions is met:
- UE is at initial setup
- UE capability is fetched
- UE handover
- UE re-establishment at current cell
pmEndcCapableUeInitSetup
Total number of EN-DC capable UE instances setup to cell at initial setup.
Stepped when EN-DC capable UE does initial setup to cell.
pmEndcSetupFailNrRa
Number of NR RACH failure when trying EN-DC configuration.
Stepped once at every received RRC SCGFailureInformationNR message indicating
reconfiguration with sync failure for an SCG.
pmEndcSetupScgUeSucc
Number of successful SCG addition attempts for EN-DC. The SCG addition is
considered successful after sending 3GPP X2-AP: SGNB RECONFIGURATION
COMPLETE message.
Stepped when sending 3GPP X2-AP: SGNB RECONFIGURATION COMPLETE to the
SgNB after either successful MeNB Initiated SgNB Modification Preparation for
addition of SCG or after successful SgNB Addition Preparation to setup EN-DC.
pmEndcSetupUeAtt
Number of EN-DC Setup attempts initiated towards SgNB.
Stepped when sending 3GPP X2-AP: SGNB ADDITION REQUEST to the SgNB.
pmEndcSetupUeSucc
Successful number of EN-DC Setup attempts.
The EN-DC setup in MeNB is considered successful after sending 3GPP X2-AP: SgNB
Reconfiguration Complete message after successful SgNB Addition Preparation to
setup EN-DC.
Stepped when sending 3GPP X2-AP: SGNB RECONFIGURATION COMPLETE to the
SgNB after successful SgNB Addition Preparation to setup EN-DC.
pmMeasConfigB1Endc
Number of UEs requested to do IRAT measurements on EN-DC frequency by using
B1 event.
Stepped each time a B1 measurement on NR frequency is requested.
GNBCUCPFunction. NRCellCU.
pmEndcPSCellChangeAttInterSgnb
Number of inter-sgNodeB Primary Secondary Cell (PSCell) change attempts for EN-
DC in source NR cell. See 3GPP TS 37.340 for definition of PSCell.
Stepped when source NR cell sends X2AP: SGNB CHANGE REQUIRED message to
master eNodeB (meNodeB).
pmEndcPSCellChangeAttIntraSgnb
Number of intra-sgNodeB Primary Secondary Cell (PSCell) change attempts for EN-
Stepped at transmission of X2AP: SGNB MODIFICATION REQUIRED message with
SCG Mobility cause.

pmEndcPSCellChangeResAllocReqInterSgnb
Number of inter-sgNodeB Primary Secondary Cell (PSCell) change resource
allocation requests for EN-DC in target NR cell. See 3GPP TS 37.340 for definition of
PSCell.
Stepped when target NR cell receives X2AP: SGNB ADDITION REQUEST message with
trigger indication SN change.
pmEndcPSCellChangeResAllocSuccInterSgnb
Number of successful inter-sgNodeB Primary Secondary Cell (PSCell) change
resource allocations for EN-DC in target NR cell. See 3GPP TS 37.340 for definition of
PSCell.
Stepped when target NR cell sends X2AP: SGNB ADDITION REQUEST ACKNOWLEDGE
message for request with trigger indication SN change.
pmEndcPSCellChangeSuccInterSgnb
Number of successful inter-sgNodeB Primary Secondary Cell (PSCell) changes for EN-
Stepped at reception of X2AP: SGNB CHANGE CONFIRM message from master
eNodeB (meNodeB), not conditional on RRC Reconfiguration Complete from UE.
pmEndcPSCellChangeSuccIntraSgnb
Number of successful intra-sgNodeB Primary Secondary Cell (PSCell) changes for EN-
Stepped at reception of X2AP: SGNB MODIFICATION CONFIRM message from master
eNodeB (meNodeB) indicating RRC Reconfiguration Complete from UE.
pmEndcSetupScgUeAtt
Number of EN-DC SCG setup attempts initiated by meNodeB.
Stepped at reception of 3GPP X2-AP SGNB ADDITION REQUEST message for EN-DC
setup or 3GPP X2-AP SGNB MODIFICATION REQUEST message for SCG addition.
pmEndcSetupScgUeSucc
Number of successful EN-DC SCG setups.
Stepped at reception of 3GPP X2-AP SGNB RECONFIGURATION COMPLETE message
received after one of following:
* Transmission of 3GPP X2-AP SGNB ADDITION REQUEST message for EN-DC setup.
* Transmission of 3GPP X2-AP SGNB MODIFICATION REQUEST message for SCG
setup.
pmEndcSetupUeAtt
Number of EN-DC setup attempts initiated by meNodeB.
Stepped when sgNodeB Addition procedure is initiated by meNodeB for EN-DC
setup.
pmEndcSetupUeSucc
Number of successful EN-DC setups.
Stepped when 3GPP X2-AP SGNB RECONFIGURATION COMPLETE message is
received from meNodeB. SgNodeB is updated with bearer configuration.
pmRrcConnEstabAtt
Number of attempted RRC Connection Establishment procedures. See 3GPP TS
38.331, RRC Setup Request.
Stepped when an RRC Setup Request message is received in gNodeB CU.
pmRrcConnEstabAttMos
Number of attempted RRC Connection Establishment procedures with
establishment cause Mobile Originating Signaling (MOS). See 3GPP TS 38.331, RRC
Setup Request.
Stepped when an RRC Setup Request message is received in gNodeB CU with
establishment cause Mobile Originating Signaling (MOS).
pmRrcConnEstabAttReatt
Number of RRC Setup Requests that are considered as re-attempts. See 3GPP TS
38.331, RRC Setup Request.
Stepped when an RRC Setup Request message is received in gNodeB CU while an
RRC Connection Establishment is already ongoing with same UE identity.
pmRrcConnEstabAttReattMos
Number of RRC Setup Requests that are considered as re-attempts for establishment
cause Mobile Originating Signaling (MOS). See 3GPP TS 38.331, RRC Setup Request.
Stepped when an RRC Setup Request message is received in gNodeB CU with
establishment cause Mobile Originating Signaling (MOS) and while an RRC
Connection Establishment is already ongoing with same UE identity.
pmRrcConnEstabSucc
Number of successfully completed RRC Connection Establishment procedures. See
3GPP TS 38.331, RRC Setup Complete.
Stepped when an RRC Setup Complete message is received in gNodeB CU.

pmRrcConnEstabSuccMos
Successful RRC Connection Establishments where establishment cause is Mobile
Originating Signaling (MOS). See 3GPP TS 38.331, RRC Setup Complete. Unit:
messages
Stepped when an RRC Setup Complete message is received in gNodeB CU and
establishment cause is Mobile Originating Signaling (MOS).
pmRwrEutranUeSuccNrCoverage
Number of UE Release with Redirection to E-Utran, that were triggered by bad
coverage in NR.
Stepped at sending of an F1AP UE Context Release Command, when the cause was
bad NR coverage and the UE will be redirected to EUtran.
4.2. PM counters definition
Attachment.

5.KPI
5.1. NSA gNB NR KPIs
1. RA_SR_in_gNB = 100 * (NRCellDU.pmRadioRaCbSuccMsg3 / NRCellDU.pmRadioRaCbAttMsg2)
2. RA_Succ_Msg3 = NRCellDU.pmRadioRaCbSuccMsg3
3. RA_Att_Msg2 = NRCellDU.pmRadioRaCbAttMsg2
4. RA_SR_Msg2 = 100 * ( NRCellDU.pmRadioRaCbAttMsg2 / NRCellDU.pmRadioRaCbPreambles )
5. ENDC_Setup_SR_in_gNB= 100 * (NRCellCU.pmEndcSetupUeSucc / NRCellCU.pmEndcSetupUeAtt)
6. Sgc_Addition_SR_in_eNB = 100 * ( EUtranCellFDD.pmEndcSetupScgUeSucc / EUtranCellFDD.pmEndcSetupScgUeAtt )
7. Sgc_Addition_SR_in_gNB = 100 * ( NRCellCU.pmEndcSetupScgUeSucc / NRCellCU.pmEndcSetupScgUeAtt )
8. B_5G_RRCConnectionUsers_Tot = ( NRCellCU.pmRrcConnLevelSumEnDc / NRCellCU.pmRrcConnLevelSamp )
9. EnDC_Succ = NRCellCU.pmEndcSetupUeSucc
10. EnDC_Att = NRCellCU.pmEndcSetupUeAtt
11. Norm_DL_MAC_Cell_Throughput_gNB_kbps = 8*((NRCellDU.pmMacVolDl)/(900*1000))
12. NR_Leg_Retainability_in_gNB = 100 * ((NRCellCU.pmEndcRelUeAbnormalMenb + NRCellCU.pmEndcRelUeAbnormalSgnb) /
(NRCellCU.pmEndcRelUeNormal + NRCellCU.pmEndcRelUeAbnormalMenb + NRCellCU.pmEndcRelUeAbnormalSgnb))
13. NR_Leg_Retainability_in_gNB_Act = 100 * ((NRCellCU.pmEndcRelUeAbnormalMenbAct + NRCellCU.pmEndcRelUeAbnormalSgnbAct)
/ (NRCellCU.pmEndcRelUeNormal + NRCellCU.pmEndcRelUeAbnormalMenb + NRCellCU.pmEndcRelUeAbnormalSgnb))
14. ENDC_UE_Abnormal_Release_act = (NRCellCU.pmEndcRelUeAbnormalMenbAct)+(NRCellCU.pmEndcRelUeAbnormalSgnbAct)
15. ENDC_RAB_SR = 100*( PpControlLink.pmEndcNrDrbSetupSucc / PpControlLink.pmEndcNrDrbSetupAtt )
16. DL_MAC_Volume = NRCellDU.pmMacVolDl
17. UL_MAC_Volume = NRCellDU.pmMacVolUl
18. Norm_DL_MAC_Cell_Throughput_Traffic_in_gNB_kbps = 64*((NRCellDU.pmMacVolDl)/(NRCellDU.pmPdschSchedActivity))
19. Norm_DL_MAC_Cell_Throughput_PDSCH_Slots_gNB_kbps = 64*((NRCellDU.pmMacVolDl)/(NRCellDU.pmPdschAvailTime))
20. DL_MAC_DRB_Throughput_gNB_kbps = 64*(NRCellDU.pmMacVolDlDrb/NRCellDU.pmMacTimeDlDrb)
21. DL_MAC_DRB_Throughput_Qos_gNB_kbps = 64*(NRCellDU.pmMacVolDlDrbQos/NRCellDU.pmMacTimeDlDrbQos)
22. UL_MAC_Cell_Throughput_gNB_kbps = 8*((NRCellDU.pmMacVolUl)/((900*4*24)*1000))
23. Norm_UL_MAC_Cell_Throughput_PUSCH_Slot_gNB_kbps = 64*((NRCellDU.pmMacVolUl)/(NRCellDU.pmPuschSchedActivity))
24. Norm_UL_MAC_Cell_Throughput_PUSCH_Avail_gNB_kbps = 64*((NRCellDU.pmMacVolUl)/(NRCellDU.pmPuschAvailTime))
25. UL_MAC_UE_Throughput_gNB_kbps = 64*(NRCellDU.pmMacVolUlResUe/NRCellDU.pmMacTimeUlResUe)
26. DL_Packet_Loss_Captured_in_gNB_kbps = (RpUserPlaneLink.pmPdcpPktTransDlDiscQos -
RpUserPlaneLink.pmPdcpPktTransDlDiscAqmQos) / RpUserPlaneLink.pmPdcpPktTransDlQos
27. UL_Packet_Loss_Captured_in_gNB_kbps = RpUserPlaneLink.pmPdcpPktLossUl5qi / (RpUserPlaneLink.pmPdcpPktRecUl5qi -
(RpUserPlaneLink.pmPdcpPktLossUlToDisc5qi - RpUserPlaneLink.pmPdcpPktLossUlTo5qi))
28. Num_EndcUeRelAbnormal = (NRCellCU.pmEndcRelUeAbnormalMenb + NRCellCU.pmEndcRelUeAbnormalSgnb)
29. Num_EndcUeRelTotal = (NRCellCU.pmEndcRelUeNormal + NRCellCU.pmEndcRelUeAbnormalMenb +
NRCellCU.pmEndcRelUeAbnormalSgnb)
30. Availability = 100 * (((900*4*24) - (NRCellDU.pmCellDowntimeAuto + NRCellDU.pmCellDowntimeMan)) / (900*4*24))
31. ENDC_UE_Abnormal_Release = (NRCellCU.pmEndcRelUeAbnormalMenbAct)+(NRCellCU.pmEndcRelUeAbnormalSgnbAct)
32. SCG_Retainability_gNB = 100*(EndcUeRelAbnormal/Num_EndcUeRelTotal)
33. DL_Active_Users = (NRCellDU.pmActiveUeDlSum)/(NRCellDU.pmActiveUeDlSamp)

34. UL_Active_Users = (NRCellDU.pmActiveUeUlSum)/(NRCellDU.pmActiveUeUlSamp)
35. DL_Sched_Activity = 100*((NRCellDU.pmPdschSchedActivity)/(NRCellDU.pmPdschAvailTime))
36. UL_Sched_Activity = 100*((NRCellDU.pmPuschSchedActivity)/(NRCellDU.pmPuschAvailTime))
37. ENDC_Intra_Freq_HO_SR_sgNB = 100*((NRCellCU.pmHoInterSgnbSuccOutEndc +
NRCellCU.pmHoExeAttOutIntraSgnbEndc)/(NRCellCU.pmHoPrepAttOutIntraSgnbEndc + NRCellCU.pmHoInterSgnbAttOutEndc))
38. DL_Leg_switch_Mcg = (GNBCUUPFunction.pmPdcpRadioResSwitchDlMcg)
39. DL_Leg_switch_Scg = (GNBCUUPFunction.pmPdcpRadioResSwitchDlScg)
40. ENDC_intra_Sg_PScellChange = 100 * ( NRCellCU.pmEndcPSCellChangeSuccIntraSgnb / NRCellCU.pmEndcPSCellChangeAttIntraSgnb
)
41. Attempts_intra_Sgnb = NRCellCU.pmEndcPSCellChangeAttIntraSgnb
42. Succ_intra_Sgnb = NRCellCU.pmEndcPSCellChangeSuccIntraSgnb
43. ENDC_inter_Sg_PScellChange = 100 * ( NRCellCU.pmEndcPSCellChangeSuccInterSgnb / NRCellCU.pmEndcPSCellChangeAttInterSgnb
)
44. Attempts_inter_Sgnb = NRCellCU.pmEndcPSCellChangeAttInterSgnb
45. Succ_inter_Sgnb = NRCellCU.pmEndcPSCellChangeSuccInterSgnb
46. NRCellAvailability = 100 * (((900*4*24) - ((NRCellDU.pmCellDowntimeAuto + NRCellDU.pmCentimeMan)/numCells)) / (900*4*24))
47. pmActiveUeDlMax = NRCellDU.pmActiveUeDlMax
48. pmRrcConnLevelMaxEnDc = NRCellCU.pmRrcConnLevelMaxEnDc
49. numCells = int(pm_count / timeInterval * 15)
5.2. NSA eNB LTE ENDC & Flex KPIs
1. To Be Added

6.References
1. Ericsson CPI NR RAN 19.Q3
2. Ericsson CPI NR RAN 20.Q1
3. EQNA 5G HelpDesk
4. NR PM v1.0 – Muhammad Usman
5. 5G NSA 19Q3 Monitoring - Salvatore Sestito
6. ITK interface Formulas - Claudio Perez
7. NR PM part B – Muhammad Usman
8. Internal sources (sporadic)

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