04_RA41334EN50GLA1_LTE Paging and RRC Connection

LTE Counters and KPI [RL50] [RL50] RA4133-50A Paging and RRC Connection

Module 4

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Course Objectives Paging and RRC Connection After completing this learning element, the participant will be able to: • Explain idle and connected states within LTE

• Describe the phases, counters and related KPI’s defined for the RRC connection setup procedure.

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Paging and RRC Connection

• Idle and Connected States within LTE • Paging and Idle Mode DRX • TTI Bundling • RRC Setup Procedure • Radio Admission Control

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RRC States in LTE E-UTRA RRC Connected Mode • UE has E-UTRAN RRC connection • UE has context in E-UTRAN • E-UTRAN knows UE’s cell • UE identified by C-RNTI • UE  Network data exchange possible • Handover mobility • Neighbour cell measurements • UE reports CQI to eNB • eNB controlled DRX/DTX period

In LTE one distinguishes just between

RRC connected RRC idle

There are no sub-states for RRC connected mode

RRC connection establishment / release

Idle Mode • No RRC context stored in the eNB • UE specific DRX configured by NAS • Cell re-selection mobility • Broadcast of system information • Paging • UE identified by ID which is unique in a tracking area 6

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NAS States in LTE - EMM Definition of main EPS Mobility Management states • EMM-DEREGISTERED – The UE is not reachable by a MME – UE context can still be stored in the UE and MME

• EMM-REGISTERED – UE enters to EMM-Registered with Attach or Tracking Area Update (TAU) procedure

– The UE location is known with accuracy of the tracking area list – UE has at least one active PDN connection – After Detach procedure the state is changed to EMM-DEREGISTERED EMM states in UE

EMM states in MME

Detach Attach reject TAU Reject All Bearer Deactivated EMM-DEREGISTERED

Detach Attach reject TAU Reject All Bearer Deactivated

EMM-REGISTERED

EMM-REGISTERED

Attach accept TAU Accept

Attach accept 7

EMM-DEREGISTERED

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NAS States in LTE - ECM Definition of EPS Connection Management states • ECM-IDLE – UE is in ECM-IDLE state when no NAS signaling connection between UE and network exists – In the EMM-REGISTERED and ECM-IDLE state, the UE shall perform  Tracking Area Update  Periodic Tracking Area Update

 Service Request  Answer to paging from MME with Service Request

– UE and MME enter the ECM-CONNECTED state when signaling connection is established.

• ECM-CONNECTED – UE location is known in the MME with an accuracy of a serving eNodeB.

– For a UE in the ECM-CONNECTED state, there exists a signaling connection between the UE and the MME – The S1 release procedure changes the state at both UE and MME from ECM-CONNECTED to ECM-IDLE ECM states in UE

ECM states in MME

RRC Released ECM-IDLE

ECM-CONNECTED RRC Established

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S1 Released ECM-IDLE

ECM-CONNECTED S1 Established

ECM Connected = RRC Connected + S1Nokia Connection RA41334EN50GLA1 ©2014 Solutions and Networks. All rights reserved.

Summary of LTE States

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EMM state

ECM state

RRC state

UE Location

Mobility

EMM_ Deregistered

ECM_IDLE

RRC_IDLE

Unknown

PLMN Selection

EMM_ Registered

ECM_IDLE

RRC_IDLE

Tracking Area

Cell Reselection

EMM_ Registered

ECM_ Connected

RRC_ Connected

Cell

Handover

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Paging and RRC Connection

• Idle and Connected States within LTE • Paging and Idle Mode DRX • TTI Bundling • RRC Setup Procedure • Radio Admission Control

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DTX and DRX for LTE • DTX/DRX means that the UE transceiver is switched off for some predefined time periods

E-UTRA RRC Connected Mode DRX

Air interface is switched off for time periods

eNodeB

Idle Mode DRX This saves power on one side but might have the following consequences

UE specific DRX configured by NAS

• Longer call setup time • Lower user throughput achievable

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DTX and DRX for LTE • DRX options according 3GPP -

In Idle mode for Paging This means that the UE is listening to page messages in predefined time opportunities only and sleeping all other time

-

E-UTRA RRC Connected Mode DRX configured by RRC

In connected mode DRX UE is switched off for predefined time interval Discontinuous monitoring of DL control channel (PDCCH) Allocations of resources done at specific times

Idle Mode UE specific DRX configured by NAS

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DRX for Paging • The UE may use DRX in idle mode in order to reduce power consumption

• One Paging Occasion (PO) is a sub-frame where P-RNTI may be transmitted on the PDCCH addressing the page message • One Paging Frame (PF) is a radio frame, which may contain one or several Paging Occasions • When DRX is used the UE needs to monitor just one PO per DRX cycle

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Paging Related Parameters • Default paging cycle defPagCyg (LNCEL, 32rf/64rf/128rf/256rf, 128rf) • Defines the cell specific paging DRX cycle duration • Value 32rf corresponds to 32 radio frames, 64rf corresponds to 64 radio frames and so on • One radio frame corresponds to 10ms in time

• Increasing the parameter value saves battery capacity in idle mode as listening to paging is less frequent. But the call setup time is getting longer due to longer average paging time • Optionally an UE specific paging cycle length might be signaled by the core network. In this case the UE follows the shorter of the two cycles

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Paging Related Parameters • Number of paging occasions pagingNb (LNCEL, oneT/halfT/quarterT/oneEighthT/oneSixteenthT/oneThirtySecondT, quarterT) • Defines the number of possible paging occasions per radio frame, i.e. the density of paging occasions • Used to calculate the number of paging occasions within one paging DRX cycle, which in turn is used to calculate the paging occasions • Example: quarterT means that there is one page occasion every ¼ x paging cycle

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Page Counters • M8008C1 -

Number of RRC paging requests

• M8008C2 -

Number of discarded paging requests

-

Updated when the maximum number of paging records is reached for the next paging occasion that corresponds to the paging request

-

S1 M 8008 C1…C3 paging messages

S1

RRC allows up to 16 paging records per paging occasion

• M8008C3 -

Number of transmitted RRC paging messages M8008C2 cell cell M8008C1

16

cell

M8008C3

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Page KPIs LTE_5031b E-UTRAN RRC Paging Discard Ratio

Describes the paging request discard ratio on RRC level

Logical formula Paging DCR = (discarded RRC paging records / transmitted RRC paging records) * 100%

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Summarization formula (PI ID)

Summarization formula (Abbreviation)

100% * sum([M8008C2]) / sum([M8008C1])

100% * sum([DISC_RRC_PAGING]) / sum ([RRC_PAGING_MES])

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Page KPIs

7,00,000

100.00

6,00,000 80.00

5,00,000

60.00

4,00,000

3,00,000 40.00 2,00,000 20.00 1,00,000

LTE_5122a Paging Messages (#) 18

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LTE_5031aPaging Discard Ratio (%) ©2014 Nokia Solutions and Networks. All rights reserved.

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25.05.2011

0 23.05.2011

0.00

PRACH Counters •

M8001C6 – Number of RACH setup attempts for small size messages – Update when eNodeB receives group A preamble

•

M8001C7 – Number of RACH setup attempts for large size messages

– Updated when eNodeB receives group B preamble

•

M8001C8 – Number of RACH setup completions – Updated when eNodeB sends preamble response

M8001C6 M8001C8

Only successful RACH setup completions counted, failures will be equal to number attempted - completions

M8001C7

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RACH KPIs RACH Setup Completion Success Ratio Describes the ratio of RA preamble responses to total number of RA preambles.

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Logical formula

Summarization formula (PI ID)

Summarization formula (Abbreviation)

RACH Stp Comp Succ rate =(RA Preamble Responses / RA Preambles)*100%

100* sum ([M8001C8])/sum([M8001 C6] + [M8001C7] + [M8001C286])

100* sum([RACH_STP_COMPLETIONS])/ sum([RACH_STP_ATT_SMALL_MSG] + [RACH_STP_ATT_LARGE_MSG] + [RACH_STP_ATT_DEDICATED])

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DRX in RRC Connected Mode

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M8021C18

Number of Handover attempts for UEs running in DRX mode

M8021C19

Number of Handover completions for UEs running in DRX mode

M8013C24

Subframes of DRX Active UE

M8013C25

Subframes of DRX Sleep UE

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DRX in RRC Connected Mode RL30 With extended DRX settings a UE may go Out of alignment due to the TAT expiring. After the STIT expires the eNB no longer schedules the UE with TA info hence the TAT expires, to move a UE back to in sync the UE is forced to TX via a PDCCH order

DRX active

UE out of sync

DRX Sleep

Data PDCCH arrives order

STIT TAT M8001C421 M8001C422 M8001C423 M8001C427

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Number of PDCCH order attempts Number of initial PDCCH order attempts Number of successful PDCCH orders Number of UE state transitions from UL-In-Sync to UL-Out-Of-Sync

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DRX in RRC Connected Mode RL50 With SMART DRX (LTE585) UEes will use the short DRX cycle with at 16 (def) repititions (good for TA) of the cycle, instead of the STIT. This gives the UE greater opportunity for battery savings whilst maintain timing.

Data arrives DRX inactivity timer Expires

DRX active

UE out of sync

Start drxShortCycle

Data PDCCH arrives order

DRX active Due to inactivity timer

DRX Sleep

Start drxLongCycle

TAT

No new counters or KPIs

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Paging and RRC Connection

• Idle and Connected States within LTE • Paging and Idle Mode DRX • TTI Bundling • RRC Setup Procedure • Radio Admission Control

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LTE907 TTI bundling RL50 • LTE907 -UEs with poor radio condition can be switched to TTI Bundling mode in which the same transport block is transmitted in 4 consecutive UL subframes - dB gain for delay constrained services, e.g. voice

HARQ RTT is longer in comparison to non-TTI Bundling mode. The next retransmission occurs 16ms after the previous one

Bundle size is fixed to 4 TTIs. In each TTI different Redundancy Versions (RV) of the same transport block are transmitted

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LTE907 TTI bundling RL50 • Increased energy per transmitted bit, improved UL coverage • One UL grant per bundle  reduced PDCCH load • RLC SDU is not segmented in TTI Bundling  reduced overhead (compared to RLC Segmentation) • 2 … 3 dB gain for delay constrained services, e.g. voice

M8011C63

Number of UL grants for TTI Bundling

M8011C62

Average number of UEs configured for TTI Bundling mode

M8011C66

Long UE retention time in TTI Bundling mode

M8011C65

Medium UE retention time in TTI Bundling mode

M8011C64

Short UE retention time in TTI Bundling mode

SHOR T

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t2 5s

0,25s

t1

MEDIU M

LONG

t1(=0,25s) and t2(=5s) Internal parameter

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Paging and RRC Connection

• Idle and Connected States within LTE • Paging and Idle Mode DRX • TTI Bundling • RRC Setup Procedure • Radio Admission Control

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Call Setup Overview Core/IMS

UE S1

E-Node B

PRACH preamble

MME

TA, scheduling, ID RRC connection request First KPI (like for WCDMA) RRC setup success

RRC connection setup RRC connection setup complete NAS service request encapsulated in RRC connection setup complete

connection service request Connection setup

Security check/command encapsulated in RRC connection reconfiguration

RRC connection Reconfiguration complete SIP invite 

Call & service setup NAS phase

Idle to active RRC phase

Physical Random Access Channel

SIP session process

SIP OK / ringing 28

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Terminating UE

RRC Connection Setup Overview (Positive) UE

NAS phase

Idle to active RRC phase

S1

29

E-Node B

1

2

3

RRCConnectionRequest

RRCConnectionSetup

RRCConnectionSetupComplete

(with encapsulated NAS message)

MME

•M8013C17:SIGN_CONN_ESTAB_ATT_MO_S •M8013C18:SIGN_CONN_ESTAB_ATT_MT •M8013C19:SIGN_CONN_ESTAB_ATT_MO_D •M8013C20:SIGN_CONN_ESTAB_ATT_OTHERS •M8013C21:SIGN_CONN_ESTAB_ATT_EMG

M8007C7: SRB1 setup attempts

M8007C8: SRB1 setup completions

M8013C5: Signaling connection establishment completions

M8007 Radio Bearer Measurements M8013 UE State Measurements

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RRC Connection Setup Overview (Positive) UE

NAS phase

Idle to active RRC phase

S1

30

E-Node B

1

2

3

RRCConnectionRequest

RRCConnectionSetup

•M8013C17:SIGN_CONN_ESTAB_ATT_MO_S •M8013C18:SIGN_CONN_ESTAB_ATT_MT •M8013C19:SIGN_CONN_ESTAB_ATT_MO_D •M8013C20:SIGN_CONN_ESTAB_ATT_OTHERS •M8013C21:SIGN_CONN_ESTAB_ATT_EMG

M8007C7: SRB1 setup attempts

RRCConnectionSetupComplete

(with encapsulated NAS message)

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MME

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RRC Connection Request (Negative) UE S1

E-Node B

MME

RRCConnectionRequest 1 RAC accepts or rejects RRC Connection Request 2

RRCConnectionReject

M8013C8

Signaling connection establishment failures due to rejection by RRM RAC UE stays in Idle Mode

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RRC Connection Setup (Negative)

UE

eNB

1

RRCConnectionRequest

2

RRCConnectionSetup

MME

M8013C6 3

Missing RRCConnectionSetupComplete

Signaling connection establishment failures due RRC setup completions missing Does NOT trigger M8007C9/C12 !! UE stays in Idle Mode

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RRC Connection Setup (Negative)

UE

eNB

1

RRCConnectionRequest

2

RRCConnectionSetup

MME

M8013C7 3

Erreneous or Incomplete RRCConnectionSetupComplete

Signaling connection establishment failures due RRC setup completions error Triggers also M8007C9/C12 SRB1/2 setup failures UE stays in Idle Mode

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RRC Connection Setup Counter Summary M8013C8

M8007C7/C10

M8013C6

RRC Setup completions missing

M8007C9/C12 M8013C7

SRB1 /2 setup failures

M8007C8/C11 M8013C5

RRC Setup completions error

SRB1 /2 setup completions RRC Setup completions At least: from all attempts minus rejects =

34

Rejections by RRM RAC

Missing/wrong completions

Setup attempts

Successful setups RA41334EN50GLA1

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RRC Connection Setup KPIs LTE_5218c E-UTRAN RRC Connection Setup Success Ratio Shows the setup success ratio for the elementary procedure "RRC connection establishment" used to set up a radio connection from UE to eNB

Logical formula RCC Con SSR = (RRC connection setup completions / RRC connection requests) * 100%

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Summarization formula (PI ID)

Summarization formula (Abbreviation)

100*sum([M8013C5]) / sum ([M8013C17]+ [M8013C18]+ [M8013C19]+ [M8013C20] + [M8013C21])

100*sum([SIGN_CONN_ESTAB_COMP]) / sum ([SIGN_CONN_ESTAB_ATT_MO_S]+ [SIGN_CONN_ESTAB_ATT_MT]+ [SIGN_CONN_ESTAB_ATT_MO_D]+ [SIGN_CONN_ESTAB_ATT_OTHERS] + [SIGN_CONN_ESTAB_ATT_EMG])

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RRC Connection Setup KPIs 100.00

25,000

80.00

20,000

60.00

15,000

40.00

10,000

20.00

5,000

LTE_5232a RRC Connection Establishment attempts due to MO-Signalling (#) LTE_5233a RRC Connection Establishment attempts due to MT-Access (#) LTE_5234a RRC Connection Establishment attempts due to MO-Data( #) LTE_5235a RRC Connection Establishment attempts due to Others (#) LTE_5220a RRC Success Ratio (%)

LTE_5218a RRC Connection Setup Success Ratio (%) 36

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0.00

RRC Connection Setup KPIs LTE_5229b, LTE_5230b, LTE_5231b E-UTRAN RRC Connection Establishment Failure Ratio per Cause

Describes the ratio of a specific RRC connection setup failure cause related to all RRC connection requests

Logical formula S1 SFR = (RRC Connection Setup failure_x / RRC Connection requests) * 100%

Summarization formula (PI ID) "RRC timer expiry" failure (RRCCOMPL_MISSING) cause 100*sum([M8013C6]) / sum([M8013C17 ]+ [M8013C18] + [M8013C19]+ [M8013C20] + [M8013C21])

Summarization formula (Abbreviation) RRC timer expiry failure failure (RRCCOMPL_MISSING) cause 100*sum([SIGN_EST_F_RRCCOMPL_MISSING]) / sum([SIGN_CONN_ESTAB_ATT_MO_S]+ [SIGN_CONN_ESTAB_ATT_MT]+ [SIGN_CONN_ESTAB_ATT_MO_D]+ [SIGN_CONN_ESTAB_ATT_OTHERS]+ [SIGN_CONN_ESTAB_ATT_EMG])

Formula related to missing RRC setup completion Other causes are; • RRC protocol error (wrong RRC setup completion)

• Radio access control failure (rejection by RRM RAC) 37

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Paging and RRC Connection

• Idle and Connected States within LTE • Paging and Idle Mode DRX • TTI Bundling • RRC Setup Procedure • Radio Admission Control

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Paging and RRC Connection

Overview of RAC within RRM - RAC admits or rejects requests for establishment of Radio Bearers per cell based on: • Number of RRC connections per cell

RAC acts on:

• Number of active users per cell

• Paging • Call establishment request • Handover request

• Non QoS aware supported by RL30 • RL40 Smart Admin Control QoS Supported

RAC algorithms controls • Signaling radio bearer • Data radio bearer RAC activities

RAC interacts with Packet Scheduler

active users

Packet Scheduler

Radio Admission control

configuration of RLC layer PDCP layer

eNodeB 39

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Paging and RRC Connection

RAC load/data measurements RAC activities

cell load measurements by UE

active users

# UE keeping and & buffered DL/UL measurements

active users & RRC connections

eNodeB

UE's with data buffered (DL/UL) M8001C147/150 average M8001C148/151 maximum 40

M8001C223 average M8001C224 maximum measurements of active users

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cell

cell

cell ©2014 Nokia Solutions and Networks. All rights reserved.

Paging and RRC Connection Objective - Operator configures both maximum number of established RRC connections and maximum number of active users per cell by O&M threshold • RRC connection is established when the SRBs have been admitted and successfully configured • UE is considered as active when Radio Bearer is established • Upper bound for maximum number of supported connections depends on the BB configuration of eNB

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Paging and RRC Connection Controlled Services - RAC acts on the basis of events like: • Paging • Call establishment request

• Handover request

- RAC algorithms controls establishment of • Signaling radio bearer • Data radio bearer

• RAC applies different criteria for call establishment and mobility (HO) • Offset in terms of the number of RRC connections or active users used • Aim is to keep the already established sessions active and support user mobility

• QoS requirements of DRBs (data radio bearers) • Resource consumption in a cell

- ARP Based Admission control for E-RABs 42

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Interaction with other RRM Entities

• RAC interacts with other RRM entities • Mobility management • Radio Bearer Management • UE State Management

- RAC interacts with Packet Scheduler - RAC supports configuration of • RLC layer • PDCP layer

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RAC Parameters - Maximum number of RRC connections maxNumRrc (LNCEL, 0..1200) • 1.3MHz default 20

• 3 MHz default 80 • 5 MHz default 300 • 10 MHz default 300 • 15 MHz default 600 • 20 MHz default 600 - Maximum number of active UEs maxNumActUe (LNCEL, 0..1200) • 1.3MHz default 20 • 3 MHz default 80 • 5 MHz 0…600, default 300 • 10 MHz 0…600, default 300 • 15 MHz 0…720, default 600 • 20 MHz 0…840, default 600 - Maximum amount of users per TTI on UL/DL maxNumUeUL/DL (LNCEL, 1..20) • 1.3MHz default 7 • 3 MHz default 7 • 5 MHz default 7 • 10 MHz default 14 • 15 MHz default 17 • 20 MHz default 20 44

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RAC Counters - Number of UEs monitored by cell load measurements - Number of active UE per cell • M8001C223 average • M8001C224 maximum

- Number of UE with data buffered on DL • M8001C147 average • M8001C148 maximum

- Number of UE with data buffered on UL • M8001C150 average • M8001C151 maximum

- Number of UE with data buffered QCI1..4 -

M8001C227..230

- Number of UE with data buffered non-GBR -

M8001C235

LTE 800 24 hour report On cell level 45

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RRC Connection re -establishment

• Motivation: – In a number of failure cases     

Radio link failure Handover failure RLC unrecoverable error Integrity check failure RRC connection reconfiguration failure

the UE may initiate the RRC connection re-establishment procedure to continue the RRC connection without going to RRC Idle mode.

• Benefit: – Improve user experience despite of exceptional radio conditions

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RRC Connection re-establishment UE

Target eNB

Source eNB

MME

Packet data

Measurement report

HO decision HO request

HO request ACK

RRC: ConnectionReconfiguration

Admin control and resource allocation

Deliver buffered and in transit packets to Target eNB

Detach from old cell

SM status Transfer

Fails to access target Cell Cell selection to Source Cell

Data Forwarding

RRC: ConnectionRe-Establishment request

Buffer packets from source eNB

Accept RRC Restablish Stop data forwarding HO cancel

RRC: ConnectionRe-establishment RRC: ConnectionRe-establishment

complete Re-establish SRB and DRB RRC: ConnectionrReconfiguration RRC: Connectionreconfiguration complete 47

Packet data RA41334EN50GLA1

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SGW

RRC Connection Re-Establishment Counter Summary M8008C0 Rejected RRC Connection reestablishments

RRC Connection Re-establishment Success Ratio 100*sum([M8008C5]) / sum([M8008C4]) Success due to HO

M8008C5

M8008C7/C9 Success due to other

Successful ReEstablishment procedures

M8008C4

Re-Establishment success per cause

M8008C6/C8

RRC Connection Re-establishment Failure Ratio 100*sum([M8008C4]- [M8008C5] - [M8008C0]) / sum([M8008C4])

Attempts due to HO failure Attempts due to other

Re-Establishment attempts

48

Re-Establishment Attempts per cause

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Thank You !

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