3G KPI Analysis Report

WCDMA : KPI ANALYSIS & OPTIMIZATION Network planning& Optimization

Illustration on RAN KPI-RU20

Presentation / Author / Date

SRNC Relocation

RNC

UEBTS2

BTS1

RNCAccessibility:RRC Setup & Access RateRAB Setup & Access Rate

Call Setup Success Rate

PS setup success rate (NRT,HSDPA,

HSUPA)

XRetainability:RRC Drop RateRAB Drop RatePS success rate (NRT, HSDPA,

HSUPA)

Mobility:SHO/ISHO Success

RateSHO Overhead

HDSPA/HSUPA SCC success rate

Usage:Cell Availability

Ave. Uplink Load

Ave. Downlink Load

HSDPA Throughput

Cell Throughput

X Pre-emption

SRNC

Genuine Call Setup Failure Scenarios

– RF issue• Interference / Dominance / Coverage• Missing neighbour

– System Issue - BTS• No response to “RRC Connection Request”• “RRC Connection Reject” to “RRC Connection Request”

– System issue - RNC• “CC Disconnect” after “Call Proceeding” due to “DL RRC

Connection Release”– Core NW

• “CM Service Abort” after “CM Service Request”– System issue (test number)

• “CC Disconnect” after “CC Progress”

Genuine Drop Call scenarios

RF issue– Interference / Dominance / Coverage

– Missing Neighbours

System issue BTS– Sudden “CC Disconnect” due to “DL RRC Connection Release”– Sudden drop to idle, no disconnect messaging

System issue RNC– Sudden “CC Disconnect” due to “DL RRC Connection Release”

KPI DefinitionsThe KPIs to be monitored from the RAN could be:

– Cell availability– Call Setup Success Rate (CSSR)– Call Drop rate– SHO/ISHO/HSPA SCC success rate– Packet Session setup/success rate (NRT, HSDPA, HSUPA)

In NOLS:– RNC counter description– NetAct DB description for RNC measurements– WCDMA RAN Key Performance Indicators– Key Indicator Changes– Measurement Changes


DRNCUE CNSRNCWBTS

2. RRC connection set-up

6. Service Established

7. Branch addition/deletion & Active set update

1. Cell search, BCCH decoding & RACH access

3. UE <--> CS-CN signalling

4. RAB set-up

8. Service Released

5. UE <--> CS-CN Signalling

AMR CS Call Phases

Start

Best server’s RSCP > -102dBm

Best server’s Ec/No > -12dB

Coverage Optimization

Dominance Optimization

AICH(ACK) received?

YesMissing Neighbour ?

Neighbour list Optimization

No

No

No

Yes

UL coverage & RACH parameter. Optimization(changing serving cell)

“RRC ConnectionSetup” received?

(DCH) “RRC Connection setupCompleted” sent from UE?

“Radio Bearer setup failure”Received?

Report & FinishCheck failure cause (Not radio problem/cell update)

Report & Finish(Check failure cause)

AC optimization (check PrxNoise& interferer around BTS)

Report & Finish

“RRC Setup Reject” received?

Yes

No

Yes

Yes

Yes

Report & Finish (Reason of problem: L1 sync fail)

Report & Finish(Check failure cause)

Call Setup Failure Analysis Process__DT

A

BC

D

E

Yes

Yes

No

No

No

No

Call setup failures – Missing Neighbour

Missing neighbour analysis over the whole route (3G-3G, 3G-2G)

Search for failures due to missing 3G-3G neighbours

Search for failures due to missing 3G –2G neighbours– It is suggested to place 2G scanner to the test vehicle

A

Call Setup Failure Analysis- Block B -

The purpose of this activity is to check the Random Access Process is working adequately by investigating whether AI (Acquisition Indicator) has been received through DL AICH

If AICH was not received by UE, the cause of the problem can be classified into:– Inadequate RAN parameter related to Random

Access: RAN parameter settings for pre-amble transmission or open loop power control information is not correct.

– UL Coverage limit: UL coverage of UE is smaller compared to serving cells DL coverage so that UE’s Tx power cannot reach serving cell.

B

Call Setup Failure Analysis- Block B -UE WBTS RNC

Preamble/RACH

Acquisition Indicator/AICH

RRC: RRC Connection Request/PRACH

NBAP: RADIO LINK SETUP REQUEST

RRC: RRC CONNECTION SETUP/FACH

L1 Synchronisation

NBAP: SYNCHRONISATION INDICATOR

RRC: RRC CONNECTION SETUP COMPLETE/DCH

UE in CELL_DCH state

NBAP: RADIO LINK SETUP RESPONSE

B

RACH Process

DownlinkBS

L1 ACK / AICH

UplinkMS Preamble

1

Not detected

Message partPreamble2

PRACH_preamble_retrans# PRACH preambles transmitted during one PRACH cycle without receiving AICH response

UEtxPowerMaxPRACH

… … … …

RACH_tx_Max# preamble power ramping cycles that can be done before RACH transmission failure is reported

PowerRampStepPRACHpreamble

PowerOffsetLastPreamblePRACHmessage

Initial preample power:•Ptx = CPICHtransmissionPower-RSCP(CPICH) +RSSI(BS) + PRACHRequiredReceivedCI

B

Call Setup Failure Analysis- Block B-

Solutions for RACH optimisationMax UE Tx power hit the UE_P_MAX(24dBm)?

To increase PRACH_Preamble_retransOr PowerRampStepPRACHPreamble

To increase PRACH_Preamble_retransOr PowerRampStepPRACHPreamble

No

Yes

Is UL Interference abnormally HIGH?

Yes

No

Report there might be an interfering source Nearby the serving cell

Report there might be an interfering source Nearby the serving cell

Change the Serving cell to cover the problem Area=> UE is too far to reach the serving cell

Change the Serving cell to cover the problem Area=> UE is too far to reach the serving cell

B

Call Setup Failure Analysis- Block BB

Open loop Power Control parameters from RACH Info message

Call setup failures – System issue BTSNo response to “RRC Connection Request”

– Good RF conditions– Wrong MHA settings or cable loss settings can cause the site not to “hear” the UE– PrxNoise statistics, receive link parameters and HW units to be checked (faulty MHA,

wrong MHA parameters, wrong cable / feeder loss parameters, faulty units)

C

Call setup failures – System issue BTS“RRC Connection Reject” after “RRC Connection

Request”– Good RF conditions– Admission Control can reject too many (or admit too

many) connection requests due to wrong PrxNoise measurements.

– PrxNoise statistics, receive link parameters and HW units to be checked

C

Call Setup Failure AnalysisUE has the appropriate DL/UL coverage but if RNC does not allow to set up the RRC

connection of the requested RAB (Radio Access Bearer), Call setup will fail.Admission Control (AC) is involved in RRC connection setup. AC can reject RRC reject

RRC connection Setup due the DL Load, UL load or DL Spreading codes

– Marginal Load Area: • If measured UL (PrxTotal) or DL (PtxTotal) load exceeds target thresholds

(PrxTarget and PtxTarget) AC can still admit new RAB to the cell if a new non-controllable load keeps below target thresholds (in practice this means that AC can admit only new controllable load RABs i.e. NRT RABs)

– Overload Area: • If measured UL (PrxTotal) or DL (PtxTotal) load exceeds overload

thresholds (PrxTarget + PrxOffset and PtxTarget + PtxOffset) then AC can't admit more RABs to the cell

C

Call Setup Failure Analysis• During the pre-optimization phase it is unlikely that AC will stop an RRC connection

setup during the drive testing because there are normally very few UEs in the network. (Traffic loading is trivial)

• However, it should be checked that measured PtxTotal and PrxTotal are less than PtxTarget (e.g. 40dBm) and PrxTarget (e.g. 4dB, 60% loading) respectively.

• If DL AC does not allow RRC setup check the Tx power of WBTS, # of channels transmitted, Signaling messages.

• If UL AC does not allow RRC setup: Check out if there is an interfering source nearby the serving cell.

C

Call Setup Failure Analysis

To check if Layer 1 Synchronization (slot/frame sync) has failed

If “RRC Connection Setup” was received by UE but UE does not send “RRC Connection Setup Completed”, we will report “L1 synchronization failure” and have to check L1 system messages.

D

• “CC Disconnect” after “Call Proceeding”

• Good RF conditions

• Failures in RAB setup occur between the “RAB Assignment Request” being received from Core Network and the RAN sending out Radio Bearer Setup. Therefore the failure is between BTS and Core Network.

ECall setup failures – System issue RNC

• “CC Disconnect” after “Call Proceeding” (cont.)

• An example (site shows high values on counter “RAB_STP_FAIL_CS_VOICE_BTS” during the drive test

• In the recent check the counter showed no failures.

ECall setup failures – System issue RNC

Call setup failures – Core NW“CM Service Abort” after “CM

Service Request”Good RF conditions“Security Mode Command”-

message not received by UE, thus the failure is believed to be at Core Network.

Security Mode Command

Common ID

UE RNC MGWNode B

RRC Connection Establishment

Initial Direct Transfer (CM Service Request) SCCP: Connection Request

SCCP: Connection ConfirmLocation Reporting Control

• RRC: Initial Direct Transfer message is sent using acknowledged mode RLC to the CS core domain. Routing is to be based upon the local P-TMSI

• The NAS message is not read by the RNC but is forwarded to the multimedia gateway. The NAS message includes the IMSI as a UE identity

• The SCCP: Connection Requestmessage establishes the connection orientated signalling link in the same way as it was for the RRC connection phase.This does not reserve any resources for the AMR call itself.

• The Connection Confirm message identifies the RNC with a destination local reference which is the same as the source reference within the Connection Request message

• The Connection Confirm message identifies the CS core with a source local reference

• The CS core sends a RANAP: Location Reporting Control message to the RNC requesting information regarding the location of a particular UE

• The RANAP: Common ID message specifies the IMSI belonging to the UE

• The Security Mode Command message triggers the start or stop of ciphering and integrity protection.

E

Call setup failures – System Issue (test number)“CC Disconnect” after “CC Progress”

Cause: recovery on timer expiryThe call goes via IN SCP to a recording. A static test was done by Nokia Customer

Care and in few instances the call dropped after 30 seconds of recording passed. Hence the problem is associated with the test number not the RAN

30 sec

Cause: recovery on timer expiry

E

CELL_PCHURA_PCH

CELL_FACHCELL_DCH

UTRA RRC Connected Mode

Fast call setup from URA_PCH

IDLE Mode

Fast call setup from CELL_PCH

After RT call with inactive PS RABs

After RT call with inactive PS RABs & high mobility in CELL_DCH

RRC Setup / Release

Phys. Reconfiguration UL/DL activation timer

Phys. Reconfiguration Cell Update, UL data, paging

Phys. Reconfiguration Frequent cell updates

Phys. Reconfiguration URA Update, UL data, Paging

RB. Reconfiguration Traffic Volume, RACH load

RB. Reconfiguration Inactivity Timer, Overload

State Transition triggers

State Transition triggersIDLE

FACH

PCH

DCH

FACH

DCH

IDLE

Call Setup 1.2 sec

Transition DCH-FACH due to inactivity 10 sec )Parameter)

Transition FACH-PCH due to inactivity 2 sec )Parameter)

Wake up time PCH – DCH due to activity 3 sec

25 © 2006 Nokia Layer 3 (RRC) / Kittipong Thamapa

CELL_DCH State

active setcell

active setcell

• DCCH and – if configured – DTCH

• Dedicate physical channel in use

• UE location known on active set cell level

• UE responsible for measurement reporting

• Cell system information on BCCH

• RRC messages on DCCH


CELL_FACH State

servingcell

• DCCH and – if configured – DTCH

• FACH used for higher layer data transfer,

• UE monitors FACH permanently

• Uplink transmission on RACH

• UE location known on serving cell level

• UE performs cell re-selection

• UE responsible for measurement reporting

• Cell system information on BCCH

• RRC messages on BCCH, CCCH and DCCH


CELL_PCH and URA_PCH State

URA – UTRAN Registration Area

URA 1

URA 2URA 3

RNCsupply

area

• one or several cells

• independent from LA /RA

• no DCCH and DTCH• Before uplink transmission UE moves to

CELL_FACH• UE must be paged• RRC messages on BCCH and PCCH• In CELL_PCH

- UE location known on cell level- UE performs cell re-selection and cell updates

• In URA_PCH- UE location known on URA level- UE performs cell re-selection and URA updates

RU20 New Counters & Measurements

/

Cell AvailabilityRNC_183c Cell Availability KPI counts Cell availability from user point of view:


DBRNWINEXISTWCELLAVAILsum

STATEWOINWCELLAVAILsumtyAvailabiliCell

_____

____*100_

M1000C178 AVAILABILITY WCELL IN WORKING STATE

• # of samples when WCELL is in WO State. Counter M1000C180 is always updated along with this counter

• Counter is updated with the value 1 once in approx. 5 seconds when the WCELL is in WO State

M1000C180 AVAILABILITY WCELL EXIST IN RNW DATABASE

• # of samples when WCELL is configured in the database. This counter is used as a denominator for cell availability calculation

• Counter is updated with the value 1 one in approx. 5 seconds when the WCELL is configured in the radio network database

Cell Availability– There is also Optional Cell availability KPI, which counts Cell

Availability from network point of view. Situation where WCELL is blocked by User are excluded from the formula.

– RNC_727a Cell Availability KPI, excluding blocked by user state (BLU), Counts Cell availability from network point of view:


USERBYBLOCKEDWCELLAVAIL

DBRNWINEXISTWCELLAVAILsum

STATEWOINWCELLAVAILsumstateBLUexcludingtyAvailabiliCell

____

_________*100

____

M1000C179 AVAILABILITY WCELL BLOCKED BY USER

• # of samples when WCELL is BLU State. Counter M1000C180 is always updated along with this counter

• Counter is updated with the value 1 once in approx. 5 seconds when the WCELL is in BLU state

CSSR definition

DNO Optimization Processes / JC Ejarque

Low in CSSR? Identify call setup failure phases


Call Setup PhasesCSSR affected if any of the

followings take place.

1. RRC Conn. Setup Fail2. RRC Conn. Access Fail3. RAB Setup Fail4. RAB Setup Access Fail

Call Setup Phase

RRC

Conn. Req

RRC

Conn. Setup

RRC

Conn. Acc

RRC

Conn. ActRAB Setup RAB Drop

Call Setup Success Call Drop

Connected

Low in CSSR?RRC/RAB Setup & Access Analysis Process Flow

Chart


Sites OK ? Cell and Neighbour

Cells availabilityAlarms/Tickets

Setup /Access

Yes

Setup /Access

Setup Failure Cause?

Capacity Optimisation

BTS/TRANS/FROZBSUL/DL

Interference (DL codes)

AC

TroubleshootingRNC

RF Optimisation

Top (N) RRC Setup and Access failures

Top (N) RAB Setup and Access failures

Coverage/Interference

setup

setup

Interference

Coverage

3G cell at inter-RNC border ?

SRNS Relocation troubleshooting

Yes

NO

Access

Access

Sites OK ? Cell and Neighbour

Cells availabilityAlarms/Tickets

Setup /Access

Yes

Setup /Access

Setup Failure Cause?

Capacity Optimisation

BTS/TRANS/FROZBSUL/DL

Interference (DL codes)

AC

TroubleshootingRNC

RF Optimisation

Top (N) RRC Setup and Access failures

Top (N) RAB Setup and Access failures

Coverage/Interference

setup

setup

Interference

Coverage


SRNS Relocation troubleshooting

Yes

NO

Access

Access

Call Setup Success Rate (CSSR) Poor CSSR could be a result of

– Poor coverage or dominance or interference issues in Radio interface– Capacity issues in Radio or Iub interface– Configuration issues in WBTS (parameters or HW)

CSSR is essentially RRC Setup Success * RAB Setup Success (or successful PS session setups in case of PS call)

CSSR covers all the steps from the initial RRC connection request from the UE to the network, through the RRC setup phase and the RAB setup phase, and until user data is starting to get transferred.

The CSSR formulas are for different traffic classes like: – CS voice calls (RNC 565 f)– CS video calls (RNC 566e)– PS RT Streaming Calls (RNC 575 d) – PS NRT Calls (Interactive & Background) (RNC 576d)


Definition of Call Set-Up Success Rate (CSSR)


UERRC: Connection Request

RRC Connection Setup phaseResource Reservation in RNC, BTS, Transmission

RRC: RRC Connection Request Setup

RRC Connection Access phase RNC waits reply from UE

RRC: RRC Connection Completed

RRC: Initial Direct Transfer cm service request

RANAP: Initial UE MessageDIRECT TRANSFER (Call

Proceeding)RANAP: RAB Assignment

Request

RRC: Radio Bearer Set-up

RRC: Radio Bearer Setup Complete

RAB Connection Setup phaseResource Reservation in RNC, BTS, Transmission

RANAP: RAB Assignment ResponseDIRECT TRANSFER (Alerting)

BTS RNC CN

DIRECT TRANSFER (Connect)DIRECT TRANSFER (Connect

Acknowledge)

RAB Connection Access phase RNC waits reply from UE

Call Set-up

Success Rate

Call Set-up Time

RRC Connection Setup & Access and Active


BTSUE RNC CN

RRC: RRC connection Request

RRC: RRC connection Setup

RRC SETUP phase

(Resource Reservation in RNC, BTS, Transport)

RRC ACCESS phase

(RNC waits for Reply from UE)

RRC: RRC connection Setup Complete

RR

C S

etu

p

time

RRC: Initial Direct Transfer

RANAP: Initial UE Message

RANAP: Iu Release Command

UE-CN Signalling

(E.g. RAB Establishment and Release)

RRC: RRC connection Release

RRC: RRC connection Release Complete

Release RRC resources in RNC, BTS, Transport

RRC ACTIVE phase

RRC ACCESS fails if the UE does not reply to RRC: RRC CONNECTION SETUP message with the RRC: RRC CONNECTION SETUP COMPLETE message in given time, if the BTS reports a radio link synchronisation failure or in an RNC internal failure occurs

RRC SETUP fails if some of the needed resources (RNC, BTS, AIR, Transport) are not available. When an RRC setup failure occurs the RNC sends an RRC: RRC CONNECTION REJECT message to UE

RRC ACTIVE fails when an interface related (Iu, Iur , Iub, or Radio) or RNC internal failure occurs, and the failure causes the release of the RRC Connection. When an RRC active failure occurs, the RRC send a RANAP: IU RELEASE REQUEST to all involved CNs and waits for RANAP: IU RELEASE COMMAND message (s)

RRC ACTIVE release cause can be either ISHO, IFHO, SRSN relocation or pre-emption

RAB Setup & Access and Active


RAB Reconfiguration Actions

(Reconfigure RAB resources in RNC, BTS, Transport)

BTSUE RNC CN

RRC: Radio Bearer Setup

RAB SETUP phase

(Resource Reservation in RNC, BTS, Transport)

RAB ACCESS phase

(RNC waits for Reply from UE)

RRC: RB Setup Complete

RA

B S

etup

tim

e

RRC: RB Reconfiguration

RANAP: RAB Assignment Response


Release RAB resources in RNC, BTS, Transmission

RRC Connection Active Phase, UE-CN Signalling

RANAP: RAB Assignment Request


RAB ACTIVE phase

(User Plane Data Transfer)

RANAP: RAB Assignment Request with IE: RAB reconfiguration

RRC: Radio Bearer Release

RRC: RB Reconfiguration Complete

RANAP: RAB Assignment Request with IE: RAB Release

RRC: Radio Bearer Release Complete

RA

B H

old

ing

T

ime

RAB SETUP fails if some of the needed resources (RNC, BTS, AIR, Transport) are not available. When an RAB setup failure occurs the RNC sends a RANAP: RAB ASSINGMENT RESPONSE message to the CN with an appropriate failure cause

RAB ACCESS fails if the UE replies with an RRC: RADIO BEARER SETUP FAILURE message or the connection cannot be established in a give time. When a RAB access failure occurs, the RNC sends a RANAP: RAB ASSINGMENT RESPONSE message to the CN with an appropriate failure cause. Immediately after this, the RNC sends also a RANAP: IU RELEASE REQUEST to the CN and waits for RANAP: IU RELEASE COMMAND message

RAB ACTIVE fails when an interface related (Iu, Iur, Iub, or Radio) or RNC internal failure occurs, and the failure causes the release of the RAB connection.

• If the UE has more than one RAB connection and the failure is not so critical that it would lease to an RRC Connection drop, only the failed RAB connection is released. The RNC sends a RANAP: RAB RELEASE REQUEST message to the CN and waits for a RANAP: RAB RELEASE COMMAND or RANAP: IU RELASE COMMAND from CN

• Otherwise, both the RRC connection and RAB connection (s) are released. The RNC send a RANAP: IU RELASE REQUEST message to the CN and waits for a RANAP: IU RELEASE COMMAND MESSAGE from the CN

RAB Access failures are not so Common

RRC connection set up failureRRC Connection is rejected ICSU can not process the call

No processing power on ICSU unit

Incoming call request can not be handled due to lack of ICSU processing“No hand free” is RNC internal clear code.

RRC Connection Reject Cause: congestion

UE BS RNC

RRC Connection RequestICSU overload

Failure CounterM1001C618

Call Setup Failures


RRC connection setupRAN resources are reserved for signaling connection between UE and RNC

RRC accessConnection between UE and RRC

RRC activeUE has RRC connection. If dropped, also active RAB is dropped.

RAB setupAttempts to start the call

RAB setup access

RAB active phaseUE has RAB connection

CSSR affected if any of the followings take

place.

• RRC Conn. Setup Fail

• RRC Conn. Access Fail

• RAB Setup Fail

• RAB Setup Access Fail

SetupComplete

SetupComplete

AccessComplete

AccessComplete

ActiveComplete

ActiveComplete

SetupSetup AccessAccess ActiveActive

Atte

mpt

s

Setup failures(blocking)

Access failures

Acce

ss

ActiveReleaseActive

Release

ActiveFailuresActive

Failures

RRCDrop

Succe

ss

Phase:

RRC and RAB phases

Call setup Success rate -CSSR

/

Call Setup Success Rate (CSSR)CSSR KPI for CS voice from end user perspective (RNC 565f)

RRC request repetitions done by UE after RRC reject are excluded from denominator (not necessarily seen as failures from the user's perspective)– Emergency calls re-directed to GSM layer are excluded from denominator

The occurred cell re-selections are subtracted both from the numerator and denominator because they are not considered as call attempts from mobile end-user point of view. The UE has made a new RRC connection via another cell and Attempts-counter is updated in the new cell for the new attempt.

))____(

)____((*

)_________

_______

_______

______

______(

)____

_______

____

______

______((*100

_VOICECSATTSTPRABsum

VOICECSCOMPACCRABsum

CALLEMERGREJSTPCONNRRCCONVMTRELACCRRC

CONVMORELACCRRCEMERGENCYRELACCRRC

EMERGENCYREPATTRRCCONVMTREPATTRRC

CONVMOREPATTRRCATTSCALLEMERGENCY

ATTSCALLCONVMTCATTSCALLCONVMOCsum

CONVMTRELACCRRC

CONVMORELACCRRCEMERGENCYRELACCRRC

FAILSCALLEMERGENCYATTSCALLEMERGENCY

FAILSCALLCONVMTCATTSCALLCONVMTC

FAILSCALLCONVMOCATTSCALLCONVMOCsum

CSSRAMR


RRC part

RAB part

_PACKET CALL SETUP SUCCESS RATE


PS Call Setup Success Rate (CSSR)

))____

____(

)____

____((

*

))________

_______

________

_______

______

______(

)________

_______

____

______

______

______

______((*100

_

BACKGPSATTSTPRAB

INTERPSATTSTPRABsum

BACKGPSCOMPACCRAB

INTERPSCOMPACCRABsum

BACKGMTRELACCRRCINTERMORELACCRRC

BACKGMORELACCRRCINTERRELACCRRC

BACKGMTREPATTRRCBACKGMOREPATTRRC

INTERMOREPATTRRCINTERREPATTRRC

ATTSCALLBACKGMTCATTSCALLINTERMTC

ATTSCALLBACKGMOCATTSCALLINTERMOCsum

BACKGMTRELACCRRCINTERMORELACCRRC

BACKGMORELACCRRCINTERRELACCRRC

FAILSCALLEMERGENCYATTSCALLEMERGENCY

FAILSCALLBACKGMTCATTSCALLBACKGMTC

FAILSCALLINTERMTCATTSCALLINTERMTC

FAILSCALLBACKGMOCATTSCALLBACKGMOC

FAILSCALLINTERMOCATTSCALLINTERMOCsum

CSSRPS


RNC_576d- Packet Call Setup Success Ratio [%] over the reporting period. Includes both Interactive and Background PS calls

RRC request repetitions done by UE after RRC reject are included in the formula* The occurred cell re-selections are subtracted both from the numerator and denominator because

they are not considered as call attempts from mobile end-user point of view. The UE has made a new RRC connection via another cell and Attempts-counter is updated in the new cell for the new attempt.

RRC part

RAB part

Low in CSSR: Failure CountersRRC Conn Setup & Access Analysis


RRC_CONN_STP_FAIL_AC

Check UL Interference, DL Power & Code occupancy if there is need to upgrade radio capacity

RRC_CONN_STP_FAIL_BTS

Evaluate NBAP counters (radio link reconf. Failures) and KPIs for troubleshooting BTS resources

Check BTS configuration in terms of CE allocation – Use Channel Element (5001) Counters in order to

evaluate lack of Channel Elements

Expand the Capacity or decrease the traffic offered to the site until the problem is solved

In case BTS is not responding delete and re-create COCO

RRC_CONN_STP_FAIL_TRANS

Evaluate Number of reconfiguration failure due the transmission

Check COCO Configuration

Expand the capacity or decrease the traffic offered to the site until the problem is solved

RRC_CONN_STP_FAIL_RNC

Typically RNC fault or Incoming SRNC Relocation Failure (inter-RNC border)

Required ICSU log tracing if no RNC fault or SRNC relocation problem

Communicate the problem to Care department

RRC_CONN_STP_FAIL_RNTI ALLO FAIL

RNC decides to reject RRC connection request due to RNTI allocation failure caused by RRMU overload

Low in CSSR: Failure CountersRRC Conn Setup & Access Analysis


RRC_CONN_STP_FAIL_IUB_AAL2_TRANS

Updated when there is shortage or blocking of AAL2 resource

A subset of RRC_CONN_FAIL_TRANS which include ERQ/ECF fail due to some reason such as DMPG

problem in RNC + ERQ/ECF fail due to transport resource needed in RNC between RNC/MGW

RRC_CONN_ACC_FAIL_RADIO

Dominant failure causes due to wrong UL or DL coverage

UL Coverage -> Check if cell is affected by an external interference (Thermal Noise measurements).

DL Coverage -> Tune SCCPCH Power if UE does not receive the RRC Setup Message

-> If UE does not synchronize, reduce N312 from 2 to 1 (depends on UE model) or tune CPICHToRefRABOffset vs.

Qqualmin (or Qrxlevmin)

RRC_CONN_ACC_FAIL_MS

UL Coverage -> Tune Cell Dominance (or CPICH) in order to balance UL and DL (if UL interference if not the cause).

Check if cell is affected by an external interference (Thermal Noise measurements).

Low in CSSR: Failure CountersRAB setup & Access Fail Root Cause Analysis: RT and NRT (I/B) domains


RAB_STP_FAIL_XXX_AC

Check UL Interference, DL Power & Code occupancy if there is need to upgrade radio capacity using the already distributed Nokia Capacity Check BO report.

Check PrxTarget / PrxOffset / of the affected cells

RAB_STP_FAIL_XXX_BTS

Evaluate NBAP counters (radio link reconf. Add failures) and KPIs for troubleshooting BTS resources

Check BTS configuration in terms of CE allocation – Use Channel Element (5001) Counters in order to evaluate lack of Channel Elements

Expand the Capacity or decrease the traffic offered to the site until the problem is solved.

In case BTS is not responding delete and re-create COCO

RAB_STP_FAIL_XXX_TRANS

Evaluate Number of reconfiguration failure due the transmission

Check M1005C128 CANC_ADD_SRNC_TRAN_STP_FAIL

Check RAB_STP_FAIL_XXX_IUB_AAL2, M1001C531-C533

Check COCO Configuration

RAB_STP_FAIL_XXX_RNC



Communicate the problem to Care department

Low in CSSR: Failure CountersRAB setup & Access Fail Root Cause Analysis: RT and NRT (I/B) domains


RAB_ACC_FAIL_XXX_UE

Evaluate Cell resource Prx and Ptx parameters (same as RAB_STP_FAIL_XXX_AC Case)

RAB_ACC_FAIL_XXX_RNC



Communicate the problem to Care department.

High in DCR?


Top (N) drops

Cell and its Neighbour

Cells availability

Alarms/Tickets

Configuration &

Parameter audit

SHO Success Rate < 90%?

Conf OK ?

Site OK ?

ISHO Failures

Iur

performance Investigation Iur

Audit adjacent sites for alarms, Availability, configuration and

capacity

TrafficNeighbours’ Performance

(use SHO success per adjs

counters to identify badly

performing neighbours) & Map

3G Cell at RNC

border?

NO

YES

New site ?

Analyse last detailed radio measurements

RF and IF/IS HO neighbour optimisation

No cell found

ratio >40 %

ISHO Success Rate < 95%

RF and ISHO neighbour optimisation

3G cell covers over a coverage

hole ?


Coverage issue (new site needed)

No cell found ratio > 90 % and enough

ADJG

Core: Inners / Outers

audit

2G : TCH blocking

3G : Wrong N’ borgs definition

NO

YES

YES

YES

NO

YES

NO

YES

YES

SHO

ISHO

Top

issues

Call drop analysis process


Start

Best server’s RSCP> -102dBm

Best server’s Ec/No> -12dB

Coverage Optimization

Dominance Optimization

Yes Neighbour list Optimization

Missing Neighbour

Yes

SHO Failed

Investigate possible BTS or RNC problem

NoISHO Failed

No

ISHO Failure Analysis

YesSHO Failure Analysis

No

No

No

AB

Call Drop Analysis process – SHO Analysis


DL ASU received

SC Clash

UE Tx Power Max

Fix SC Clash

CPICH Optimisation

Uplink Interference

Load Optimisation/ External Interferer

Link Unbalanced

Inter RNC HOCheck Iur

Congestion on target cell

Load Optimisation

Check neighbor definition parameters

Check RF Levels

DL Tx Power Max

Start

Yes

No

Yes

No

No

No

Yes

Yes

Yes

Yes

Yes

No

No

No

Yes

No

C

D

Drop call failures – RF issue


RF drops mostly due to poor dominance or interference

Poor coverage could lead to ISHO, although poor dominance or interference can cause ISHO to fail.

Rapid field drop can cause drop due to coverage

Poor dominance or interference can cause Compressed Mode (CM) to start even if RSCP is still good.

In CM UE transmits with higher power (more interference) and spends less time on 3G (less accurate measurement reporting)

Poor dominance or interference can lead to Active Set update failures and eventually to drop call.

Poor dominance causes Active Set update failures

A



DL synchronisation is lost -> UE has stopped transmitting

TrChAgg and DL DPCCH BER high

A



Transport Channel BER. Btw UE<->RNC (MAC layer)

Sometimes DPCCH BER (btw UE<->WBTS) can be a better indicator of what's happening to the dedicated channel than the CPICH EcNo, in particular in the case that power control may not be tracking well

Fairly good CPICH Pilot EcNo

A

Drop Call Failures – System issue BTS

Sudden drop to idle, no disconnect messaging– Site malfunctions to be checked– In the example below site had faulty unit (WTR)


B

Drop to IDLE

Drop Call Failures – System Issues RNC


Sudden “RRC Connection Release”

DPCCH BER“CC Disconnect” due to

“DL RRC Connection Release”

No response to UL Measurement Reports

In the example site had no alarms, good RF & BER

Not able to add SC265 to Active Set, next call on the same cell => no failure.

Difficult to troubleshoot if the failure does not happen systematically => follow up in the next weeks drive / do a separate drive test in the area

B

Drop call failures (SC conflict)


Sudden drop to idle mode (no disconnect messaging)

Cause of the failure: overshooting site and SC reuse

Short term solution to add overshooting neighbour in ADJS definitions

Cell ABC, SC258

Transport channel BLER 100%

C

Drop call failures – Uplink Interference


DUL interference from the SIB7 message

Drop call failures – Link Balance


DUL & DL Power Control commands can help indicating problems in link balance.

PC frequency is 1500 Hz, thus ideally the sum of PC commands to increase or decrease power is 1500

E.g. if the sum of UL PC commands is < 1500, this would indicate UE is starting to loose synchronization

in Compressed Mode there is less PC commands, UE spends time on 2G

UE RX power control message: DL reception weak -> UE is ordering WBTS to increase power.

Sum of UL PC commands < 1500, UE not receiving all the PC commands.

Drop call failures – System issue RNC or BTS ?

“CC Disconnect” due to “DL RRC Connection Release” is just a consequence of failure which can be due to different reasons

– From UE point of view L3-messaging does not identify the point of failure distinctly

– BTS or RNC failure? => Suspect BTS first, then RNCRule out BTS failures

– Check the site performance from Counters (Iub, Service level, cell resources SHO, etc) and that site is carrying traffic

– PrxNoise, receive link parameters, alarms – SC–reuse– UE performance ?

Identified causes for Active Set Update failure– “Deaf” sites (PrxNoise)– Faulty HW– SC-reuse Presentation / Author / Date

HSDPA low throughput?


OSS counters measurement data

collection

Identify Low

throughput areas if

exist

Low throughput due to low Ec/No or CQI Identify reason for low

throughput if not RF• Mobility (cell change too frequent)• No HSDPA coverage• Iub / Iu User Plane Capacity• Other HSDPA users in same WBTS/Cell• DCH traffic too High (DPA, HSDPA Priority)Start Parameter Optimisation by tuning• HSPDA Mobility parameters (FMCS)• PtxMaxHSDPA (WCEL)• Dynamic Flow Control set to ON (WBTS)

If low throughput due to low Ec/No or Poor CQI, identify reason • Bad Coverage Planning• Quality issue due the neighbour planning

No Optimisation Required

Implement Changes

NO

• HSDPA Parameters are correctly set up• Change Antenna tilt etc.

START

NO

If throughput is low in network level, the reason can be also

FTP/HTTP server settings (fire wall), Measurement tools

etc.

• Low HSDPA throughput root causes analysis process

Business Object report already delivered in order to measure all

related HSDPA throughput KPIs

YES

YES

RU10 Reporting Suite• RNC level system

program added• Corrections to

Capacity report• Modifications to

Service level report (Streaming class added+ some other corrections)

Report Topic Name Report Name Report ID

1. System Program System Program RNC Level RSRAN0841. System Program System Program Cell Level RSRAN0002. Capacity RNC Capacity RSRAN0682. Capacity Node B Capacity RSRAN0662. Capacity Cell Capacity RSRAN0672. Capacity NRT Radio Bearer Statistics RSRAN0133. Service Level Service/Session Accessibility Analysis RSRAN0733. Service Level Service/Session Retainability Analysis RSRAN0793. Service Level RAB Holding Times RSRAN0213. Service Level Service Summary RSRAN0034. Traffic Allocated Traffic Amounts (R99 + HSPA) RSRAN0704. Traffic Cell Data Volume and Throughput at RNC RSRAN0774. Traffic Traffic Summary RSRAN0264. Traffic Used CE Capacity per RB Type in RNC RSRAN0224. Traffic Utilization Shares of Total Traffic Allocation Amounts RSRAN0715. Mobility and Handover Active Set Size for NRT-RT Traffic RSRAN0785. Mobility and Handover HSPA Serving Cell Change RSRAN0335. Mobility and Handover IFHO Adjacencies RSRAN0445. Mobility and Handover Inter-System Handover per Cause RSRAN0195. Mobility and Handover Inter-System Handover Performance RSRAN0235. Mobility and Handover Inter-System Handover Reasons RSRAN0185. Mobility and Handover ISHO Adjacencies RSRAN0455. Mobility and Handover Load Based HO Related Resources RSRAN0475. Mobility and Handover Load Based IFHO/ISHO Performance RSRAN0485. Mobility and Handover Load Based IFHO/ISHO Triggering RSRAN0495. Mobility and Handover Service Based IFHO/ISHO Performance RSRAN0505. Mobility and Handover SHO Adjacencies RSRAN0465. Mobility and Handover Soft Handover Performance RSRAN028


RNC_169e:DR + GAN HO

added, but load & service based

counters removed

RU10 Reporting Suite• Modifications to

KPIs due to streaming class + 64 HSDPA users/cell

Report Topic Name Report Name Report ID

8. Transport ATM Interface Traffic Load RSRAN0818. Transport ATM VCC Traffic Load RSRAN0838. Transport ATM VPC Traffic Load RSRAN0828. Transport FTM Packet Transport Performance RSRAN0768. Transport FTM Performance RSRAN0728. Transport Iu-PS Throughputs RSRAN0648. Transport Iub Throughputs RSRAN0808. Transport Traffic on AAL5 RSRAN0318. Transport Traffic on ATM Layer RSRAN0298. Transport Traffic on Physical Medium Sub-Layer RSRAN0308. Transport Transport Resource Reservations RSRAN0697. HSPA Channel Switching and HSPA Layering RSRAN0757. HSPA CQI Distribution RSRAN0397. HSPA HSPA Code and Modulation Usage RSRAN0347. HSPA HSPA Power Distribution RSRAN0747. HSPA MAC-hs Efficiency RSRAN0407. HSPA MAC-hs Retransmissions by Code and Modulation Usage RSRAN0417. HSPA Number of HSPA Users and UE capability RSRAN0516. Signalling NBAP Signalling RSRAN0276. Signalling RRC Signalling RSRAN038


3G KPI Analysis Report

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