WCDMA : KPI ANALYSIS & OPTIMIZATION
Network planning& Optimization

Illustration on RAN KPI-RU20
SRNC
Relocation

RNC
Accessibility:
RRC Setup &
Access Rate
RAB Setup &
Access Rate
Call Setup Success
Rate
PS setup success rate (NRT,HSDPA,
HSUPA)

SRNC

UE

BTS1

X

Retainability:
RRC Drop Rate
RAB Drop Rate
PS success rate
(NRT, HSDPA,
HSUPA)

RNC
Usage:
Cell Availability
Ave. Uplink
Load
Ave. Downlink
Load
HSDPA
Throughput
Cell Throughput

Mobility:
SHO/ISHO Success
Rate
SHO Overhead
HDSPA/HSUPA SCC success / Date
Presentation / Author rate

BTS2

X

Preemption

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 Definitions

The 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

Presentation / Author / Date

AMR CS Call Phases
UE

WBTS

DRNC

1. Cell search, BCCH decoding & RACH access
2. RRC connection set-up
3. UE <--> CS-CN signalling
4. RAB set-up
5. UE <--> CS-CN Signalling
6. Service Established
7. Branch addition/deletion & Active set update
8. Service Released

SRNC

CN

Call Setup Failure
Analysis
Process__DT

Start

A

Best server’s
RSCP > -102dBm

Missing
Neighbour ?

Yes
Best server’s
Ec/No > -12dB

Coverage Optimization

No

No

Yes

No

Dominance Optimization

Neighbour list Optimization

Yes

B

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

No

AICH(ACK) received?

Report & Finish
(Check failure cause)
No

Yes
“RRC Connection
Setup” received?

No

Yes

D

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

No

No

AC optimization (check PrxNoise
& interferer around BTS)

(DCH) “RRC Connection setup
Completed” sent from UE?

“Radio Bearer setup failure”Received? Ye s C

Yes

Report & Finish

Yes
Report & Finish
(Check failure cause)

“RRC Setup
Reject” received?

E

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

Call setup failures – Missing
A
Neighbour
Missing neighbour analysis over the whole route (3G-3G, 3G-2G)
Search for failures due to missing 3G3G neighbours
Search for failures due to missing 3G –
2G neighbours
– It is suggested to place 2G scanner to the test vehicle

Call Setup Failure Analysis-B
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

Call Setup Failure Analysis-B
RNC
WBTS
UE
Block B Preamble/RACH

Acquisition Indicator/AICH
RRC: RRC Connection Request/PRACH
NBAP: RADIO LINK SETUP REQUEST
NBAP: RADIO LINK SETUP RESPONSE

RRC: RRC CONNECTION SETUP/FACH
L1 Synchronisation
NBAP: SYNCHRONISATION INDICATOR

RRC: RRC CONNECTION SETUP COMPLETE/DCH
UE in CELL_DCH state

B

RACH Process
Downlink
BS

L1 ACK / AICH
Not detected
UEtxPowerMaxPRACH

PowerRampStepPRACHpreamble

……
Uplink
MS

……
Message part

Preamble Preamble
1
2

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

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

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

Call Setup Failure Analysis-B
Block BSolutions for RACHNo To increase PRACH_Preamble_retrans optimisation Max UE Tx power hit
To increase PRACH_Preamble_retrans
Or PowerRampStepPRACHPreamble
Or PowerRampStepPRACHPreamble

the UE_P_MAX(24dBm)?

Yes
Yes
Is UL Interference abnormally HIGH?

Report there might be an interfering
Report there might be an interfering source Nearby the serving cell source Nearby the serving cell

No
Change the Serving cell to cover the problem Area
Change the Serving cell to cover the problem Area
=> UE is too far to reach the serving cell
=> UE is too far to reach the serving cell

Call Setup Failure Analysis-B
Block B
Open loop Power
Control parameters from
RACH Info message

Call setup failures – System
C
No response to “RRC Connection Request” issue BTS
–
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)

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

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.

D
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.

Call setup failures – System
E
issue RNC
• “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.

•

Call setup failures – System
E
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.

Call setup failures – Core
“CM Service Abort” after
NW
“CM Service Request”
Good RF conditions
“Security Mode
Command”-message
not received by UE, thus the failure is believed to be at Core
Network.

UE

Node B

E

MGW

RNC

RR C Connection E stablishment
Initial Direct Transfer (CM Service Request)

SC CP : Connection R equest
S CCP : Connection Confirm
Location Reporting Control
Common ID
S ecurity Mode Command

• R R C: Initial Direct Transfer message is sent using acknowledged mode R LC 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 ultimedia gateway. The NAS the m message includes the IMSI as a UE identity

• The SCCP : Connection R equest message establishes the connection orientated signallingn link i

the same way as it was for the R RC connection phase.This does no t reserve any resources for the
AMR call itself.

• The Connection Confirm message identifies the RNC with a destination local reference w the hich is 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. Call setup failures – System
E
“CC Disconnect” after “CC (test number)
Issue
Progress”
Cause: recovery on timer expiry
The 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

State Transition triggers

Phys. Reconfiguration

After RT call with inactive
PS RABs

Frequent cell updates

Phys. Reconfiguration

UTRA RRC Connected Mode

URA Update, UL data, Paging

Fast call setup from
CELL_PCH

CELL_PCH

URA_PCH

Fast call setup from
URA_PCH

Phys. Reconfiguration UL/DL activation timer

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

CELL_FACH

CELL_DCH

Phys. Reconfiguration
Cell Update, UL data, paging

RB. Reconfiguration
Traffic Volume, RACH load
RRC Setup / Release

RB. Reconfiguration
Inactivity Timer, Overload
IDLE Mode

State Transition triggers
IDLE

Call Setup 1.2 sec

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

Transition FACH-PCH du to inactivity  2 sec
)Parameter)

FACH
DCH

IDLE

Wake up time PCH – DC due to activity  3 sec

CELL_DCH State

• 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 active set cell 25

© 2006 Nokia
Layer 3 (RRC) /
Kittipong Thamapa

active set cell CELL_FACH State
• 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

26

© 2006 Nokia
Layer 3 (RRC) /
Kittipong Thamapa

serving cell CELL_PCH no DCCH and DTCH and URA_PCH State
•

• 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 •one or several cells
URA – UTRAN Registration Area
•independent from LA
URA 1
RNC
supply area URA 2
27

© 2006 Nokia
Layer 3 (RRC) /
Kittipong Thamapa

URA 3

RU20 New Counters &
Measurements

/

Cell Availability
RNC_183c Cell Availability KPI counts Cell availability from user point of view:
Cell _ Availability =

100 * sum( AVAIL _ WCELL _ IN _ WO _ STATE ) sum( AVAIL _ WCELL _ EXIST _ IN _ RNW _ DB )

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

Presentation / Author / Date

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 _ STATE )
100 * sum AVAIL _ WCELL _ IN _ WO by
Cell _ Availabilitystate (BLU), Counts Cell availability from network user _ excluding _ BLU _ state =
 AVAIL _ WCELL _ EXIST _ IN _ RNW _ DB  sum  − AVAIL _ WCELL _ BLOCKED _ BY _ USER 

point of view:


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 Presentation / Author / Date

CSSR definition

DNO Optimization Processes / JC
Ejarque

Low in CSSR?
Call Setup Phases
Identify call setup failure phases

CSSR affected if any of the followings take place. 1.
RRC Conn. Setup Fail
2.
RRC Conn. Access Fail
3.
RAB Setup Fail
4.
RAB Setup Access Fail

Call Setup Success

Call Drop

Connected

Call Setup Phase
RRC
RRC
RRC
RRC
Conn. Req Conn. Setup Conn. Acc Conn. Act

RAB Setup

DNO Optimization Processes / JC
Ejarque

RAB Drop

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

Top (N) RAB Setup and Access failures

Top (N) RRC Setup and Access failures

Cell and Neighbour
Cells availability
Alarms/Tickets

Setup Failure
Cause?

Sites OK ?

RNC
Yes
Setup
/Access

setup

Setup
/Access

Troubleshooting

BTS/TRANS/FROZBS
AC

setup

UL/DL
Interference
(DL codes)

Access

Capacity Optimisation
Access

Yes
3G cell at inter-RNC border ?

SRNS Relocation troubleshooting NO
Interference
Coverage/Interf erence RF Optimisation
Coverage

DNO Optimization Processes / JC
Ejarque

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)
Presentation / Author / Date

UE

Definition of Call Set-Up
Success Rate (CSSR)

RRC: Connection Request

RNC

BTS

CN

RRC Connection Setup phase

Resource 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
DIRECT TRANSFER (Call
Proceeding)

RANAP: Initial UE Message

RAB Connection Setup phase

RANAP: RAB Assignment
Request

Resource Reservation in RNC, BTS, Transmission

RRC: Radio Bearer Setup

RAB Connection Access phase
RNC waits reply from UE

RRC: Radio Bearer
Setup Complete
DIRECT TRANSFER (Alerting)
DIRECT TRANSFER (Connect)
DIRECT TRANSFER (Connect
Acknowledge)
Presentation / Author / Date

RANAP: RAB Assignment
Response

Call Setup
Success
Rate
Call Setup Time

UE

RRC Connection Setup &
Access and Active
RNC

BTS

CN

RRC: RRC connection Request
RRC SETUP phase
RRC Setup time

(Resource Reservation in RNC, BTS,
Transport)
RRC: RRC connection Setup
RRC ACCESS phase
(RNC waits for Reply from UE)
RRC: RRC connection Setup Complete
RRC ACTIVE phase
RRC: Initial Direct Transfer
RANAP: Initial UE Message
UE-CN Signalling
(E.g. RAB Establishment and Release)

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 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 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)

RANAP: Iu Release Command
RRC: RRC connection Release
RRC: RRC connection Release Complete
Release RRC resources in RNC, BTS,
Transport

RRC ACTIVE release cause can be either
ISHO, IFHO, SRSN relocation or preemption
Presentation / Author / Date

RAB Setup & Access and
Active

RAB Access failures are not so Common

UE

RNC

BTS

CN

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

RRC Connection Active Phase, UE-CN Signalling
RANAP: RAB Assignment Request
RAB SETUP phase
RAB Setup time

(Resource Reservation in RNC, BTS, Transport)
RRC: Radio Bearer Setup
RAB ACCESS phase
(RNC waits for Reply from UE)
RRC: RB Setup Complete
RANAP: RAB Assignment Response

RAB ACTIVE phase

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

(User Plane Data Transfer)
RAB Holding Time

RANAP: RAB Assignment Request with IE: RAB reconfiguration
RAB Reconfiguration Actions
(Reconfigure RAB resources in RNC, BTS,
Transport)
RRC: RB Reconfiguration
RRC: RB Reconfiguration Complete
RANAP: RAB Assignment Response
RANAP: RAB Assignment Request with IE: RAB Release
RRC: Radio Bearer Release
RRC: Radio Bearer Release Complete
RANAP: RAB Assignment Response
Release RAB resources in RNC, BTS,
Transmission

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

Presentation / Author / Date

RRC connection set up failure o processingConnection unit
RRC power on ICSU is rejected ICSU can not process the call

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

UE

BS
RRC Connection Request

RNC
ICSU overload

RRC Connection Reject
Cause: congestion

Failure Counter M1001C618

Call Setup Failures
RRC and RAB phases
Phase:

Setup

Active

Access
Complete

Active
Release

Attempts

Active
Failures

Success

Active
Complete
Access

Setup
Complete

Access

RRC
Drop

Access failures
Setup failures
(blocking)
Presentation / Author / Date

RRC connection setup
RAN resources are reserved for signaling connection between UE and RNC
RRC access
Connection between UE and
RRC
RRC active
UE has RRC connection. If dropped, also active RAB is dropped. RAB setup
Attempts to start the call
RAB setup access
RAB active phase
UE 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

Call setup Success rate
-CSSR

/

Call Setup Success Rate
(CSSR) user perspective (RNC 565f)
CSSR KPI for CS voice from end
100 * ( sum( MOC _ CONV _ CALL _ ATTS − MOC _ CONV _ CALL _ FAILS
+ MTC _ CONV _ CALL _ ATTS − MTC _ CONV _ CALL _ FAILS
+ EMERGENCY _ CALL _ ATTS − EMERGENCY _ CALL _ FAILS
− RRC _ ACC _ REL _ EMERGENCY − RRC _ ACC _ REL _ MO _ CONV
− RRC _ ACC _ REL _ MT _ CONV )
AMR _ CSSR = sum( MOC _ CONV _ CALL _ ATTS + MTC _ CONV _ CALL _ ATTS
+ EMERGENCY _ CALL _ ATTS − RRC _ ATT _ REP _ MO _ CONV

RRC part − RRC _ ATT _ REP _ MT _ CONV − RRC _ ATT _ REP _ EMERGENCY
− RRC _ ACC _ REL _ EMERGENCY − RRC _ ACC _ REL _ MO _ CONV
− RRC _ ACC _ REL _ MT _ CONV − RRC _ CONN _ STP _ REJ _ EMERG _ CALL )

*

( sum( RAB _ ACC _ COMP _ CS _ VOICE ) sum( RAB _ STP _ ATT _ CS _ VOICE ))

RAB part 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
Presentation / Author / Date and denominator because they are not considered as call attempts

_PACKET CALL SETUP
SUCCESS RATE

Presentation / Author / Date

PS Call Setup Success Rate
(CSSR)
RNC_576d- Packet Call Setup Success Ratio [%] over the reporting period.
Includes both(MOC _ INTER _ CALL _ ATTS − MOC _Background PS calls
Interactive and INTER _ CALL _ FAILS
100 * ( sum
+ MOC _ BACKG _ CALL _ ATTS − MOC _ BACKG _ CALL _ FAILS
+ MTC _ INTER _ CALL _ ATTS − MTC _ INTER _ CALL _ FAILS
+ MTC _ BACKG _ CALL _ ATTS − MTC _ BACKG _ CALL _ FAILS
+ EMERGENCY _ CALL _ ATTS − EMERGENCY _ CALL _ FAILS
− RRC _ ACC _ REL _ INTER − RRC _ ACC _ REL _ MO _ BACKG
( sum( RAB _ ACC _ COMP _ PS _ INTER
− RRC _ ACC _ REL _ MO _ INTER − RRC _ ACC _ REL _ MT _ BACKG )
+ RAB _ ACC _ COMP _ PS _ BACKG )
PS _ CSSR =
*
sum( MOC _ INTER _ CALL _ ATTS + MOC _ BACKG _ CALL _ ATTS sum( RAB _ STP _ ATT _ PS _ INTER

RRC part MTC _ INTER _ CALL _ ATTS + MTC _ BACKG _ CALL _ ATTS
− RRC _ ATT _ REP _ INTER − RRC _ ATT _ REP _ MO _ INTER
− RRC _ ATT _ REP _ MO _ BACKG − RRC _ ATT _ REP _ MT _ BACKG
− RRC _ ACC _ REL _ INTER − RRC _ ACC _ REL _ MO _ BACKG
− RRC _ ACC _ REL _ MO _ INTER − RRC _ ACC _ REL _ MT _ BACKG ))

+ RAB _ STP _ ATT _ PS _ BACKG ))

RAB part 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 enduser point of view. The UE has made Author / Date connection via another cell and
Presentation / a new RRC
Attempts-counter is updated in the new cell for the new attempt.

Low in CSSR: Failure Counters
RRC 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
DNO Optimization Processes / JC
Ejarque

Low in CSSR: Failure Counters
RRC 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).

DNO Optimization Processes / JC
Ejarque

Low in& CSSR: Failure Counters
RAB 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
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
DNO Optimization Processes / JC
Ejarque

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

DNO Optimization Processes / JC
Ejarque

High in DCR?
Top (N) drops

Cell and its Neighbour
Cells availability
Alarms/Tickets

Neighbours’ Performance
(use SHO success per adjs counters to identify badly performing neighbours) & Map

Site OK ?
YES

Audit adjacent sites for alarms, Availability, configuration and capacity NO

Configuration &
Parameter audit

Conf OK ?
YES
SHO
Success
Rate <
90%?

SHO

3G Cell at
RNC
border?

ISHO
Failures

ISHO

Core: Inners / Outers audit YES

No cell found ratio >40
%

Iur performance Investigation Iur

New site ?
Analyse last detailed radio measurements

NO

YES

To p iss ue s

YES

YES

NO

2G : TCH blocking
3G : Wrong N’ borgs definition

Traffic

RF and IF/IS HO neighbour optimisation

3G cell covers over a coverage hole ?

3G cell at inter-RNC border ?

RF and ISHO neighbour optimisation YES

NO
ISHO
Success
Rate <
95%

No cell found ratio > 90 % and enough
ADJG

DNO Optimization Processes / JC
Ejarque

Coverage issue (new site needed) Call drop analysis process
Start

SHO Failure
Analysis

Yes

SHO Failed
No

ISHO
Failure
Analysis

Yes

ISHO Failed
No
No

Best server’s
RSCP> -102dBm

No

Coverage Optimization
No

Missing
Neighbour
Best server’s
Ec/No> -12dB

B

Investigate possible
BTS or RNC problem

A

Presentation / Author / Date

Yes

Dominance Optimization
Neighbour list
Optimization

Call Drop Analysis process –
SHO Analysis
Start

Check Iur

Yes

Inter RNC HO

Check neighbor definition parameters
No
Fix SC Clash

Load
Optimisation

Yes

C
Yes

No

SC Clash
No

Yes

Congestion on target cell

UE Tx
Power Max

Yes

No

Check RF Levels

Yes

No
DL Tx
Power Max

DL ASU received No

Uplink
Interference

Yes

Load Optimisation/
External Interferer

D

No

Link
Unbalanced
No
Presentation / Author / Date

Yes

CPICH Optimisation

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.

Presentation / Author / Date

Poor dominance causes Active Set update failures

A

Drop call failures – RF issue

DL synchronisation is lost ->
UE has stopped transmitting
TrChAgg and DL
DPCCH BER high

Presentation / Author / Date

A

Drop call failures – RF issue

A

Fairly good
CPICH Pilot
EcNo
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

Presentation / Author / Date

Drop Call Failures – System B issue BTS
Sudden drop to idle, no disconnect messaging
– Site malfunctions to be checked
– In the example below site had faulty unit (WTR)

Drop to
IDLE

Presentation / Author / Date

Drop Call Failures – System B
DPCCH
Issues RNC
“CC Disconnect” due to
BER
“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 Sudden “RRC
Connection
Release”
Presentation / Author / Date

Drop call failures (SC conflict) Transport
Sudden drop to idle channel mode (no disconnect messaging) Cause of the failure: overshooting site and
SC reuse
Short term solution to add overshooting neighbour in ADJS definitions BLER 100%

Cell ABC, SC258

Presentation / Author / Date

C

Drop call failures – Uplink
Interference
UL interference from the
SIB7 message

Presentation / Author / Date

D

Drop call failures – Link
UL & DL Power Control commands can help indicating problems in link Balance 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

D

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.

Presentation / Author / Date

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 RNC
Rule 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
• Low HSDPA throughput root causes analysis process throughput? START
OSS counters measurement data collection Identify
Low
throughput areas if exist YES

YES

Low through put due to low
Ec/No
or CQI
If low throughput due to low Ec/No or
Poor CQI, identify reason • Bad Coverage
Planning
• Quality issue due the neighbour planning • HSDPA
Parameters are correctly set up
• Change Antenna tilt etc.
Implement
Changes

NO

If throughput is low in network level, the reason can be also
FTP/HTTP server settings (fire wall),
Measurement tools etc. No Optimisation
Required
NO
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 Business Object report already delivered in same WBTS/Cell order to measure all
Start Parameter
• DCH traffic too High (DPA, related HSDPA
Optimisation by
HSDPA Priority) tuning throughput KPIs
• HSPDA Mobility parameters (FMCS)
• PtxMaxHSDPA (WCEL)
• Dynamic Flow Control set to ON (WBTS)

DNO Optimization Processes / JC
Ejarque

RU10 Reporting Suite
• RNC level system program added • Corrections to
Capacity report
• Modifications to
Service level report (Streaming class added+ some other RNC_169e:DR
+ GAN HO corrections) added, but load
& service based counters removed

Report Topic Name
1. System Program
1. System Program
2. Capacity
2. Capacity
2. Capacity
2. Capacity
3. Service Level
3. Service Level
3. Service Level
3. Service Level
4. Traffic
4. Traffic
4. Traffic
4. Traffic
4. Traffic
5. Mobility and Handover
5. Mobility and Handover
5. Mobility and Handover
5. Mobility and Handover
5. Mobility and Handover
5. Mobility and Handover
5. Mobility and Handover
5. Mobility and Handover
5. Mobility and Handover
5. Mobility and Handover
5. Mobility and Handover
5. Mobility and Handover
5. Mobility and Handover

Report Name
System Program RNC Level
System Program Cell Level
RNC Capacity
Node B Capacity
Cell Capacity
NRT Radio Bearer Statistics
Service/Session Accessibility Analysis
Service/Session Retainability Analysis
RAB Holding Times
Service Summary
Allocated Traffic Amounts (R99 + HSPA)
Cell Data Volume and Throughput at RNC
Traffic Summary
Used CE Capacity per RB Type in RNC
Utilization Shares of Total Traffic Allocation Amounts
Active Set Size for NRT-RT Traffic
HSPA Serving Cell Change
IFHO Adjacencies
Inter-System Handover per Cause
Inter-System Handover Performance
Inter-System Handover Reasons
ISHO Adjacencies
Load Based HO Related Resources
Load Based IFHO/ISHO Performance
Load Based IFHO/ISHO Triggering
Service Based IFHO/ISHO Performance
SHO Adjacencies
Soft Handover Performance

Presentation / Author / Date

Report ID
RSRAN084
RSRAN000
RSRAN068
RSRAN066
RSRAN067
RSRAN013
RSRAN073
RSRAN079
RSRAN021
RSRAN003
RSRAN070
RSRAN077
RSRAN026
RSRAN022
RSRAN071
RSRAN078
RSRAN033
RSRAN044
RSRAN019
RSRAN023
RSRAN018
RSRAN045
RSRAN047
RSRAN048
RSRAN049
RSRAN050
RSRAN046
RSRAN028

•

RU10 Reporting Suite

Modifications to KPIs due to streaming class
+ 64 HSDPA users/cell Report Topic Name
8. Transport
8. Transport
8. Transport
8. Transport
8. Transport
8. Transport
8. Transport
8. Transport
8. Transport
8. Transport
8. Transport
7. HSPA
7. HSPA
7. HSPA
7. HSPA
7. HSPA
7. HSPA
7. HSPA
6. Signalling
6. Signalling

Report Name
ATM Interface Traffic Load
ATM VCC Traffic Load
ATM VPC Traffic Load
FTM Packet Transport Performance
FTM Performance
Iu-PS Throughputs
Iub Throughputs
Traffic on AAL5
Traffic on ATM Layer
Traffic on Physical Medium Sub-Layer
Transport Resource Reservations
Channel Switching and HSPA Layering
CQI Distribution
HSPA Code and Modulation Usage
HSPA Power Distribution
MAC-hs Efficiency
MAC-hs Retransmissions by Code and Modulation Usage
Number of HSPA Users and UE capability
NBAP Signalling
RRC Signalling

Presentation / Author / Date

Report ID
RSRAN081
RSRAN083
RSRAN082
RSRAN076
RSRAN072
RSRAN064
RSRAN080
RSRAN031
RSRAN029
RSRAN030
RSRAN069
RSRAN075
RSRAN039
RSRAN034
RSRAN074
RSRAN040
RSRAN041
RSRAN051
RSRAN027
RSRAN038

/