94516831 3G KPI Analysis Report

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Full text

(1)

WCDMA : KPI ANALYSIS & OPTIMIZATION

(2)

Illustration on RAN KPI-RU20

Presentation / Author / Date SRNC Relocation RNC UE BTS1 BTS2 RNC Accessibility: RRC Setup & Access Rate RAB Setup &

Access Rate Call Setup Success

Rate PS setup success rate (NRT,HSDPA, HSUPA)

X

Retainability: RRC Drop Rate RAB Drop Rate PS success rate (NRT, HSDPA, HSUPA) Mobility: SHO/ISHO Success Rate SHO Overhead HDSPA/HSUPA SCC success rate Usage: Cell Availability Ave. Uplink Load Ave. Downlink Load HSDPA Throughput Cell Throughput

X

Pre-emption SRNC

(3)

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)

(4)

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”

(5)

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

(6)

DRNC

UE WBTS SRNC CN

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

(7)

Start Best server’s RSCP > -102dBm Best server’s Ec/No > -12dB Coverage Optimization Dominance Optimization AICH(ACK) received?

Yes Missing Neighbour ?

Neighbour list Optimization

No No

No Yes

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

“RRC Connection Setup” received?

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

“Radio Bearer setup failure”Received?

Report & Finish Check 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

B

C

D

E

Yes Ye s No No No No

(8)

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

(9)

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.

(10)

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

(11)

RACH Process

Downlink BS L1 ACK / AICH Uplink MS Preamble 1 Not detected Message part Preamble 2 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

(12)

Call Setup Failure Analysis-

Block

B-Solutions for RACH optimisation

Max UE Tx power hit

the UE_P_MAX(24dBm)? To increase Or To increase PRACH_Preamble_retransOr PowerRampStepPRACHPreamblePowerRampStepPRACHPreamblePRACH_Preamble_retrans

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

(13)

Call Setup Failure Analysis-

Block B

B

Open loop Power

Control parameters from RACH Info message

(14)

Call setup failures – System

issue BTS

No 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)

(15)

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

(16)

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

overload thresholds (PrxTarget + PrxOffset and PtxTarget +

PtxOffset) then AC can't admit more RABs to the cell

(17)

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.

(18)

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.

(19)

• “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.

E

Call setup failures – System

issue RNC

(20)

• “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.

E

Call setup failures – System

issue RNC

(21)

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 Node B RNC MGW

RRC Connection Establishment

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

SCCP : Connection Confirm Location Reporting Control

RRC: Initial Direct Transfermessage 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 Confirmmessage identifies the RNC with a destination local reference which is the same as the source reference within the Connection Requestmessage

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

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

• The RANAP: Common IDmessage specifies the IMSI belonging to the UE

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

(22)

Call setup failures – System

Issue (test number)

“CC Disconnect” after “CC 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

E

(23)

CELL_PCH URA_PCH

CELL_FACH CELL_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

(24)

State Transition triggers

IDLE 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)

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

CELL_DCH State

active set cell active set cell • 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

(26)

26 © 2006 Nokia Layer 3 (RRC) / Kittipong Thamapa

CELL_FACH State

serving cell • 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

(27)

27 © 2006 Nokia Layer 3 (RRC) / Kittipong Thamapa

CELL_PCH and URA_PCH State

URA – UTRAN Registration Area

URA 1 URA 2 URA 3 RNC supply 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

(28)

RU20 New Counters &

Measurements

(29)

Cell Availability

RNC_183c Cell Availability KPI counts Cell availability from

user point of view:

Presentation / Author / Date

(

)

(

AVAIL WCELL EXIST IN RNW DB

)

sum STATE WO IN WCELL AVAIL sum ty Availabili Cell _ _ _ _ _ _ _ _ _ * 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

(30)

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:

Presentation / Author / Date

(

)

    − = USER BY BLOCKED WCELL AVAIL DB RNW IN EXIST WCELL AVAIL sum STATE WO IN WCELL AVAIL sum state BLU excluding ty Availabili Cell _ _ _ _ _ _ _ _ _ _ _ _ _ * 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

(31)

CSSR definition

DNO Optimization Processes / JC Ejarque

(32)

Low in CSSR?

Identify call setup failure phases

DNO Optimization Processes / JC Ejarque

Call Setup 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 Phase

RRC Conn. Req RRC Conn. Setup RRC Conn. Acc RRC Conn. Act

RAB Setup RAB Drop

Call Setup Success Call Drop

(33)

Low in CSSR?

RRC/RAB Setup & Access Analysis

Process Flow Chart

DNO Optimization Processes / JC Ejarque

Sites OK ? Cell and Neighbour

Cells availability Alarms/Tickets Setup /Access Yes Setup /Access Setup Failure Cause? Capacity Optimisation BTS/TRANS/FROZBS UL/DL Interference (DL codes) AC Troubleshooting RNC RF Optimisation Top (N) RRC Setup

and Access failures and Access failuresTop (N) RAB Setup

Coverage/Interf erence setup setup Interference Coverage 3G cell at inter-RNC border ? SRNS Relocation troubleshooting Yes NO Access Access Sites OK ? Cell and Neighbour

Cells availability Alarms/Tickets Setup /Access Yes Setup /Access Setup Failure Cause? Capacity Optimisation BTS/TRANS/FROZBS UL/DL Interference (DL codes) AC Troubleshooting RNC RF Optimisation Top (N) RRC Setup

and Access failures and Access failuresTop (N) RAB Setup

Coverage/Interf erence setup setup Interference Coverage 3G cell at inter-RNC border ? SRNS Relocation troubleshooting Yes NO Access Access

(34)

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)

(35)

Definition of Call Set-Up

Success Rate (CSSR)

Presentation / Author / Date UE

RRC: Connection Request

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

RANAP: Initial UE Message DIRECT TRANSFER (Call

Proceeding)

RANAP: RAB Assignment Request

RRC: Radio Bearer Set-up

RRC: Radio Bearer Setup Complete

RAB Connection Setup phase

Resource Reservation in RNC, BTS, Transmission

RANAP: RAB Assignment Response

DIRECT 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

(36)

RRC Connection Setup &

Access and Active

Presentation / Author / Date

BTS UE 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

R R C S e tu p ti m e

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

(37)

RAB Setup & Access and

Active

Presentation / Author / Date

RAB Reconfiguration Actions (Reconfigure RAB resources in RNC, BTS,

Transport) BTS

UE 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 R A B S e tu p tim e RRC: RB Reconfiguration

RANAP: RAB Assignment Response

RANAP: RAB Assignment Response Release RAB resources in RNC, BTS,

Transmission

RRC Connection Active Phase, UE-CN Signalling RANAP: RAB Assignment Request

RANAP: RAB Assignment Response

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

R A B H o ld in g T im e

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

(38)

RRC connection set up

failure

RRC 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 Request ICSU overload

(39)

Call Setup Failures

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

Setup Complete Setup Complete Access Complete Access Complete Active Complete Active Complete

Setup

Setup

Access

Access

Active

Active

A tte m p ts Setup failures (blocking) Access failures A cc e ss ReleaseActive Active Release Active Failures Active Failures RRC Drop S u cc e ss Phase:

(40)

Call setup Success rate

-CSSR

(41)

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 _ VOICE CS ATT STP RAB sum VOICE CS COMP ACC RAB sum CALL EMERG REJ STP CONN RRC CONV MT REL ACC RRC CONV MO REL ACC RRC EMERGENCY REL ACC RRC EMERGENCY REP ATT RRC CONV MT REP ATT RRC CONV MO REP ATT RRC ATTS CALL EMERGENCY ATTS CALL CONV MTC ATTS CALL CONV MOC sum CONV MT REL ACC RRC CONV MO REL ACC RRC EMERGENCY REL ACC RRC FAILS CALL EMERGENCY ATTS CALL EMERGENCY FAILS CALL CONV MTC ATTS CALL CONV MTC FAILS CALL CONV MOC ATTS CALL CONV MOC sum CSSR AMR − − − − − − − + + − − − − + − + − =

Presentation / Author / Date

RRC part

RAB part

(42)

_PACKET CALL SETUP

SUCCESS RATE

(43)

PS Call Setup Success Rate

(CSSR)

)) _ _ _ _ _ _ _ _ ( ) _ _ _ _ _ _ _ _ ( ( * )) _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ( ) _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ( ( * 100 _ BACKG PS ATT STP RAB INTER PS ATT STP RAB sum BACKG PS COMP ACC RAB INTER PS COMP ACC RAB sum BACKG MT REL ACC RRC INTER MO REL ACC RRC BACKG MO REL ACC RRC INTER REL ACC RRC BACKG MT REP ATT RRC BACKG MO REP ATT RRC INTER MO REP ATT RRC INTER REP ATT RRC ATTS CALL BACKG MTC ATTS CALL INTER MTC ATTS CALL BACKG MOC ATTS CALL INTER MOC sum BACKG MT REL ACC RRC INTER MO REL ACC RRC BACKG MO REL ACC RRC INTER REL ACC RRC FAILS CALL EMERGENCY ATTS CALL EMERGENCY FAILS CALL BACKG MTC ATTS CALL BACKG MTC FAILS CALL INTER MTC ATTS CALL INTER MTC FAILS CALL BACKG MOC ATTS CALL BACKG MOC FAILS CALL INTER MOC ATTS CALL INTER MOC sum CSSR PS + + − − − − − − − − + + − − − − − + − + − + − + − =

Presentation / Author / Date

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

(44)

Low in CSSR: Failure Counters

RRC Conn Setup & Access

Analysis

DNO Optimization Processes / JC Ejarque

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

(45)

Low in CSSR: Failure Counters

RRC Conn Setup & Access

Analysis

DNO Optimization Processes / JC Ejarque

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).

(46)

Low in CSSR: Failure Counters

RAB setup & Access Fail Root Cause Analysis: RT and NRT

(I/B) domains

DNO Optimization Processes / JC Ejarque

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

(47)

Low in CSSR: Failure Counters

RAB setup & Access Fail Root Cause Analysis: RT and NRT (I/B)

domains

DNO Optimization Processes / JC Ejarque

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.

(48)

High in DCR?

DNO Optimization Processes / JC Ejarque

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

Traffic Neighbours’ 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 neighbour optimisationRF and IF/IS HO

No cell found ratio >40 % ISHO Success Rate < 95%

RF and ISHO neighbour optimisation 3G cell covers over a coverage hole ? 3G cell at inter-RNC border ?

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 To p iss ue s

(49)

Call drop analysis process

Presentation / Author / Date

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 No ISHO Failed No ISHO Failure Analysis Yes SHO Failure Analysis No No No

A

B

(50)

Call Drop Analysis process –

SHO Analysis

Presentation / Author / Date

DL ASU received SC Clash UE Tx Power Max Fix SC Clash CPICH Optimisation Uplink Interference Load Optimisation/ External Interferer Link Unbalanced Inter RNC HO Check 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

(51)

Drop call failures – RF issue

Presentation / Author / Date

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

(52)

Drop call failures – RF issue

Presentation / Author / Date DL synchronisation is lost ->

UE has stopped transmitting

TrChAgg and DL DPCCH BER high

(53)

Drop call failures – RF issue

Presentation / Author / Date 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

(54)

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)

Presentation / Author / Date

B

Drop to IDLE

(55)

Drop Call Failures – System

Issues RNC

Presentation / Author / Date

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

(56)

Drop call failures (SC

conflict)

Presentation / Author / Date

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

(57)

Drop call failures – Uplink

Interference

Presentation / Author / Date

D

UL interference from the SIB7 message

(58)

Drop call failures – Link

Balance

Presentation / Author / Date

D

UL & 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.

(59)

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

(60)
(61)

HSDPA low

throughput?

DNO Optimization Processes / JC Ejarque OSS counters measurement data collection Identify Low throughput areas if exist Low through put 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

(62)

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 RSRAN084

1. System Program System Program Cell Level RSRAN000

2. Capacity RNC Capacity RSRAN068

2. Capacity Node B Capacity RSRAN066

2. Capacity Cell Capacity RSRAN067

2. Capacity NRT Radio Bearer Statistics RSRAN013

3. Service Level Service/Session Accessibility Analysis RSRAN073

3. Service Level Service/Session Retainability Analysis RSRAN079

3. Service Level RAB Holding Times RSRAN021

3. Service Level Service Summary RSRAN003

4. Traffic Allocated Traffic Amounts (R99 + HSPA) RSRAN070

4. Traffic Cell Data Volume and Throughput at RNC RSRAN077

4. Traffic Traffic Summary RSRAN026

4. Traffic Used CE Capacity per RB Type in RNC RSRAN022

4. Traffic Utilization Shares of Total Traffic Allocation Amounts RSRAN071

5. Mobility and Handover Active Set Size for NRT-RT Traffic RSRAN078

5. Mobility and Handover HSPA Serving Cell Change RSRAN033

5. Mobility and Handover IFHO Adjacencies RSRAN044

5. Mobility and Handover Inter-System Handover per Cause RSRAN019

5. Mobility and Handover Inter-System Handover Performance RSRAN023

5. Mobility and Handover Inter-System Handover Reasons RSRAN018

5. Mobility and Handover ISHO Adjacencies RSRAN045

5. Mobility and Handover Load Based HO Related Resources RSRAN047

5. Mobility and Handover Load Based IFHO/ISHO Performance RSRAN048

5. Mobility and Handover Load Based IFHO/ISHO Triggering RSRAN049

5. Mobility and Handover Service Based IFHO/ISHO Performance RSRAN050

5. Mobility and Handover SHO Adjacencies RSRAN046

5. Mobility and Handover Soft Handover Performance RSRAN028

Presentation / Author / Date

RNC_169e:DR + GAN HO added, but load & service based

counters removed

(63)

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 RSRAN081

8. Transport ATM VCC Traffic Load RSRAN083

8. Transport ATM VPC Traffic Load RSRAN082

8. Transport FTM Packet Transport Performance RSRAN076

8. Transport FTM Performance RSRAN072

8. Transport Iu-PS Throughputs RSRAN064

8. Transport Iub Throughputs RSRAN080

8. Transport Traffic on AAL5 RSRAN031

8. Transport Traffic on ATM Layer RSRAN029

8. Transport Traffic on Physical Medium Sub-Layer RSRAN030

8. Transport Transport Resource Reservations RSRAN069

7. HSPA Channel Switching and HSPA Layering RSRAN075

7. HSPA CQI Distribution RSRAN039

7. HSPA HSPA Code and Modulation Usage RSRAN034

7. HSPA HSPA Power Distribution RSRAN074

7. HSPA MAC-hs Efficiency RSRAN040

7. HSPA MAC-hs Retransmissions by Code and Modulation Usage RSRAN041

7. HSPA Number of HSPA Users and UE capability RSRAN051

6. Signalling NBAP Signalling RSRAN027

6. Signalling RRC Signalling RSRAN038

(64)

Figure

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References

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