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
Presentation
/ Author rate
/ Date
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 – MissingA
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
WBTSB UE
Block
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 BNo
Solutions
for
RACH
optimisation
To
Max UE Tx power hit
Toincrease
increasePRACH_Preamble_retrans
PRACH_Preamble_retrans
Or
OrPowerRampStepPRACHPreamble
PowerRampStepPRACHPreamble
the UE_P_MAX(24dBm)?
Yes
Yes
Is UL Interference
abnormally HIGH?
Report
Reportthere
theremight
mightbe
bean
aninterfering
interfering
source
Nearby
the
serving
source Nearby the servingcell
cell
No
Change
Changethe
theServing
Servingcell
cellto
tocover
coverthe
theproblem
problemArea
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 – SystemC
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 – SystemC
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 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 – SystemE
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 – SystemE
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
-TMSI
P
• The NAS message is not read by the RNC but is forwarded to ultimedia
the m
gateway. The NAS
message includes the IMSI as a UE identity
• The SCCP : Connection R equest
message establishes the connection orientated signallingnlink i
the same way as it was for the R RC connection phase.This does
t reserve
no
any resources for the
AMR call itself.
• The Connection Confirmmessage identifies the RNC with a destination local reference
hichwis 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 aRANAP: Location Reporting Control
message 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 Command
message triggers the start or stop of ciphering and integrity
protection.
Call setup failures – SystemE
“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
and
URA_PCH State
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
•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
blocked
100KPI,
* sum(excluding
AVAIL _ WCELL
_ IN _ WO _by
STATE )
Cell _ Availabili
ty
_
excluding
_
BLU
_
state
=
user state (BLU), Counts Cell
availability
from
network
_ WCELL _ EXIST
_ IN
_ RNW _ DB 
 AVAIL


sum
point of view:
−
AVAIL
_
WCELL
_
BLOCKED
_
BY
_
USER


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 phases
Setup Phases
Identify call setup failure
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 processing
power on ICSU unit
RRC Connection
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)
CSSR KPI for CS voice from end user perspective (RNC 565f)
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-selectionsPresentation
are subtracted
/ Author / Date both from the numerator
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
Interactive and Background PS calls
100 * ( sum( MOC _ INTER _ CALL _ ATTS − MOC _ INTER _ CALL _ FAILS
+ 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
a new
RRC connection via another cell and
Presentation
/ Date
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
CSSR:
Failure
Counters
RAB 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
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
•
DCHParameter
traffic too High (DPA,
related HSDPA
Optimisation
by tuning
HSDPA
Priority)
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
/