Part 3 optimization 3G

Presentation / Author / Date
Using Reporting Suite 3G RAN Reports or MS
Access KPI QueriesWeekly KPI
( PLMN)
< X %
No action
needed
No
Yes
Yes
No
System Program (PLMN)
Weekly KPI
(RNC)
< X % ?
System Program (RNC)
Daily KPI
(WCEL)
< X%
Identify Call failure
phases of bad
performing KPIs, for
example CSSR
Identify failures root-
causes and failure
distribution of bad KPIs
Identify Top50 Worst
Cells based on
highest number of root
causes failures
System Program (WCEL) Others 3G RAN Reports
Others 3G RAN Reports
Yes
Mataching failure
distribution into
network topology
System Program (WCEL)
Solution Proposal
Mapinfo
High level PM data analysis and assessment

PM Data analysis process

Principles of traffic monitoring -
bottlenecks
Both interfaces and internal resources of
WCDMA network should be monitored
UserPlane
RNC
UE
WBTS
DNBAP
AAL2 or IP SIG
CNBAPPRACH
FACH-c&u
DCH
Air Interface Iub Interface
User Plane
Iur Interface
IuCS Interface
User Plane
SS7 (RANAP)
IuPS Interface
User Plane
User Plane
SS7 (RANAP)
PCH
WSP
Resource
Code
Capacity
Throughput
Connectivity
Unit Load
DSP Usage
D-RNC

Principles of traffic monitoring - reactive /
proactiveReactive monitoring
• Consider setup failure (already discussed in chapter 2)
• Daily BH analysis needed
Proactive monitoring
• Consider amount of traffic
• Weekly analysis enough

Principles
Transmitted carrier power
Node B reporting
Total DL power
R99 power
HSDPA power
Received total wideband power
Code tree allocation
Channel element allocation
Iub transmission
RNC processing load
Number of users
Traffic Monitoring

Node B informs RNC about air interface load by the following messages
Common NBAP radio resource indication
• Transmitted carrier power
• Total power R99 + HSDPA
• R99 power
• Received total wideband power
• Total power R99 + HSUPA
• HSUPA power (calculated by Node B, not directly measured)
Dedicated NBAP measurement report
• Power of each dedicated radio link
IuB
C - NBAP
D - NBAP
Node B RNC
Node B reporting

High total DL
power
High pilot
pollution
Otherwise
Total DL power - optimization flow
Check SHO parameter
settings
Check adjacent cell
interference
Neighbor
analysis
High SHO
overhead
Add second
carrier

Number of radio resource indications falling into specific R99 power interval
The definition of the load target depends on the presence of HSDPA users
• No HSDPA user present → static load target PtxTarget
• At least one HSDPA user present → dynamic load target PtxTargetPS
R99 power -

HSPA power
HSPA power includes
• HS-PDSCH
• All HS-SCCH
• All HSUPA DL signaling channels (E-AGCH, E-RGCH, E-HICH)

DL power shared dynamically between R99 and HSDPA
Realized by dynamic load target for NRT R99 traffic PtxTargetPS
For RT R99 traffic still static load target PtxTarget
PtxTargetPS is adjusted between
• Minimum load target PtxTargetPSMin (default 36 dBm)
• Maximum load target PtxTargetPSMax (default 40 dBm)
RNC checks periodically, whether adjustment of PtxTargetPS needed
Period defined by PtxTargetPSAdjustPeriod (default 5 RRI periods)
PtxTargetPSMin ≤ PtxTargetPS ≤
PtxTargetPSMax
HSDPA power - dynamic share with R99

PtxTargetPS adjusted under the following conditions
1) HSDPA congestion
• Too much total DL power present in cell
• PtxHighHSDPAPwr defines overload threshold for HSDPA cell (default 41 dBm)
2) DCH congestion
• Too much R99 power present in cell
• The offset is fixed to 1 dB
PtxTotal ≥
PtxHighHSDPAPwr
PtxNonHSPA ≥
PtxTargetPS -
Offset

HSDPA Congestion
HSDPA power congestion, if
Ptxtotal ≥ PtxHighHSDPAPwr
PtxMax 43 dBm
PtxNC
PtxNRTPtxNonHSDPA
PtxTotal
PtxTargetPSMin
-10..50; 0.1; 36 dBm
PtxTargetPSMax
-10..50; 0.1; 40 dBm
PtxHighHSDPAPwr
-10..50; 0.1; 41 dBm
PtxTargetPS
If actual load target PtxTargetPS > optimum load target
Decrease PtxTargetPS by PtxTargetPSStepDown (default 1 dB)
Optimum
load target

DCH Congestion
PtxMax 43 dBm
PtxNC
PtxNRTPtxNonHSDPA
PtxTargetPSMin
PtxTargetPSMax
PtxHighHSDPAPwr
DCH power congestion, if
PtxNonHSDPA ≥ PtxTargetPS - 1dB
If actual load target PtxTargetPS < optimum load target
Increase PtxTargetPS by PtxTargetPSStepUp (default 1 dB)
PtxTotal
PtxTargetPS
Optimum
load target

Noise rise due to
real traffic
Own cell load factor
(throughput)
i-factor
PrxTarget
e.g. 4 dB above PrxNoise
RTWP sources
-108 dBm
Receiver noise figure (e.g. 2 dB)
Thermal noise -108 dBm
-106 dBm
Intermodulation out of band (e.g. 1 dB)
-105 dBm
RTWP of empty cell
MUST be equal PrxNoise
PrxOffset
e.g. 1 dB above PrxTarget
High adjacent cell
interference
Low adjacent cell
interference
-101 dBm
-100 dBm

Total UL power - role of BTS commissioning
RTWP measured by BTS at antenna connector
Then corrected due to
• Feeder loss
• MHA gain
RTWPcorrected = RTWPmeasured + feeder loss – MHA gain
Corrected RTWP reported to RNC
With wrong settings wrong RTWP values reported
Previous example for 2 GHz range
Probably feeder loss underestimated → corrected RTWP underestimated

Total UL power
Close to -112
dBm
Often > -100
dBm
Total UL power - optimization flow
Check feeder loss / MHA gain
commissioning setting
Check HW
Still below BTS
receiver noise
Check
- High traffic density
- HW
- Intermodulation

SF=64
SF=32
SF=16
SF=8
SF=128
R99 code allocation - principles
Code resource required depends on type of radio bearer
• Signaling SF 256 for 3.4 Kbit/s, SF 128 for 13.6 Kbit/s
• Voice HR SF 128 or SF 256
• Voice FR, 16K data SF 128
• 32K data SF 64
• 64K data SF 32
• 128K data SF 16
• 256K data, 384K data SF 8
Only 1 code per bearer allocated

Total blocking rate
Blocking rate
for SF16
Blocking rate
for SF8
R99 code allocation - blocking
Practical example – single cell
Blocking per SF per hour
Very high blocking especially for SF8
But still also for SF16 and sometimes
even for SF32

R99 code allocation - re-arrangement
Code tree quickly fragmented, if not re-arranged from time to time
Then few users of high SF (low data rate) block huge amount of resources
for users of low SF (high data rate)
Re-arrangement performed
• Periodically according CodeTreeOptTimer (default 1h) OR
• If code tree occupation > CodeTreeUsage (default 40%) OR
• If more than MaxCodeReleases consecutive releases of codes (default 40)
Blocking before re-arrangement Blocking after re-arrangement

1514131211109876543210
………. ……….
1514131211109876543210 1514131211109876543210
………. ……….
1514131211109876543210
HSDPA code allocation - principles
For HSDPA fixed SF16
But several codes per bearer available
• Minimum guarantee of 5 codes
• Maximum number set usually to 15 codes
• Code resource has to be shared with R99
SF=8
SF=4
SF=2
SF=1
SF=16
R99 + HSPA signaling CH Guarantee for HSDPA
Dynamically shared between
R99 and HSDPA

Number of codes reserved for HSDPA can be adjusted dynamically
in dependence on R99 traffic
Possible levels configured with parameter HSPDSCHCodeSet
16 bit parameter to enable / disable each possible level individually
HSDPA code allocation - dynamic share with R99
Examples
00000 00000 100000 = always 5 codes reserved (default)
11010 10100 100000 = number of reserved codes adjustable (5, 8, 10, 12, 14 or 15 codes,
recommended)
0-4 codes always disabled11-15 codes
6-10 codes

Upgrade
RNC checks periodically, whether more codes can be reserved for HSDPA
Requirements for upgrade
• Free adjacent codes to go to next higher level defined by HSPDSCHCodeSet
• After upgrade still enough codes with SF128 available for R99 (at least HSPDSCHMarginSF128,
default = 8)
• Upgrade to 15 codes possible only with HSPDSCHMarginSF128 = 0
HSDPA code allocation - dynamic share
with R99

HSDPA code allocation - dynamic share with R99
Downgrade due to NRT R99 traffic
If a NRT R99 request cannot be served due to code blocking, HSDPA is
downgraded only, if the actual number of codes exceeds
Maximum code set – DPCHOverHSPDSCHThreshold
• Default = 0 → HSDPA always has higher priority than incoming NRT R99 request
• Threshold = 5 → HSDPA downgraded due to incoming NRT R99 request, if actually
more than 15 - 5 = 10 codes reserved for HSDPA
NumberofallocatedSF16codes
DPCHOverHSPDSCHThreshold
6
7
8
9
10
11
12
13
14
15 Maximum code set
5

HSDPA code allocation - impact of HSUPA
SF=1
SF=2
SF=4
SF=8
SF=16
SF=32
SF=64
SF=128
SF=256
14 HS-PDSCH codes14 HS-PDSCH codes
Up to three HS-
SCCH codes
Up to three HS-
SCCH codes
Codes for common
channels in the cell
Codes for common
channels in the cell Codes for associated DCHs
and non-HSDPA users
Codes for associated DCHs
and non-HSDPA users
E-AGCH (256)E-AGCH (256)
E-RGCH/E-HICH (128)E-RGCH/E-HICH (128)
New DL signaling channels occupying at least the following codes
• 1 x SF256 by E-AGCH
• 1 x SF128 by E-RGCH / E-HICH (these two channels share one code)
Loss of a second code with SF16 → maximum of 14 codes for HSDPA

High code
congestion
Many DCH of
low activity
High code congestion - optimization flow
Enable throughput
based optimization
(R99 DCH)
Check SHO parameter
settings
Check adjacent cell
interference
High SHO
overhead
Enable code tree
optimization
Still high
congestion
Enable F-DPCH
(associated DCH)
Many
associated
DCH

•Principles
•Transmitted carrier power
•Received total wideband power
•Code tree allocation
•Channel element allocation
•Monitoring
•BTS channel cards
•R99 dimensioning (optional)
•HSDPA dimensioning (optional)
•HSUPA dimensioning (optional)
•Iub transmission
•RNC processing load
•Number of users
Traffic Monitoring

For daily work often more convenient to know the percentage of occupied CE
instead the absolute number
Both for DL and UL six to indicate, how often total utilization falls into
certain interval
• 0-49 %
• 50-69 %
• 70-79 %
• 80-89 %
• 90-99 %
• 100 %
Monitoring - total utilization
80-89%
90-99%
70-79%
100%

Monitoring - total utilization
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%11.03.2010__09:00:00
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11.03.2010__21:00:00
11.03.2010__23:00:00
12.03.2010__01:00:00
12.03.2010__03:00:00
12.03.2010__05:00:00
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12.03.2010__13:00:00
12.03.2010__15:00:00
70.00
75.00
80.00
85.00
90.00
95.00
(100 or more)% M5001C20
(90 - <100)% M5001C19
(80 - <90)% M5001C18
(70 - <80)% M5001C17
(50 - <70)% M5001C16
(0 - <50)% M5001C15
Avg Ratio of Used CE for UL in BTS
RNC_731A
Practical example – UL on single BTS
In most cases very high
utilization
Typically 80-89 % or 90-99 %

Both for DL and UL five additional to indicate, how often utilization by HSPA
falls into certain interval
• 0-19 %
• 20-39 %
• 40-59 %
• 60-79 %
• 80-100 %
Monitoring - utilization by HSPA

Monitoring - utilization by HSPA
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1
1
.0
3
.2
0
1
0
_
_
0
9
:0
0
:0
0
1
1
.0
3
.2
0
1
0
_
_
1
1
:0
0
:0
0
1
1
.0
3
.2
0
1
0
_
_
1
3
:0
0
:0
0
1
1
.0
3
.2
0
1
0
_
_
1
5
:0
0
:0
0
1
1
.0
3
.2
0
1
0
_
_
1
7
:0
0
:0
0
1
1
.0
3
.2
0
1
0
_
_
1
9
:0
0
:0
0
1
1
.0
3
.2
0
1
0
_
_
2
1
:0
0
:0
0
1
1
.0
3
.2
0
1
0
_
_
2
3
:0
0
:0
0
1
2
.0
3
.2
0
1
0
_
_
0
1
:0
0
:0
0
1
2
.0
3
.2
0
1
0
_
_
0
3
:0
0
:0
0
1
2
.0
3
.2
0
1
0
_
_
0
5
:0
0
:0
0
1
2
.0
3
.2
0
1
0
_
_
0
7
:0
0
:0
0
1
2
.0
3
.2
0
1
0
_
_
0
9
:0
0
:0
0
1
2
.0
3
.2
0
1
0
_
_
1
1
:0
0
:0
0
1
2
.0
3
.2
0
1
0
_
_
1
3
:0
0
:0
0
1
2
.0
3
.2
0
1
0
_
_
1
5
:0
0
:0
0
0
5
10
15
20
25
30
35
40
UL(90 - <100)% M5001C31
UL (80 - <90)% M5001C30
UL (70 - <80)% M5001C29
UL (50 - <70)% M5001C28
UL (0 - <50)% M5001C27
Max HSUPA Users M1031C1
Max HSDPA Users M1031C0
Avg ratio of Used CE for UL for HSUPA in
BTS RNC_948A
Avg ratio of Used CE for DL for HSUPA in
BTS RNC_947A
Practical example – UL on single BTS
In most cases very high
utilization due to HSUPA
Typically 80-89 %

In general, each DCH occupies a certain number of CE in dependence
on the type of service
The CE occupation is the same for
• FSMC/D/E and WSPF cards
• R99 DCH and associated DCH
R99 dimensioning
Service CE
SRB / voice / 16 K data 1
32 K data 2
64 K data 4
128 K data 4
256 K data 9
384 K data 12

Less CE needed for DCH of 256 K and 384 K
All other rules remain unchanged
R99 dimensioning
Service CE
SRB / voice / 16 K data 1
32 K data 2
64 K data 4
128 K data 4
256 K data 6
384 K data 8

High CE occupation - optimization flow
High CE
occupation
Many DCH of
low activity
Enable throughput
based optimization
(R99 DCH)
Check SHO parameter
settings
Check adjacent cell
interference
High SHO
overhead
Enable F-DPCH
(associated DCH)
Many
associated
DCH

Principles
Iub transmission
Implementation principles
Monitoring options
Examples
RNC processing load
Number of users
Traffic Monitoring

M550 – CAC AAL2 Path Measurements
2 VCs with 8250 (ATM) cells per second per VC on 1 IMA group
Examples - physical ATM traffic
Two VC multiplexed by IMA
Cell rate reserved by CAC per VC
Configured bandwidth
Maximum reserved bandwidth
Minimum reserved bandwidth
Free bandwidth
Even maximum reserved bandwidth
far below configured bandwidth
No risk of physical congestion

Examples - logical ATM traffic
Two VC multiplexed by IMA
Number of AAL connections established by CAC per VC
Even in busy hour number of AAL connections
clearly below maximum of 248
No risk of logical congestion

Principles
Iub transmission
RNC processing load
RNC block diagram
Monitoring options
Number of users
Traffic Monitoring

After the patch is installed for the RNC, almost all the call drops with the cause being “Other” have disappeared
and the PS call drop rate is obviously lower, as shown in the following table. The problem is thus solved.
Solution
Note: You can get the table on the right via custom report or “Performance Query” of Nastar.
Case — High Call Drop Rate due to RNC Traffic
Measurement Defect (Continued)

•Principles
•Transmitted carrier power
•Received total wideband power
•Code tree allocation
•Channel element allocation
•Iub transmission
•RNC processing load
•Number of users
Traffic Monitoring

Number of users - licenses
R99
• No license for specific number of users per cell required
• New user allocated, as long all types of RAN resources available
HSPA
• License for specific number of users per cell required
• The following levels are available
• 16 users
• 48 users
• 64 users
• 72 users
• If maximum number of users present, new user rejected, even if all
types of RAN resources still available

RRC connection setup
RAN resources 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
dropped
RAB setup
Attempts to start call
RAB setup access
Connection between UE and core
RAB active phase
UE has RAB connection
CSSR affected if any of the following
events takes place
• RRC Connection Setup Fail
• RRC Connection Access Fail
• RAB Setup Fail
• RAB Setup Access Fail
Setup
Complete
Setup
Complete
Access
Complete
Access
Complete
Active
Complete
Active
Complete
SetupSetup AccessAccess ActiveActive
Attempts
Setup failures
(blocking)
Access failures
Access
Active
Release
Active
Release
Active
Failures
Active
Failures
RRC
Drop
Success
Phase:
RRC and RAB
Call setup - phases

[RACH] RRC Connection RequestRACH] RRC Connection Request
UEUE Node BNode B RNCRNC
ALCAP ERQ
NBAP RL Setup Request
[DCH] RRC Connection Setup Complete[DCH] RRC Connection Setup Complete
L1 Synchronisation
Start TX/RXStart TX/RX
[FACH] RRC: RRC Connection Setup
NBAP RL Setup Response
AC to check to accept
or reject RRC
Connection Request
AC to check to accept
or reject RRC
Connection Request
ALCAP ECF
NBAP Synchronization Indication
RRC Connection Setup
phase
RRC Connection
Access phase
RRC Connection Active phase
Allocation of UTRAN
resources
Waiting for UE reply
Three phase for RRC
Call setup – successful RRC establishment
Signalling and trigger
=

RRC Connection – SETUP and ACCESS PHASE
[RACH] RRC Connection RequestRACH] RRC Connection Request
UEUE Node BNode B RNCRNC
ALCAP ERQ
NBAP RL Setup Request
[DCH] RRC Connection Setup Complete[DCH] RRC Connection Setup Complete
L1 Synchronisation
[FACH] RRC: RRC Connection Setup
NBAP RL Setup Response
AC to check to accept or
reject RRC Connection
Request
AC to check to accept or
reject RRC Connection
Request
ALCAP ECF
NBAP Synchronization Indication
RRC Connection Setup
phase
RRC Connection Access
phase
Allocation of UTRAN
resources
Waiting for UE reply
Three phase for RRC
Signalling and trigger
=

1. RRC setup attempts.
2. RRC setup attempts per setup cause.
(SEE NEXT SLIDE)
3. RRC setup failures due to
• handover control , • admission control
• transport (Transmission)• RNC internal
• frozen BTS • BTS • ICSU overload
4. RRC setup failure per cause.
5. RRC setup complete.
6. RRC access failures due to
• radio interface • UE• RNC internal
7. RRC access complete.
8. Special reason: RRC active release
due to
• SRNC Relocation • Pre-emption
• User inactivity • RNC HW resources
• ISHO to GAN • Inter-system handover to GSM • IF
inter-RNC hard handover • Inter-frequency inter-
RNC hard handover
9. RRC active failures due to
• Iu interface (transport) • radio interface
(synchronisation) • BTS • Iur interface (DRNC) •
RNC internal • UE • Transmission
10. RRC active complete

1. RAB setup attempts. Separate counter
per each RAB type.
2. RAB setup failures due to
• admission control • transport (transmission) • RNC
internal • frozen BTS • BTS (RT only) • anchoring (NRT
only) • capacity license (for CS voice RAB only)
3. RAB setup complete. Separate counter
per each RAB type.
4. RAB access failures due to
• UE • RNC internal
5. RAB access complete. Separate counters
per each RAB type.
6. Special reason: RAB active release due to
• SRNC relocation • pre-emption • capacity license pre-
emption (only for CS voice RAB)
7. RAB active failures due to
• Iu interface (transport) • radio interface (synchronisation) •
BTS • Iur interface (DRNC) • RNC internal • UE •
Transmission
8. RAB reconfiguration attempts.
9. RAB reconfiguration failures.
10. RAB active complete. Separate
counters per each RAB type.

Drop Call Analysis

Case 1: Drop due to missing neighbor
Problem: Detected Nighbor (DN)
UE sends a Measurement Report that contains an event1a means
adding a new RL (cell) to Active Set
If the reported cell is not in the current neighbor cell list and the
reported Ec/No is better than the best serving cell Ec/No in AS
by some dBs (set by a RNC parameter)
If for any reason the new cell can not be added to AS, call will be
released

Case 1: Drop due to missing neighbor
“DN” cell better than the serving cell
DL BLER gets worse
“DN” cell better than the serving cell
DL BLER gets worse

Case 2: Drop due to Poor Coverage (low RSCP)
Problem: Poor DL coverage
When UE gets to an area with low RSCP ( < -105 dBm)
regardless Ec/No values there is high risk for drop.
UE will likely ramp up the transmitted power and reach its
max power. The DL BLER will probably increase and SIR
target cannot maintain anymore, finally the call drops.

Case 2: Drop due to DL Poor Coverage
Very bad RSCP
UE max Tx power
and
high DL BLER
Very bad RSCP
UE max Tx power
and
high DL BLER

Case 3:
PS: Session Error due to Poor DL Coverage
UE enters a very low coverage area (RSCP < – 105 dBm).
The packet connection is carried on a 64/64 DCH Channel
as consequence of the low coverage conditions.
The UE will likely ramp up its power to the maximum, goes
to Idle Mode and the Application and RLC throughputs go
to zero.
At this point the RAS application will start the Session
Timeout timer, if the throughput is not resumed the Session
Error event is triggered with cause “session timeout”.

PS: Session Error due to Poor DL Coverage
App throughput ~64kbps
Very low RSCP
App throughput ~64kbps
Very low RSCP

FINAL WORDS
For network tuning, we need to rely on field measurements which require extensive
drive tests
Finding the best possible configuration for antenna heights, tilts, azimuths and
parameter setting for all the present cells/sectors in the network and also for
any new sites that might be needed to improve coverage
Power adjustment can also be used for network tuning but can become
complicated and result in poor network performance
Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt
antenna
Neighbour definition is of prime importance in UMTS network (Soft handover gain
and interference reduction). Keep neighbour list upto 20.
Automated tools are needed that could suggest the best possible neighbour
relations, antenna heights and tilts by using both the field measurements and
the propagation models & simulations
Skilled people, right methods and advanced tools are needed to perform 3G tuning
and optimisation

Call Drop analysis
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
RF and IFHO
neighbour
optimisation
No cell
found
ratio >40
%
ISHO
Success
Rate <
90%
RF and ISHO
neighbour
optimisation
3G cell
covers over
a coverage
hole ?
3G cell at
inter-RNC
border ?
Wrong reference
clock (10MHz tuning)
No cell
found
ratio > 90
% and
enough
ADJG
2G Cell Doctor
2G
Investigation :
TCH blocking
or TCH
seizure failure
(interference)
NO
YES
YES
YES
NO
YES
NO
YES
YES
SHO
ISHO
Top
iss
ues
SHO based on
DSR, CPICH
EcNo
difference,
SHO branch
setup fail
BTS/Iub
HHO RSSI &
BSIC time,
ISHO
cancellation
Max HSPA users in cell/RNC,RNC
licensed capacity:Max AMR/Iups
throughput
Relocation success in
target RNC
HSDPA IFHO failures, reject CM for IFHO

Call Drop analysis
1. Check high call drop cells and its neighbouring cells of any faulty alarms
2. Identify call drop root cause failure distribution and main failure contributor (radio, Iu, BTS,
Iur, MS, RNC)
3. Check SHO KPI if performance < 90% ( leads to radio failure)
• Check if cells are at RNC border (check Iur capacity and SRNC relocation problem)
• Detect badly performing neighbours using HO success rate per adjacency counters (M1013)
• High incoming HO failure rate in all adjs – check sync alarms
• Assessing neighbor list plan and visualization check with map
• Evaluate HO control parameters and trigger threshold
4. Check ISHO KPI if RT ISHO < 90% or NRT < 80% (leads to radio failure)
 Check missing neighbour (M1015), GSM frequency plan neighbour RNC and MSC database
consistency audit, check alarm of reference clock in 3G or in 2G, check 2G TCH congestion
 Check RRC Drop ISHO RT / NRT

Call Drop analysis
5. Detecting DL or UL path loss problem if RAB drop due to radio (dominant call
drop cause > 50%)
 Check UL Lost Active KPI from Iub counters (active L1 synchronization failure) to check UL/DL
path loss problem
 Check ASU failure rate (UNSUC_ASU) which link to NO RESPONSE FROM RLC
 Mapping radio failures with Tx power and CPICH related parameters ->
CPICHToRefRABOffset, PTXDPCH MAX
 Check Call reestablishment timer -> T315
 Ecno distribution for bad coverage issue (M1007C38-M1007C47)
6. Check core network parameter setting if RAB_ACT_FAIL_XXX_IU
 Check SCCP SGSN/RNC IuPS Tias/Tiar if RAB_ACT_FAIL_BACKG_IU
7. If high RAB_ACT_FAIL_XXX_BTS
 Check if any BTS faulty alarm (7653 cell faulty alarm)
 If no alarms, COCO detach/attach
8. If high RAB_ACT_FAIL_XXX_MS
• Check physical channel reconfiguration failure rate (IFHO, ISHO, code optimisation)

HSDPA Low Throughput

HSDPA Throughput Analysis

Good CQI but poor HSDPA throughput

COMMON CALL PERFORMANCE ISSUES

Common Call Performance Issues

Video Call Performance Issues

ISHO Performance Issues

Soft Handover Neighbour Tuning

Active Set Usage
M1013
(These counters are referred to cell addition and cell replacement – no target for deletion)
Absolute Value must be considered not Failure Rate!

Active Set Usage
High # out-
going
attempts?
In – out
pairs?
Zero
attempts?
Ping-Pong
No Adjs
Low used Adjs
Yes
Yes
Yes
Unbalanced WCEL
High #
attempts for
a source?
Unbalanced ADJS
Yes
Mino
r
Filtering over attempts must be taken into count
that:
- statistical data must stabilized over time.
- traffic distribution is not considered and a
double-check to localize the event and DT
feedback is required to understand if fenomena
is traffic driven or cell dependent
High # out-
going fails for a
defined ADJS?
Major
Failure
ADJS
Yes
High # fails for
a source?
Failure
WCEL
Yes
Min
or
Filtering over failure in
absolute terms it is possible
to find the major critical
events

Active Set Usage
Filtering criteria:
Major
- High number of failures for a defined out-going adjs failure(
ADJS)
- high number of fail for a defined source failure WCEL( )
Minor
- high number of attempts in-comig and out-going for a defined pair
with occasional failure ping-pong( )
Filtering action are required to find bi-lateral corrispondence
- very low number of attempt with failure low used adjs( )
- zero number of attempt for declared adjs stabilized value no adjs– ( )
- high number of attempts with occsional failure for an out-going adjs
unbalanced ADJS( )
Either in-coming or out-going condition is sufficient
- high number of attempts with occsional failure for a defined source
unbalanced WCEL( )

Failure ADJS
Once anlyzed the
RSCP, the coverage
plot taking care to
the evaluation of
intersite-distance, it
is easy to
understand if
target can be used.
If not only down
tilt is possible or
DERR (ADJS object
Paremeter) cell to
avoid the failure
during SHO.
Down tilt must be
carefully anlyzed.
If from Ec/No the
cell can be recovered
an individual offset
or filtering (ADJS
object Parameter)
can be introduced
Failure ADJS
Analyze RSCP from DT
& NWP coverage plot
considering inter-site
distance
Target act
as polluter?
Down tilt
Yes
Analyze Ec/No from DT
Down tilt
possibile?
DERR cell
Yes
Ec/No offset
Very low value of
RSCP that not
allow the adjs to
be used
…
Attempt Fail Attempt Fail Attempt Fail Attempt Fail
Source_cell_A 2 1 23 1 442 34 4 0
Source_cell_B 1 0 11 0 53 25 345 0
…
Source_cell_Z 322 54 15 0 2 0 12 0
Target_cell_A Target_cell_ZTarget_cell_CTarget_cell_B

Failure ADJS – Individual Ncell Offset
time
P CPICH 1
P CPICH 2
P CPICH 3
Reporting
Range
Reporting
Event 1B
Reporting
Event 1A
AdjsEcNoOffset
to modify
measurement
reporting
behaviour.
Effectively
'moves' cell
border (shrinks or
enlarges cell)
Enlarging Cell 3 by x dB
Ec/Io

Failure ADJS – Forbidding Neighbour Cell
Time
P CPICH 1
P CPICH 2
P CPICH 3
PCPICH3 is
forbidden to affect
the reporting range as
its quality is quite
unstable.
Report
ing
Range
AdjsDERR
to forbid a cell from
reporting range
calculation in some
instances
Ec I/ o

Failure WCEL
KPI(1) ?
Failure WCEL
Tune 1A
Yes
KPI(2) ? Tune 1C
Yes
Analyze Ec/No &BLER
from DT & NWP coverage
plot considering inter-site
distance
WCEL
polluted/interfered?
Yes
Pollution/Interference
Most of the Target failure during the 1A or 1C
event.
Once anlyzed the Ec/No, BLER, the coverage plot
taking care to the evaluation of intersite-
distance, it is easy to understand if the WCEL is
interferered/Polluted
If not, two KPIs allow to separate the dominant
contribute among the 1A and 1C.
Relaxing the parameters an improvement should be
achieved
The following gives the number of attempts per event
RT Services
KPI 1 M1007C10 CELL ADD REQUEST ON SHO FOR( ) = _
RT TRAFFIC
KPI 2 M1007C12 CELL REPL REQUEST ON SHO( ) = _
FOR RT TRAFFIC NRT Services
KPI 1 M1007C27 CELL ADD REQUEST ON SHO( ) = _
FOR NRT TRAFFIC
KPI 2 M1007C29 CELL REPL REQUEST ON SHO( ) = _
FOR NRT TRAFFIC
The failure rate for all the procedure can be estimated as well
ADD REPL FAIL ONSHO FOR x( )_ _ _ _ /
ADD REPL REQ ON SHO FOR x ADD REPL( )_ _ _ _ _ + ( )_
FAIL ONSHO FOR x_ _ _
M1007C14 M1007C12 M1007C14/ +
M1007C36 M1007C11 M1007C36/ +
M1007C30 M1007C27 M1007C30/ +
M1007C37 M1007C28 M1007C37/ +
M1007C31 M1007C29 M1007C31/ +
…
Source_cell_A 2 1 23 15 442 34 124 23
Source_cell_B 1 0 11 0 53 0 345 0
…
Source_cell_Z 322 1 15 0 2 0 12 0

Failure WCEL - 1A
RNC
Strongest CPICH in AS:
time
Ec/Io
P CPICH 3
P CPICH 1
P CPICH 2
1A
AdditionWindow
determines the
relative
threshold used
by the UE to
calculate the
reporting
range of event
1A. The threshold
is either relative
to the CPICH
Ec/No
measurement
result of the
best active set
cell (0), or to
the sum of
active set
measurement
results (<>0)
AdditionTime
defines the
'time-to-trigger'
interval
between the
cell entering
the reporting
range and the
UE sending the
measurement
report to the
RNC with the 1A
event
AdditionReportingInterval
defines the period of
time that the UE wait,
if the RNC is unable
to add Ncell to AS,
before sending
further reports
periodically, with
interval
AdditionReportingInterval,
until the Ncell moves
out of reporting
range, or RNC adds
Ncell to AS.
Measurement
Report
Add to
the AS?
no
ActiveSetWeightingCoefficient
is used to weight either
the measurement result
of the best active set cell
(0) or the sum of
measurement results of all
active set cells (<>0)

Failure WCEL - 1C
time
weakest CPICH in AS
Ec/Io
P CPICH 3
P CPICH 1
P CPICH 2
P CPICH 4
AS has 3 cells
ReplacementReportingInterval
If the RNC is not able to
replace the active cell with the
monitored cell, the UE continues
reporting after the initial
report by reverting to
periodical measurement
reporting. The parameter
Replacement Reporting Interval
determines the interval of
periodical measurement reports
when such reporting is
triggered by the event 1C.
ReplacementWindow
determines the margin by which the
CPICH Ec/No measurement result of
the monitored cell (MNew) must exceed
the CPICH Ec/No measurement result
of the an active set cell (MInAS)
before the UE can send the event 1C
triggered Measurement Report to the
RNC: MNew >= MInAs +
ReplacementWindow / 2
ReplacementTime
Defines the period of time the
monitored cell must continuously
stay within the reporting range
before the UE can send a
Measurement Report to the RNC
in order to replace an active
set cell with the monitored cell
(event 1C).
Measurement
Report
RNC
AS
update?
no
1C

NO ADJS
No Adjs
Remove ADJS
Zero
attempts?
Statistic
Stable?
Yes
Repeat Analysis
Yes
DT analysis for the Adjs
Comparing the ADJS plan provisioned
into the network with the M1013
matrix, it is easy to find if one
declared ADJS is not used (not
present in the list)
Statistic data must be stabilized
before decide to remove it and DT
analysis can help n estimating the
amount of residual noise if down tilt
is not possible
…
Source_cell_A 2 1 0 - 442 34 124 23
Source_cell_B 0 - 11 0 53 0 345 0
…
Source_cell_Z 322 1 15 0 2 0 12 0

Low used ADJS
Low used Adjs
Remove ADJS
Analyze DT
result and
NWP data
Monitored Qual
from DT
acceptable?
Alter. ADJS
present?
Yes
Interference
evaluation
Yes
ADJ Offset
It is not difficult in live network to
find some pair working with very low
For low used ADJS has to be
intended and ADJS that has few
number of attemps in one day (e.g
<3)
with occasional failure.
The ADJS removal has to be
considered as the last option, after
the quality has been monitored by
drive test result, considering the
overall capability of the target to be
recovered (e.g. inter-site distance,
power budget) and other options are
available for that area.
Statistic data must be stabilized
before decide to remove it and DT
analysis can help in estimating the
amount of residual noise if down tilt
is not possible
…
Source_cell_A 2 1 25 4 442 34 124 23
Source_cell_B 245 23 11 0 53 0 345 0
…
Source_cell_Z 322 1 3 1 2 1 123 20

Unbalanced ADJS
Unbalance ADJS
Ec/No offset
Analyze RSCP from DT & NWP
coverage plot considering inter-
site distance e traffic
distribution
Target act
as polluter?
Down tilt
Yes
& evaluate unbalance
Down tilt
possibile?
DERR cell
Yes
Attempt over
the same UE?
Yes
An high number of attempt
could be an indication of a
problem and even in case of
the failure is not associated
an evaluation is required.
The key point is the
inviduation of the attempt
distribution, that in case are
not justified but partcualar
populated area, coluld
generate lot of signalling.
The attempts could be
genarated by 1B event ever
the same UE not counted in
the M1013.
The possibility to recover the
ADJS is the favourite option
and the down tilt carefully
analyzed considering the
failure associated.
No action
required
…
Source_cell_A 54 3 345 10 23 1 124 5
Source_cell_B 25 1 11 0 137 3
…
Source_cell_Z 32 2 45 2

Unbalanced WCEL
KPI(1) ?
Unbalanced WCEL
Tune 1A
Yes
KPI(2) ? Tune 1C
Yes
Analyze RSCP from DT & NWP
coverage plot considering
inter-site distance and traffic
distribution
WCEL interfered
polluted?
Yes
Interference /
pollution
Attempt over
the same UE?
Yes
No action
required
An high number of attempt
problem and even in case of the
failure is not associated an
evaluation is required.
The key point is the inviduation
of the attempt distribution,
that in case are not justified
but partcular populated area,
coluld generate lot of signalling.
The attempts could be
genarated by 1B event ever the
same UE not counted in the
M1013.
The possibility to have an
interference/pollution increase
respect to the unbalanced ADJS.
The optimization should be
performed at WCEL level
The KPI reported are the same
of Failure WCEL
…
Source_cell_A 543 13 345 10 876 7 124 5
Source_cell_B 25 1 11 0 137 3
…

Ping Pong
Ping-pong
Analyze RSCP from DT &
NWP coverage plot
considering inter-site
distance
One of them act
as polluter?
Comparable
value?
Histeresys
using
Ec/NoOffset
on the pair
Not stable,
Fading?
Filtering
Yes
Yes
Down tilt
Down tilt
possibile?
DERR cell Yes
Yes
Attempt from
the same UE?
No action
required
pollution
In this particular case the
high number of attempt is
concentrated in a pair
From A >> B and from B >>A
as in the picture
As in the previous case
problem and even in case
of the failure is not
associated an evaluation is
required to avoid to use a
lot signalling.
The optimization should be
performed at ADJS level
considering that the
filtering option could get
to smoother measured
value
…
Source_cell_A 54 3 345 10 23 1 124 5
Source_cell_B 987 13 11 0 137 3
…

Ping Pong - Filtering
Node B
UTRAN
RNC
UE
Measurement Control [ ]
I am in the
CELL_DCH sub-state
Measurement Type: Intra-frequency measurements
Reporting events:
1A: Event 1A triggered when CPCIH Ec/Io of the measured cell enters
UE
reporting range for a defined period of time
1B: Event 1B triggered when CPICH EC/I0 of the measured cell drops out
of the UE reporting range for a defined period of time
1C: Event 1C triggered when CPICH EC/IO of the measured cell enter in
AS by a defined margin for a defined period of time
System Information [ ]
EcNoFilterCoefficient EcNoAveragingWindow
Applied for averaging of
periodical meas. reports
Ec/NoFilterCoeff
controls the higher layer
filtering of physical layer
measurements before the
event evaluation and
measurement reporting is
performed by the UE.

Polluter Detection
The best way to individuate a Polluter is the Drive Test
A feedback can come from coverage plot, RNP feedback and Counters
A polluter can be of different type:
1. PSC Pollution
Too high reuse factor for the PSC. New PSC plan is required
2. DL Noise raise
ADJS signal strength out of usage window (will be never utilized
by the UE)
A down tilt or power reduction is the solution evaluating all the
side effects
3. Dominant site
A dominant site over-shooting the ADJ becoming congested
A down tilt or power reduction is the solution evaluating all the
side effects

PSC Pollution
A confirm for the polluter of the first type can come from the counter
M1007C38-47 CELL SPECIFIC CPICH EC NO - CLASS x/
Pollution Criteria:
The M1007C38-47 gives an indication of Ec No distribution value/
measured during event 1A . Having the distribution highly unbalanced
normally centered on class 2, 3, 4( ) we have an indication of a probable
problem. For example unbalancing towards the scarce value of Ec No but/
continuing to add cells to AS could give an indication of pollution
Polluted WCEL
Yes
High number
of class0-3?
High number of
class>6?
Not Polluted WCEL
Yes
Isolated/unavailable
WCEL

DL Noise Raise
The NO ADJS and low used ADJS criteria before presented can
give a confirm for a pollution of this type.
After the statistical data are stabilized, making across-check with
the provisioned ADJS Plan the probable polluters are individuated.
This is obviously a cautelative estimation to be integrated and
confirmed by drive test results
…
Source_cell_A 2 1 25 4 0 - 124 23
Source_cell_B 245 23 11 0 53 0 345 0
…
Source_cell_Z 322 1 3 1 0 - 123 20

Dominant site
Filtering the M1013 pairs for the recurrent target cell with
associated occasional failure we have an estimation of the probable
polluters
For the polluters, originating failures a down tilt is required
Polluted Cell Criteria:
SHO over head can give a soft help in individuating cell where
polluter overshooting site can be present or where unbalanced cell/
criteria could apply
( )
( ) %1001
T_NRT_IN_ACT_SETHREE_CELLM1007C21T_RT_IN_ACT_SETHREE_CELLM1007C2
NRTN_ACT_SET_TWO_CELL_IM1007C20RTN_ACT_SET_TWO_CELL_IM1007C1
NRTN_ACT_SET_ONE_CELL_IM1007C19RTN_ACT_SET_ONE_CELL_IM1007C0
3T_NRT_IN_ACT_SETHREE_CELLM1007C21T_RT_IN_ACT_SETHREE_CELLM1007C2
2NRTN_ACT_SET_TWO_CELL_IM1007C20RTN_ACT_SET_TWO_CELL_IM1007C1
NRTN_ACT_SET_ONE_CELL_IM1007C19RTN_ACT_SET_ONE_CELL_IM1007C0
RNC_79BOverheadHandoverSoft
⋅




















−
+
++
+
⋅+
+⋅+
+
==
…
Source_cell_A 2 1 25 4 26 3 124 23
Source_cell_B 245 23 11 0 53 0
… … …
Source_cell_Z 245 45

Cell Reselection List
GSM MS starts WCDMA measurements if :
RLA_C< F(Qsearch_I) for 0<Qsearch_I<=7
or
RLA_C> F(Qsearch_I) for 7<Qsearch_I<=15
If, for suitable UMTS cell
& for a period of 5 s:
CPICH RSCP > RLA_C + FDD_Qoffset
CPICH Ec/No ≥ FDD_Qmin
and
WCDMA cell
reselection
BCCH: FDD_Qmin, FDD_Qoffset
Cell Reselection 2G -> 3G
Start
measurement

Depending on operator´s 2G – 3G interworking strategy parameter Q_search_I should planned accordingly.
Configuration 1
RLA_C<
F(Qsearch_I)
( 0<Qsearch_I<=6 )
GSM 3G
Configuration 2
RLA_C> F(Qsearch_I)
( 7<Qsearch_I<=15 )
In the best case, 3G cell
measurements are
restricted to the condition:
RLA_C level > –78 dBm
GSM
3G
In the best case, 3G
cell measurements are
possible when RLA_C
level < –74 dBm
GSM
3G
Configuration 3
RLA_C< ∞ (always).
(Qsearch_I=7)
2G -> 3G Measurement

2G -> 3G Cell Re-selection Parameters
Qsearch_I and Qsearch_P define the threshold for non-GPRS/GPRS (respectively) capable UEs to measure 3G
neighbour cells when a running average of the received downlink signal level (RLA_C) of the serving cell
below (0-7) or above (8-15) the threshold
Value 0 1 … 6 7 8 9 10 … 14 15
dBm -98 -94 … -74 Always -78 -74 -70 … -54 Never
FDD_Qoffset and FDD_GPRS_Offset the non-GPRS/GPRS (respectively) capable UEs add this offset to the
RLA_C of the GSM cells. After that the UE compares the measured RSCP values of 3G cells with signal levels
of the GSM cells
Value 0 1 2 3 … 8 … 14 15
dBm Always -28 -24 -20 … 0 … 24 28
Always select irrespective
of RSCP value
Reselect in case RSCP >
GSM RXLev (RLA_C) +28dB
If RLA_C < -94 UE starts
3G measurements
UE always measures 3G
cells
If RLA_C > -70 UE starts
3G measurements
FDD_Qmin, defines minimum Ec/No threshold that a 3G cell must exceed, in order the UE makes a cell
reselection from 2G to 3G.

Cell Re-selection Example-Weaker WCDMA
Non GPRS case
t
Serving GSM Cell
Neighbour WCDMA Cell
Ec/No
RSCP/
RLA_C
5 sec.
Cell re-selection to WCDMA
FDD_Qmin=0
(-20 dB)
FDD_Qoffset =6 (-8 dB)
Qsearch_I=0
(-98 dBm)
RLA_C
Measurements starts (serving cell)
Minimum Quality Requirement for WCDMA
Ec/N0
RSCP

Cell Re-selection Example-Weaker WCDMA
GPRS case
t
Serving GSM Cell (Best)
Neighbour WCDMA Cell
Ec/No
RSCP/
RLA_C
5 sec.
Cell re-selection to WCDMA
FDD_Qmin
=-20 dB
FDD_GPRS_Qoffset =10 (8 dB)
Qsearch_P=0
(-98 dBm)
RLA_P
Measurements starts (serving cell)
Minimum Quality Requirement for WCDMA
Ec/N0
RSCP

Whilst camping in a 3G cell the UE performs intra-frequency, inter-frequency, and inter-system
measurements based on the measured CPICH EcNo.
Serving cell parameters Sintrasearch, Sintersearch and SsearchRAT are compared with Squal (CPICH
Ec/No – Qqualmin) in S-criteria for cell re-selection
1 - None (Squal > Sintrasearch )
2 - WCDMA intra-frequency (Sintersearch< Squal ≤ Sintrasearch)
3 - WCDMA intra- and inter- frequency, no inter-RAT cells (SsearchRAT < Squal ≤ Sintersearch)
4 - WCDMA intra- and inter-frequency and inter-RAT cells (Squal ≤ SsearchRAT )
Sintrasearch Sintersearch SsearchRAT
WCDMA
CELL
1234

First ranking of all the cells based on
CPICH RSCP (WCDMA) and RSSI (GSM)
Rs = CPICH RSCP + Qhyst1
Rn= Rxlev(n) - Qoffset1
First ranking of all the cells based on
CPICH RSCP (WCDMA) and RSSI (GSM)
Rs = CPICH RSCP + Qhyst1
Rn= Rxlev(n) - Qoffset1
Rn (GSM) > Rs (WCDMA)
And
Rxlev (GSM) >QrxlevMin
Rn (GSM) > Rs (WCDMA)
And
Rxlev (GSM) >QrxlevMin
YesNo
Cell re-selection
to GSM
Cell re-selection
to GSM
Neighbour WCDMA or GSM
cell calculation with offset
parameter
Serving WCDMA cell
calculation, with
hysteresis parameter
UE starts GSM measurements if
CPICH Ec/No =< qQualMin + sSearchRAT
UE starts GSM measurements if
CPICH Ec/No =< qQualMin + sSearchRAT
SintraSearch
SinterSearch
SsearchRAT
CPICH EcNo
qQualMin
Second ranking only for WCDMA
cells based on CPICH Ec/No
Rs = CPICH Ec/No + Qhyst2
Rn=CPICH_Ec/No(n)-Qoffset2
Second ranking only for WCDMA
cells based on CPICH Ec/No
Rs = CPICH Ec/No + Qhyst2
Rn=CPICH_Ec/No(n)-Qoffset2 Cell re-selection to
WCDMA cell of highest
R value
Cell re-selection to
WCDMA cell of highest
R value

UE ranks the serving cell and the measured neighboring cells to find out if reselection should be made
• All the measured suitable cells (S-criteria) are included in the ranking.
• Criteria for a suitable cell (S-criteria) is defined as
– WCDMA intra-frequency neighbour cell:
CPICH Ec/No > AdjsQqualmin and CPICH RSCP > AdjsQrexlevmin
– WCDMA inter-frequency cell:
CPICH Ec/No > AdjiQqualmin and CPICH RSCP > AdjiQrexlevmin
– GSM cell:
Rxlev > Qrxlevmin
Ranking is done using Criteria R, and the UE reselects to the cell with highest R-criteria. R-criteria is
defined
as:
• For serving cell: Rs = Qmeas,s + Qhysts
• For neighboring cell Rn = Qmeas,n – Qoffsetts,n
Qmeas is CPICH Ec/No for WCDMA cell and RxLev for GSM cell

How to avoid ping pong ?
When phone is camped on 3G, GSM measurements can start when CPICH Ec/Io of serving cell is below
Ssearch_RAT + QqualMin.
When phone is camped on GSM, cell reselection to 3G is possible if CPICH Ec/Io of the candidate is above
FDD_Qmin.
Therefore, to avoid ping pongs between 3G and GSM the following condition should be met:
FDD_Qmin >= QqualMin + Ssearch_RAT
QqualMin=-18 dB
Ssearch_RAT=4 dB
CPICH Ec/Io
FDD_Qmin >= -12 dB
QqualMin +Ssearch_RAT
t
Camping on 3G Measure GSM Camping on 3G

How to avoid ping pong ?
Parameters for cell reselections
• Qqualmin = -18dB Ssearch_RAT =2dB -> the 3G->2G cell reselection starts when Ec/No hits -16dB
• FDDQmin(GPRSFDDQmin) = -14dB (6) and QsearchP/QsearchI = always
The cell reselection paramters 3G -> 2G and 2G -> 3G provide only 2dB hysteresis which is not enough and should be
noticed from the RNC statistics as high amount of INTR_RAT_CELL_RE_SEL_ATTS from all the RRC Connection
Setup Attempts
• Recommendation is to adjust the FDDQmin from -14dB to -10dB (or even up to -8dB) to provide 6 to 8 dB
hysteresis between 3G to 2G cell reselection and 2G to 3G cell reselection
• Another parameter to tune is Qrxlevmin
On top of Treselection the above parameters will slow down further the 2G to 3G and 3G to 2G cell reselections

Treselection
How long the reselection conditions must be fulfilled before reselection is triggered?
Treselection
Impacts all cell reselections : Inter RAT, intra frequency and inter frequency
The UE reselects the new cell, if the cell reselection criteria (R-criteria, see next slide) are fulfilled during a time
interval
Treselection
As this parameter impacts on all the cell reselections too long Treselection timer might cause problems in high mobility
areas but too short timer causes too fast cell reselections and eventually causes also cell reselection ping pong
Recommended value 1s should work in every conditions i.e. enough averaging to make sure that correct cell is
selected
However careful testing is needed to check the performance of different areas
• (Dense) Urban area, slow moving UEs with occasional need for fast and accurate (to correct cell) reselections e.g.
outdoor to indoor scenarios or city highways – in some cases cell by cell parameter tuning is performed to find
most optimal value between 0s and 2s but typically 1s is optimal value when workload is considered as well
• Highways, fast moving UEs must reselect correct cell – typically 1s works the best (however occasionally also 0s
might be needed in fast speed outdoor to indoor cell reselections e.g. tunnels)
• Rural areas, slow or fast moving UEs need very often reselect between different RATs and make proper cell
reselections even when the coverage is poor – typically 1s works the best
• Location Area Borders, usually the coverage is fairly poor – typically 1s works the best but sometimes to reduce
location area reselection ping pong 1s is used when going from LA1 to LA2 and 2s from LA2 to LA1

IRATHO
As M1013 described in PartI, M1015 return statistic for intesystem HO. The filtering criteria
can be replicated with the exception of ping-pong
Filtering criteria:
Major
- High number of failures for a defined out-going adjg (failure ADJG)
- high number of fail for a defined source (failure WCEL)
Minor
- very low number of attempt with failure (low used adjg)
- zero number of attempt for declared adjs– stabilized value (no adjg)
- high number of attempts for an out-going adjs (unbalanced ADJG)
out-going condition is sufficient
- high number of attempts for a defined source (unbalanced WCEL)
Same procedures can be applied to the case considering that the event related are 1E and 1F

1E/1F Events for CPICH Ec/No and RSCP
time
Cell 1
Cell 2
Cell 3
e.g.P-CPICHEc/No
HHoEcNo(RSCP)Cancel
Defines the threshold of Ec/No(RSCP)
that must be exceeded by a measurement
of an active set cell to be canceled the
event 1F related
HHoEcNo(RSCP)CancelTime
determines the time period during which the CPICH
RSCP of the active set cell must stay better than the
threshold HHoRscpCancel before the UE can trigger the
reporting event 1E.
HHoEcNo(RSCP)Thres
hold
determines the absolute CPICH
Ec/No threshold which is used by the
UE to trigger the reporting event 1F.
When the measured CPICH Ec/No of
all active set cells has become worse
than or equal to the threshold in
question, the RNC starts inter-
frequency or inter-RAT (GSM)
measurements in compressed mode
for the purpose of hard handover.
HHoEcNo(RSCP)TimeHysteresis
determines the time period during which the CPICH Ec/No of the active
set cell must stay worse than the threshold HHoEcNoThreshold before
the UE can trigger the reporting event 1F.
1E
1F

IRATHO – Triggering reason
4. DL DPCH approaches its
maximum allowed power
FMCG: GSMcauseTxPwrDL
5. Quality deterioration report
from UL outer loop PC
FMCG: GSMcauseUplinkQuality
3. UE Tx power approaches
its maximum allowed
power, event 6A/6D
FMCG: GSMcauseTxPwrUL
2 . Low measured absolute
CPICH RSCP, events 1E/1F
FMCG: GSMcauseCPICHrscp
1. Low measured absolute
CPICH Ec/No, event 1E/1F
FMCG: GSMcauseCPICHEcNo
GSMcauseX
These parameters indicates whether a handover to GSM caused by low measured absolute CPICH Ec/No of the serving cell is
enabled (1)
6 . Others
- Load and Service based HO
- IMSI based HO
- Emergency ISHO
Triggering reason gives
an indication

∑
=
Allcauses
RTNxxxCMODWHHOIS
RTNxxxCMODWHHOIS
percCausexxx
)_(____
)_(____
__
It’s important to know which is the most frequent triggering reason:
It’s possible to diffentiate between quality and coverage reasons and understand the
network limiting factors:
1. CPICH coverage
2. Pilot pollution
3. UL/DL Service coverage
In actual case is possible to dsciminate between low CPICH coverage triggered by high# RSCP
attempts or probable pilot pollution triggered by high # Ec/No attempts
A KPI that gives reason for that is

High # Ec/No?
Start
UL level limiting
Yes
High # RSCP?
High # UE
Tx pwr?
High # UL Qual?
New site required or new
Parametrization for IRATHO
UL qual limiting
Yes
Load analisys and UL
interference evaluation
DL Qual limiting
Yes
DL interference/ Pollution
should be evaluated
DL level limiting
Yes
CPICH power analisys/ new
site required
UL
DL
This condition
should be the
dominannt one
without
associated
failure
Enabling all the causes a screaning on the network is returned individuating the limiting factor
and the required action.
High # DL
DPCH?
Service limiting
Yes
New planning for service is
required
End

IRATHO - Failure
Failure can happen
at different point:
Before decision
- Before CM
- During CM
- Measuring GSM
cell
After decision
- Drop
Utran and ue have to
treated as particular
case
UE Node B RNC
RRC: Measurement Report
RRC: Measurement Control
NBAP: Radio Link Reconfiguration Prepare
NBAP: Radio Link Reconfiguration Ready
NBAP: Radio Link Reconfiguration Commit
RRC: Physical Channel Reconfiguration
RRC: Physical Channel Reconfiguration Complete
NBAP: Compressed Mode Command
GSM RSSI
Measurement
ISHO triggering
(5 reasons are
possible)
Initial
Compressed
Mode
Configuration
CN
RANAP: SRNS Context Request
RANAP: SRNS Context Response
RANAP: IU Release Command
RANAP: IU Release Complete
RRC: Cell Change Order from UTRAN
RANAP: SRNS Data Forward Command

CM not possible
The following KPI gives an indication of the number of CM
procedure not started
If CM fails one of the following mus be checked:
Not enough resources – AC reject CM.
Evaluate interference
Expand capacity
(see PartI)
RNCRNCUEUE
RRC: Measurement Report (3,4,5)
BTSBTS
Admission Control
check for CM
Admission Control
check for CM
NBAP: Radio Link Reconfiguration Prepare
NBAP: Radio Link Reconfiguration Ready
NBAP: Radio Link Reconfiguration Commit
RRC: Physical Channel Reconfiguration
RRC: Physical Channel Reconfiguration Complete
BSIC verification phase for target cell
RX Level measurement phase for
all ISHO neighbours
AC is responsible for checkiing if CM is possiblle
∑+
j
jMODIS_HHO_W_COS_STA_NOT_PIS_COM_MOD
OS_STA_NOT_PIS_COM_MOD
Considering that M1010C2 (INTER SYST COM MOD STA NOT POS FOR RT) is updated if it is
not possible to start inter-system compressed mode measurement due to radio resource
congestion, BTS- or UE-related reasons to have a better insight on radio congestion it could
be better to use, e.g. for UL the M1002C361 REQ FOR COM MODE UL REJECT TO INT SYST
HHO IN SRNC and the M1002C357 REQ FOR COM MODE UL TO INT SYST HHO IN SRNC and
use the following :
M1002C361/M1002C357

NO Cell Found
Missing ADJG could be the reason or a dedicated parameter tuning for the 1F event.
The KPI can be madified taling care of the WO_CMOD events
The following KPI gives an indication of the number of GSM cell not found
NO Cell Found means:
there is no suitable gsm target cell in terms of RX Level
OR
the target gsm is suitable but its BSIC verification fails
AND
the maximum number of measurement reported are received
AND
maximum measurement interval is not expired
Compressed
Mode start
No Cell Found
Counters
HHO Attempt
Counters
… measurement
fail
… measurement not
fail
∑
∑
=
Allcauses
Allcauses
RTNxxxCMODWHHOIS
RTNxxxCELLNOHHOIS
RateFailMeasISHO
)_(____
)_(____
___

NO Cell Found
High #
NO Cell?
ADJG
Addition?
Yes
Verify
ADJG
Yes
Start
Reduce “Cancel”
Increase “Time hysteresis”
Good GSM coverage
in the near field?
Yes
Coverage anlisys
End
End
Good GSM coverage
in the far field?
Reduce
“thershold”
New site
requiredGSMCause=Ec/
Nol?
Yes
Pollution evaluation

DROP & UNSUCCESS IRATHO
∑
∑
=
Allcauses
Allcauses
RTNxxxATTHHOIS
RTNxxxHHOISDRPSCON
RateDropISHO
)_(___
)_(____
__
In this case the optimization is required and
pass through the evaluate of GSM and 3G plot
coverage. Optimize If necessary number of
ADJG or NWP parameters otherwise tune
RNW parameters.
Thresholds can be relaxed to favourite an
early exit from 3G layer
RRC Drop
Counters
RRC Drop
Counters
HHO Attempt
Counters
HHO Attempt
Counters
ISHO Success
Counters
ISHO Success
Counters
ISHO Unsuccess
Counters
ISHO Unsuccess
Counters
UE Failure
Counter
UE Failure
Counter
UTRAN Failure
Counter
UTRAN Failure
Counter
Optimization for unsuccess is not possible
because the reason are:
- physical channel failure (the UE is not able to
establish the phy.
- Protocol error
- Inter-Rat protocol error
- Unspecified
Drop are related to drop call occurred
during the procedure

3G –> 2G Unbalancing
VOICECSCOMPACCRAB
RTxxxATTHHOIS
ISHOCallVoicePerc Allcauses
____
____
___
∑
=
This topic present the inherent problem due to the fact that the 2G layer is not involved in
the analisys.
Few consideration can be performed under some assumption:
The following KPIs used over a cluster for CS voice service gives the percentage of the CM
started over all the RAB, giving an idea of the attempted mobility procedure requested for a
cluster where the 3G coverage should be assured
Once Correlated with voice drop due to radio link failure and rrc drop during ISHO, the KPI can
help operator in understand the ISHO strategy. Similar KPI is possible for PS
Threshold to shrink the HO area or inhibit the procedure has to be setted
Better to use completes: failures, normal & SRNC reloc on denominator and use the KPI inside the
3G cluster or difining a polygon where 3G service is required

Part 3 optimization 3G

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