Part 3 optimization 3G

Part 3 :Optimization

Network Deployment Steps

Presentation / Author / Date

Using Reporting Suite 3G RAN Reports or MS Access KPI Queries

Weekly 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

Traffic Monitoring

Principles of traffic monitoring - bottlenecks

Both interfaces and internal resources of WCDMA network should be monitored

User P

lane

RNCUE

WBTS

DNBAP

AAL2 or IP SIG

CNBAPPRACHFACH-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

WSPResource

CodeCapacity

Throughput

Connectivity

Unit Load

DSP Usage

D-RNC

Principles of traffic monitoring - reactive / proactive

Reactive 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

R99 power -

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

HSDPA power - dynamic share with R99PtxTargetPS 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 - dynamic share with R99

HSDPA power congestion, ifPtxtotal ≥ 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 targetDecrease PtxTargetPS by PtxTargetPSStepDown (default 1 dB)

Optimum load target

HSDPA power - dynamic share with R99DCH Congestion

PtxMax 43 dBm

PtxNC

PtxNRTPtxNonHSDPA

PtxTargetPSMin

PtxTargetPSMax

PtxHighHSDPAPwr

DCH power congestion, if

PtxNonHSDPA ≥ PtxTargetPS - 1dBIf actual load target PtxTargetPS < optimum load targetIncrease PtxTargetPS by PtxTargetPSStepUp (default 1 dB)

PtxTotal

PtxTargetPS

Optimum load target

Noise rise due toreal traffic

Own cell load factor (throughput)

i-factor

PrxTargete.g. 4 dB above PrxNoise

RTWP sources

-108 dBmReceiver noise figure (e.g. 2 dB)

Thermal noise -108 dBm

-106 dBmIntermodulation out of band (e.g. 1 dB)

-105 dBmRTWP of empty cellMUST be equal PrxNoise

PrxOffsete.g. 1 dB above PrxTarget

High adjacent cell interference

Low adjacent cell interference

-101 dBm

-100 dBm

Total UL power - role of BTS commissioningRTWP 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 - principlesCode 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 - blockingPractical example – single cell

Blocking per SF per hour

Very high blocking especially for SF8But still also for SF16 and sometimes even for SF32

R99 code allocation - re-arrangementCode 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 - principlesFor 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 R99Downgrade 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

Nu

mb

er

of

all

oc

ate

d S

F1

6 c

od

es

DPCHOverHSPDSCHThreshold

6789101112131415 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 cellCodes for common channels in the cell Codes for associated DCHs

and non-HSDPA usersCodes 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)



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 utilizationPractical example – UL on single BTS

In most cases very high utilizationTypically 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 HSPAPractical example – UL on single BTS

In most cases very high utilization due to HSUPATypically 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)



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 trafficTwo VC multiplexed by IMA

Cell rate reserved by CAC per VC

Configured bandwidth

Maximum reserved bandwidth

Minimum reserved bandwidth

Free bandwidthEven maximum reserved bandwidth far below configured bandwidthNo risk of physical congestion

Examples - logical ATM trafficTwo 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 248No 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 - licensesR99• 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 setupRAN resources reserved for signaling connection between UE and RNC

RRC accessConnection between UE and RRC

RRC activeUE has RRC connection

If dropped, also active RAB dropped

RAB setupAttempts to start call

RAB setup access

Connection between UE and core

RAB active phaseUE 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

SetupComplete

SetupComplete

AccessCompleteAccess

Complete

ActiveComplete

ActiveComplete

SetupSetup AccessAccess ActiveActive

Att

em

pts

Setup failures(blocking)

Access failures

Acc

ess Active

ReleaseActive

Release

ActiveFailuresActive

FailuresRRCDrop

Succ

ess

Phase:

RRC and RABCall 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 establishmentSignalling 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 powerandhigh DL BLER

Very bad RSCP

UE max Tx powerandhigh 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 WORDSFor 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 availabilityAlarms/Tickets

Configuration & Parameter audit

SHO Success Rate < 90%?

Conf OK ?

Site OK ?

ISHO Failures

Iur

performance Investigation Iur

Audit adjacent sites for alarms, Availability, configuration and

capacity

TrafficNeighbours’ Performance

(use SHO success per adjs counters to identify badly

performing neighbours) & Map

3G Cell at RNC border?

NO

YES

New site ?

Analyse last detailed radio measurements

RF and 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 issues

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 UsageM1013 (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

Minor

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

Minor

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 to fovourite it

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 0Source_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

AdjsEcNoOffsetto 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.

Reporting

Range

AdjsDERRto forbid a cell from reporting range calculation in some instances

Ec/Io

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_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

AdditionWindowdetermines 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)

AdditionTimedefines 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

AdditionReportingIntervaldefines 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.

MeasurementReport

Add tothe AS?

no

ActiveSetWeightingCoefficientis 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

ReplacementTimeDefines 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).

MeasurementReport

RNC

ASupdate?

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 23Source_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_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

Analyze Ec/No from DT & evaluate unbalance


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 5Source_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 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 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





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


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 could be an indication of a 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





Ping Pong - Filtering

Node B

UTRAN

RNCUE

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 UEreporting range for a defined period of time1B: Event 1B triggered when CPICH EC/I0 of the measured cell

drops outof the UE reporting range for a defined period of time1C: Event 1C triggered when CPICH EC/IO of the measured cell

enter inAS by a defined margin for a defined period of time

System Information [ ]

EcNoFilterCoefficient EcNoAveragingWindow

Applied for averaging of periodical meas. reports

Ec/NoFilterCoeffcontrols the higher layer filtering of physical layer measurements before the event evaluation and measurement reporting is performed by the UE.

Pollution

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 23Source_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_CELL M1007C21T_RT_IN_ACT_SETHREE_CELL M1007C2

NRTN_ACT_SET_TWO_CELL_I M1007C20RTN_ACT_SET_TWO_CELL_I M1007C1

NRTN_ACT_SET_ONE_CELL_I M1007C19RTN_ACT_SET_ONE_CELL_I M1007C0

3T_NRT_IN_ACT_SETHREE_CELL M1007C21T_RT_IN_ACT_SETHREE_CELL M1007C2

2NRTN_ACT_SET_TWO_CELL_I M1007C20RTN_ACT_SET_TWO_CELL_I M1007C1


RNC_79B OverheadHandover Soft

%1001

T_NRT_IN_ACT_SETHREE_CELL M1007C21T_RT_IN_ACT_SETHREE_CELL M1007C2

NRTN_ACT_SET_TWO_CELL_I M1007C20RTN_ACT_SET_TWO_CELL_I M1007C1


3T_NRT_IN_ACT_SETHREE_CELL M1007C21T_RT_IN_ACT_SETHREE_CELL M1007C2

2NRTN_ACT_SET_TWO_CELL_I M1007C20RTN_ACT_SET_TWO_CELL_I M1007C1


RNC_79B OverheadHandover Soft



… … …Source_cell_Z 245 45


Cell Reselection

Cell Reselection List

GSM MS starts WCDMA measurements if :RLA_C< F(Qsearch_I) for 0<Qsearch_I<=7

orRLA_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 cellreselection

BCCH: FDD_Qmin, FDD_Qoffset

Cell Reselection 2G -> 3G

Startmeasurement

Depending on operator´s 2G – 3G interworking strategy parameter Q_search_I should planned accordingly.

Configuration 1RLA_C<

F(Qsearch_I) ( 0<Qsearch_I<=6 )

GSM 3G

Configuration 2RLA_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 3RLA_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 WCDMANon GPRS case

t

Serving GSM Cell

Neighbour WCDMA Cell

Ec/NoRSCP/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 WCDMAGPRS case

t

Serving GSM Cell (Best)

Neighbour WCDMA Cell

Ec/NoRSCP/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 + Qhyst1Rn= Rxlev(n) - Qoffset1

First ranking of all the cells based on CPICH RSCP (WCDMA) and RSSI (GSM)

Rs = CPICH RSCP + Qhyst1Rn= 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 + Qhyst2Rn=CPICH_Ec/No(n)-Qoffset2

Second ranking only for WCDMA cells based on CPICH Ec/No

Rs = CPICH Ec/No + Qhyst2Rn=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 definedas:• 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 frequencyThe UE reselects the new cell, if the cell reselection criteria (R-criteria, see next slide) are fulfilled during a time

intervalTreselectionAs 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 pongRecommended value 1s should work in every conditions i.e. enough averaging to make sure that correct cell is selectedHowever 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

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 1Cell 2

Cell 3e.g

. P-C

PIC

H E

c/N

oHHoEcNo(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)Thresholddetermines 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)TimeHysteresisdetermines 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 itsmaximum 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 absoluteCPICH 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

RTNxxxCMODWHHOISpercCausexxx

)_(____

)_(______

Allcauses

RTNxxxCMODWHHOIS

RTNxxxCMODWHHOISpercCausexxx

)_(____

)_(______

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

YesLoad analisys and UL interference evaluation

DL Qual limiting

YesDL interference/ Pollution should be evaluated

DL level limiting

YesCPICH 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

YesNew 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


RRC: Measurement ControlGSM 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 interferenceExpand 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

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

CompressedMode start

No Cell FoundCounters

HHO AttemptCounters

… measurement fail

… measurement not fail

Allcauses

Allcauses

RTNxxxCMODWHHOIS

RTNxxxCELLNOHHOISRateFailMeasISHO

)_(____

)_(_______

Allcauses

Allcauses

RTNxxxCMODWHHOIS

RTNxxxCELLNOHHOISRateFailMeasISHO

)_(____

)_(_______

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

RTNxxxHHOISDRPSCONRateDropISHO

)_(___

)_(______

Allcauses

Allcauses

RTNxxxATTHHOIS

RTNxxxHHOISDRPSCONRateDropISHO

)_(___

)_(______

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 DropCountersRRC DropCounters

HHO AttemptCounters

HHO AttemptCounters

ISHO SuccessCounters

ISHO SuccessCounters

ISHO UnsuccessCounters

ISHO UnsuccessCounters

UE FailureCounter

UE FailureCounter

UTRAN FailureCounter

UTRAN FailureCounter

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

RTxxxATTHHOISISHOCallVoicePerc Allcauses

____

_______

VOICECSCOMPACCRAB

RTxxxATTHHOISISHOCallVoicePerc 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

Engineering

Transcript of Part 3 optimization 3G