Parameter Optimization

Review

Parameter optimization is an important step

after RF Optimization.

Parameter optimization improves service

quality and utilization of network resources.

Review

New Sites Intergrated

Single Site Verification

Cluster of Sites

ready?

RF Optimisation

Services Testing &

Parameter Optimisation

Regular Reference Route

Testing & Stats Analysis

Re- optimisation

Needed?

YES

NO

YES

NO

Objectives

Understand the process of parameter

optimization

Master the contents of parameter

optimization

Upon completion of this course, you can:

Contents

Parameter optimization procedure

Parameter optimization contents

Parameter Optimization Process

Data Input and Find

Problems

Verify Parameter Problems

Other ProcessClassify Parameter Problems

Determine Parameter Values to be

Modified and List MML Commands

Evaluate Changing Effects

Prepare Test Plan and Implement

Changing

Test , Get Data again and Compare

Problems Eliminate Or Need not Change more

End

Determine whether Changing

End

N

N

Y

Y

Y

N

Data Input and Find Problems

Data Input

Drive Test Data

KPI Network Statistic Data

Network Tracing Message

Network Warning Information

Problems

Find problems from the input data, such as:

• Low success rate of call setup

• Low success rate of handover

• High rate of call drop

Verify Parameter Problems

Parameter Problems

No RF Problems

No Hardware/Software Problem

Related with Environment

Or Speed

Parameters never Optimized

Before

Parameter Classification

Mobile Management Parameters

Power Control Parameters

Power Configuration Parameters

Load Control Parameters

Other Parameters

Determine Parameter Values

List the form for changing parameters

(original parameter values vs. new parameter values)

List MML commands for changing parameters

Note:

Maybe some tradeoff considerations need to be considered to assure

the maximal improvement in the whole view such as “coverage and

capacity”,“ fast and stable”, “improvement and risk”, “cost (or efforts)

and gain”.

Impact

Impact on customer service and other networks

Impact on OMC (efforts, maintenance)

Prepare Test Plan and Change Parameters

Prepare test schedule, routes, tools and be ready to get

Information.

Change parameters and make records.

Course Contents

Parameter optimization Procedure

Parameter optimization Contents

Parameter Optimization Contents

Mobile Management parameter optimization

Power Control parameter optimization

Power Configuration parameter optimization

Load Control parameter optimization

Note:

There are too many parameters to introduce. Only some parameters about

network optimization are mentioned here and maybe more parameters

need to be added in the future.

Mobile Management Parameter Optimization

Cell Selection & Reselection

The changing of cell on which UE camped in idle mode or in Cell FACH, Cell

PCH, URA PCH states. That assures UE camping the most suitable cell,

receiving system information and establishing an RRC connection on a best

serving cell.

Handover

The changing of cells with which UE connected in DCH mode.

That assures seamless coverage and load balancing.

Cell Selection & Reselection Procedure

InitialCell Selection

Any CellSelection

go herewhen noUSIM inthe UE

USIM inserted

Camped on

any cell

go here whenever anew PLMN is

selected

1no cell information

stored for the PLMNcell information

stored for the PLMN

Storedinformation

Cell Selection

no suitable cell found

no suitablecell found

Cell Selectionwhen leaving

connectedmode

suitable cell found 2

suitablecell found

Campednormally

suitable cell found

no suitablecell found

leaveidle mode

return toidle mode

Connectedmode

CellReselectionEvaluationProcess

suitablecell found

trigger

no suitablecell found

1

Cell Selectionwhen leaving

connectedmode

no acceptable cell found

acceptablecell found

acceptablecell found

suitablecell found 2

leaveidle mode

return toidle mode

Connectedmode

(Emergencycalls only)

CellReselectionEvaluationProcess

acceptablecell found

trigger

no acceptablecell found

NAS indicates thatregistration on selected

PLMN is rejected(except with cause #14

or #15 [5][16])

Cell Selection Criteria (S Criteria)

The cell selection criterion S is fulfilled when:

for FDD cells: Srxlev > 0 AND Squal > 0

for TDD cells: Srxlev > 0

Where:

Squal = Qqualmeas – Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

When a UE wants to select a UMTS cell, the cell must satisfy S criterion.

Cell Selection Parameters

Cell Re-selection Measure Condition

Use Squal for FDD cells and Srxlev for TDD for Sx

1. If Sx > Sintrasearch, UE need not perform intra-frequency measurements.

If Sx <= Sintrasearch, perform intra-frequency measurements.

If Sintrasearch, is not sent for serving cell, perform intra-frequency measurements.

2. If Sx > Sintersearch, UE need not perform inter-frequency measurements.

If Sx <= Sintersearch, perform inter-frequency measurements.

If Sintersearch, is not sent for serving cell, perform inter-frequency measurements.

3. If Sx > SsearchRAT m, UE need not perform measurements on cells of RAT“ m".

If Sx <= SsearchRAT m, perform measurements on cells of RAT "m".

If SsearchRAT m, is not sent for serving cell, perform measurements on cells of

RAT "m".

Cell Reselection Criteria (R Criteria)

All cells should satisfy S Criteria.

Select the Cell with the highest R value using the following method to compute.

Rs = Qmeas,s + Qhysts

Rn = Q meas,n - Qoffsets,n

The cells shall be ranked according to the R criteria specified above, deriving Qmeas,n and

Qmeas,s and calculating the R values using CPICH RSCP, P-CCPCH RSCP and the averaged received

signal level for FDD, TDD and GSM cells, respectively.

The offset Qoffset1s,n is used for Qoffsets,n to calculate Rn, the hysteresis Qhyst1s is used

for Qhysts to calculate Rs.

If an FDD cell is ranked as the best cell and the quality measure for cell selection and re-selection is set to

CPICH Ec/No, the UE shall perform a second ranking of the FDD cells according to the R criteria specified

above, but using the measurement quantity CPICH Ec/No for deriving the Qmeas,n and Qmeas,s and

calculating the R values of the FDD cells. The offset Qoffset2s,n is used for Qoffsets,n to calculate Rn, the

hysteresis Qhyst2s is used for Qhysts to calculate Rs. Following this second ranking, the UE shall perform cell

re-selection to the best ranked FDD cell.

In all cases, the UE shall reselect the new cell, only if the following conditions are met:

- the new cell is better ranked than the serving cell during a time interval Treselection.

- more than 1 second has elapsed since the UE camped on the current serving cell.

Cell Reselection Parameters

Cell Reselection Parameters

Cell Reselection from GSM to UMTS

If the 3G Cell Reselection list includes UTRAN frequencies, the MS shall, at least every 5 s

update the value RLA_C for the serving cell and each of the at least 6 strongest non-serving

GSM cells.

The MS shall then reselect a suitable (see TS 25.304) UTRAN cell if its measured RSCP value

exceeds the value of RLA_C for the serving cell and all of the suitable (see 3GPP TS 03.22) non-

serving GSM cells by the value XXX_Qoffset for a period of 5 seconds and, for FDD, the UTRAN

cells measured Ec/No value is equal or greater than the value FDD_Qmin. In case of a cell

reselection occurring within the previous 15 seconds, XXX_Qoffset is increased by 5 dB.

where Ec/No and RSCP are the measured quantities.

FDD_Qmin and XXX_Qoffset are broadcast on BCCH of the serving cell. XXX indicates

other radio access technology/mode.

Note:The parameters required to determine if the UTRAN cell is suitable are broadcast on

BCCH of the UTRAN cell. An MS may start reselection towards the UTRAN cell before

decoding the BCCH of the UTRAN cell, leading to a short interruption of service if the

UTRAN cell is not suitable.

Cell reselection to UTRAN shall not occur within 5 seconds after the MS has reselected a

GSM cell from an UTRAN cell if a suitable GSM cell can be found.

If more than one UTRAN cell fulfils the above criteria, the MS shall select the cell with the

greatest RSCP value.

Cell Reselection Parameters from GSM to

UMTS

Handover Procedure

Node B

Node B

Node B

Intra-frequency cells

Neighbor cells both from same NodeB or

other NodeBs

Measurement report

Handover decision

Measurement control

Measurement and filtering

Handover execution

Soft Handover Example

Soft Handover Procedure

Soft Handover Event – 1A

1A (add a cell in Active Set)

)2/(10)1(1010 11

1

aaBest

N

i

iNewNew HRLogMWMLogWCIOLogMA

MNew : the measurement result of the cell entering the reporting range.

CIONew : the individual cell offset for the cell entering the reporting range

if an individual cell offset is stored for that cell. Otherwise it is equal to 0.

Mi : measurement result of a cell not forbidden to affect reporting range in

the active set.

NA : the number of cells not forbidden to affect reporting range in the

current active set.

MBest : the measurement result of the cell not forbidden to affect reporting range

in the active set with the highest measurement result, not taking into account

any cell individual offset.

W : a parameter sent from UTRAN to UE.

R1a : the reporting range constant.

H1a : the hysteresis parameter for the event 1a.

Soft Handover Event – 1B

1B (Remove a cell from Active Set)

)2/(10)1(1010 11

1

bbBest

N

i

iOldOld HRLogMWMLogWCIOLogMA

MOld : the measurement result of the cell leaving the reporting range.

CIOOld : the individual cell offset for the cell leaving the reporting range if

an individual cell offset is stored for that cell. Otherwise it is equal to 0.

Mi : measurement result of a cell not forbidden to affect reporting range in the

active set.

NA : the number of cells not forbidden to affect reporting range in the current

active set.

MBest : the measurement result of the cell not forbidden to affect reporting range

in the active set with the lowest measurement result, not taking into account

any cell individual offset.

W : a parameter sent from UTRAN to UE.

R1b : the reporting range constant.

H1b : the hysteresis parameter for the event 1b.

Soft Handover Event – 1C

1C (a non-active primary CPICH becomes better than an active

primary CPICH. If Active Set is not full, add the non-active cell into

active set .Otherwise use the cell substitute the active cell.)

2/1010 1cInASInASNewNew HCIOLogMCIOLogM

MNew : the measurement result of the cell not included in the active set.

CIONew : the individual cell offset for the cell becoming better than the cell in the active

set if an individual cell offset is stored for that cell. Otherwise it is equal to 0.

MInAS : the measurement result of the cell in the active set with the highest

measurement result.

MInAS : the measurement result of the cell in the active set with the lowest

measurement result.

CIOInAS : the individual cell offset for the cell in the active set that is becoming worse

than the new cell.

H1c : the hysteresis parameter for the event 1c.

Soft Handover Event – 1D

1D (Change of best cell. If the chosen cell is not in Active Set,

add the cell into Active Set and modify measurement

control .Otherwise only modify measurement control. )

2/1010 1dBestBestNotBestNotBest HCIOLogMCIOLogM

MNotBest : the measurement result of a cell not stored in "best cell"

CIONotBest : the cell individual offset of a cell not stored in "best cell" .

MBest: the measurement result of the cell stored in "best cell".

CIOBest : the cell individual offset of a cell stored in "best cell" .

H1d : the hysteresis parameter for the event 1d.

Soft Handover Parameters

Parameter Name Description Default Setting

IntraRelThdFor1A Relative thresholds of soft handover for Event 1A (R1a) 10, namely 5dB (step 0.5)

IntraRelThdFor1B Relative thresholds of soft handover for Event 1B (R1b) 10, namely 5dB (step 0.5)

Hystfor1A, Hystfor1B,

Hystfor1C, Hystfor1D

Soft handover hysteresis (H1x) 6,namely 3dB (step 0.5) for H1a .

8,namely 4dB(step 0.5) for H1b,

H1c,H1d.

CellIndividalOffset Cell CPICH measured value offset; the sum of this

parameter value and the actually tested value is used for

UE event estimation. (CIO)

0

WEIGHT Weighting factor, used to determine the relative

threshold of soft handover according to the measured

value of each cell in the active set.

0

TrigTime1A,TrigTime1B,

TrigTime1C,TrigTime1D

Soft handover time-to-trigger parameters (event time-to-

trigger parameters. Only the equation are always

satisfied during the trigger time, the event will be

triggered).

D640, namely 640ms .

FilterCoef Filter coefficient of L3 intra-frequency measurement D5,namely 5

Inter-system Handover – CS Domain

Procedure

UE

1. RRC Connect Req

15. RAB Assign Req

NODEB RNC 3G MSC BSS 2G MSC

2. RRC Setup Complete

3. Measure Control (measure ID 0x1 )

4. Measure Control (measure ID

0x2 ) 5.Initial UE message(service request)

6.DL DT (Authentication Request)

7.UL DT (Authentication Response) 8.Common ID

9. Security Mode Command 10. Security Mode Command

11. Security Mode CMP 12. Security Mode CMP

13. UL DT(Setup)

14. DL DT(Call proceeding)

17.RL Recfg Ready

21 RAB Assign Resp 20 RB Setup

Cmp

19 RB Setup

16.RL Recfg Prep

18.RL Recfg Commit

22. DL DT( Alerting )

23. DL DT( Connect)

24. UL DT(Connect Ack)

26.RL Recfg Prep

28 PhyCh Reconfig 29.RL Recfg Comit

27.RL Recfg Ready

30 PhyCh Reconfig CMP

31 Meaure Control(ID3 )

32Measure Report 33 Relocation Required

34 Relocation Command 35. HandoverFromUtranCommand

44 Iu Release Req

46 RL Del Resp 45 RL Del Req

47 Iu Release Complete

25 Measure Report(2D)

Inter-system Handover Measure

1) Use Inter-frequency measurement reporting Event 2d, 2f

to reflect the currently used frequency quality.

Event 2d: The estimated quality of the currently used frequency is below a certain threshold.

The variables in the formula are defined as follows:

QUsed is the quality estimate of the used frequency.

TUsed 2d is the absolute threshold that applies for the used frequency and event 2d.

H2d is the hysteresis parameter for the event 2d.

Event 2f: The estimated quality of the currently used frequency is above a certain threshold.

The variables in the formula are defined as follows:

QUsed is the quality estimate of the used frequency.

TUsed 2f is the absolute threshold that applies for the used frequency and event 2f.

H2f is the hysteresis parameter for the event 2f.

2/22 ddUsedUsed HTQ

2/22 ffUsedUsed HTQ

Inter-system Handover Measure

2） When Received 2D reports ( that means the currently used frequency signal is poor ), RNC

sends Measurement Control (ID3) to let UE begin to measure other system signal . UE will

send measurement result reports periodically . When Received 2F reports (that means the

currently used frequency signal is not poor), RNC sends Measurement Control (ID3,but

different contents) to let UE stop measuring other system signal .

3) When received the periodical reports, RNC use the following formula to judge whether should

handover UE to another system .

Mother_RAT + CIO > Tother_RAT + H/2

Tother_RAT : the inter-system handover decision threshold;

Mother_RAT : the inter-system (GSM RSSI) measurement result received by RNC;

CIO: Cell Individual Offset, which is the inter-system cell setting offset;

H : refers to hysteresis,

If the formula is met, a trigger-timer called TimeToTrigForSysHo will be started, and a handover decision will be

made when the timer times out;

Note: if the inter-system quality satisfies the following condition before the timer times out:

Mother_RAT + CIO < Tother_RAT - H/2

The timer will be stopped, and RNC will go on waiting to receive the next inter-system measurement report.

The length of the trigger-timer is called time-to-trigger.

Inter-system Handover Parameters

Parameter Optimization Contents

Mobile Management parameter optimization

Power Control parameter optimization

Power Configuration parameter optimization

Load Control parameter optimization

Power Control parameter optimization

Power Control Characteristics

Minimize the interference in the network, thus improve

capacity and quality

Maintain the link quality in uplink and downlink by adjusting

the powers

Mitigate the near far effect by providing minimum required

power

level for each connection

Provides protection against shadowing and fast fading

Power Control Classification

UE NodeB RNC

SIR Target

Bler/BerSIR

TPC Command

Outer Loop Power Control

Inner Loop Power Control

Open Loop Power Control

Open Loop Power Control

Open loop power control is used to determine UE’s initial uplink transmit power in PRACH and

NodeB’s initial downlink transmit power in DPDCH. It is used to set initial power reference values for

power control.

Outer Loop power control

Outer loop power control is used to maintain the quality of communication at the level of bearer service

quality requirement, while using as low power as possible.

Inner loop power control (also called fast closed loop power control)

Inner loop power control is used to adjust UE’s uplink / NodeB’s downlink Dpch Power every one slot

in accordance with TPC commands. Inner loop power control frequency is 1500Hz.

Open Loop Power Control - Uplink

Preamble_Initial_Power = Primary CPICH TX power - CPICH_RSCP

+ UL interference + Constant Value

where Primary CPICH TX power, UL interference and Constant Value are broadcasted

in the System Information，and CPICH_RSCP is the measured value by UE。

Open Loop Power Control - Downlink

• Where R is the user bit rate. W is the chip rate (3.84M).

• Pcpich is the Primary CPICH transmit power.

• Eb/Io is the downlink required Eb/Io value for a bearer service.

• (Ec/Io)cpich is measurement value reported by the UE.

•αis downlink cell orthogonal factor.

• Ptotal is the current cell’s carrier transmit power measured at the NodeB

and reported to the RNC.

))/(( total

o

cCPICH

o

b PcpichI

EP

W

R

I

EP

Open Loop Power Control Parameters

Outer Loop Power Control

Outer loop control is used to setting SirTarget (Signal to Interference Ratio Target) for inner loop power control. It is

divided into uplink outer loop power control and downlink outer loop power control.

The uplink outer loop power control is controlled by SRNC (serving RNC) for setting a target SIR for each UE. This

target SIR is updated according to the estimated uplink quality (Block Error Ratio/ Bit Error Ratio).

If UE is not in DTX (Discontinuous Transmission)status (that means RNC can receive uplink traffic data),

RNC will use Bler (Block Error Ratio) to compute SirTarget . Otherwise, RNC will use Ber (Bit Error Ratio) to compute

SirTarget.

The downlink outer loop power control is controlled by the UE receiver to converge to required link quality (BLER)

set by the network (RNC) in downlink.

Outer Loop Power Control Parameters

Inner Loop Power Control

The inner loop power control adjusts the UE or NodeB transmit

power in order to keep the received signal-to-interference ratio

(SIR) at a given SIR target, SIRtarget.

It is also divided into uplink inner loop power control and

downlink inner loop power control.

Uplink Inner Loop Power Control

UTRAN behaviour

The serving cells (cells in the active set) should estimate signal-to-interference ratio

SIRest of the received uplink DPCH. The serving cells should then generate TPC

commands and transmit the commands once per slot according to the following rule: if

SIRest > SIRtarget then the TPC command to transmit is "0", while if SIRest < SIRtarget

then the TPC command to transmit is "1".

UE behaviour

Upon reception of one or more TPC commands in a slot, the UE shall derive a single TPC

command, TPC_cmd, for each slot, combining multiple TPC commands if more than one

is received in a slot. This is also valid when SSDT transmission is used in the downlink.

Two algorithms shall be supported by the UE for deriving a TPC_cmd. Which of these

two algorithms is used is determined by a UE-specific higher-layer parameter,

"PowerControlAlgorithm", and is under the control of the UTRAN. If

"PowerControlAlgorithm" indicates "algorithm1", then the layer 1 parameter PCA shall

take the value 1 and if "PowerControlAlgorithm" indicates "algorithm2" then PCA shall

take the value 2.

Uplink Inner Loop Power Control

The step size DTPC is a layer 1 parameter which is derived from the UE-specific higher-

layer parameter "TPC-StepSize" which is under the control of the UTRAN. If "TPC-

StepSize" has the value "dB1", then the layer 1 parameter DTPC shall take the value

1 dB and if "TPC-StepSize" has the value "dB2", then DTPC shall take the value 2 dB.

The parameter "TPC-StepSize" only applies to Algorithm 1 . For Algorithm 2 DTPC shall

always take the value 1 dB.

After deriving of the combined TPC command TPC_cmd using one of the two supported

algorithms, the UE shall adjust the transmit power of the uplink DPCCH with a step of

DDPCCH (in dB) which is given by:

DDPCCH = DTPC TPC_cmd.

Uplink Inner Loop Power Control

Algorithm 1 for processing TPC commands

When a UE is not in soft handover, only one TPC command will be received in each

slot. In this case, the value of TPC_cmd shall be derived as follows:

- If the received TPC command is equal to 0 then TPC_cmd for that slot is –1.

- If the received TPC command is equal to 1, then TPC_cmd for that slot is

Algorithm 2 for processing TPC commands

When a UE is not in soft handover, only one TPC command will be received in each

slot. In this case, the UE shall process received TPC commands on a 5-slot cycle,

where the sets of 5 slots shall be aligned to the frame boundaries and there shall

be no overlap between each set of 5 slots.

The value of TPC_cmd shall be derived as follows:

- For the first 4 slots of a set, TPC_cmd = 0.

- For the fifth slot of a set, the UE uses hard decisions on each of the 5

received TPC commands as follows:

If all 5 hard decisions within a set are 1 then TPC_cmd = 1 in the 5th slot.

If all 5 hard decisions within a set are 0 then TPC_cmd = -1 in the 5th slot.

Otherwise, TPC_cmd = 0 in the 5th slot.

Downlink Inner Loop Power Control

UE behaviour

The UE shall generate TPC commands to control the network transmit power

and send them in the TPC field of the uplink DPCCH. The UE shall check

the downlink power control mode (DPC_MODE) before generating

the TPC command:

If DPC_MODE = 0 : the UE sends a unique TPC command in each slot and the

TPC command generated is transmitted in the first available TPC field in the uplink

DPCCH;

If DPC_MODE = 1 : the UE repeats the same TPC command over 3 slots and the

new TPC command is transmitted such that there is a new command at the

beginning of the frame.

The DPC_MODE parameter is a UE specific parameter controlled by the

UTRAN.

Downlink Inner Loop Power Control

UTRAN behaviour

Upon receiving the TPC commands UTRAN shall adjust its downlink DPCCH/DPDCH

power accordingly. For DPC_MODE = 0, UTRAN shall estimate the transmitted TPC

command TPCest to be 0 or 1, and shall update the power every slot. If DPC_MODE = 1,

UTRAN shall estimate the transmitted TPC command TPCest over three slots to be 0 or

1, and shall update the power every three slots.

Inner Loop Power Control Parameters

Parameter Optimization Contents

Mobile Management parameter optimization

Power Control parameter optimization

Power Configuration parameter optimization

Load Control parameter optimization

Physical Channels Types

Common Channel Parameters

All channels’ power refers to PCPICH power expect PCPICH.

Dedicated Channel Parameters

Dedicated Channel Power refers to PCPICH Power.

Parameter Optimization Contents

Mobile Management parameter optimization

Power Control parameter optimization

Power Configuration parameter optimization

Load Control parameter optimization

Load Control Parameter Optimization

Call Admission Control (CAC)

Call admission control is used to control cell’s load by

admission/rejection request to assure a cell’s load under control.

Dynamic Channel Configuration Control (DCCC)

Dynamic Channel Configuration Control is used to dynamically

change a connection’s load to improve cell resource utilization

and control cell’s load.

Call Admission Control Procedure

call admisson request arrive

Get the service characteristic and

the current load

Uplink call admission

control evaluation

admitted?

Downlink call admission

control evaluation

admitted?

call admitted call rejected

end

n

y

y

n

Call Admission Control Parameters

Different service type can be configured different threshold. That means leave some

resources for important service ( or request), such as HO > Conversation > Other.

Ul(Dl)TotolKThd is used when NodeB load report is not available . It uses equivalent

12.2k-voice users number method.

Dynamic Channel Configuration Control

Dynamic channel configuration control (DCCC) aims to make full use

of radio resource (codes, power, CE )

- Configured bandwidth is fixed with no DCCC

- Configured bandwidth is changing with DCCC

- Traffic rate

Rate or band

DCCC Procedure

Measurement report

DCCC decision

Traffic Volume measurement

control

UE and RNC Measurement

DCCC execution

Traffic Volume Measurement

Threshold

Transport

Channel

Traffic

Volume

Reporting

event 4A

Time

Reporting

event 4A

Threshold

Transport

Channel

Traffic

Volume

Reporting

event 4B

Time

Reporting

event 4B

Reporting

event 4B

DCCC Decision

1) 4a event report -> increase bandwidth

4b event report -> decrease bandwidth

2) if current bandwidth <= DCCC threshold,

do not decrease bandwidth

Dynamic Channel Configuration Control

Parameters

Dynamic Channel Configuration Control

Parameters

Summary

Parameter Optimization improves network quality and solves

network problems.

Parameter Optimization is a complicated procedure and

needs parameter and algorithm knowledge.

Parameter Optimization will be combined with other

optimization activities making network better !