T-Mobile Module 7 - Parameter Optmisation

1 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials

3G RANOP

Module 7– Parameter Optimisation


3G RAN Optimisation

RF Optimisation

and Neighbour Planning

• RF optimisation• New Site Integration• Neighbour plan

optimisation

Signalling Flows

• RRC Establishment• RAB Establishment• SHO• ISHO

Drive Test Analysis

• Drive Survey Analysis• System Performance

(RRC and RAB phases)

ClusterPreparati

on

• Cluster health checks• Parameter consistency

check• Neighbour list

verification• Uplink interference as

a problem indicator

Inter-System Working and Optimisation

• 3G<>2G Cell reselection

• Neighbour Planning• Handover Process and

compressed mode• 3G ISHO service

analysis (AMR and PS)• GSM ISHO Optimisation

Parametric

Optimisation

• Use of Parameters to optimise network performance

Network Statistics

• Cell Resources• RRC/RAB Performance• Handovers• Abnormal Release


Module 7 – Parameter Optimisation

Objectives

After this module the delegate shall be able to:-

• List some of the parameters that can be tuned for

improved performance

• Match these parameters to Call Setup and Call

Retention improvement areas


Parameter Optimisation Introduction

• The foundation of good network performance comes from a well optimised:• RF Plan• neighbour plan• Scrambling plan

• The maximum benefits from parameter optimisation can only be realised if the above are in place.

• Although parameter optimisation can provide short term gains they do not correct underlying network problems. (E.g SHO <> Dominance)

• The UE types in the network needs to be taken into account during parameter optimisation

• There are always tradeoffs (e.g setup time versus success rate)

• Parameter values may be different from network to network due to NW plan and operator strategy and therefore these parameters should be tuned in every networkBasic Radio Platform (Site/Antenna Location,etc)

Scrambling Code Planning

Neighbour Definition

Parameterisation

Feature Strategy


Nokia Parameters an Introduction

• RNC = Radio Network Controller• WBTS = WCDMA Base Station• WCEL = WCDMA Cell• ADJ = Adjacency for WCDMA cell

• ADJS = intra-frequency adjacency

• ADJI = inter-frequency adjacency

• ADJG = inter-system adjacency

• HOP = Handover Path• HOPS, HOPI, HOPG

• FMC = Frequency Measurement Control

• FMCS, FMCI, FMCG• COCO = Radio Network

Connection ConfigurationSee RNC Parameter Dictionary

DN00211177

RNC

WBTS

WCELL

ADJS

HOPS

ADJG

HOPG

FMCG

ADJI

HOPI

FMCI

FMCS

COCO

Managed Objects


Common Channel Power settings

• Common Channel power settings are critically important as they define the cell edge.

• The latest recommended settings are based on Nokia’s global experience and have been seen to work well. Care should be taken when optimising these parameters.

• The link budget of the PCCPCH and SCCPCH can be compared with Data on the DPCH.

• There tends to be plenty of margin in AICH and PICH.

• In general neighbouring cells should not have CPICH power differences greater than 3dB otherwise this can lead to soft handover radio link failures.

• Exceptions may occur if one cell is an indoor solution and the other is a macrocell


DL Common Control Channel

• DL Common control channels must be heard over the whole cell.

• The only common physical channel that can have power control is SCCPCH, when it carries the FACH transport channel.

• All other downlink common physical channels don't use power control: PCCPCH, CPICH, P-SCH, S-SCH, PICH, AICH and SCCPCH

• The power of the common physical channels are set relative to the CPICH:

Parameters Default (Relative) Default (Absolute)

PtxPrimaryCPICH 33 dBm 33 dBmPtxPrimarySCH -3 dB 30 dBmPtxSecSCH -3 dB 30 dBmPtxPrimaryCCPCH -5 dB 28 dBmPtxSecCCPCH 0 dB 33 dBmPtxPICH -8 dB 25 dBmPtxAICH -8 dB 25 dBm



Different quality requirement for the common channels make power planning a non-trivial task

Pilot coverageP-CCPCHcoverage

In this example the mobile "sees" the cell but cannot access it as it cannot decode the BCH

Possible values in dBm

CPICH = 33dBmP-CCPCH= 28 dBmS-CCPCH= 33 dBmSCH1= SCH2 = P-CCPCH = 28dBm

Possible values in dBm

CPICH = 33dBmP-CCPCH= 28 dBmS-CCPCH= 33 dBmSCH1= SCH2 = P-CCPCH = 28dBm



• Not all the CCCH need to be treated in the same way:• Only Power Setting (depending on coverage)

• CPICH• P-CCPCH• P/S-SCH• AICH

• Power Setting and channel availability for multiple access/depending on coverage and traffic)

• PICH depending on paging repetition used per radio frame (10ms)

• S-CCPCH depending on traffic load on FACH

• Setting the DL Common Control Channel Power is a trade off between:• cell coverage: all the channels must be decoded at the cell edge• cell capacity: the common channel power steal resources from the traffic

channels


Effects CPICH Power modification

CPICH Transmit Power

Increased soft handover overhead

Too much power

Too little power

Less Power Available for traffic

CPICH coverage holes

Unreliable scrambling code detection

Unreliable channel estimation

Early cell reselection /handover

Increased Eb/No requirement

Reduced system capacity


Reduced system coverage

Slow initial synchonisation

Non-ideal traffic distribution

Late cell reselection /handover


CPICH Transmit Power

Increased soft handover overhead

Too much power

Too little power

Less Power Available for traffic

CPICH coverage holes

Unreliable scrambling code detection

Unreliable channel estimation

Early cell reselection /handout too early

Increased Eb/No requirement



Reduced system coverage

Slow initial synchronisation


Late cell reselection /handout too late



Common Channel Power Configuration

• Soft handover is driven by the CPICH Ec/Io which means that CPICH power allocations are important

• If neighbouring cells have different CPICH allocations then radio links will be unbalanced during soft handover and radio links may fail

• Requirement to align CPICH allocations as much as possible

• Neighbouring Node B with equal CPICH result in balanced radio links during soft handover

• Inner loop power control will be driven by both Node Bs

20 W 20 W

20 W 20 W

33 dBm CPICH

• Scenario results in unbalanced radio links during soft hand over. Inner loop power control will be driven by Node B with 28dBm CPICH and therefore the radio link to the second Node B may fail

33 dBm CPICH

33 dBm CPICH

28 dBm CPICH

30 dBm CPICH

28 dBm CPICH

• Slightly unbalanced radio links during soft handover

• Inner loop power control will be driven primarily by the 28dBm CPICH Node B

20 W 20 W


Call Setup – Key Areas for investigation

• Cell Selection and Reselection• Initial cell selection to a good cell and subsequent cell reselections to

better cells is essential to increase the Call Setup Success Rate (CSSR) and speed up the call setup time.

• RACH Process• Improve the RRC Setup Performance

• Activation Time Offset• Improve PS Call Setup success rate by allowing more time for Radio

Bearer setup and Reconfiguration procedures

• SRB changes• Decrease call setup time by increasing the speed of the signalling bearer


Cell Reselection Parameter Examples• Cell reselection triggering time (WCEL-Treselection = 2s)

• Reselection takes place immediately when the UE notices that there is difference between the cells’ Ec/No values (in worst case scenario there can be up to 3dB + Qhyst difference based on the measurement accuracy requirement)

• Cell reselection hysteresis 2 (WCEL-Qhyst2 = 4dB)• This will add 4dB hysteresis to the neighboring cell evaluation (target for the

cell reselection)

• Cell Re-selection Quality Offset 2 (HOPS-AdjsQoffset2 = 0dB)• This parameter is used in the cell re-selection and ranking between WCDMA

cells. The value of this parameter is subtracted from the measured CPICH Ec/No of the neighbor cell before the UE compares the quality measure with the cell re-selection/ ranking criteria

• Sintrasearch (WCEL-Sintrasearch = 12dB)• This parameter is used by the UE to calculate the threshold (CPICH Ec/No) to

start intra frequency (SHO) measurements (Sintrasearch above QqualMin value)

• Minimum required quality level in the cell (WCEL- QqualMin = -18dB)• Minimum required RX level in the cell (WCEL- QrxlevMin = -111dBm)


Qqualmeas (dB)(CPICH Ec/N0)

Qrxlevmeas (dBm)CPICH RSCP

Qqualmin(–24...0)

Qrxlevmin(–115...–25)

Srxlev > 0

Pcompensation(typ =>0db)

Squal > 0S-Criterion

fulfilledSqual >0 AND

Srxlev > 0

Cell Selection - S Criterion

• The Qqualmin and Qrxlevmin parameters should be tuned carefully as non optimum settings can have significant impact on CSSR, Call setup time and time on 3G

• If the cell does not fulfill the suitable cell criteria (i.e. S-criteria) the UE cannot access the cell and therefore the UE is out of the coverage


BLER for Each Ec/No

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10%

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100%

> -4 -4 to -

6

-6 to -

8

-8 to -

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-10 to

-12

-12 to

-14

-14 to

-16

-16 to

-18

-18 to

-21

<-21

Ec/No [dB]

[%]

BLER for Each RSCP

0%

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100%

> -60 -60 to -

70

-70 to -

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-80 to -

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-90 to -

100

-100 to -

112

-112 to -

115

< -115

RSCP (dBm)

[%]

These calls may be unable to setup the call after Qqualmin is changed to –18dB from current –20dB

Call Setup status statistics for each Ec/No rangeCall Setup status statistics for each RSCP range

Cell Selection example

• There is a tradeoff between maximising 3G utilisation and CSSR (end user experience)

• Even though the CSSR is ~ 70% successful in poor RF conditions (Ec/No<-18 dB)

• It is recommended to leave the Qqualmin and Qrxlevmin as –18dB and –111 dBm respectively


Cell Reselection and Call Setup Time

• Poor cell reselection can lead to poor call setup time distribution (due to UE having to send several RRC Connection Requests

0.0%

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.7s

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Setup Time (seconds)

Call Setup Delay (PDF & CDF)

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0 0 to 3000 3000 to 5000 5000 to 8000 8000 to 10000 > 10000Setup Time [ms]

PDFCDF

Call Setup Delay CDF

Poor Cell Reselection Performance Corrected Reselection Performance


• Default – ‘Normal’ conditions• Qqualmin = -20dB• Search when CPICH<-8dB, neighbours must be 2dB better, delay reselection by 3s

• Set1 – Aggressive Reselection• Start Searching Earlier (-6dB), no hysteresis to neighbour, change after 1s delay

• Set2 – Faster Change• Change ‘immediately’ but capped by hysteresis

• Set3 – Search earlier with faster Change • Searching starts at -6dB, hysteresis to neighbours but change ‘immediately’

Cell Reselection Test Case Example

Parameter Default Set1 Set2 Set3Sintrasearch 12dB 14dB 12dB 14dBQhyst2 2dB 0 2 2Treselection 3s 1 0 0


Cell Reselection Test Case Results

•Note: With common channel setting in this network: base Ec/No (own cell) is around -4 dB (that’s why not more than 1 cell at Ec/No > -4 dB)

Start the measurements at Ec/No ~-8dB -> with Qqualmin = -20 dB -> Sintrasearch >= 12dB -> test at least 12dB and 14dB

•If the reselection happens at about –16dB there is only 30% possibility that the second best server is >2dB lower than best server

•This does not leave enough room for deviation between best and second best server

Scanner data chart:•If the measurements for cell reselection happens at about Ec/No –8dB, there is 95% possibility that second best server is >2dB lower than the best server

•This means that the cell reselection has 80% probability it does not to lead to ping pong

SIrons

But this is scanner not UE!!Also why would you start at -8 if 95% chance of not finding better server?Also Qualmin=-20 not -18


RACH Process

• Optimum RACH performance is needed to ensure;

• High RRC Setup performance and RRC Connection Access Success. • In both cases the testing is concentrated on RRC Setup success rate, and the

number of RRC Connection Requests sent.

• Minimise the impact of UE Tx power (preamble power) to the cell capacity.

• Minimise call setup delay

• Different UE performance is taken into account


RRC Setup Phase

• This phase starts when UE sends the “RRC CONNECTION REQUEST” message using the PRACH channel

• It is completed when RNC, after reserving all the necessary resources for the RRC Connection (RNC, BTS, Radio and Transmission), replies with DL “RRC CONNECTION SETUP” message, carried over S-CCPCH (FACH sub-channel)

[RACH] RRC:RRC Connection Request

UEUE Node BNode B RNCRNC

ALCAP:ERQ

ALCAP:ECF

NBAP: RL Setup Request

Start TX/RXStart TX/RX


[FACH] RRC: RRC Connection Setup

NBAP: RL Setup Response

[DCH] RRC: RRC Connection Setup Complete

NBAP: Synchronisation Indication

L1 Synchronisation


RACH Process

DownlinkBS

L1 ACK / AICH

UplinkMS Preamble

1

Not detected

Message partPreamble2

PRACH_preamble_retrans# PRACH preambles transmitted during one PRACH cycle without receiving AICH response

UEtxPowerMaxPRACH

… … … …

RACH_tx_Max# preamble power ramping cycles that can be done before RACH transmission failure is reported

PowerRampStepPRACHpreamble

PowerOffsetLastPreamblePRACHmessage

Initial preample power:•Ptx = CPICHtransmissionPower-RSCP(CPICH) +RSSI(BS) + PRACHRequiredReceivedCI


RACH Process parameters

• Main parameters to improve the RRC Connection Setup performance are listed below

• WCEL-PRACH_preamble_retrans & RACH_tx_Max (def 8 & 8)• WCEL-PowerOffsetLastPreamblePRACHmessage (def 2dB)• WCEL-PowerRampStepPRACHpreamble (def = 2dB)

• The RRC Connection Access success is highly dependent on the UE so all used UEs should be tested carefully before making any changes.

• Note, Some of the UEs (especially the ones with, early, Qualcomm chipset) could have fixed values for some parameters (an example from Sanyo):

• PRACH_preamble_retrans & RACH_tx_Max = 8 & 8

• PowerRampStepPRACHpreamble = 3dB


RACH Process test• Two values for PRACHRequiredReceivedCI tested (drive testing)

• -20dB & -25dB : UL interference conditions are at the same level (reported in SIB 7 for both cases)

100%

0% 0% 0%

88%

2% 5% 6%

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40%

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100%

1 2 3 4

# RRC Connection Request Messages per call setup

%

PRACH req. C/I = -20dB PRACH req. C/I = -25dB

• Clear improvement in number of needed RRC Connection Request messages per call.

• For –20dB 100% of established calls are setup with only 1 RRC Connection Request message

• Clear improvement number of sent preambles per RRC Connection Request for –20dB case.

• For –20dB 50% of cases the needed number of preambles is <=4 where as for –25dB it is ~6.5

• There should also be improvement of the call setup time

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PRACH req. C/I = -25dB PRACH req. C/I = -20dB


RACH Process test• Two values for

PRACHRequiredReceivedCI tested (drive testing)

• -20dB• -25dB

• UL interference conditions are at the same level (reported in SIB 7 for both cases)

• Clear improvement in call setup delay for –20dB case. ~65% of the established calls are through with only 3.5 – 3.7s delay and the >5.5s delay “tail” disappears (in this case).

96.2%

100.0%

94%

95%

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100%

-25dB -20dB

Call Setup Success Rate

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<3

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Call Setup Delay (seconds) RRC Conn. Req. to Alerting

PRACH req. C/I = -25 PRACH req. C/I = -20


RNC receives RRC Connection Setup Complete –message ->

RNC receives RRC Connection Setup Complete –message ->

RRC Connection Setup Complete –message SENT after 7 TSLs from DL sync is achieved

RRC Connection Setup Complete –message SENT after 7 TSLs from DL sync is achieved

L1 Synchronization established

BTS sends NBAP: SYNCHRONIZATION

IDICATION -message

L1 Synchronization established

BTS sends NBAP: SYNCHRONIZATION

IDICATION -message

UE initiates physical dedicated channel establishment before sending e.g. RRC Connection Setup Complete –message on DPDCH

UE initiates physical dedicated channel establishment before sending e.g. RRC Connection Setup Complete –message on DPDCH

Timer T312 startedTimer T312 started

“in sync” indicators on L1

“in sync” indicators on L1

Timer T312 stopped

Timer T312 stopped

N312 L1 “in sync” indicators

N312 L1 “in sync” indicators

L1 Synchronizati

on established

L1 Synchronizati

on established

N_INSYNC_IND indicators on

L1

N_INSYNC_IND indicators on

L1

1

• When a physical dedicated channel establishment is initiated by the UE, the UE starts a timer WCEL-T312 (def=10s) and waits for layer 1 to indicate WCEL-N312 (def=4) "in sync" indications

• On receiving N312 "in sync" indications, the physical channel is considered established and the timer T312 is stopped and reset

• On the BTS side after receiving synchronisation indicators the BTS sends NBAP: SYNCHRONIZATION INDICATION –message to RNC after which the closed loop and outer loop PC start to control the powers

RRC Setup & Access Phase


RRC Setup & Access Phase

• In case UE is not able to establish synchronisation within timer T312 it stops TX on the DCH

• In case BTS is not able to establish synchronisation it does not send NBAP:Synchronization Indication –message to RNC

• The BTS tries to establish synchronization until RNC sends NBAP:Radio Link Deletion message

[RACH] RRC:RRC Connection Request

UEUE Node BNode B RNCRNC

ALCAP:ERQ

ALCAP:ECF

NBAP: RL Setup Request



[FACH] RRC: RRC Connection Setup

NBAP: RL Setup Response

L1 Synchronisation


• Call Setup Success Rate (CSSR) depends on how well UE responds to the Radio Bearer (RB) Reconfiguration or RB Setup processes

• If UE does not have enough time to setup the lower layers for the new RB configuration then call setup will fail.

• This could be improved by increasing the Activation Time Offset (ATO) parameter:

• Connection Frame Number (CFN) is used in NBAP and RRC messages, when a radio link is reconfigured.

• It is used to indicate the activation time of the reconfiguration, and it is set by the Packet Scheduler

• The CFN, which is set to the "activation time" field in L3 messages, is:

(the CFN provided by FP + (ActivationTimeOffset + SignalingDelayOffset)/10) mod 256

• Call Setup time can be improved by changing ATO and/or changing the Signalling Radio Bearer (SRB) bit rate

• Both call setup delay and access performance should be considered and balanced.

Radio Bearer Process


ATO• In RAN1.5. 2 ED2 the total offset consists of ActivationTimeOffset parameter

part and fixed SignallingDelayOffset part• ActivationTimeOffset part represents the processing delay of RNC and BTS. • The SignalingDelayOffset is an RNC internal parameter that implies a

required offset based on the SRB bit rate, the actual procedure and the length of a RRC message. The fixed values set in RNC are below (ms)

RB Procedures Transport channel procedures

Service SRB 3,4 SRB 13,6 Service SRB 3,6 SRB 16,6

AMR 280 70 AMR 240 60

CS 280 70 CS 240 60

PS 200 50 PS 160 40

Physical channel and measurement procedures

Service SRB 3,6 SRB 16,6

All services 80 20

• The recommended value for ”ActivationTimeOffset” is 700ms for RAN1.5.2 (For RAN04 it will be 300ms) has been used.

SIrons

Pekka to check with PL reasoning.


ATO change case

AMR_701

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1 2 3 4 5 6 7 8 9 10 11 12

Tim

e(m

s)

1500 500 200 1 RRCConnectionRequest <=> RRCConnectionSetup2 RRCConnectionSetup <=> RRCConnectionSetupComplete3 RRCConnectionSetupComplete <=> MM CM Service Request4 MM CM Service Request <=> MM Authentication Request5 MM Authentication Request <=> MM Authentication Response6 MM Authentication Response <=> SecurityModeCommand7 SecurityModeCommand <=> SecurityModeComplete8 SecurityModeComplete <=> CC SetUp9 CC SetUp <=> CC Call Proceeding

10 CC Call Proceeding <=> RadioBearerSetup11 RadioBearerSetup <=> RadioBearerSetupComplete12 RadioBearerSetupComplete <=> CC Alerting

1300ms

1000ms

The difference in call setup time to the previous page is almost the difference between the RadioBearerSetup and RadioBearerSetupcomplete messages (part 11).


SRB change case

94

95

96

97

98

99

100

RRC Setup SuccessRate RRC Access SuccessRate RRC Setup & Access SuccessRate

SRB 13.6kbpsSRB 3.4kbps

• RRC Connection Access phase Success Rate should be evaluated when changing the SRB bit rate

• Example of RRC performance with SRB 3.5 kbits/s and 13.6 kbits/s

SIrons

Need more on SRB. Also mention the downside.


• If call setups are attempted and are failing in bad Ec/No or RSCP conditions then one solution to improve the call setup success rate might be to tune CPICHtoRefRABOffset

• The max DL power is determined by Admission Control as

Maximum DL power

EbNoref is the (linear) value of the planned downlink Eb/No of the reference service which is defined with parameter Downlink BLER target of the reference service (DLreferenceTargetBLER).

EbNoDCH is the (linear) value of the planned downlink Eb/No of the service transferred on the DCH

RDCH is the maximum transport channel bit rate of downlink DCH.

Rref is the maximum DCH bit rate of the reference service (parameter DLreferenceBitRate).

Ptx,DPCH,max is the value of WCEL-PtxDLabsMax - WCEL-PtxDPCHMax.

Ptx,off defines the power of the primary CPICH in relation to the maximum code power of the ref. service (WCEL-CPICHtoRefRABoffset)


• However, it should be noted that the minimum power used is increased if Offset is reduced as well (Minimum power=Max power – DL PC Range) which might lead to the situation where too high powers are allocated even in the good coverage conditions -> too much power is wasted in BTS.

• CPICHtoRefRABOffset of 0 dB (default 2 dB) could be tested with RNC-PCrangeDL of 20 dB (default 15 dB)

Maximum DL power

Service Type

3.4 kbps standalone

SRB

13.6 kbps standalone

SRB

12.2 kbpsspeech +3.4 kbps

SRB

64 kbpsdata +

3.4 kbps SRB

128 kbpsdata +

3.4 kbps SRB

384 kbpsdata +

3.4 kbps SRB

Maximum 27.8 dBm 31.8 dBm 32.2 dBm 35.2 dBm 38.0 dBm 40 dBm

Minimum 15 dBm 16.8 dBm 17.2 dBm 20.2 dBm 23.0 dBm 25 dBm

• Example Maximum and Minimum Power for different services• WCEL-CPICHtoRefRABOffset = 2dB and RNC-PCrangeDL = 15dB


SHO Optimisation

• The main emphasis in SHO optimisation is related to SHO overhead, SHO success rate, call drop rate and average Active Set size.

• Neighbor planning is more important than SHO parameter optimisation, so it should be done properly

• Acceptable SHO overhead in this case is 50 % or less, one example below

0 50 100 150 2000

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Soft handover overhead [%]


SHO Failures

• The SHO failures are mainly related to:

• Initial Synchronization Failure of the new added RL

• Active Synchronization Failure of the existing RL(s)

• Different soft handover parameters can help with synchronization problems between radio links.

• When new radio link is added to the Active set the L1 synchronization between the UE and the new BTS must be achieved. The UL/DL synchronization procedures are needed to establish reliable new connection between BTS and UE.

• Some of the initial synchronization failures are due to the fact that there can be difference in the UL noise rise levels of the adjacent cells (check Noise rise from Module1)

• If a lot of initial synchronization failures for SHO links are seen then one possibility is to try to reduce those by delaying the additions.

SIrons

Example of SHO failure from Drive Survey.


SHO Failure

• If there are many Active Synchronization Failures detected, one action could be to advance the SHO activity (e.g. using cell individual offsets) or in general use different FMCS (usually these conditions are improved when addition is done earlier e.g. add 4dB and drop 6dB).

If UE does not have enough level to receive ActiveSet Update message it is possible that call drop happen because of H/O failure.

Call drop be avoided by setting earlier timing (timing for sending out Measurement report )of H/O between targeted cells.

Use FMC parameter Use ADJSEcNooffset

Impact all of FMC targeted areas

Impact only between 2 targeted

cells


• The most important FMCS parameters to be used for SHO optimisation are

SHO Parameters

Parameters Default value

CPICH Ec/No Filter Coefficient 600 msAddition Window 2.5 dBAddition Time 100msDrop Window 4 dBDrop Time 640ms

• Default values should work fine, but in some cases more conservative SHO settings (add 4 dB, drop 6 dB) could be used to avoid high ASU period (time between Active Set Update message)


Packet Scheduler Parameters

• The focus for PS data tests is to minimize the PS call drop and keep the throughput high

• The performance depends on the usage of certain bit rate and different RRC states of the connection.

• Dynamic Link Optimisation (DyLo) feature could impact the achieved throughput

• Maximum allowed bitrate in certain cells (e.g. Rural, Highway) could be set to a lower value if there is risk of capacity shortage (Radio, Iub)

• Further performance/throughput could be optimized with different bearer activity/inactivity timers and traffic volume parameters.

• The optimum set of parameters depend on the used application (FTP, MSS, email) and amount of data.

SIrons

Insert parameters vslide from RANPAR.Interruption Timer in RAN04.


DyLO Improves NRT traffic coverage

Dylo restrictions• Radio link conditions under DRNC cannot trigger DyLO• The reconfiguration of Iub AAL2 transmission resources is not

performed due to DyLO• DyLO is not allowed during compressed mode measurement

UE384kbps

128kbps

BTS

Radio link is modified to use lower bit rate (with physical channel reconfiguration

message) when Tx power is getting close to maximum, in order to ensure sufficient

quality

SIrons

check with chris if any branch can trigger Dylo


Triggering of DyLO

time

Ptx, RLdistance

Ptx, ave

Triggering of DyLO

Ptx, maxOffset

Ptx, ave is averaged radio link power, measured and reported to RNC by BTS

Ptx, max is determined by Admission Control

The value of the Offset is fixed at 2 dB

DyLO is triggered if

Ptx, ave > Ptx, max – Offset

Dylo can be started only if the current bitrate is higher than Maximum Allowed DL User Bitrate in HHO


Dylo Bit Rate Upgrade

• After downgrade of DCH bit rate due to DyLO, upgrade of the bit rate can only be performed from the initial bit rate

• Cell level parameter Initial and minimum allowed bit rate in downlink is configurable by operator

• Bit rate upgrade from any other bit rate is not possible

• Bit rate upgrade is based on downlink traffic volume measurement reports (capacity requests)

• A change in radio link power conditions does not trigger upgrade

• Possible triggering of the DyLO is checked before the bit rate is upgraded, in order to avoid ping-pong effect

• New Ptx, max is calculated by AC according to the new bit rate

• Initial Tx power Ptx, init is calculated by AC according to the new bit rate

• DyLO is possible if Ptx, init < (Ptx, max – Offset)

• Upgrade is not possible, the next lower bit rate is tried (lower power)

Fixed, 2 dB


DyLO Test example –parameter settings

Time spent on different bearers’ spreading factorsDefault Set1 Set2sf8 36:45.873 24:27.095 16:37.340sf16 00:00.000 12:30.764 24:27.813sf32 02:07.373 08:43.990 08:46.952FACH 14:37.097 09:26.672 10:19.881Idle 00:37.344 00:21.919 00:10.115

Default Set1 Set2PtxDLabsMax 43 43 38 or 36InitialAndMinimumAllowedBitrateDL 384kbps 64kbps 64kbps MaxBitRateDLPSNRT 384kbps 384kbps 384kbps

Set 2 gives smallest time in

idle mode & more time in 128

kbits/s: improved NRT coverage

BTS types of Supreme,Optima ： 38dBm, Metrosite 36dBm

384 kbits/s as initial & Minimum Bitrate gives

poor results


Dylo Test example- compare throughput with the coverage

CPICH RSCP and RB Status (Set2)

0

100

200

300

400

16:4

1:39

:209

16:4

1:44

:736

16:4

1:49

:754

16:4

1:57

:764

16:4

2:05

:265

16:4

2:14

:159

16:4

2:21

:229

16:4

2:25

:084

16:4

2:33

:295

16:4

2:40

:816

16:4

2:50

:761

16:4

2:53

:485

16:4

2:58

:402

16:4

3:07

:605

16:4

3:16

:879

16:4

3:22

:396

16:4

3:28

:805

16:4

3:34

:344

16:4

3:39

:451

16:4

3:45

:459

16:4

3:49

:866

16:4

3:53

:491

16:4

3:54

:864

16:4

3:59

:009

16:4

4:05

:037

16:4

4:13

:620

16:4

4:19

:109

16:4

4:23

:935

16:4

4:25

:667

16:4

4:28

:191

16:4

4:34

:199

16:4

4:41

:209

16:4

4:44

:274

Time

RB

_S

tatu

s

-130

-120

-110

-100

-90

-80

-70

-60

StatusID

RSCP

CPICH Ec/No and RB Status (Set2)

0

100

200

300

400

16:4

1:39

:209

16:4

1:44

:245

16:4

1:49

:252

16:4

1:56

:252

16:4

2:02

:351

16:4

2:11

:234

16:4

2:19

:786

16:4

2:21

:789

16:4

2:28

:799

16:4

2:35

:809

16:4

2:43

:821

16:4

2:51

:702

16:4

2:54

:256

16:4

2:59

:204

16:4

3:07

:875

16:4

3:16

:387

16:4

3:21

:895

16:4

3:27

:894

16:4

3:32

:901

16:4

3:37

:549

16:4

3:43

:416

16:4

3:48

:454

16:4

3:51

:289

16:4

3:54

:502

16:4

3:56

:325

16:4

4:00

:220

16:4

4:06

:039

16:4

4:15

:594

16:4

4:19

:619

16:4

4:23

:935

16:4

4:25

:637

16:4

4:28

:111

16:4

4:32

:206

16:4

4:39

:717

16:4

4:44

:114

Time

RB

_S

tatu

s

-24

-19

-14

-9

-4

StatusID

Ec/No

Sf8

sf16

sf32FACHIdle

Sf8

sf16

sf32FACHIdle

RB Status Statistics(vs EcNo)

0.00%

20.00%

40.00%

60.00%

80.00%

100.00%

120.00%

> -4 -4 to -6 -6 to -8 -8 to -10 -10 to -12 -12 to -14 -14 to -16 -16 to -18 < -18

Ec/No [dB]

sf8

sf16

sf32

100.00%

0.00%0.00%

51.03%

38.30%

10.67%

40.72%

47.55%

11.73%

30.34%

56.40%

13.26%

17.03%

57.16%

25.81%

11.54%

56.09%

32.37%

11.32%

37.74%

50.94%

5.21%

18.75%

76.04%

6.98%

4.65%

88.37%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

> -4 -4 to -6 -6 to -8 -8 to -10 -10 to -12 -12 to -14 -14 to -16 -16 to -18 < -18

Ec/No [dB]

RB Status Statistics(vs EcNo)

sf32

sf16

sf8

384 128 64

RB Status for each Ec/No

≒-7 ～ -8 ≒-14 ～ -15


Module 7 – Parameter Optimisation

Summary

• Parameter optimisation is not a substitute for RF

Optimisation

• In optimisation we have to consider the balances

between power (resources) and success/speed

• Call Setup can be improved by improving Cell Selection

and Reselection, SRB Rate and ATO

• Call retention can be improved by adjusting SHO

parameters at the expense of resource usage

• DyLO can affect the measured throughput from surveys

T-Mobile Module 7 - Parameter Optmisation

Documents

ppt yyyy

dd initials

rl setup request

planned downlink

initial synchronization

loop power

rb status

lower bit