03 Network Performance Optimization

Network Performance Optimization RANOP / 2007

Company Confidential 1

© 2007 Nokia

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Summary • PM Theory • Dx Causes • Counters, Tables • Formulas • KPIs • PM Process • Network Monitoring • Performance Monitoring • Performance Analysis and Troubleshooting • Trouble Ticket and Work Order (Change Requests) • PM Tools – Optional • Optimizing Tools • Testing Tools • Reporting Tools • Monitoring Tools

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PM Theory Dx Causes Counters, Tables KPIs Formulas

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PM Theory Dx Causes

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Levels of information

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Performance Reports

KPI's

BSS Measurements

Counters

Observations

DX-causes

GSM Causes and DX Causes → 1

1←

N

DX CAUSE

N

Successful

DX CAUSE

Unsuccessful = CLEAR CODES

GSM CAUSE

BSC

1←

N

MSC

COUNTERS

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BTS

Where are DX causes used ? Observation report DX Cause In (Phase, Channel, Cause In)

DX Cause Out (Phase, Channel, Cause Out)

Program block A

DX Cause In (Phase, Channel, Cause In)

DX Cause Out (Phase, Channel, Cause Out)

Program block B

Service Block controlling the Program Blocks A, B, …. Company Confidential 7

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How to detect faults? DX Cause In (Phase, Channel, Cause In)

DX Cause Out (Phase, Channel, Cause Out)

Program block A

NO
Successful Event Cause In Cause Out ? YES
Unsuccessful Event (CLEAR CODE) Company Confidential 8

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Counters triggering Program block in BSC (e.g. ABIPRB) Different checking e.g. Channel request

Establishment cause valid ?

rej_phantom_res

Acknowledgement correct ?

ch_act_nack

SDCCH act. fail

DX cause code out

counter

Ghost CCCH Res

Channel activation Channel activation ackn.

Phase ended successfully ?

cause code in = cause code out Company Confidential 9

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Program blocks in the BSC • ABIPRB

Abis Interface Program Block

• AIVPRB

A interface Signaling Program Block in BSC

• HASPRB

Handover Attempt Supervisor Program Block

• RC0PRB

Resource Control Program Block in BSC

• RCSPRB

Radio Connection Supervision Program Block

• RRMPRB

Radio Resource Management Program Block

• SC7PRB

Speech Circuit Control in GSM BSC A Interface

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Example of PRB transactions RRMPRB

Channel allocation H O IF cause is HOPC CAUSE _T _ BSC_T RHO _C update 1167 checks % free TCHs in target cell IF lower than amhMaxLoadOf TgtC ell then allocate TCH update 1168 IF greater send NO _ RADIO _RESOURCE _AVAILABLE to HASPRB update 1169

1

RR M_BTS_LOAD_INFO_S

load info of own & adj cells every 20 s

3 RR M_TCH _HO_SERV_REQ_EXTENDED _S

RCSPRB

TRHO decision on cell load & evaluate target cell AV_RXLEV_NCELL(n)> TrhoTargetL evel( n) am hTrhom arginPBGT 100 OR

• Sorted by SDCCH drop radio rate • Filtered by SDCCH bids (seizures) > 100 • Formula : SDCCH success ratio, SDCCH Drop ratio • Target value : SDCCH drop total SDCCH drop radio

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< 10% < 3%

SDCCH failure analysis example

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SDCCH failure analysis example • Ghost SDCCH • Double-Access /Multiple reservations due to co-Bsic, co-BCCH. Check and improve frequency plan. • RACH retransmissions/Multiple reservations due to bad coverage or interference and high numberOfRachRetransmissions. Lower RACH retransmission parameter value. Check and improve frequency plan and/or downtilt. • RACH retransmissions/Multiple reservations due to mass paging deleted. During festivals/ holidays/ concerts many subscribers are located at the same LAC, paging and rach load increases considerably. Consider LAC optimization, Abis expansion, paging group optimization, reduce paging repeat & rach retransmission times during busy hour.

CM FM • Radio Fails • Check alarms and RxQuality report to verify whether there is a badly functioning TRX. Fix hardware problem. Check antenna line.

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SDCCH failure analysis example • Radio Fails (cont.) • Coverage. Verify TA report and planning tool. • Interference. Check Frequency Plan. Solution e.g. add sites, downtilt antennas, increase RxLevAccessMin.

PM

• Extended coverage of cells in location area borders. Check LU parameters and/or downtilt

• 100% ABIS Fails • Failure in BTS software (BCSU reset in BSC).

Change Request! • 100% AIF Fails • BTS connected to other BSC or BTS is not declared in MSC.

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TCH blocking • Can be taken out from Network Doctor report 182 • Sort descending by blocking in Busy hour • Formula : TCH denied for call request ratio, TCH call blocking • Target value :

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< 2%

(could be anticipated by traffic consideration)

TCH blocking

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TCH blocking • TCH availability

FM

• Check alarms (are TRXs & TSLs in Working State? ), check availability report and RxQuality report to verify whether there is a badly functioning TRX. Make Loop Tests on TRX. Fix hardware problem.

• TCH capacity • Bad TCH capacity dimensioning. Check number of TRXs.

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CM

TCH blocking PM • TCH traffic • Cell is covering a region greater than planned. Verify TA statistics. Change DMAX, or downtilt. • High traffic in some cells. Solution .eg.: Quality degradation Add Macrocells

no

Add Microcells

no

Add TRXs with new freq

no

Add TRXs without new freq

no/yes (IUO, FH)

Activate Directed Retry

no/yes

Activate Queuing

no

Activate HR

yes

Activate AMR-HR Activate DADL/B

no/yes

Activate AMH

no/yes

Activate C2 parameter

yes

Modify hoMarginPBGT

yes

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no

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Change Request!

TCH drop • Can be taken out from Network Doctor report 163 • Sorted by TCH drop total rate • Filtered by TCH norm seizures > 100 OR

• Sorted by TCH drops absolute number • Filtered by TCH drop rate > 3 % • Formula : TCH drop call ratio (w/o re-est.), TCH dropped conv. (after TCH ass) • Target value : TCH drop total

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UL: It will be necessary to add a MHA in BTS in order to increase BTS sensitivity and balance the situation. Another solution can be to decrease cell size and reduce BTS power. • UL > DL: In this case a Booster can be used to increase DL coverage or to improve indoor levels.

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PM Process Trouble Ticket, Work Order (Change Request)

Company Confidential Confidential Company 123

© 2007 Nokia

13-468260 3. Network Performance v1.0 Optimization / 2007-05-31

Trouble Ticket • When a problem is identified in the Network, it is recommended to document it by means of a Trouble Ticket (TT) with the following information: • Site/Area Identification (Cell ID) • Problem description (Drop Call etc) • Problem Identifier (Statistics, Drive Test, Customer Complaint etc) • Every TT requires at least one Work Order (WO).

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Work Order (Change Request) • A WO is a document containing a group of actions to be taken in order to: correct a disturbance or adapt some network element to a new configuration. • A WO is opened when O&M need to modify tilts, block TRXs etc. • WOs are useful to track and control all the proposed changes on the Network. • WOs should contain the following information: • Responsible Engineer • Site Name/BTS ID • Source of data (NMS/Drive Test) • Problem description • Action type (Hardware/Software) • Proposed changes • Conclusion (If the objective was achieved or not) Company Confidential 125

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Work Order (Change Request) • The possible changes requested can be: • Software changes: • Changing a frequency. • Changing a parameter.

OMC Group

• Adding/deleting/correcting an adjacency definition. • Activating/deactivating a feature. • Hardware changes: • Modifying an antenna direction or tilt. • Checking and fixing a detected hardware problem.

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Implementation Group

Work Order (Change Request) • After implementation of the related WO, it is necessary to verify changes have been correctly implemented in the network. • Effectiveness of the change must be checked only after a period of time long enough to collect significant statistics.

 

If the changes were useful to the network and the objectives of the related WO were achieved, the WO can be closed. If the proposed changes don’t achieve the desired results it must be stated on the WO conclusion the reason for the failure. Another WO should be opened for the same TT.

• If all the WOs of a TT are closed, then the TT can be closed.

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TT and WO - process OPEN WO

STATUS = OPEN

NECESSITY IDENTIFICATION CUSTOMER APPROVAL

REPLAN ACTIONS PLAN ACTIONS

IMPLEMENTATION

STATUS = ONGOING

NO PROBLEM RELATED EXISTENT TT?

OPEN TT

STATUS = ONGOING

VERIFICATION

NO RESULT OK?

YES YES RELATED EXISTENT WO?

YES CLOSE WO

TRACK STATUS

NO

ANY WO OPPENED FOR THIS TT?

NO CLOSE TT

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YES TRACK STATUS

PM Tools - Optional Optimizing Tools* Testing Tools Reporting Tools Monitoring Tools

* Nokia NetAct Optimizer has already been presented in Configuration Management part of the course Company Confidential 129

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PM Tools Optimizing Tools • Nokia NetAct Optimizer *

“On demand” solutions: • Automatic Trouble Shooting Tool (ATS) ** • Remote Performance Analysis (RPA) **

* Nokia NetAct Optimizer has already been presented in Configuration Management part of the course ** Not a sellable Product Company Confidential 130

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Automatic Trouble-Shooting Tool

• Analysis of a cell takes from few seconds to 1 minute (depending on LAN and database speed) • Requires LAN access to NetAct database

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Automatic Trouble-Shooting Tool Process Consists on: 1) Automatic Fault Detection detection of badly performing cells based on separate and existing fault detection modules 2) Automatic Cause Diagnosis automated reasoning mechanism to find the cause of problem and the solution 3) Semi-automatic Solution Deployment  automated repair actions using existing tools

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Existing Fault Detection

1) Detect the badly performing cells

NetAct Tools NDW Network Doctor

Cause Diagnosis

2) Find out the cause of the problem

None

Solution Deployment

3) Apply repair action to fix the problem

Very limited & manual

Remote Performance Analysis • Uses the results of a series of SQL query on the NMS/OSS database, together with cell location and azimuth information, to analyse key aspects of network performance and provide a detailed report • The service is a very cost-effective method of analysing critical aspects of network optimisation. It is quick to turn around as results are produced within about 48 hours of data being provided. Further time is needed for analysis of results and customer report generation. • Some of the aspects investigated include: adjacency Planning (missing, obsolete, too far), Downtilt Optimisation, HW Problem identification, Interference Analysis etc.

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PM Tools

Testing Tools • Drive Test Tools: TEMS, NEMO • Nokia Mobile Quality Analyser (MQA)

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Drive Test Tools a • Used for monitoring and validation of new functionalities or changes d done in the network

• Graphical reports on maps allow to easily identify “hot areas” • Only DL information is available • Use of Field Tests is an expensive way to monitor wide areas

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Nokia Mobile Quality Analyser (MQA) Monitor

Optional Optional

Report

Games Games MMS MMS SMS SMS MQA MQA Agent Agent

Analyse

Voice Voice Radio Radio counters counters

• MQA Agent is a background process running on a commercial Nokia mobile • Capturing true end-user experience combined with radio interface details • Capturing service / application and terminal usage • Over the air administration and measurement collection • Turns thousands of mobiles into service monitoring devices Company Confidential 136

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Nokia Mobile Quality Analyser (MQA) • Let customers measure coverage! • MQA allows measuring the coverage where subscribers are: • At home, work and spare time • In-house, street, car, train, … • Phone in pocket, suitcase, … • 2G verus 3G coverage

• Collects facts about network coverage and go for improvements

RSSI and RSCP (dBm)

• Verifies the results for improvements • Reduces traditional drive test

Coverage vs. Power

10.00

6

,79

5

-50.00

UeTxPower (dBm)

,83

5.00 -60.00

-68 -70.00

,25

,33

-69

,37

-71

-73

0.00

-65

-67

,12

,01

,17

-5.00 -10.00

-80.00

-15.00 -90.00

-93

,68

-97

,39

-100.00

-98

-20.00

-21

,13

,57

-22

,50

-103

,98

-25

,88

-110.00

-30.00 12307

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-25.00

12922 RSSI

12341 CellIDs RSCP

11274 UeTXpwr

10047

PM Tools

Reporting Tools • Nokia NetAct Reporter • Network Data Warehouse • Network Doctor

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Nokia NetActTM Reporter

• Create and manage KPIs, reports, permission to access data etc.

• Web user interface • Report Results shown in tables or in graphs

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Nokia NetActTM Reporter • Viewing KPI Counters: Counter values are stored in the background and can be viewed for each KPI if more through analysis are required

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Network Data Warehouse • Provides the global PM database and global reporting functionalities for collecting, storing, managing, and presenting data on a long-term basis • Analysis and trend reporting oriented. PM data can be observed in NDW by predefined report sets

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Network Doctor • Network Doctor is a tool used for network troubleshooting and Segment/TRX/adjacency object level performance analysis • In order to do it, a selection of reports is provided. Those reports provide information about: • • • • • • • • • • • • • • • • • •

Consistency check Quality of radio network plan Cell dimensioning Call success Transmission (availability, capacity) Network element availability Interference Intelligent underlay-overlay Network configuration Alarms Locating network elements Named sets Half/Full Rate (E)GPRS Adaptive multirate Position based services Other measurable qualities Benchmark and analysis

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Network Doctor will be replaced by the BSS Reporting Suite

Network Doctor : Worst Cells Detection • ND134: • This report gives information about the RACH performance per cell • ND163: • This report gives information about the dropped TCH rate per cell as well as where the TCH dropped • ND166: • This report gives information about the dropped SDCCH rate per cell as well as where the SDCCH dropped • ND182: • This report gives information about TCH traffic and TCH blocking per cell as well as about SDCCH traffic and SDCCH blocking per cell • ND186: • This report gives information about the paging performance per cell • ND202: • This report gives information about the Access Grant performance per cell Global Reporter (NDW) is more appropriate for the task of detecting worst cells Company Confidential 143

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Network Doctor: Cell Level Performance • Benchmarking Reports: used to orient analysis and solution of the detected problem, output of the worst cell detection process • ND204 • • • • • • • • • • • • •

RACH performance PCH performance AGCH performance blocking SDCCH drop SDCCH per cause blocking TCH drop TCH per cause Handover distribution Handover failure causes Idle UL interference RxQuality/RxLev distribution FER distribution Availability SDCCH, TCH, GPRS

• ND213: Cell Doctor • ND216: Cell Analyzer Company Confidential 144

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Network Doctor: Other useful reports • ND181: TCH Traffic profile • ND190: Interference Idle UL profile • ND153: Handover per relation • ND196: RxQuality distribution per TRX • ND197: RxQuality distribution per TRX • ND244: RxQuality distribution per AMR codec per TRX • ND245: FER distribution per AMR codec per TRX • ND195: Link Balance per TRX • ND232: TA distribution • ND229: GPRS related KPIs

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PM Tools

Monitoring Tools • Nokia NetActTM Traffica • Nokia NetActTM Service Quality Manager • Trace Viewer • Abis Monitoring • A-interface Monitoring

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Nokia NetActTM Traffica • Real-time traffic monitoring: visualizes the network traffic with real-time graphs and alarms • For customer complaints analysis: gives very detailed information on subscriber level with off-line tools • Troubleshooting tool • Speech, Data and SMS specific performance • Examples of monitorization • Number of calls • Clear codes and error causes • Average call duration • Network entities • Data calls • PDP Context activation & deactivation

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Nokia NetActTM Traffica Traffica Network Element Server

Database queries Traffica Database

Database Export

Real Time Traffic Reports

OFF-LINE

MSC

ON-LINE Statistic Reports GTP, CDR (15 min)

90 80 70 60 50 40 30 20 10 0

SMSC Clear Code Matrix (CCMA)

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Real time graphs 1st Qtr 2nd Qtr3rd Qtr4th Qtr

Alarms

Nokia NetActTM Traffica Daily: situation cumulated since midnight

Users can also define their own Time Classes Hourly: past 24h in one-hour time slices
See the exact busy hour Minutes: past 30 minutes in one-minute time slices
Point out problems as soon as they happen, see how they develop Different Time Aggregation Levels for Real-Time Data Company Confidential 149

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Nokia NetActTM Traffica • In Traffica, Service specific monitoring can be implemented based on, for example • IMSI or Direction_Number ranges • Traffic Category, Route Category • IN indicator • TCH Access Information • Used CGRs

• User can define KPI-based alarms that are triggered by thresholds • Detect problems proactively • Detect how physical network problems affect actual traffic EXAMPLE OF TRAFFICA - Service Specific Monitoring Company Confidential 150

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Nokia NetActTM SQM • Enables end-to-end monitoring of services as perceived by subscribers: • Focuses on services as used by subscribers, instead of network elements only • Integrates all data from the network to determine the Quality of Service • Alerts the operator in real-time when the Quality of Service is degrading or below promised level

• SQM is composed by three different tools, each of them in charge of a different function: • Service Editor Tool: used to define each service with certain attributes, and create rules consisting on trigger event types and a procedure that is executed based on the event from the network • Service Monitor Tool: used to display services in geographical and/or logical views • Problem Inspector Tool

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Nokia NetActTM SQM : Service problem without fault • There are situations when there is no fault in the network, but the services are not available; for example: •

no fault in the network, no alarm

•

but high demand for the service

⇒ temporary capacity problem ⇒ some customers will not get access to the service

B T S

BTS

BS C

DN2

BTS

BTS Border Gateway

GPRS backb one

Charging Gateway

GGS N Lawful Interception Gateway (LIG)

Company Confidential © 2007 Nokia

CC &B

Mobile ISP NM S

Intern et

InterPLMN networ k

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Problem in the service

Operator Services

SS7 Netw ork

SGS N

BTS

152

HLR/Au C EIR/SM SC

MSC/V LR

router/firewa ll Corpor ate Custo mer router/firewa ll

Applica tion Server

Applica tion Server

without fault in the network

Nokia NetActTM SQM : Fault without service problem • Conversaly, we can have a fault in the network, but this will not generate a problem for the services; for example: •

a TRX goes down --> fault, alarm

•

but this happens e.g. during night time, when demand for the service is low

⇒ no capacity problem induced ⇒ the service is still available to all customers who need it

B T S

BTS

BS C

DN2

BTS

BTS Border Gateway

GPRS backb one

Charging Gateway

GGS N Lawful Interception Gateway (LIG)

Company Confidential © 2007 Nokia

CC &B

Mobile ISP NM S

Intern et

InterPLMN networ k

13-468260 v1.0

Fault in the network

Operator Services

SS7 Netw ork

SGS N

BTS

153

HLR/Au C EIR/SM SC

MSC/V LR

router/firewa ll Corpor ate Custo mer router/firewa ll

Applica tion Server

Applica tion Server

but no problem in the services

Nokia NetActTM SQM one global view over the services

service levels, service problems

Service Quality Manager

service level objectives

end-to-end service monitoring real time traffic data

alarms, topology

several views over the technologies

Traffica

Monitor

counters, KPIs

IP perf. data

Reporter

InSPector

IT events

BTS BSC

BTS

BTS

HLR/AuC EIR/SMSC MSC/VLR

DN2

Operator Services

SS7 Network

global infrastructu re 154

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SGSN

BTS

Company Confidential 13-468260 v1.0

HP OV any other system

CC&B BTS

Border Gateway Inter-PLMN network

GPRS backbone

Charging Gateway

Mobile ISP NMS router/firewall

Internet GGSN Lawful Interception Gateway (LIG)

Corporate Customer router/firewall

Application Server

Application Server

Nokia NetActTM SQM Geographical or logical views

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Check the level of service with the attribute values of each monitored service

Trace Viewer • Real-time troubleshooting to solve customer complaints • Solve efficiently the problem of an individual end-user • Find out fast whether the problem is a network or a terminal problem • Follow the functionality of the network and possible problems on call level • Trace individual mobile equipments or subscribers in GSM and GPRS networks

• Make testing phase fast and effective • Online GSM and GPRS tracing • Save the test call data for more detailed off-line investigation • Regional or global analysis

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Trace Viewer Examples of Presented Data • GPRS textual reports (SGSN, GGSN) • GSM textual reports (MSC, HLR, BSC) • BSC SDCCH & TCH

• TBF allocation, reallocation & release

• BSC handover & measurement reports

• PDP context activation, modification & deactivation

• HLR subscriber information

• Routing Area update

• MSC handover & location update

• GPRS Attach & detach

• GSM graphical reports • Signal quality & signal level

• SMS sent & received

• GPRS graphical reports

• Adjacent cells

• Flow Control

• Timing advance

• Number of MCS changes • Data transferred per MCS

• 3G networks

• Number of TCHs

• Location update and Handover events • UE capabilities • Performance and Traffic volume in both up and downlink directions Company Confidential 157

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Trace Viewer

Graphical Reports -RxQual

Graphical Reports - RxLev

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Trace Viewer

Graphical Reports – Data Transferred per MCS

Graphical Reports – Adjacent Cells

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Abis monitoring Provides very detailed information on the Abis interface and thus also on the radio interface • Data analysis can be difficult and very time consuming • Other tools or specific scripts should be used to facilitate the post-processing of the traces collected • Use only when absolutely necessary!

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Abis monitoring

One possible tool to collect Abis traces is Nethawk, others exist

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Abis monitoring 115017 13:47:12.793 Conn:2 Line:1 TS:30 Subch:0 CHAN RQD

(CCh)

T=0

Channel Nr - uplink CCCH (RACH) - timeslot : 0 Req. Ref - Est. cause : Paging: SDCCH - random reference : 7 (7h) - N32 : 6 (6h) - N26 : 20 (14h) - N51 : 27 (1bh) Access Delay - value : 0 (00h)

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Conn:2 Line:1 TS:30 Subch:0 115021 13:47:12.801 CHAN. ACT. (DCh) T=0 Channel Nr - SDCCH/4 subchannel 1 - timeslot : 0 Act. Type - initial activation - immediate assignment procedure Channel Mode - length : 4 - downlink DTX not used, uplink DTX

not used - signalling - SDCCH - no resources required BS Power - power control level : 0 (0h) MS Power - power control level : 5 (5h) Timing Adv. - 0 (00h) (0 km)

A- interface monitoring • Through A-if monitoring it is possible to find the distribution of drop calls related to signaling phase

• Find out problems in cooperation settings between BSS & NSS, e.g. timer cooperation settings.

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Thank you! RANOP / 2007

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