Gsm rf-optimization

GSM Network RF Optimization

Lucent Technologies ProprietaryUse Pursuant to Company Instructions - All Rights ReservedSlide No.1

Lucent Technologies

RF OptimizationWorkshop

Macro Cell

Lucent Technologies - Proprietary

Micro Cells

AGENDAAGENDA

�� IntroductionIntroduction

�� Single Band Optimization Philosophy Single Band Optimization Philosophy

�� Network Optimization Process Network Optimization Process

�� Optimization PhasesOptimization Phases

�� Lucent BSS Optimization ParametersLucent BSS Optimization Parameters

�� Cell Selection/ Cell Reselection Cell Selection/ Cell Reselection


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�� Power ControlPower Control–– ProceduresProcedures

�� HandoverHandover–– ProceduresProcedures

�� Drive Testing and AnalysisDrive Testing and Analysis

�� Drive Test EquipmentDrive Test Equipment

Single Band Optimization Philosophy Single Band Optimization Philosophy

Network Optimization Process Network Optimization Process

Lucent BSS Optimization ParametersLucent BSS Optimization Parameters

Cell Selection/ Cell Reselection Cell Selection/ Cell Reselection


IntroductionIntroduction

� What is Optimization ?

- Activity of achieving and maintaining the required quality as designed


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� Why Optimization ?

- Deviations between plan and reality

Activity of achieving and maintaining the required


Deviations between plan and reality

What is Optimization ?What is Optimization ?

Design


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Optimization

Implementation

What is Optimization ?What is Optimization ?

Design


Planning

Implementation

Why Optimization ?Why Optimization ?

• Inaccuracy of radio planning- Statistical variations in the path loss characteristics- Finite terrain database resolution

• Implementation- Antenna radiation pattern and effective radiated power


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- Antenna radiation pattern and effective radiated power- Antenna pattern distortion

• Environment- Seasonal environmental changes, e.g trees, leaves- Environmental changes such as new highways, new buildings

Inaccuracy of radio planningStatistical variations in the path loss characteristicsFinite terrain database resolution

Antenna radiation pattern and effective radiated power


Antenna radiation pattern and effective radiated power

Seasonal environmental changes, e.g trees, leavesEnvironmental changes such as new highways, new buildings

Single Band Optimization PhilosophySingle Band Optimization Philosophy

� Coverage - Good signal level across the whole cell, coverage holes within a cells service area must be minimized.

� Interference - A reasonable level of interference must be contained at cells service area in order to provide a quality air


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service area in order to provide a quality air

� Handover Behavior - The quality of the airto handover behavior is good, no unnecessary handovers, Rxquality at acceptable level, BTS & MS use minimum transmit power.

� Traffic Distribution - The quality of the airto traffic distribution is good, maximum amount of traffic can be handed.

Single Band Optimization PhilosophySingle Band Optimization Philosophy

Good signal level across the whole cell, coverage holes within a cells service area must be minimized.

A reasonable level of interference must be contained at cells service area in order to provide a quality air-interface.


service area in order to provide a quality air-interface.

The quality of the air-interface in a cell with respect to handover behavior is good, no unnecessary handovers, Rxquality at acceptable level, BTS & MS use minimum transmit power.

The quality of the air-interface in a cell with respect to traffic distribution is good, maximum amount of traffic can be handed.

Optimization PhasesOptimization Phases

Initial Optimization

Primary Optimization

c

•Site Audit

•Proper Parameters use

•Verify Neighbors list

•Reviewing Frequency Plan

•Verify existing coverage, site design objectives

•Analysis & Identification of Problem areas/cells

•from PMS & drive test statistics,

•customer complaints


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Primary Optimization

Maintenance Optimization

c

•customer complaints

•Prioritization of problems

•Identify Solution and Implement

•Retest the problem areas

•Consistency Check of the OMC database

•Fine-tuning of parameters

•On going process, weekly optimization

• Database maintenance and consistency audits

Proper Parameters use

Verify Neighbors list

Reviewing Frequency Plan

Verify existing coverage, site design objectives

Analysis & Identification of Problem areas/cells

from PMS & drive test statistics,

customer complaints


customer complaints

Prioritization of problems

Identify Solution and Implement

Retest the problem areas

Consistency Check of the OMC database

tuning of parameters

On going process, weekly optimization

Database maintenance and consistency audits

BSS BSS parameters related to Optimizationparameters related to Optimization

� CELL (RE) SELECTION

� POWER CONTROL


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� HANDOVER CONTROL

parameters related to Optimizationparameters related to Optimization


BSS BSS parameters related to Optimizationparameters related to Optimization

Areas of improvement :

� Minimization of interference


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� Minimization of interference

� Handover behavior improvement

� Traffic distribution

parameters related to Optimizationparameters related to Optimization

Areas of improvement :

Minimization of interference


Minimization of interference

Handover behavior improvement

Cell (Re)SelectionCell (Re)Selection

?


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?

2 cell (re)selection criteria:

C1 & C2



C1 Criteria

Used for cell selection and re


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C2 Criteria

Used in a hierarchical hierarchical selection only

Used for cell selection and re-selection


hierarchical hierarchical cell structure for re-


C1 = (A-

where:

A = Received Level Average

B = MS_TXPWR_MAX_CCH


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B = MS_TXPWR_MAX_CCH

Criteria met if C1> 0. MS will camp on to the cell with the highest C1 value.

-Max(B,0))

= Received Level Average - RXLEV_ACCESS_MIN

= MS_TXPWR_MAX_CCH - max.output power of the MS


= MS_TXPWR_MAX_CCH - max.output power of the MS

Criteria met if C1> 0. MS will camp on to the cell with the highest

Cell Reselect HysteresisCell Reselect Hysteresis

LAC 1


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LAC 2

Location Update 1

Location Update 2



LAC 1


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LAC 2

Reselect Hysteresis LAC1

Reselect Hysteresis LAC2


Power ControlPower Control

SignalLevel

Range (in dBm)

0123

Rxlevel < -110 < Rxlevel < -109 < Rxlevel <


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3..........6263

-108 < Rxlevel <

-49 < Rxlevel < Rxlevel >

SIGNAL LEVELSSIGNAL LEVELS

Range (in dBm)

Rxlevel < -110110 < Rxlevel < -109109 < Rxlevel < -108


108 < Rxlevel < -107..........

49 < Rxlevel < -48Rxlevel > -48

SIGNAL LEVELSSIGNAL LEVELS

Power ControlPower Control

SignalQuality

Range (in BER)

012

BER < 0.20.2 < BER < 0.40.4 < BER < 0.8


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234567

0.4 < BER < 0.80.8 < BER < 1.61.6 < BER < 3.23.2 < BER < 6.4

6.4 < BER < 12.8BER > 12.8

SIGNAL QUALITY LEVELSSIGNAL QUALITY LEVELS

Range (in BER)

BER < 0.20.2 < BER < 0.40.4 < BER < 0.8


0.4 < BER < 0.80.8 < BER < 1.61.6 < BER < 3.23.2 < BER < 6.4

6.4 < BER < 12.8BER > 12.8

SIGNAL QUALITY LEVELSSIGNAL QUALITY LEVELS

Handover ControlHandover Control

TYPES OF HANDOVERS

� Mandatory HO

RXQUAL

RXLEVEL


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DISTANCE

� Power Budget HO

� Duration of stay counter

(Hierarchical Cell)

� Preprocessing to support the

following handover types:

Internal Intra-Cell Handover (BSC-

controlled)

Internal Inter-Cell Handover (BSC-

controlled)


controlled)

External Inter-Cell Handover (MSC-

controlled)

� Inter Cell Handover may occur from:

SDCCH to SDCCH

SDCCH to TCH (directed retry)

TCH to TCH

Handover ControlHandover Control

-------------------------------------------------------------------------------

Rxlevel(receivedby MS)

SERVER


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-------------------------------------------------------------------------------

NEIGHBOR

Power Budget Handover MarginPower Budget Handover Margin

HO_MARGIN

-------------------------------------------------------------------------------


---------------------------------------------------------------------------------------------------

HandoverTime

Power Budget Handover MarginPower Budget Handover Margin

Handover ProceduresHandover Procedures

HO Process

� BTS measures the UL and DL

measurements every 480 ms.

RXLEV-XL

RXQUAL-XL

RXLEV-NCELL(1-6)


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RXLEV-NCELL(1-6) DIST (timing advance)

� BTS reports measurements to BSC.

� BSC calculates the averaged

parameters using a sliding window:AV-RXLEV-HOAV-RXQUAL-XL-HOAV-RXLEV-SCELLAV-RXLEV-NCELL(I)AV-DIST

� BSC decides the HO execution by

comparing with threshold values.

Handover Algorithm Basic Steps

– HO Measurement Averaging (Preprocessing)

– HO Threshold Comparisons


– HO Target Cell Identification

– HO Decision (BSC internal or

MSC)

– HO Execution (BSC internal or

MSC)

BSS Optimization ParametersBSS Optimization Parameters

Performance Determinants

� Coverage

� Interference

� Handover Behaviour

� Traffic Distribution


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Optimization Solutions

� Enable/Disable GSM features

� BSS parameters

� Neighbour cell lists

� Antenna tilt, height & azimuth

� Frequency changes

BSS Optimization ParametersBSS Optimization Parameters

Discontinuous Transmission

� Decreases interference level

� Saves battery power (uplink)

Frequency Hopping

� Decrease interference


� Decrease interference

� Suppress Rayleigh Fading

Power Control

� Saves battery power

� Decrease interference level

Network Parameter and Network Parameter and Performance DeterminantsPerformance Determinants

Performance

Determinants

Enable

GSM BSS

meters


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GSM

Featuresmeters

Coverage

Interference

HO Behavior

Traffic Distribution


Adjustments

Para-

meters

N'bour

Cell List

Antenna

Tilt, etc

Frequency

Change


meters Cell List Tilt, etc Change


Performance

Determinants

Enable

GSM BSS

meters


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GSM

Featuresmeters

Coverage * *

Interference * *

HO Behavior *

Traffic Distribution *


Adjustments

Para-

meters

N'bour

Cell List

Antenna

Tilt, etc

Frequency

Change


meters Cell List Tilt, etc Change

* *

* * * *

* *

* * *

Drive Testing and AnalysisDrive Testing and Analysis

• Trouble Ticket - Is a document by which various problems reported

by customers are passed along through the organization

- Must reply upon experience and knowledge to


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- Must reply upon experience and knowledge to determine which option to overcome the problem

- Different scenarios can be followed to solve the problem, such as drive testing, parameters changes, antenna adjustment, etc…..

- To verify if the problem is not related to MS itself


Is a document by which various problems reported

by customers are passed along through the

Must reply upon experience and knowledge to


Must reply upon experience and knowledge to determine which option to overcome the problem

Different scenarios can be followed to solve the problem, such as drive testing, parameters changes, antenna adjustment, etc…..

To verify if the problem is not related to MS itself


• Air Interface Information

- RXLEVEL

- RXQUALITY


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- BCCH, BSIC of the serving cell

- BCCH, BSIC and RXLEVEL of the 6 best neighbours

- TIMING ADVANCE

- GSM BEST SERVER


Air Interface Information


BCCH, BSIC of the serving cell

BCCH, BSIC and RXLEVEL of the 6 best neighbours


• Drive Testing

- Propagation Measurements


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- Mobile Network Performance Monitoring•Quality Assessment•Optimization


Propagation Measurements


Mobile Network Performance Monitoring


• Drive Tests for Optimization

- Initial network coverage verification and benchmarking- Verification before and after changes


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- Verification before and after changes- Locating and measuring interference- Locating areas where traffic problems exist- Locate coverage holes- Preventive maintenance- Simultaneous measurements of the other networks


Drive Tests for Optimization

Initial network coverage verification and

Verification before and after changes


Verification before and after changesLocating and measuring interferenceLocating areas where traffic problems exist

Simultaneous measurements of the other networks


Drive Test Data Collection

- CELL ID including BSIC, LAC, and time slot- RXLEVEL for the serving and the neighbour cells- RXQUALITY for the serving cell


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- RXQUALITY for the serving cell- BCCH, BSIC for the serving and the neighbour cells- TIMING ADVANCE- TRANSMIT POWER- GPS POSITION DATA- TIME STAMPS


Drive Test Data Collection

CELL ID including BSIC, LAC, and time slotRXLEVEL for the serving and the neighbour cellsRXQUALITY for the serving cell


RXQUALITY for the serving cellBCCH, BSIC for the serving and the neighbour cells


Drive Test Route Planning

- Primary route(street level)Includes all major roads,highways and wide thoroughfares

- Secondary route(street level)Includes all streets, subdivisions and compounds when


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Includes all streets, subdivisions and compounds when accessable

- Miscellaneous routes (in-building and special locations)Includes golf courses, beach resorts, shopping mails,

department stores, convention centers, hotels and resorts


Drive Test Route Planning

Includes all major roads,highways and wide thoroughfares

Secondary route(street level)Includes all streets, subdivisions and compounds when


Includes all streets, subdivisions and compounds when

building and special locations)Includes golf courses, beach resorts, shopping mails,

department stores, convention centers, hotels and resorts


Performance Problems that often encountered:

- Cell Dragging

- Dropped Calls


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- Dropped Calls

- Ping-Ponging

- System Busy

- Handover boundary


Performance Problems that often encountered:



Cell Dragging Cell Dragging -- Calls may drag a cell beyond the desired

handover boundary. This might result dropped calls or bad Rxquality.

Suggestions:

• Create an appropriate neighbour cell list


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• Create an appropriate neighbour cell list• Change HO parameters such as thresholds, margin, cell baring, etc• Check serving cell’s cell identifier in the neighbour cell’s neighbour list• Check neighbour cell’s BCCH, BSIC, LAC, Cell ID, etc


Calls may drag a cell beyond the desired

handover boundary. This might result dropped calls or bad

Create an appropriate neighbour cell list


Create an appropriate neighbour cell listChange HO parameters such as thresholds, margin, cell

Check serving cell’s cell identifier in the neighbour cell’s

Check neighbour cell’s BCCH, BSIC, LAC, Cell ID, etc


Dropped Calls Dropped Calls -- Caused by either RF environments or

incorrect system parameters

Suggestions:

• Check if an appropriate neighbour cell list is defined


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• Check if an appropriate neighbour cell list is defined• Check HO parameters • Existing or new coverage holes• Interference, Co-channels, Adjacent channels or External interference• Serving cells might go down, coverage smaller as before• Abnormalities such as call setup failure


Caused by either RF environments or

Check if an appropriate neighbour cell list is defined



Existing or new coverage holeschannels, Adjacent channels or External

Serving cells might go down, coverage smaller as beforeAbnormalities such as call setup failure


Ping Ponging Ping Ponging -- Serving keep changing and as a result of

bad audio quality

Suggestions:

• Check if an appropriate neighbour cell list is defined


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• Check if an appropriate neighbour cell list is defined• Check HO parameters • Interference, Co-channels, Adjacent channels or External interference• Lack of dominant server• Poor coverage• Not optimal antenna configuration


Serving keep changing and as a result of




channels, Adjacent channels or External

Not optimal antenna configuration


System Busy System Busy -- System busy on several call attempts and

site appears consistently on the traffic report

Suggestions:

Short Term

• Reduce the traffic on the congested cell/site. However, the


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• Reduce the traffic on the congested cell/site. However, the proposed changes MUST NOT create any unacceptable problems such as coverage holes, dropped calls, etc Shot term solutions are re-design the antenna configuration,Add additional RTs, Change BTS configuration

Long Term

• Build a new cell site to off-load traffic


System busy on several call attempts and

site appears consistently on the traffic report

Reduce the traffic on the congested cell/site. However, the


Reduce the traffic on the congested cell/site. However, the proposed changes MUST NOT create any unacceptable problems such as coverage holes, dropped calls, etc

design the antenna configuration,Add additional RTs, Change BTS configuration

load traffic


Handover Boundary Handover Boundary -- Handovers do not occur at the

desired HO boundary, the result is an imbalance in traffic distribution across the system

Suggestions:• Check if an appropriate neighbour cell list is defined


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• Check if an appropriate neighbour cell list is defined• Check HO parameters • Inappropriate antenna configurations of the serving and neighbour cells• Interference, Co-channels, Adjacent channels or External interference• No TCH available (neighbour cells congestion)


Handovers do not occur at the

desired HO boundary, the result is an imbalance in traffic distribution across the system




Inappropriate antenna configurations of the serving and

channels, Adjacent channels or External

No TCH available (neighbour cells congestion)

Drive Test EquipmentDrive Test Equipment

Typical example of drive test equipment components:

• Test Mobile phone• Scanning receiver• Transceiver system• Antennas• GPS


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• GPS• Visual display unit• Microphone• Loudspeaker box• Laptop computer

Typical example of drive test equipment components:



ERICSSON TEMS 900/1800

� Test 2 Network simultaneously

� Full Layer 2 & 3 decoding

� Control of Layer 3 msg

� Forced selection of idle and dedicated mode


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dedicated mode

� Filtering msg streams

� Rxqual in idle mode

� Sending SMS

� SIM card information

COMARCO WIRELESS

� Test 4 networks simultaneously

� GSM 900/1800, ETACS, AMPS

� Partial Layer 2 & 3 decoding

� Fast scanning receiver, GSM RF Spectrum


Spectrum

� Ability to display adjacent channel interference screen

� Noise measurements

SAFECO WALKABOUT

� In-building coverage


AGILENT TECHNOLOGIES(HP)


� Fast scanning receiver, UL & DL

� Frequency Hopping Table

� Spectrum Analysis


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� Channel Power

� CW Measurement

� Interference Measurement

� GSM Broadcast Channel Analysis

QVOICE98


� Evaluate measurement both way

� Good Presentation

� Capable on measuring MOS, Speech Quality, Rxquality, Rxlevel


Speech Quality, Rxquality, Rxlevel

Gsm rf-optimization

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