NSN GSM Frequency Optimization

1 Nokia Siemens Networks OS8669HEN04GLA0

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NetAct Optimizer 3.1 CD2 for GSM

GSM Frequency Optimization



Nokia Siemens Networks Academy

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At the end of this module the trainee should be able to:

Plan new frequencies for added TRXs

Outline the steps of the measurement based frequency

planning process

Assign and modify frequency groups, forbidden channels,

set manual separations and separation violation penalties

Perform frequency and Base Station Identity Code (BSIC)

allocation for non-hopping, baseband hopping, and

synthesized (RF) hopping networks

Compare different allocations, save and verify the results

Module Objectives



Select the scope

Add frequencies to new TRXs

Check that you have measurements needed for frequency optimization

Import forbidden channels

Start the Frequency Optimization tool

Create frequency groups

Set violation penalties

Assign frequency groups to BTSs

Set manual separations

Define forbidden channels

Set hopping mode

Define allocation targets and start allocation

Check the results

Save and provision the frequency plan

Steps in Frequency optimization



Interference Analysis

Before starting the Frequency optimization it is useful to find the worst interferers that cause problems over a long distance.

These problem cells should be treated first and new measurements run.



Select the scope










Set hopping mode


Check the results





Add frequencies to new TRXs Optimizer can generate frequencies for new TRXs in BTSs

No plan is needed (close plan before starting)

Select BTSs, cells or sites on the Navigator, Map or Browser and use menu Tools->Frequency Optimization->Add New Frequency



New Frequency: General Settings

New TRXs can be added to TCH or underlayer

Only non-hopping or BB- hopping TRXs

Frequency selection can be based on

optimization cost function

Interference

Assign Default Frequencies if frequency groups are not available or applicable

Select Interference type and separation violation penalties in the Interference tab



New Frequency: Interference Settings

Select Interference type

Violation penalties are explained later in this module



New Frequency: Select Target BTSs

In case of Master and Slave BTSs the user has to select the targets



New Frequency: Select Target BTSs



New Frequency Results

To view and modify the results later select

Tools->Frequency Optimization->Cell Frequency Manager...

The results disappear after the new TRXs become actual



Exercise

Create new frequencies for one site

Study the results when using different selection methods

Incoming cost, outgoing interference, etc.



STU CHU CMSTU CHU CM

STU CHU CM

WDU

CTU

WDU

OMU OMU

M M

CCMU CCMUCLS

PDE

DX 200

BSC PM database

MMR every 480ms

Raw data

Interference matrix

Automatic optimization

Configuration data

Algorithm parameters

User input

Measuring

New Plan

Configurator

Optimizer

Data Flow Example



Select the scope










Set hopping mode


Check the results





Exercise check measurements

1. Measurements need to be activated in the network elements

2. Check that all BCCHs have been measured: Select an Interference Matrix

View the Interference Matrix (Show Set command)

Open one BTS in the Interference Matrix

Select all BTSs under the selected BTS

List these selected BTSs to Browser

Check that all BCCHs are listed = have been measured



Select the scope










Set hopping mode


Check the results





Import Forbidden Channels




Examples for adding and removing forbidden channels:




Forbidden channels need to be imported before starting Frequency Optimization.



Select the scope










Set hopping mode


Check the results





Start Frequency optimization

Select the target object(s) from the Navigator, Map, or Browser or use the active scope



Select Interference Type

Select Interference Type (CIP + ARP or FEP)

External interference comes from cells that have not been identified (not found in the CM database)



Frequency Optimization Tabs

Navigator Optimization Statistics and Results



Statistics

Check the amount of elements

Buffer area is automatically selected to include neighbor cells, second level neighbors and all measured cells



Conflicts

ARP data: Tools->Network Statistics->Interference Matrices

KPIs: Tools->Network Statistics->Key Performance Indicators

Frequency Groups: Created in this tool

CIP data: Tools->Network Statistics->Interference Matrices

Site Data: Correct in Antenna Data Editor or CM Editor



Iterations

Iteration 1 -> Original

Keep a clean starting point in Original

All parameters, settings, Frequency Groups and the allocation results are stored in the open iteration -> different allocation strategies

Only one iteration can be saved to a plan



Select the scope










Set hopping mode


Check the results





Create Frequency Groups

Default Groups are based on the current actual allocation

Frequency Groups are user specific and iteration specific

Frequency Groups can also be created and assigned manually

Frequency Groups are stored when the results are saved into the plan

All user's plans will use the same (stored) Frequency Group settings



Selecting Frequency Groups

Select a frequency group in navigator (frequency band, TRX layer)

You can select all groups for editing and viewing by using Show menu



Modifying Frequency Groups

Double click Channels column

To add channels: choose from the left and click >>

To remove channels: choose from the right and click



Select the scope










Set hopping mode


Check the results





Separation Violation Penalties



Separation Violation Penalties

Interference Scales multiply the values in the interference matrix

Outgoing adjacency target cells should not have the same BCCH channel



Select the scope










Set hopping mode


Check the results





Assign a Frequency Group to a Layer

The selected frequency group will be assigned to all BTSs under the

selected layer



Assign a Frequency Group to one BTS



Select the scope










Set hopping mode


Check the results





Manual Separations

In Navigator, open a pop-up menu and then select Edit Manual Separations



Select the scope










Set hopping mode


Check the results





Define Forbidden Channels

Select Show->Scope BTSs



Select the scope










Set hopping mode


Check the results





Frequency Hopping Settings Select Show->Scope BTSs and check Hopping Modes and configurations

Baseband or Synthesized hopping

Cell hopping or Site hopping

If synthesized hopping is selected for the specific TRX layer

Select Scope BSCs from the Navigator and check MAL Allocation Mode

Allocate or Use Predefined



Select the scope










Set hopping mode


Check the results





Allocation Parameters



AFP Parameters optimization == Fast with minimum changes (improvements only)

Average interference divides interference over the TRXs of a cell

Interference reduced from cells with high traffic or importance



BSIC Parameters

TSC = Training Sequence Code (TRX parameter)

TSC must be the same as BSIC BCC

1.With BCCH TRX

2. When Baseband hopping is in use



HSN Parameters



Allocation Progress

Close after allocation



Select the scope










Set hopping mode


Check the results





Results



Results : Planned channels



Interference Distribution

Average Interference Distribution Graph for the Scope

Number of TRXs

Interference Probability



Channel Distribution

Even distribution theoretically the best

Decimal numbers because of frequency hopping (see tooltip)



Cell Level Interference Graph

Number of cells vs. Average Interference Probability (CIP)

Read the interference level from the Y-axis

X-axis then shows the number of cells that have higher interference than that



Separation Violations

Note: It is not possible to reduce the number of violations by changing the violation penalties

Frequencies need to be added or the separation requirements loosened



Compare Allocations

Different allocations can be compared against each other or against the actual configuration




Interference is the result of the allocation

Choose Interference Analysis or Interference Delta for visualization in Dominance or in Cell Icon

Adjust the parameters to get what you want




If a plan is open Interference Analysis shows the planned situation



Interference Delta

Interference Delta = Interference(plan) Interference(actual)



Frequency Visualization

Cell icons or dominance area colored according to BTS quality indicator BCCH or BCCH-BSIC combination

Select CELL parameter Frequency Channels for cell label



Frequency Reuse Display

To find where a particular frequency or BCCH-BSIC combination is used

RF hopping TRXs not taken into account



Frequency Display



Select the scope










Set hopping mode


Check the results





Saving Results to Plan

Only one iteration can be saved to plan

Frequency group settings saved also

Only open iteration can be saved

Save only to new plan or originally open plan



Exercise

Create a new frequency plan for the selected BSC

How much lower is the interference on BCCH layer, or is it?



Exercise

Visualize Interference Analysis and Delta for visible cells

Display the allocated frequencies in cell labels

Color cell icons according to the BCCH frequencies.

Use Frequency Reuse Visualization to check your new plan



Summary

Frequencies for new TRXs can be found with Optimizer

To create a new frequency plan select scope and use popup menu Tools->Frequency optimization

Check the conflicts and make corrections if needed

Duplicate the first iteration, rename and open the duplicate

Create Frequency Groups

Modify the Separation Violation Penalties and define Manual Separations

Select allocation target and strategy and define the settings accordingly

Target BTSs, BSCs, Layers, MALs

Perform Frequency optimization with selected options

Compare iterations to each other and to actual

Save one iteration into the plan

Verify the results on the Map and in the Browser

NSN GSM Frequency Optimization

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