ilsa v2.0

ENTERPRISE V5.0 ILSA V2.0 Tool User

PS-TR-PDF-TC-E104-V5.0-1.doc

AIRCOM International

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ILSA V2.0 Tool User

The information in this document is subject to change without notice and describes only the product defined in the introduction of this documentation. This document is intended for the use of AIRCOM Internationals customers only for the purposes of the agreement under which the document is submitted, and no part of it may be reproduced or transmitted in any form or means without the prior written permission of AIRCOM International. The document has been prepared to be used by professional and properly trained personnel, and the customer assumes full responsibility when using it. AIRCOM International welcomes customer comments as part of the process of continuous development and improvement of the documentation.

The information or statements given in this document concerning the suitability, capacity, or performance of the mentioned hardware or software products cannot be considered binding but shall be defined in the agreement made between AIRCOM International and the customer. However, AIRCOM International has made all reasonable efforts to ensure that the instructions contained in the document are adequate and free of material errors and omissions. AIRCOM International will, if necessary, explain issues, which may not be covered by the document.

AIRCOM Internationals liability for any errors in the document is limited to the documentary correction of errors. AIRCOM International WILL NOT BE RESPONSIBLE IN ANY EVENT FOR ERRORS IN THIS DOCUMENT OR FOR ANY DAMAGES, INCIDENTAL OR CONSEQUENTIAL (INCLUDING MONETARY LOSSES), that might arise from the use of this document or the information in it.

This document and the product it describes are considered protected by copyright according to the applicable laws.

ILSA is a registered trademark of AIRCOM International.

Other product names mentioned in this document may be trademarks of their respective companies, and they are mentioned for identification purposes only.

Copyright AIRCOM International 2004. All rights reserved.

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Contents

Contents

Scope and Course Objectives ..............................................................................7 Course Objectives ...................................................................................................7 Sessions ......................................................................................................8 Course Timetable ....................................................................................................8

1 Introduction to ILSA ..................................................................9 1.1 Objective of this session.............................................................. 9 1.2 What is ILSA?.............................................................................. 9 1.3 ILSA concepts.............................................................................. 9 1.4 ILSAs inputs and outputs ..........................................................10 1.5 Limitations of ILSA .....................................................................12 1.6 ILSA Process and data flow ....................................................12 1.7 Explaining the inputs ..................................................................12 1.7.1 Constraints .................................................................................12 1.7.2 Frequency information ...............................................................14 1.7.3 Interference costs ......................................................................15 1.8 Using ILSA the basic steps .....................................................16 1.8.1 Defining the scope of the frequency plan ..................................17 1.8.2 Choosing the array area ............................................................17 1.9 Starting ILSA ..............................................................................17 1.10 Setting up ILSA ..........................................................................18 1.10.1 Network Pane ............................................................................18 1.10.2 Interference Pane ......................................................................21 1.10.3 Handover Counts Pane .............................................................21 1.11 Define the Frequency Plan ........................................................21 1.11.1 ILSA Frequency Planning window .............................................22 1.11.2 ILSA Display Menus ..................................................................23 1.11.3 Defining the Data in the Cost Matrix Editor ................................25 1.11.4 ILSA Plan List window ...............................................................31

1.11.6 Running ILSA .............................................................................36 1.11.5 ILSA Options window .................................................................32

1.11.7 Stopping ILSA ............................................................................39 1.11.8 Analysing ILSAs Results ...........................................................39 1.12 Session Summary Checklist ; ..............................................43

2 Frequency Plan a Network of sites ........................................45 2.1 Objective of session ...................................................................45 2.2 Creating a new frequency plan ..................................................45 2.2.1 Create prerequisites ..................................................................45 2.2.2 Set-up ILSA ...............................................................................54 2.2.3 ILSA Plan List window ...............................................................59 2.2.4 ILSA Options window .................................................................59 2.2.5 Run ILSA ...................................................................................61 2.2.6 Stopping ILSA ............................................................................62 2.2.7 Analysing ILSAs Results ...........................................................62 2.2.8 Analysing the Carrier Assignment .............................................63


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2.3 Exercise: Creating a New Frequency Plan .......................... 74 2.4 Session Summary Checklist ; ............................................. 77

3 Make Improvements to an ILSA plan .................................... 79 3.1 Objective of session .................................................................. 79 3.2 Why make improvements to ILSAs output? ............................. 79 3.3 How to make improvements to an ILSA plan ............................ 79 3.3.1 Identify undesirable reuses ....................................................... 80 3.3.2 Add appropriate exceptions ...................................................... 82 3.3.3 Rerun ILSA ............................................................................... 84 3.3.4 Analyse the results .................................................................... 84 3.4 Exercise: Make Improvements to an ILSA plan .................... 86 3.5 Session Summary Checklist ; ............................................. 88

4 Re-plan a Network with new sites ......................................... 89 4.1 Objective of this session ........................................................... 89 4.2 Overview ................................................................................... 89 4.2.1 Defining the scope of the plan .................................................. 89 4.2.2 Create prerequisites .................................................................. 90 4.2.3 Set-up ILSA ............................................................................... 92 4.2.4 Run ILSA ................................................................................... 94 4.2.5 Stopping ILSA ........................................................................... 95 4.2.6 Analyse the results .................................................................... 95 4.3 Exercise: Replan a Network with new sites ......................... 97 4.4 Session Summary Checklist ; ........................................... 100

5 Specialised Frequency Planning concepts ........................ 101 5.1 Objectives of this session ....................................................... 101 5.2 Group Planning ....................................................................... 101 5.2.1 What is Group Planning? ........................................................ 101 5.2.2 When should ILSA be used for Group Planning? ................... 102 5.2.3 Configuring ASSET/3g for Group planning ............................. 102 5.3 Exercise: Planning with Groups ........................................ 113 5.4 Planning a Frequency hopping Network ................................. 116 5.4.1 What is Frequency Hopping? .................................................. 116 5.5 Baseband Frequency Hopping ............................................... 117 5.5.1 Configuring ASSET/3g to plan a Baseband Hopping

Network ................................................................................... 117 5.5.2 Exercise: Planning a Baseband Frequency Hopped

Network ............................................................................. 128 5.6 Synthesised Frequency Hopping ............................................ 130 5.6.1 Configuring ASSET/3g to plan for Synthesised

Synchronisation ...................................................................... 130 5.6.2 Create Prerequisites ............................................................... 133 5.6.3 Configuring ASSET/3g to plan for Site Synchronisation ....... 143 5.7 RF Hopping Tools ................................................................... 143 5.7.1 Frequency Hopping Process Selector .................................... 144 5.7.2 MALID Planner ........................................................................ 145


Contents

5.7.3 MAIO Planner ..........................................................................146 5.7.4 HSN Planner ............................................................................148 5.7.5 Exercise: Planning a Synthesised Network .....................151 5.8 Planning with Multiple Reuse Patterns ....................................153 5.8.1 What are Multiple Reuse Patterns (MRP)? ..............................153 5.8.2 Configuring ASSET/3g to plan an MRP Network .....................154 5.8.3 Exercise: Planning with MRPs ........................................175 5.9 Session Summary Checklist ; ............................................178


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Scope and Course Objectives

Scope and Course Objectives

This document provides notes and supporting material for the standard 1-day ILSA V2.0 User Training Course. It is assumed that ASSET/3g V5.0 has been installed with a suitable Oracle database.

Details of how to install the software tool and how to setup a new database source are covered by the ENTERPRISE Administration Course and not by the ILSA User Training Course.

Course Objectives

ILSA is AIRCOMs Frequency Planning module for use with ASSET/3g. This course is designed to give ASSET/3g users an in-depth understanding of how to use ILSA and builds on the ASSET/3g training course.

The course is aimed at radio planning engineers already familiar with ASSET/3g but requiring more knowledge on ILSA.

At the end of the course, delegates should gain a good knowledge of ILSA and also be able to complete the following objectives:

Carry out basic Frequency Planning with ILSA Improve an existing Frequency Plan Re-plan with new sites Plan a network using Frequency Groups -or- Implement a Frequency Plan with Frequency Hopping

-or- Plan a network with Multiple Re-use Patterns


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Sessions

This course is divided into the following sessions:

1. Introduction to ILSA

2. Frequency Plan a network of sites

3. Make Improvements to an ILSA Plan

4. Re-plan a network with new sites

5. Specialised Frequency Planning concepts:

Planning with Groups Planning a Frequency Hopping Network Planning with Multiple Reuse Patterns

Course Timetable

Day 1 Day 1

Period Plan Period Plan

0930-1000 Introduction to the Course 1330-1415 Session 3 : Make Improvements to an ILSA Plan

1000-1045 Session 1: Introduction to ILSA 1415-1500 Session 4 : Re-plan a network with new sites

1045-1100 Break 1500-1515 Break

1100-1145 Session 2 : Frequency Plan a network of sites

1515-1600 Session 5 : Specialised Frequency Planning concepts

1145-1230 Session 2 : Frequency Plan a network of sites

1600-1630 Course Evaluation and Feedback

1230-1330 Lunch


Introduction to ILSA

1 Introduction to ILSA

1.1 Objective of this session

In this session you will learn:

What is ILSA?

ILSA concepts.

ILSAs inputs and outputs.

Limitations of ILSA.

The basic steps involved in producing the frequency plan.

Defining the scope of the frequency plan.

Choosing the array area.

Running ILSA.

Analysing the results.

1.2 What is ILSA?

ILSA (Intelligent Local Search Algorithm) is ASSET/3gs own unique frequency planning tool. It is fully integrated into ASSET/3g and is flexible enough to allow it to be used for a variety of different frequency allocation strategies.

1.3 ILSA concepts

One of the most challenging tasks for a radio-planning engineer is the allocation and reuse of a given frequency allocation.

Frequencies must be allocated to provide sufficient capacity for the system users whilst minimising interference caused by sites reusing the same frequency and observing any constraints caused by the equipment in use.

The performance of the network is heavily dependent on the allocation of frequencies. Even in a relatively small network there are a staggering number of different frequency allocations possible.


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Evaluating each different possible allocation would take a prohibitive period of time, so how can an engineer identify a good allocation without running through an exhaustive analysis?

The answer, employed by most advanced radio planning tools today, is to use a search algorithm. A search algorithm is designed to search for a solution to a complex problem through the use of a particular strategy.

Some algorithms employ a very simple strategy (for instance when looking for the centre of a maze always take the left path) which can be combined with the ability to recognise when it has been somewhere before to prevent looping.

However this type of algorithm usually takes too long to solve, even in a moderately sized frequency-planning problem. ILSA uses an extremely advanced heuristic (the exploration of possibilities rather than set rules) search algorithm, which utilises the latest techniques in combinatorial mathematics.

It works by evaluating the cost of a particular frequency plan and then tries to minimise the cost of the whole plan by changing the frequency allocation, but initially concentrating its efforts on the high cost areas.

In addition to this, ILSA will make random changes when it finds that it is making slow progress, or has reached a dead end.

This strategy means that ILSA will at first make rapid improvements to the plan but when the rate of progress is reduced, it will try to do something radical to move forward.

A plan can incur cost in one of two ways:

1. Firstly, when a frequency plan results in predicted interference, the cost for each frequency allocation is equal to the level of traffic affected by the interference. (units milli-Erlangs)

2. Secondly, constraints might be placed on the plan by the equipment used (e.g. channel spacing on a cell) or the technology used (e.g. GSM or TETRA). If these constraints are broken then a cost (unit milli-Erlangs) will be allocated to the plan. Typically this cost will be in the order of 1000 milli-Erlangs for a particularly important constraint.

1.4 ILSAs inputs and outputs

The many inputs to ILSA are shown in Figure 1. Some of the inputs are mandatory and others are optional but recommended (shown with an asterisk).

Some of these inputs such as the Interference Table and Cost Matrix should be created specifically for the planning task that is underway.

Most of the other inputs are taken directly from the ENTERPRISE database and need minimal user input.



The output is a frequency allocation, which can be viewed as a report.

If this frequency allocation is applied to the database, it can be analysed further using either the frequency plan reporter or the interference arrays.

SiteDatabase

Cost MatrixWizard

ILSA

Neighbours *

Exceptions *ForbiddenCarriers *Fixed Carriers*

Carrier Costs InterferenceTable

Wizard

InterferenceCosts *

CoveragePredictor

RF Parameters

Predictions

ArrayCreation

Best ServerArray

FrequencyPlan

TrafficRasterWizard

Traffic Raster *

PropagationModel Editor

TerminalTypes

PropagationModel

Traffic Spread

SeparationCosts

RequiredCarriers

FH Settings

DTX Settings

Current FreqPlan * Carrier Layers

Cell List

Figure 1 Flow of Data within the ILSA Planning Process (Neglecting Neighbour Generation)


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1.5 Limitations of ILSA

ILSA will always make a frequency allocation, which it will constantly try to improve within the constraints that have been set by the user. However it is important to realise that if ILSA is set unrealistic constraints, it will produce an unrealistic frequency plan.

Note: The user should always check that the default constraints are necessary and realistic.

If ILSA does not come up with a workable frequency allocation then the user should consider relaxing the constraints in some way or expanding the scope of the problem by increasing the number of cells (e.g. cell splitting) and frequencies involved. This will be demonstrated in a later session.

1.6 ILSA Process and data flow

The secrets of generating a good frequency plan with ILSA can be summarised as:

9 Understanding how to perform the procedural steps involved

9 Understanding what inputs are required and whether they are mandatory or optional

9 Understanding what outputs you can expect and how to interpret them

1.7 Explaining the inputs

The inputs to ILSA depicted in Figure 1 can be divided into three basic groups.

a) Constraints.

b) Frequency Information.

c) Interference costs.

1.7.1 Constraints

Constraints are the main way in which the user can guide ILSA to a good solution. If ILSA is having difficulty arriving at a good solution then these are the parameters that need to be changed to improve the plan.



These constraints are explained in further detail below:

Site Lists:

The Site lists define the scope of the frequency-planning problem i.e. which sites are to have frequencies allocated or changed and which sites are to remain unchanged but taken into account when changes are made to other sites?

Neighbours:

In a mobile radio system it is common for a mobile station to move mid way through a call into an area which is better served by another transmitter. In these occasions, the fixed part of the network usually allows the mobile station to switch or hand-off to the other transmitter so that is will be better served.

It is normal practice for these hand-offs to be restricted to a short list for each serving cell known as a neighbour or adjacency list rather than allow them to happen in an uncontrolled manner.

Depending on the technology in use there might be a restriction in the frequencies between cells that hand-off to each other. In this case ILSA can use the neighbour list as a constraint in conjunction with the separation costs, for example, the GSM system will not tolerate a handoff to a neighbour cell using the same frequency (separation 0). It will in some circumstances tolerate a hand-off to a cell using an adjacent frequency (separation 1) but for maximum performance the neighbour cell should use a separation of 2.

Forbidden Carriers:

Most networks have a set number of frequencies that are allocated to it nationally by their respective regulatory authority. However it is normal that this frequency allocation is restricted in certain geographic areas. This might be because:

The network borders with another country where a foreign network has been allocated the same frequencies and co-ordination is required to minimise interference between the different networks.

Other users in the same country have previously been allocated the same spectrum and the new network is required not to interfere with the existing system.

Certain frequencies might interfere with Military installations.

The ENTERPRISE database allows the user to forbid individual frequencies on a sub-cell by sub-cell basis. ILSA will consider such allocations as high cost and so will avoid making such an allocation.

Exceptions:

Frequency allocations by ILSA are based on the predicted coverage (and therefore interference) of each sub-cell. Because the predictions are derived from an empirical mathematical model, they will never be completely accurate and will contain a degree of error.


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If an input to ILSA is sub-optimal then the output will also be sub-optimal. In these cases ILSA might calculate that a particular frequency reuse is possible and allocate it when in fact such a reuse will cause bad quality.

Sometimes an experienced radio planner will spot such a reuse before implementation but often these reuses are only discovered following implementation. In either case, once such a reuse has been identified it can be recorded as an exception in the ENTERPRISE database. ILSA will consider reuses in the exception list as high cost and so will avoid making such an allocation.

Fixed Carriers:

The site lists contain details of sites to be planned and sites to be planned against. However not all frequencies on a site need to be planned. Sometimes only one frequency needs to be planned and the remaining frequencies should remain unchanged. In this case the frequencies to remain static should be fixed in the ENTERPRISE database and ILSA can then be instructed to leave these frequencies unchanged.

Separation Costs:

Each different technology (e.g. GSM or TETRA) used in mobile radio systems will impose a number of restrictions on the allocation of frequencies. These are normally expressed in terms of minimum separation between frequencies. This can be for frequencies:

On the same cell.

On the same site but a different cell.

A neighbour of the site. A second order neighbour of the site.

ILSA will consider breaking the separation as high cost and so will avoid making such an allocation.

Carrier Costs:

Carrier costs are the cost of either changing a fixed carrier or making a forbidden carrier allocation.

1.7.2 Frequency information

Frequency information is stored in the ENTERPRISE database and doesnt require much input from the user, provided the database is up to date. It contains details of the existing frequencies; new carrier requirements and other carrier related parameter settings.



The frequency information is explained in more detail below:

Carrier Layers:

Carrier layers are the way in which ASSET/3g organises and stores frequency information in the ENTERPRISE database. The carrier layers are dependent on the frequency allocation strategy that is being used in the area to be planned. For example, a basic GSM system might use two carrier layers, BCCH and TCH. However a more complex GSM strategy such as MRP (multiple reuse patterns) might use four carrier layers, BCCH, TCH1, TCH2 and TCH3.

Current Frequency Plan:

This is the current frequency allocation on all the cells in the network.

FH Settings:

These are the settings in the ENTERPRISE database relating to the use of frequency hopping on cells. To make use of this information ILSA needs to have the frequency diversity gain radio button activated.

DTX Settings:

These are the settings in the ENTERPRISE database relating to the use of discontinuous transmission on cells. To make use of this information ILSA needs to have the use DTX load factors as set in the site database radio button activated.

Required Carriers:

This is the number of frequencies required on each carrier layer on each cell being planned.

1.7.3 Interference costs

Interference costs come in the form of an interference table. This matrix contains predictions of how much interference one cell would cause to every other cell as the result of cells having a co-channel or adjacent channel frequency allocation. The table lists both the surface area (km) and traffic (milli-Erlangs) as totals and percentages that are affected by interference.

Interference tables are generated by ASSET/3g from a best server coverage array and a traffic array, which estimates where the traffic is located.


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1.8 Using ILSA the basic steps

The flowchart in Figure 2 depicts at a high level the planning process when using ILSA. Later sessions in this course will provide more details of the sub tasks involved. Before commencing the planning process the user needs to consider two factors: -

I. Defining the scope of the frequency plan.

II. Choosing the array area.

Start

CreatePrerequisites

Setup ILSA/CostMatrix

Run ILSA

Analyse Results

Finish

Analyse ExistingPlan

AcceptableImprovement?

Yes

No

y Worst Interferer Statisticsy Average Connection Statisticsy Frequency Plan Report

y Carriers Requiredy Interference Tabley Neighbours and Exceptions

y ILSA Setupy Cost Matrix Setup

y Worst Interferer Statisticsy Average Connection Statisticsy Frequency Plan Report

Figure 2 High level Flow Chart of ILSA Planning Process



1.8.1 Defining the scope of the frequency plan

Before a user starts to plan it is necessary to consider the extent of the frequency plan that ILSA is required to produce. Is it a single frequency to be added to an existing cell, is it a new site to be integrated or is it a re-tune of a large number of sites? Whatever the task is, the planner will have to produce site lists detailing which sites are to be planned and which sites are to remain unchanged (but should be taken into consideration into the plan). When this is known, the user must create filters identifying these two categories of sites.

1.8.2 Choosing the array area

When the scope of the frequency plan has been identified, the user should decide on what size of array is required for the task in hand. The array should be large enough to show the coverage area of any site affected by new or different frequency allocations. If the array is too small then the interference table might not contain all the information required to avoid bad allocations and this would result in bad quality in the radio network. If the array is unnecessarily large then ASSET/3g will take much longer to create the interference table and in extreme cases the table will not be able to be created due to memory limitations on the hardware.

1.9 Starting ILSA

ILSA is started from the ENTERPRISE Main Menu by selecting Tools Frequency Planning ILSA Frequency Planner. The Initialise ILSA Automatic Frequency Planner window depicted in Figure 3 will then appear:

Figure 3 Initialise ILSA Automatic Frequency Planner window


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The Initialise ILSA Automatic Frequency Planner window can be divided into three functional areas:

1) The Network pane.

2) The Interference pane.

3) The Handover Counts pane.

1.10 Setting up ILSA

The first step in setting up ILSA is to select the planning data to be used. This is done using the various options within the Initialise ILSA Automatic Frequency Planner window. Having selected the relevant data it can then be loaded into ILSA by clicking on the Initialise button.

1.10.1 Network Pane

o Data from memory:

Selecting this option allows you to specify which Filters are to be used in the Frequency Planning process. This is done by clicking on the Import Filters button:

Within the Import Filters Wizard (Step 1 of 4) select the Filters that are to be included/considered, clicking on the Next button will progress to the next wizard screen:



Figure 4 Import Filter wizard - Step 1 of 4

Step 2 of 4 of the wizard allows you to use the up and down arrows to set the order of Filter preference:


Click the Next button to continue to step 3 of 4.


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Now select the Cell Layers you want to include/consider from the global list that appears:


Clicking on the Next button to advance to the next wizard screen.

Step 4 of 4 of the wizard prompts you to select the Filters and Cell Layer combinations you wish to import:




Finally click on the Finish button to import the selected Filters.

o File:

The File option within the Initialise ILSA Frequency Planner window allows you to use the browse button to select an appropriate file.

Note: Only ASSET/3g XML network files may be used.

1.10.2 Interference Pane

o Data from memory:

This option instructs the software to use the current Interference information (i.e. Interference Table) created within ENTERPRISE.

o File:

The File option can be used, in conjunction with the browse button, to import Interference information contained within a file. This interference information will be in the form of an exported Interference table from ENTERPRISE.

1.10.3 Handover Counts Pane

o None:

If you are planning without Handover Counts select this option.

o File:

A Handover Counts File, which is produced from OPTIMA, can be used within the Frequency Planning Process. This is done by selecting this option and using the browse button to locate and select the file you wish to use.

Clicking on the Initialise button will then load the above information into ILSA.

1.11 Define the Frequency Plan

The ILSA Frequency Planning window presents the action sequence of Frequency Planning in a clear and logical way.


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This will enable you to define the Frequency Plan easily by amending settings and viewing the results.

Figure 8 ILSA Frequency Planning window

1.11.1 ILSA Frequency Planning window

The ILSA Frequency Planning window is divided into three key areas:

1) Plan pane

2) Plan Status pane

3) Interference pane

1.11.1.1 Plan pane

Within the Plan pane decide whether ILSA should create a new plan or load the current frequency plan from the ENTERPRISE database.

1.11.1.2 Plan Status pane

Within this pane information about the plan is displayed (i.e. Name of the Plan, Plan Status, Start Time, Carriers to Plan, Initial Cost of Plan, Current Cost of Plan and Iteration).



1.11.1.3 Interference pane

The average and worst interference values within the Plan can be displayed here by selecting the Show check-box.

Note: These values are not editable.

1.11.2 ILSA Display Menus

There are four menu options available within the ILSA display:

1) File

2) View

3) Cost Matrix

4) Tools

Figure 9 ILSA Display Menus within the ILSA Frequency Planner window

1.11.2.1 File Menu

Within the File menu various options are available which allow you to build up a history of previous frequency plans. This could be useful in comparing old plans with new plans.

Save Network: Allows you to save the complete Network in XML format.

Export Assignments: Allows you to export the carrier assignments to an XML file.

Import Assignments: Allows you to import a carrier plan in XML format.

Close: Allows you to close ILSA but not ASSET/3g.


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1.11.2.2 View Menu

Plan List: Allows you to view the Carrier Plan list

Assignments: Allows you to view the Carrier Assignment

Graph: Allows you to view the ILSA Cost Matrix graph

1.11.2.3 Cost Matrix Menu

Within the Cost Matrix the rules within which ILSA operates are defined.

Load: Brings up a Browse window allowing you to locate the saved Cost Matrix (.cmx file). Having located the file click on the OK button.

Save: Launches a Save As window which enables you to browse to the location you wish to save the Cost Matrix to. Enter a name for the Cost Matrix and click on the OK button. The Cost Matrix will be saved as a .cmx file.

Edit: Allows you to edit the Cost Matrix.

1.11.2.4 Tools Menu

Initialise: This displays the Initialise Network window (as previously described).

Apply to Database:

Applies the Frequency Plan to the database.

Options: Displays an Options window

1.11.2.5 Help Menu

Launches the ENTERPRISE Help topics window.



1.11.3 Defining the Data in the Cost Matrix Editor

Having chosen to Edit the Cost Matrix the Cost Matrix Editor window appears. The rules within which ILSA operates can now be defined.

Figure 10 Cost Matrix Editor window

The Cost Matrix Editor window is divided into a number of sub-areas (Folders) each having a specific purpose. Each of these sub-areas (Folders) are covered below in more detail:

1.11.3.1 Carrier Costs Folder

Within the Carrier Costs folder costs associated with a single carrier on a single carrier layer of a single sub-cell can be viewed and edited.

Figure 11 Cost Matrix Editor window Carrier Costs Folder


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The Cost relates to the retuning of a Fixed carrier or an allocation of a Forbidden carrier, as set in the Site Database:

Fixed Carrier Forbidden Carrier

1.11.3.2 Carrier Layer Costs Folder

If you want any Carrier Layers that you may have Fixed to be retuned, in the Allow Retune column select the check-box and then enter a cost (between 0 and 50000) in the Retune Cost column. If the cost set is high, ILSA will try not to change the Fixed carriers unless it must to obtain a plan with low interference.

Figure 12 Cost Matrix Editor window Carrier Layer Costs Folder

Assign Cell Layer/Carrier Layer combinations a weighting, in the appropriate column usually between 1 and 10 (although you can go to 99999). Weighting a layer increases the costs incurred during the frequency planning process by a selected factor. Using weightings discourages ILSA from



breaking constraints on higher weighted layers, or increases the effect of interference on a higher weighted layer.

E.g. If we weighted the BCCH carrier layer to a value of 2 this will instruct ILSA to double any costs on the BCCH layer, which will result in a BCCH allocation with less interference than the TCH allocation

1.11.3.3 Equipment Costs Folder

Costs incurred for breaking the minimum separations or preferred separations for the equipment are set within the Equipment Costs folder.

Having selected the Equipment, Cell Layer and Carrier Layer that you want to plan enter the minimum separation and the minimum cost that would be incurred if the minimum separation is not met.

Figure 13 Cost Matrix Editor window Equipment Costs Folder

If you want the separation to be of greater quality than the minimum, set a preferred separation. Then set the preferred cost which will be incurred if the preferred separation is not met.

Note: You need to have Cell Equipments defined within ASSET/3g/3G to be able to specify the separation costs for the cells using the Cell Equipment. Otherwise the only two categories displayed under the Equipment column will be Site and Cell.

1.11.3.4 Neighbour Costs Folder

The costs incurred if the minimum or preferred separations for Neighbours are not met are set within the Neighbour Costs folder.


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Having selected the Neighbour, Cell Layer and Carrier Layer you want to plan, enter the minimum separation and the minimum cost that would be incurred if the minimum separation is not met.

Figure 14 Cost Matrix Editor window Neighbour Costs Folder

If you want the separation to be of greater quality than the minimum, set a preferred separation. Set the preferred cost which will be incurred if the preferred separation is not met.

1.11.3.5 Exception Costs Folder

The cost of breaking various separation constraints (indicating how bad the effect of breaking a constraint is) is set within this folder.

Although default values are entered you can set new ones to a value between 0 and 99999999999. For example, an exception cost would indicate what degree of risk would be associated if two adjacent cells are given frequencies near each other, breaking the exceptions you have defined in the Site Database.

Figure 15 Cost Matrix Editor window Exception Costs Folder



1.11.3.6 Filter Priorities Folder

The priority order for sites you want to plan can be changed within this folder.

If you use more than one Filter, and a site is present in more than one Filter, then the settings used are taken from the first Filter in the list. The priority order can be changed by editing the values.

Figure 16 Cost Matrix Editor window Filter Priorities Folder

1.11.3.7 Handover Count and Intermodulation Costs Folder

Having selected to Use Handover Count, by selecting the check-box, you can either:

Click the Autoscale checkbox and set the scale factor to normalise the handover count to a similar level as all the other costs

-or-

Enter the Scale factor manually to give more importance. For example, by setting the scale factor at 2, ILSA will make the handover count costs twice more important than other costs.


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Figure 17 Cost Matrix Editor window Handover Count and Intermodulation Costs Folder

Handover counts can be imported from OPTIMA, or created manually, to show the number of times a handover occurs between two carriers.

You can also set the costs for 2nd and 3rd order intermodulation interference through this folder, together with an Uplink Weighting.

Because uplink frequencies are a lot less significant than downlink frequencies an Uplink Weighting is applied (a figure less than 1) to any intermodulations that involve uplink frequencies in the calculation.

1.11.3.8 Separation Costs Folder

The costs of making close allocations to two separate Carrier Layers within a SubCell or between Sub-Cells is entered within the Separation Costs folder:

Figure 18 Cost Matrix Editor window Separation Costs Folder



This will allow you to plan for known trouble spots in your network by assigning costs according the different levels of importance you assign to the different separations in the network, and to the level of constraint that you decide to use.

Importance should be placed on the cost of cell co-channel separation to ensure it is greater than the cost of a site co-channel separation, which in turn is grater than the cost of a neighbour co-channel separation, and so on.

Clicking on the Default cost button will reset the separation costs to those stored in the Database. However, returning the costs to default values will remove any data you may have inserted in the grid.

The Search button allows you to search for a particular value by entering a Cell Id for the X axis and a Cell Id for the Y axis:

Figure 19 Search for Separation Cost window

On clicking the OK button the relevant cells will appear in the window.

1.11.4 ILSA Plan List window

When you have created a cost matrix, you can define the Filter/Cell Layer/Carrier Layer combinations that are to be considered by the plan within the Plan List window.


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This is accessed through the View menu of the ILSA Frequency Planner window:

Figure 20 Plan List window

For each combination one of the following choices is available for selection, within the Status column:

Plan: Selecting this option will plan the carriers required within sites satisfying the Filter/Cell Layer/Carrier Layer criteria. The carrier allocations can be modified and are considered by other carrier allocations as interferers.

Read Only: This option disables ILSA from planning the carrier allocations required within sites satisfying the Filter/Cell Layer/Carrier Layer criteria. The current carrier allocations can still be considered as interferers by ILSA when planning other carrier allocations.

Ignore: This option ignores sites satisfying the Filter/Cell Layer/Carrier Layer criteria.

1.11.5 ILSA Options window

Using the ILSA Options window you can control the calculation and display of Frequency Planning data. The Options window can be found within the Tools menu of the ILSA Frequency Planner window and is divided into two areas:

a) General Tab

b) Planning Features Tab



1.11.5.1 General Tab

Within the General tab you can:

Set the Graph X Axis options as either Iteration or Increment

Set the Refresh Rate to determine how quickly the Plan Status pane will update when planning

Have the current cost of Plan written to the message log every minute (this is done by selecting the Log Results in Message Log check box)

Automatically save the assignments to File (this is done by selecting the Auto-Save Assignments check box, and entering a time for how often the Plan is updated, together with a Path name for where the assignment is to be saved).

1.11.5.2 Planning Features Tab

Within the Planning Features tab you can:

Select Use Frequency (Hopping) Diversity Gain if you want ILSA to take into account that during Hopping different frequencies suffer from different fading losses, and so a frequency diversity gain is obtained. The gain is dependent on the number of hopping frequencies used, the values of which are taken from the FH Diversity Gain table. ILSA will convert this dB value to a weighting by which the cost is then multiplied.

e.g. hopping over 2 carriers gives a gain of 3dB. The invLog of 3 is 1.995. If the cost weighting applied is 1, then the ILSA weighting applied to the costs will be 0.501 (cost reduced by half).


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Select Aggregate carriers required under site hopping to allow ILSA to take the number of carriers required for each sub-cell to be the number of carriers required across all subcells with which it is synchronised in frequency hopping (e.g. terminal type has been used to set the carriers required). If unselected ILSA will presume that site hopping synchronised subcells on a site have already had their carrier requirements set (e.g. carriers calculated using live traffic figures).

By selecting Use Antenna Hopping Gain you are instructing ILSA to take into account the diversity gain achieved when multiple antennas are exposed to different multipath fading. Antenna Hopping is a transmit diversity scheme in which consecutive bursts of information are transmitted on different antennas. The gain is dependent on the number of antennas deployed (or Antenna slots per sub-cell in ASSET/3g). The number of antenna slots used is substituted for carriers in the FH Diversity Gain table. ILSA will convert this dB value to a weighting by which the cost is then multiplied.

Note: If both Use Frequency (Hopping) Diversity Gain and Use Antenna Hopping Gain are selected the amount of FH Carriers is multiplied by the number of Antenna Slots, the result is then applied to the carriers column of the FH Diversity Gain table in order to calculate the gain. ILSA will convert this dB value to a weighting by which the cost is then multiplied.

Select Use DTX load factors as set in the site database if you want to reduce the interference caused by sub-cells with DTX set. The weighting of the cells on which DTX is enabled is multiplied by the Voice Activation Factor (VAF) as set in the site database.

e.g. If a voice activity factor of 0.7 is set, ILSA will reduce any costs incurred by that sub-cell by 30%.

Note: DTX cannot be enabled on the BCCH carrier so some carrier allocations within the network will have DTX enabled, and others will not. The carrier allocations without DTX enabled need to be planned more carefully than allocations with DTX and so setting up DTX for use within ILSA allows you to discriminate between the two settings.

Select Consider intermodulation interference for ILSA to take into consideration inter-modulation interference created by carrier frequency bi-products.

You can then specify the order up to which intermodulation is to be considered. For example, if you select 3rd order, both 2nd and 3rd order intermodulations will be reported on. You can also indicate a tolerance value, which specifies how close an intermodulation frequency would need to be to a carrier before it is considered to interfere. Costs incurred for breaking the tolerance value are taken from the cost matrix.

Select Use group planning to enable ILSA to use Group Planning as a method of allocating frequencies to the carrier layer.

Note: This assumes that Group Planning has been enabled and a Re-use Pattern chosen within ASSET/3g.



Minimise Interference by:

Traffic: If you have reasonable or high confidence in the traffic statistics that you have used to generate the interference table select this method for Frequency Planning.

ILSA will then pay more attention to high traffic areas when reducing interference. The Cost function takes, as an input, the value of the traffic affected due to an allocation from the interference table.

The Cost of an allocation breaking a co-channel or adjacent channel constraint is the mE value of interference between two cells multiplied by 2, then added to the separation cost.

Note: This option is only available if the interference table has been generated with a Traffic Array.

Area: If you have little confidence in the traffic statistics that you used to generate the interference table or you did not use a Traffic Array to create the interference table, the Area option should be selected for Frequency Planning.

The Cost of an allocation breaking a co-channel or adjacent channel constraint is the area in km (indicated in the interference table) multiplied by a factor of 200.

Combination: If you have partial confidence in the traffic statistics, or you wish to bias the plan, for example, towards the urban areas while maintaining reasonable quality across the network, choose this option.

This option is only available if the interference table has been generated with a Traffic Array.

The ratio entered is Traffic versus area, so 0 indicates that only Area will be used and 100 indicates that only traffic will be used.

The interference cost will comprise of both traffic and area values but the percentage determines which option is dominant. For example, if you select traffic:area to be 70% then the mE value will be multiplied by 0.7, and the km value will be multiplied by 0.3 before being added to the separation cost.

Note: To avoid the allocation of adjacent channels you must increase the separation cost.

Having set up ILSA in the way you require, the next step is to run ILSA.


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1.11.6 Running ILSA

Once the user has set up ILSA, and created a cost matrix, the algorithm can be initiated by clicking on the Start button, within the Plan pane of the ILSA Frequency Planner window. At first ILSA will begin Initialising by making first-pass frequency allocations to all sub-cells. ILSA will then attempt to meet all the rules that have been defined within the cost matrix, and simultaneously try to reduce the average level of interference per carrier.

Once ILSA has been started the following fields within the Plan Status pane of the ILSA Frequency Planner window can be viewed:

Plan: Displays the Plan identity

Status: Indicates at what stage ILSA is at in the Frequency Planning process (i.e. Initialising, Planning, Finished)

Start Time: The Plan start date and time is displayed (e.g. Sept 22 2004 13:01:00)

Carriers to Plan: The total amount of carriers to be planned is displayed

Initial Cost: The cost of the plan following initialisation.

Current Plan Cost: The cost of the lowest cost plan so far.

Iteration: Each time ILSA tries a new plan, this field will be incremented.

Within the Interference pane of the ILSA Frequency Planner window, when the Show box is selected, the average interference per carrier and worst case interference per carrier fields will be updated by ILSA. The interference per carrier is determined by the amount of traffic (mE) affected by interference.

To show the graph whilst ILSA is running, select the Graph option within the View menu of the ILSA Frequency Planning window:

Figure 21 ILSA Frequency Planner window Selecting to view the ILSA Cost/Interference Graph



The graph that appears shows the cost of the best plan (in red), the average interference (in green) and the worst interference (in blue).

Figure 22 ILSA Cost/Interference Graph

Once the Planning process is halted/suspended the ILSA Cost/Interference Graph can be printed or saved to file:

1.11.6.1 Printing the ILSA Graph

Having selected the Print button a Page Setup for Printing Chart window appears:

Figure 23 Page Setup for Printing Chart window


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Having chosen the appropriate settings click on the OK button.

A Print window will then appear which allows you to configure and set up the necessary printing options.

Figure 24 Print window

Click on the OK button to print the ILSA Cost/Interference Graph.

1.11.6.2 Saving the ILSA Graph to File

On selecting the Snapshot option within the ILSA Graph window a Save As window appears prompting to you to specify a location to save the Graph to:

Figure 25 Save As window

Having located the appropriate folder in which to save the Graph a File Name can be entered. A File Format can also be chosen (using the drop down menu) before clicking on the Save button.



1.11.7 Stopping ILSA

At any time ILSA can be paused to analyse the current plan by clicking on the Stop button and then restarted by clicking on the Continue button.

If the cost matrix contains high costs and separations you may need to leave ILSA running for several hours at a time. ILSAs algorithm decreases the rate of improvement with time so vast improvements are made within a relatively short period and only modest (but potentially beneficial) improvements are made over many hours.

ILSA will run until the cost of the plan has reached zero (0) or when the user clicks on the Stop button.

If the plan does not stop due to zero cost then after some time, it will become clear that ILSA is no longer making improvements and the plan can be paused by clicking on the Stop button in the Plan pane before analysing the results.

1.11.8 Analysing ILSAs Results

Once ILSA has been stopped, you can view the allocations that have been made in the current best plan.

1.11.8.1 Viewing the Carrier Assignment

From the View menu of the ILSA Frequency Planner window, select Assignments:

Figure 26 ILSA Frequency Planner window Selecting to view carrier assignments


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The Carrier Assignments window displays:

Carrier Statistics: The number of times each frequency is allocated, and the minimum reuse distance between each site using that frequency.

Cell Statistics: Shows the interference value on each allocation that is made.

Figure 27 ILSA Carrier Assignments window

Having viewed the carrier assignment:

If the assignments are acceptable: Close the Carrier Assignments window and apply the plan to the database.

If the assignments are unacceptable:

Continue planning by clicking on the Continue button within the Plan pane of the ILSA Frequency Planner window.

Note: You can also apply the plan to the database and restart planning. This can improve the quality of the plan, due to the random element within the ILSA algorithm.

When you have applied the plan to the database, you can perform further analysis to verify if any improvement has been made on original frequency plans. You may also highlight areas where improvements can be made in the current applied plan.



1.11.8.2 What are Acceptable Statistics?

When you have produced a frequency plan that ILSA has analysed, statistics are displayed within the carrier assignments window. The following areas may help you decide whether the statistics are acceptable to you:

9 If only alternate carriers have been assigned, even though you have a contiguous band of carriers, this indicates that the adjacent interference is more dominant than co-channel, which is incorrect. The most common reason for this is that the C/I adjacent offset (set within the Array Settings window) has been set incorrectly. It should be a negative (-) setting (i.e. the default setting being -18db).

9 The interference value is a cumulative figure derived from all the associated costs of making that assignment. If this value is less than the minimum separation or retune cost, then this is purely an interference cost. If a large number of assignments have high costs then the constraints have been broken and may need to be relaxed. For example, too few carriers or unrealistic separation requirements for the neighbours or second order neighbours.

You achieve a good plan if the resultant cost is less than the minimum separation cost since all the separation constraints were met and the plan is just based on interference.

1.11.8.3 Exporting the Carrier Assignments

You may wish to analyse the ILSA carrier assignments using another software program. You can do this by exporting the Carrier Assignment to a file.

From the File menu, within the ILSA Frequency Planner window, select the Export Assignments option:

Figure 28 ILSA Frequency Planner window Selecting to Export Assignments


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Having browsed to a suitable location and entered a filename, click on the OK button.

The ILSA Carrier Assignment will then be exported to an XML File, enabling you to import and analyse the assignment in other tools.

Note: You can also import Carrier Assignment XML Files into ILSA by selecting this choice from the File menu of the ILSA Frequency Planner window.



1.12 Session Summary Checklist ; This checklist has been provided as a self-assessment of the objectives stated at the beginning of the session.

Please tick all objectives covered in this Session:

Expand the term ILSA and describe its function within ASSET/3g F Explain the basic concept of how ILSA works F

List the mandatory inputs of ILSA F

State the outputs of ILSA F

Describe the possible limitations of ILSA F

Describe the basic steps involved in producing a frequency plan F Explain how to define the scope of a frequency plan F

Successfully run ILSA to produce a frequency plan F

Describe the various ways of analysing frequency plan results F

Additional Notes:


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Frequency Plan a Network of sites

2 Frequency Plan a Network of sites

2.1 Objective of session

In this session you will learn, with the help of a practical exercise, how to create a new plan for a complete network of sites.

2.2 Creating a new frequency plan

A portion of the electro-magnetic radio spectrum is assigned to Operating Companies of Mobile phone networks for radio communication using cellular phones. The use of a frequency division multiple access (FDMA) scheme is one choice for networks operating according to the GSM standards. FDMA takes the available portion of the radio spectrum and partitions it into slots of equal size, called channels. Radio links to cellular phones are established via stationary transceivers. Each transceiver uses a fixed channel, whereas cellular phones tune to the channel of the transceiver via which they are communicating.

A central problem in radio communications is that the signals of transceivers (and cellular phones) may be subject to interference. Interference usually comes from a near-by transceiver transmitting at the same or an adjacent channel. In practice, the number of transceivers in a cellular phone network exceeds the number of available channels by a factor of 50 or more. Thus, channels have to be reused often.

Prior to creating a frequency plan it is vital to the planning process that the prerequisites are correctly set-up and checked. If the inputs to ILSA are of poor quality then it cannot be expected that the outputs will offer an improvement in the performance of the network.

2.2.1 Create prerequisites

The main prerequisites involved in creating a new frequency plan are:

9 Setting carrier requirements. 9 Creating an interference table. 9 Defining neighbour relations. 9 Defining exceptions.


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2.2.1.1 Setting Carrier Requirements

The carrier requirements are recorded on each carrier layer allocated to a sub-cell within the Site Database, as depicted in Figure 29.

Figure 29 Carrier requirements location in the Site Database

The carrier requirements can be set in three ways:

i. Individually using the site database:

Globally using

ii. the global editor:

To change the data using the global editor click on the Global Edit button and move to the Carrier Layer tab.

Note: If all the cells have the same carrier requirement, the most suitable method is to use the global editor.



iii. Using ASSET/3gs traffic analysis tool:

2.2.1.2 Create Interference Table

Prior to creating an Interference Table the following steps should have already been performed:

Create a coverage array

Having opened a new 2D Map View window show suitable map data and display the sites to be planned using the appropriate filter selection Figure 30.

Figure 30 2D View showing sites and Map data


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Now perform coverage prediction calculations (often termed simply predictions), using the Predictor Tool. This is accessed either from the ENTERPRISE Main Menu by selecting Tools Pathloss Predictor or by clicking on the button on the 2D Map View Toolbar. The window in Figure 31 will appear:

Figure 31 Pathloss Prediction Manager Window

Within the Define Objects to Predict pane select an appropriate Filter from the choices listed. Next decide if you want to override the Object Settings in the Site Database, choosing an appropriate Radius and Resolution if you do.

Having set the required parameters in the Coverage Predictor Window, click on the Start button.

Prior to the array creation certain parameters need to be set within the Array Settings window; this can be accessed through the ENTERPRISE Main Menu by selecting Arrays Array Settings.

Figure 32 Array Settings Window



Under the Serving and Interfering Cells tab ensure the Use carrier layers when calculating a best server array box is checked. Also ensure that the carrier layer boxes are selected in both the Serving cell and the Interfering Signal panes as depicted in Figure 33.

Figure 33 Array Settings Window - Serving and Interfering Cells tab

Next click on the button on the 2D Map View Toolbar, and after selecting the Non Sim option the Create Coverage/Interference window appears (as in Figure 34):

Figure 34 Create Coverage/Interference window

Select an appropriate Filter (e.g. All Filter) and select the Best Server check-box. Clicking on the OK button will start the array creation process.

Within the Show Data Types list under the Coverage category select the Best Server option to display the Best Server array in the 2D Map View window (Figure 35):


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Figure 35 Best Server Array as viewed in the 2D View

Create a Traffic Array

From the ENTERPRISE Main Menu select Arrays Traffic Traffic Array Wizard

Figure 36 Traffic Array Wizard

Within the opening screen of the Wizard select the desired view for the Traffic Wizard to use. Click on the Next > button to continue through the wizard.



Within the Second screen of the wizard select the relevant terminal type (as created previously) and click the Next > button. Continue navigating through the wizard clicking on the Finish button on the final screen.

Set Carrier Requirements

This is achieved firstly by combining the information contained in the newly created Traffic Array with the Best Server information to calculate the total traffic captured by the service area of each cell. Secondly, from the traffic per cell information it is now possible to calculate the number of carriers required to provide a specified GoS. The total carrier requirement for each sub-cell will then be assigned to the database.

To ensure our Frequency Plan has the correct number of carriers on each sub-cell select Tools Static Traffic Analysis from the ENTERPRISE Main Menu.

Having selected the All Filter from the combo-box, click on the Capture Traffic button. A report now appears in Microsoft Excel detailing the Traffic captured by each sub-cell. Close the report and click the Traffic button within the Apply on SubCells pane of the Traffic Analysis window.

After specifying a Quality of Service objective (e.g. 2%),Traffic per Customer (e.g. 25 mE) and Traffic Model (e.g. Erlang B) click on the Analyse button. Another report in Microsoft Excel will appear giving details of the carrier requirements.

To store the carrier requirements into the database, click on the Apply Carriers Required on SubCells button.

Define neighbour relations

In a normal operational network, the neighbour list is not created afresh every time a plan is created; instead it is maintained and updated on a daily basis by the radio planning engineers.

In ASSET/3g, a Neighbour list can be created manually or by using the wizard. This list will be stored in the Site database and ILSA will automatically use this neighbour list for planning.


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Figure 37 Neighbour Analysis Window

Define exceptions

Exceptions are used by ILSA to avoid particular reuses. They can be ignored for the moment.

Create an interference table.

To start the Interference Table Wizard select Tools Interference Tables Interference Table Wizard from the ENTERPRISE Main Menu. The opening screen of the interference table wizard will then appear (Figure 38):

Figure 38 Interference Table Wizard opening screen



As with all the wizards the first screen allows the user to select a view to determine the area for the wizard to use. Having done this click on the Next > button to continue.

Screen two of the wizard presents the user with a number of choices relating to site selection, method of calculation, the optional use of traffic data and a choice of how to calculate the Interference Probability.

Figure 39 Interference Table Wizard second screen

When you have set up these options click the Next> button to move on to the final page of the Wizard.

The Final screen of the Wizard gives the user the option to save the results to File. Click on the Finish button to start the Wizard.

The results of the Interference Table Wizard can then be viewed by selecting Tools Interference Tables View Interference Table(Figure 40):

Figure 40 Interference Table Results


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2.2.2 Set-up ILSA

ILSA can be started from the ENTERPRISE Main Menu by selecting Tools Frequency Planning Frequency Planning (ILSA) The following Initialise ILSA Automatic Frequency Planner window will then appear (Figure 41):

Figure 41 Initialise ILSA Automatic Frequency Planner window

The first step in setting up ILSA is to select the planning data to be used through the various options within this window. Having selected the relevant data (as previously described) it can then be loaded into ILSA by clicking on the Initialise button.

The ILSA Frequency Planning window will then appear enabling you to define the Frequency Plan easily by amending settings and viewing the results.

2.2.2.1 Create the Cost Matrix

The first step in the process is to create a Cost Matrix. This can be done within the Cost Matrix menu of the ILSA Frequency Planning window.

Having chosen to Edit the Cost Matrix the Cost Matrix Editor window appears. The rules within which ILSA operates can now be defined.

The Cost Matrix Editor window is divided into a number of sub-areas (Folders) each having a specific purpose.

2.2.2.2 Carrier Costs Folder

Within the Carrier Costs folder enter any costs relating to the retuning of Fixed or Forbidden carrier allocations, as set in the Site Database.



2.2.2.3 Carrier Layer Costs Folder

If you want any Carrier Layers that you may have Fixed to be retuned, in the Allow Retune column select the check-box and then enter a cost (between 0 and 50000) in the Retune Cost column. In the example below there were no Fixed carriers to be retuned, so the check-boxes within the Allow Retune column were deselected.

Weight the carrier layers by increasing the costs incurred during the frequency planning process on the BCCH Layer by a factor of two. This will result in the BCCH layer allocation having less interference due to the extra costs involved.

Figure 42 Cost Matrix Editor window Carrier Layer Costs Folder

2.2.2.4 Equipment Costs Folder

Costs incurred for breaking the minimum separations or preferred separations for the equipment are set within this folder.

Figure 43 Cost Matrix Editor window Equipment Costs Folder


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In the above example the Minimum Carrier Separation between Cells has been set to three, with a Preferred Separation of four. Appropriate costs have been allocated should this constraint be broken.

Between Sites a Minimum Carrier Separation of two has been set, with a Preferred Separation of three. Again appropriate costs have been allocated should this constraint be broken.

2.2.2.5 Neighbour Costs Folder

The costs incurred if the minimum or preferred separations for Neighbours are not met are set within the Neighbour Costs folder.

Having selected the Neighbour, Cell Layer and Carrier Layer you want to plan, enter the minimum separation and the minimum cost that would be incurred if the minimum separation is not met.

Figure 44 Cost Matrix Editor window Neighbour Costs Folder

In the example given, a Minimum Carrier Separation between Neighbours has been set to one, with an appropriate cost if this constraint is broken. A Preferred Carrier Separation of two has been chosen with an associated Preference Cost should the constraint be broken.

Between 2nd Order Neighbours no Minimum Carrier Separation has been defined (set to zero), however a Preferred Carrier Separation of one has been selected with an associated cost if the constraint is broken.

2.2.2.6 Exception Costs Folder

The cost of breaking various separation constraints (indicating how bad the effect of breaking a constraint is) is set within this folder. Although default values are entered you can set new ones to a value between 0 and 99999999999.



As this is a new Frequency Plan no Exceptions have been set within the Site Database and as a result the Exception Costs Folder contains no entries (Figure 45).

Figure 45 Cost Matrix Editor window Exception Costs Folder

2.2.2.7 Filter Priorities Folder

The priority order for sites you want to plan can be changed within this folder.

Figure 46 Cost Matrix Editor window Filter Priorities Folder

In this example only the All Filter is being used.

2.2.2.8 Handover Count and Intermodulation Costs Folder

Handover counts can be imported from OPTIMA, or created manually, to show the number of times a handover occurs between two carriers.


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However, in this example we will not use Handover Counts to aid the Frequency Planning Process so the Use Handover Count check-box is deselected.

Figure 47 Cost Matrix Editor window Handover Count and Intermodulation Costs Folder

Within ASSET/3g we have chosen not to consider Intermodulation Interference and as a result the Intermodulation Interference Costs within this folder are left as default values.

2.2.2.9 Separation Costs Folder

The costs of making close allocations to two separate Carrier Layers within a SubCell or between Sub-Cells is entered within the Separation Costs folder:

Figure 48 Cost Matrix Editor window Separation Costs Folder



In the example given (Figure 48), the default Separation Costs have been set to:

Separation Value

0 1000

1 100

2 10

This will place more importance on the cost of Cell and Site co-channel separation to ensure it is greater than the cost of Cell and Site adjacent channel separation.

2.2.3 ILSA Plan List window

When you have created a cost matrix, you can define the Filter/Cell Layer/Carrier Layer combinations that are to be considered by the plan within the Plan List window:

Figure 49 Plan List window

In the above example (Figure 49) the Plan option has been selected which allows for the carriers to be planned for all the sites within the All Filter according to the criteria set in the Cost Matrix. The carrier allocations will be considered by the other carrier allocations during the frequency planning process as interferers.

2.2.4 ILSA Options window

Within the ILSA Options window the calculation and display of Frequency Planning data is controlled.


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2.2.4.1 General Tab

Within the General tab:

Set the Graph X Axis options as either Iteration or Increment

Set the Refresh Rate to determine how quickly the Plan Status pane will update when planning

Have the current cost of Plan written to the message log every minute (this is done by selecting the Log Results in Message Log check box)

Automatically save the assignments to File (this is done by selecting the Auto-Save Assignments check box, and entering a time for how often the Plan is updated, together with a Path name for where the assignment is to be saved).

Planning Features Tab

In the example below, we have chosen, under the Planning Features tab, to:

9 Minimise Interference by:

Combination 80% traffic vs area.

This means that the interference cost will comprise of both traffic and area values but the mE value (of traffic affected by interference) will be multiplied by 0.8, and the km value (of area affected by interference) will be multiplied by 0.2 before being added to any separation the separation cost.



Finally select the Create New Plan option within the Plan pane of the ILSA Frequency Planner window:

Figure 50 ILSA Frequency Planner window Create New Plan

Having set up ILSA in the way you require, the next step is to run ILSA.

2.2.5 Run ILSA

The algorithm can be initiated by clicking on the Start button, within the Plan pane of the ILSA Frequency Planner window. At first ILSA will begin Initialising by making first-pass frequency allocations to all sub-cells. ILSA will then attempt to meet all the rules that have been defined within the cost matrix, and simultaneously try to reduce the average level of interference per carrier.

When the Show check-box is selected, within the Interference pane, the average interference per carrier and worst case interference per carrier fields will be updated by ILSA.

To show the graph whilst ILSA is running, select the Graph option within the View menu of the ILSA Frequency Planning window.

The graph will show the cost of the best plan as a red line, the average interference value (mE) as a green line and the worst interference value (mE) as a blue line.

Figure 51 ILSA Cost/Interference Graph


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Once the Planning process has been halted the ILSA Graph can be printed or saved to file.

2.2.6 Stopping ILSA

At any time ILSA can be paused to analyse the current plan by clicking on the Stop button and then restarted by clicking on the Continue button. ILSA will run until the cost of the plan has reached zero (0) or when the user clicks on the Stop button.

2.2.7 Analysing ILSAs Results

Having stopped the Planning Process you can now view the allocations that have been made in the current best plan.

2.2.7.1 Viewing the Carrier Assignment

From the View menu of the ILSA Frequency Planner window, select Assignments.

Figure 52 Carrier Assignments window

Within the Carrier Statistics pane we can view the number of times each frequency has been allocated together with the minimum reuse distance between each site using that frequency allocation.

In the Carrier Statistics pane we can view the interference values (Cost) for each allocation made.



The plan, if acceptable, can then be saved to the database where further analysis can be carried out to identify any improvements which can be made.

2.2.8 Analysing the Carrier Assignment

2.2.8.1 Site Database

Once saved to the database the carrier assignment can be further analysed in the Site Database. The carrier assignment being located within the Carriers tab on the Cell Layer Level of the respective Site.

Figure 53 Carrier Assignment as viewed in the Site Database

2.2.8.2 Frequency Plan Reporter

The Frequency Reporter can also be used to quickly identify where ILSA may have broken any of the constraints set.


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The Frequency Plan Reporter is launched through the ENTERPRISE Main Menu by selecting Tools Frequency Planning Frequency Plan Reporter

Figure 54 Frequency Plan Report Generator

Having chosen the appropriate Filter, together with the separation thresholds you want to query against, select the Report categories to be included in the report. Click on the Generate button to produce a text file identifying the constraints broken with appropriate details (see Figure 55).

Figure 55 Generated Frequency Plan Report



2.2.8.3 Interference Arrays

Once a Frequency plan has been created and saved to the database it is then possible to view the resulting interference graphically in the 2D Map View window. The Interference arrays are chosen through the same Array Creation window used for creating the Best Server arrays.

Prior to using the Array Creation window, it is necessary to set up some initial parameters, such as interference options and cell/carrier layers to examine. This is done through the Array Settings window, which can be accessed through the ENTERPRISE Main Menu by selecting Arrays Array Settings

Under the Interference tab (Figure 56) we need to specify to the tool whether we want to display co-channel, adjacent-channel or the sum of the two. To do this, select the appropriate option within the Channel selection pane of the Interference tab.

Figure 56 Array Settings window Interference tab


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Within the Interference options pane the following items are available for selection:

Use Frequency Hopping:

This option takes into account the partial use (loading) of carriers during frequency hopping, automatically assigning an appropriate weighting with respect to the number of carriers in use.

Use Frequency Diversity:

Having selected Use Frequency Hopping, in addition, you can select to consider Frequency Diversity within the creation of an array. This will take into account that during Hopping different frequencies suffer from different fading losses, and so a frequency diversity gain is obtained. The gain is dependent on the number of hopping frequencies used, the values of which are taken from the FH Diversity Gain table.

Use DTX: This option instructs the software to scale down the power of the transmitter based on the voice activity factor of the terminal. Using DTX helps to reduce interference between different cells and increases the capacity of the system.

Use Traffic: This option uses any traffic per subcell information when creating arrays. The traffic is converted to a number of channels using the selected Erlang formula. The channels for a cell together with the number of channels being used are taken and the proportion in use at any time is worked out. The interference is then reduced by that amount.

Use Antenna Hopping: This option will take into account the diversity gain achieved when multiple antennas are exposed to different multipath fading. Antenna Hopping is a transmit diversity scheme in which consecutive bursts of information are transmitted on different antennas. The gain is calculated using the FH Diversity Gain table by substituting the number of antenna slots used for carriers.

Note: If both Use Frequency Diversity Gain and Use Antenna Hopping are selected the amount of FH Carriers is multiplied by the number of Antenna Slots, the result is then applied to the carriers column of the FH Diversity Gain table in order to calculate the gain.



Finally, before creating the array ensure that the correct Cell and Carrier Layers have been selected/included to enable the interference analysis to be performed. This is done in the Interfering signal pane of the Serving and Interfering Cells tab, as shown in Figure 57.

Figure 57 Array Settings window Serving and Interfering Cells tab

Note: The Interfering signal pane can also be used to just look at certain cells or cell layers individually by selecting them from the list.

In the 2D Map View window, select the Create Arrays button ( ) from the ENTERPRISE Main Toolbar and having chosen the Non Sim option the Create Coverage/Interference window will then appear:

There are two options for interference analysis within the window, and these are described below:

Worst Interferer: This array is for Non-hopping networks and calculates the interference between the serving carrier at that location (pixel) and the strongest interfering carrier.


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Total Interference:

This array is also for Non-hopping networks and calculates the interference between the serving carrier at that location (pixel) and the summed interference from all cells using the interfering carrier.

Having selected the appropriate interference array click on the OK button to perform the calculation.

The created array can be displayed in the normal way by going to the Show Data Types list in the 2D Map View window and selecting the appropriate array within the Coverage category.

In the above example, a Worst Interferer array has been calculated.

By double-clicking, with the left mouse button, on the appropriate array category, the user can change the display properties of the array (Figure 58):

Figure 58 Worst Interferer Display Properties window

Note: The Category values (coverage colours, labels and levels) can be changed using the Modify button.



2.2.8.4 Interference Statistics

As with other arrays you can use the Coverage Statistics tool to compute area-based statistics on the interference in your network. This can be accessed through the ENTERPRISE Main Menu by selecting Arrays Coverage/Interference Coverage Statistics or by clicking on the Coverage Statistics button ( ) from the 2D Map View Toolbar.

Having chosen the Non Sim option, within the Coverage/Interference Statistics window (Figure 59) select the type of interference array you have created and the level you want to analyse to:

Figure 59 Coverage/Interference Statistics window

Note: You can also restrict the Statistics to an area within a Polygon by choosing the appropriate option in the Coverage area pane.

Click on the OK button to get a text report (in Microsoft Excel) giving you statistics on the interference performance, as shown in Figure 60:

Figure 60 Worst Interferer Interference Statistics Report


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2.2.8.5 GSM Cell Info Report

This report can be accessed through the ENTERPRISE Main Menu by selecting Reports GSM Cell Info Report

Figure 61 Cell Info window

There are two facilities provided by the reporter:

a) Searching for cells with Co-channels or Adjacent channels to the target cell.

b) Searching for cells with specific carriers assigned.

Search by Cell Identity

Searching by Cell Identity makes it possible to enter a cell name in the Cell Identity pane and indicate whether to search for other cells with co-channel allocation or adjacent channels. Matching cells will be displayed in the lower pane of the window together with any cell parameters selected under the Cell Parameter tab.



The number of sites considered in the search may be limited through the use of Filters. These are selected through the Filters tab using the drop-down menu.

Figure 62 Cell Info window Filter tab

Search by Carrier

With the second option it is possible to find all cells using specified carriers. A wildcard (*) can be used to display all the carriers on the filter of cells selected:


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The resulting information can then be viewed or stored to a text file for future reference by clicking on the Export button.

2.2.8.6 Frequency Re-use Display

Within the Cell Info category of the Show Data Types list there is an item called Freq Re-Use. This option allows the user to display cell service areas coloured according to the carriers in use on that cell:

By double-clicking on the Freq Re-Use option its respective display properties window will appear (Figure 63).



Within this window you define the carri

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