aircom-umts network dimensioning

Commercial-in-Confidence

UMTS Network DimensioningUMTS Network Dimensioning

UMTS network dimensioning


ContentsContents• Network Dimensioning?• Spreadsheet dimensioning.• Benchmark planning• Graphical dimensioning.



Network Dimensioning (1)Network Dimensioning (1)• Network dimensioning is carried out at the start a project.• It is a process through which an initial estimate of the

amount of network equipment and possible configurations are determined.

• The inputs to the process can be:! Spectrum availability.! License conditions.! Equipment characteristics.! Link budget.! Geographic/Demographic data.! Market projections



Network Dimensioning (2)Network Dimensioning (2)• The outputs of network dimensioning are used for:

! Budgetary purposes." Negotiations with vendors." Manpower resource estimations." Business plans." Network rollout plans." Negotiations with financial backers.

! License applications." Auction price." Spectrum requirement / license preference.

! Implementation." Rollout Timetable and Resource Requirements" Coverage strategy.



The Network Dimensioning ProcessThe Network Dimensioning Process

CoverageRequirements

CapacityRequirements

QualityRequirements

Dimensioning

Rough estimateof Number

of Base Stations

Rough estimateof Configurationof Base Stations

Area Type&

Radio Propagation Data



Network Dimensioning MethodsNetwork Dimensioning Methods• There are two main methods of dimensioning a network.

! Spreadsheet based. ! Benchmark planning - Dart throwing!

• Many companies use a sophisticated spreadsheet approach to model the combination of network coverage and capacity.

• Alternatively it is possible to dimension the network by benchmark, or first-pass, planning

• AIRCOM are currently developing an GIS based dimensioning tool to combine the advantages of these two methods

• This section looks at all three approaches.



Spreadsheet DimensioningSpreadsheet Dimensioning• We shall look at 4 scenarios

! A simple coverage driven spreadsheet! A simple capacity driven spreadsheet ! A simple combined approach! A complex coverage vs capacity tradeoff planning tool



• Link budgets are used to calculate max path losses.• Path loss is converted into cell radii for different environments.• Cell radii are used to estimate typical site coverage areas.• Estimate the average site coverage area for each environment.• No. sites (per environment) = Environment Area

• Add together the number of sites per environment required for each zone.

• Assumptions on cell loading and services offered are made in the link budget process.

Spreadsheet Dimensioning Spreadsheet Dimensioning -- Simple Simple Coverage Coverage

Average Site Coverage Area___________________



Spreadsheet Dimensioning Spreadsheet Dimensioning -- Simple Simple Coverage (2)Coverage (2)

Site ParametersType 1 Type 2 Type 3

Frequency 2000 2000 2000 MHzTransmitter Height 25 15 30 mReceiver Height 1.5 1.5 1.5 mSite Location urban suburban ruralNo. BT's 3 3 1

MAPL 155 155 155 dBReliability in coverage area 95 95 95 %Log Normal SD (Terrain) 5 5 5 dBLog Normal fade margin (Terrain) 18 25 8 dBMAPL w / Log Norm. fade margin 137 130 147 dB

Typical Cell Radii for 150MHz < f < 1500MHzurban 1.03 0.55 2.13 kmurban large 1.03 0.55 2.12 kmsuburban 2.26 1.18 4.73 kmrural 4.38 2.22 9.25 kmopen 8.34 4.12 17.78 km

Typical Cell AreasUrban 3.33 0.96 14.23 km2Urban large 3.31 0.95 14.14 km2Suburban 16.11 4.35 70.38 km2Rural 60.31 15.45 268.64 km2Open 218.73 53.30 993.02 km2

Geographic DataCoverage Area 151207 km2Urban Area 5000 km2Urban Large Area km2Suburban Area 20632 km2Rural Area 111156 km2Open Area km2

Site DataNo. of sites 1500 4747 414No. of BT's 4499 14240 414

Total Sites 6660Total BT 19153



Spreadsheet Dimensioning Spreadsheet Dimensioning -- Simple Simple CapacityCapacity

• Given an estimate of the traffic profile per subscriber we can calculate the offered traffic per km2 per environment

• Given the capacity of a cell we can estimate the average site capacity area per environment

! Note we may wish to take factors such the uneven distribution of traffic between sectors into account

• No. sites (per environment) = Environment Area

• Add together the number of sites required per environment for each zone.

Average Site Capacity Area___________________



Spreadsheet analysis Spreadsheet analysis -- Simple Simple Combined Coverage/Capacity ApproachCombined Coverage/Capacity Approach• Given the simple analysis that we have carried out above

for coverage and capacity we could:! Compare the number of sites required per zone derived from the

capacity approach and the coverage approach! This tells us if the zone is:

" Coverage Constrained" Capacity Constrained

! The output of the dimensioning would be the largest number of sites per zone



• The above approach is ‘acceptable’ for GSM• Unfortunately the coverage and capacity relationship in UMTS is

much closer• Typically spreadsheet dimensioning tools for UMTS take a combined

iterative approach:! The range of a cell is calculated from a link budget containing an

interference margin calculated from the loading! The area covered by the cell is then calculated from the range! The traffic captured by a cell is then calculated from the area and

subscriber density! The loading of the cell is then calculated from the captured traffic! And then the link budget is recalculated from the new loading

• The loop is repeated until convergence is reached

Dimensioning for UMTSDimensioning for UMTSUMTS network dimensioning


Dimensioning Tools for UMTSDimensioning Tools for UMTS• However it isn’t really that ‘easy’, problems can occur with:

! Microcells! Road coverage and Urban coverage overlapping! Transmission dimensioning

• The spreadsheets tend to get a little bit complicated...• A number of commercially available tools are available on

the market to dimension UMTS networks



Dimensioning by planningDimensioning by planning• However the drawback with the ‘spreadsheet’ approach is that it does

not give the user a very good visualisation of what the results mean• An alternative approach is to create a ‘first pass’ or ‘benchmark’ plan• The planning for this would be similar to nominal planning as we will

discuss later! Create a link budget and propagation model! Place sites and predict! Check for broken loading assumptions

• Not so much effort should go into the plan as nominal planning as it is expected to be rough - not the foundation for the network



Graphical Dimensioning ToolsGraphical Dimensioning Tools• Aircom’s 3G contains a graphical dimensioning tool • This allows you to quickly estimate and visualise the number of sites

required in a new network.• Currently on the first release - more features will be added.



Create Terminal TypeCreate Terminal Type• Create a 3g terminal type.• Allocate 1000 terminals• Spread terminals according to

the weights listed here.

Clutter Type WeightUnclassified 0

Urban 500Suburban Residential 20

Village 10Isolated Dwellings 1

Open Rural 1Woodland Forest 2Park Recreational 5

Industry 10Water 0Airport 5

Open in urban 30Agricultural land 1

Pylons 1Sea 0

Rivers 0



Spread TerminalsSpread Terminals• Use the traffic wizard to spread

the terminals over the island.• The resultant raster shows the

the terminal density.



Define Default SitesDefine Default Sites• Click on the button.

• Enter! Cell Radius = 4000m! Overloaded threshold = 800kb/s! Underloaded threshold = 300kb/s



Position First SitesPosition First Sites• Select “3G Dimensioning Sites”

in the 2D window display list.• Click on the button.

• Drag a box around the island with the left hand mouse button.

• Click in the box with the right hand mouse and select:

! “Fill Rectangle with Correctly Loaded Dimensional Sites…”

• The box will be filled with a grid of sites of the defined radius.



Split Overloaded CellsSplit Overloaded Cells• The “Calculation Parameter”

window will appear.• Select the desired terminal type.• Enter the mean data rate per

terminal.• Confirm other settings.• “Customize” button is disabled

in this version.• Click “Calculate”.• Overloaded cells will be

sectorised and then split until convergence is reached.



Result Result -- Dimensioned NetworkDimensioned NetworkUMTS network dimensioning

aircom-umts network dimensioning

Documents

network equipment

graphical dimensioning

dimensioning tool

network rollout plans

typical site coverage

environment area

simple combined approach

link budget process