3GPlanningMethods

3G Planning Methods

3G Planning Methods

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3G Planning Methods

Contents • • • • • •

Planning Methodologies Static Calculation Static Simulation Dynamic Simulation Comparison Planning Processes

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3G Planning Methods

Introduction • This section includes a comparison of the different methods of analysis that could be carried out to analyse a UMTS network

• It is important the we understand the differences between these methods to understand: !

their merits and demerits

!

likely advantages of tools employing them

• The aim of this section is to understand the alternatives and how/when they might be used

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3G Planning Methods

Planning Methodologies • There are basically two possible types of 3rd Generation planning methods !

Static Calculation " A deterministic algorithm is used to analyse the performance of the

network configured within the planning tool " Repeating an analysis gives the same result !

Simulation " Statistical processes and an iterative system status calculation

used to analyse the performance of the network configured within the planning tool " Repeating an analysis may give different results

• Some tools use a combination of methods or hybrid methods Commercial-in-Confidence

3G Planning Methods

Static Calculation • Static Calculation is a similar approach to that taken in ASSET for GSM planning

• A statistical analysis of the network is used to derive design thresholds

• In UMTS the following mechanisms must be accounted for: !

Soft handover gain (typically ~5dB at the cell edge)

!

Interference Margins (both intra cell and inter cell)

!

Control and signalling overheads

!

Fade Margins (to design to a given coverage probability)

!

Special technique margins(Adaptive antennas, Transmit diversity, Smart Radio…) Commercial-in-Confidence

3G Planning Methods

Simulation • There are two types of simulation that might be used for radio planning

• Static Simulations !

!

Static simulations analyse the performance of a ‘snapshot’ of the network A snapshot is an instance in time, with UEs in statistically determined places

• Dynamic Simulations !

Dynamic simulations simulate UEs moving through the network in successive timeslots

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3G Planning Methods

Static Simulations • One or more snapshots of the network are taken • In each snapshot a mobile or terminal list is generated • The ability of each terminal to make its connection to the network is calculated through an iterative process

• Various failure mechanisms will typically be considered (maximum mobile power, maximum Node B power reached, no available channels, low pilot Ec/Io, uplink/downlink interference)

• The performance of the network is then analysed from the results of the snapshots carried out

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3G Planning Methods

Monte Carlo Simulations • Monte Carlo Simulations are a form of static simulation !

Also a very trendy form…the Gucci of simulators

• They rely upon a large  number of statistically independent snapshots

• The mean performance of the network over these snapshots is then determined

• 3G uses a Monte Carlo Simulation engine

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3G Planning Methods

Monte Carlo Simulation - Coverage Probability 100%

20%

60%

100%

0%

75%

60%

40%

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3G Planning Methods

Monte Carlo Simulation

1 iteration

500 iteration

10 iteration

1000 iteration

100 iteration

10000 iteration

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3G Planning Methods

Dynamic Simulations • Dynamic simulations look at mobiles moving through the network

• A mobile list is generated and solved for the first timeslot • The simulation may consider time to be split into: !

chip periods

!

bit periods

!

timeslots (SNR considered)

• Successive timeslots are then simulated dependant upon the results of the previous timeslot

• New mobiles are simulated coming into the network and terminating their calls Commercial-in-Confidence

3G Planning Methods

Dynamic Simulation I think I’ll make a call

I think I’ll make a call

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3G Planning Methods

Which method is best? • This is a little like saying - which is the best tool: !

A hammer

!

A screwdriver

!

A spanner

• All three methods have different advantages and disadvantages - and may be used for different tasks

• These can be broadly considered in three areas: !

Accuracy

!

Complexity

!

Computational overhead -i.e. time taken to use the tool

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Comparison of methods Static Analysis

Accuracy

Complexity

Time Taken

Static Simulation

Not very – particularly Reasonable – but with global margins doesn’t deal with the (IS-95 experience) dynamic network performance Relatively More difficult to straightforward to use configure and more once configured complicated results. Shortest – as ‘quick’ as for GSM

Dynamic Simulation Probably quite high assuming no bad assumptions are made to speed it up Difficult to judge results.

Moderate –  Extremely long if depending on number multiple runs of terminals and cells performed for statistical validity

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3G Planning Methods

Planning Processes • Due to the difference in performance of the techniques we probably want to use a combination for our planning ‘toolbox’

• Our aims are to achieve: !

Fast Network Rollout

!

Good Network Design

• A number of tasks are highlighted in the following slides

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3G Planning Methods

Nominal Planning • Nominal Planning requires: !

Quick issue of SARFs etc to Site Acquisition

!

Approximate Site Densities and Locations

!

Detailed optimisation of nominal sites is pointless

• Probably best to use: !

Static Analysis for bulk of planning

!

Static Simulation for regional validation

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Final Site Selection and Detailed Design • Final Site Selection requires !

Relatively quick analysis of candidates

!

Confidence in Final Candidate Selection

!

A reasonable amount of work on individual selected sites can be expected

• Probably best to use: !

Static analysis for initial candidate shortlisting

!

Static Simulation over a small area for final candidate selection

!

Static Simulation over a large area for final validation

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3G Planning Methods

Optimisation • Repeated Static and Dynamic simulations may prove useful for detailed optimisation of !

site configurations

!

problem/high sensitivity areas

!

call admission and radio resource management algorithms

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