atoll

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IntroductionIntroduction

Why should simulation be performed in CDMA radio network planning?

Simulation is one of important steps for CDMA radio network planning, it can

Simulate network running effect to guide engineering construction

Serve as an important means to assist decision-making

Since CDMA system is of self-interference, it is very difficult to calculate its complicated forward links due to multiple factors, such as user distribution. In this sense, if conditions permit, perform simulation unless the network configuration is extremely simple.

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Simulation Is One of Important Steps for CDMA Radio Network Planning

Simulation Is One of Important Steps for CDMA Radio Network Planning

Simulation is oriented to simulate the running situation of networks under the

current network configuration so as to facilitate decision-making adjustment.

Adopt the planning software to perform simulation based on various types of

BTS coverage area, the number of BTSs within the coverage area, and the

configuration of each BTS. All these are obtained from traffic coverage

analysis. AtollAtollAtoll网络规划软件网络规划软件网络规划软件

After the traffic coverage analysis, acquire the BTS coverage range based on the link budget and calculate the BTS number in the coverage area, and then obtain the BTS configuration based on the traffic distribution.

Select some devices, and perform simulation using the network planning software, targeting at ensuring the coverage and capacity in the area and avoiding the interference.

The simulation result can be used to confirm ideal site to perform the next step of network planning---survey, based on the ideal site. If the ideal site is unviable during the survey, adjust the site correspondingly. If the adjustment range exceeds the one-quarter cell radius, re-perform the simulation, which is a repeated process.

After the simulation through the network planning software, implement the network design (such as coverage predication, traffic distribution, adjacent cell allocation, frequency planning, interference analysis, and micro-wave transmission), and simulate the network running effect to instruct the engineering construction through the setting and analysis of system hardware parameter, network capacity, and PN code allocation scheme before the network construction.

The simulation result can be used to check whether current network configuration meets the coverage and capacity requirements of network design, and whether the BTS distribution and height, azimuth, and tilt angle are appropriate.

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Introduction to Atoll SoftwareIntroduction to Atoll Software

Be a professional radio network design tool, supporting

GSM/TDMA, GPRS-EDGE, cdmaOne,W-CDMA/UMTS and CDMA

2000/1x RTT/EVDO. It is specially designed for 3G.

Realize mobility of planning design, supporting both single system

configuration and Enterprise server-based network configuration.

The single system configuration does not require connecting

external database and users still can share engineering data.

Feature modern software structure as well as open and extendable

platform

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Simulation step by step -UNet(Atoll)Simulation step by step -UNet(Atoll)

Coverage by transmitter

Traffic model

Simulation

Coverage prediction

Are Parameters ready? (site, transmitter, cell…)

Parameters modification? (site, transmitter, cell…)

Result OK?Result OK?

NNOverOver YY

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Table of ContentsTable of Contents

Chapter 1 Importing a Digital MapChapter 1 Importing a Digital Map

Chapter 2 Data Importing

Chapter 3 Atoll Propagation Model

Chapter 4 Analog Prediction

Chapter 5 Traffic Model

Chapter 6 Monte carlo Simulation

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Composition of a Digital MapComposition of a Digital Map

A digital map basically consists of the following three components,

stored under three directories respectively.

\Heights

Digital elevation model (DEM): describe basic landforms of this area and

directly participate in radio propagation model calculation

\Clutter

Digital clutter model (DOM): clutter classification data describes clutter

coverage on the ground, such as forest, lake, open area, industrial area,

urban area, high-storey building area. It is used during calculating radio

propagation path loss.

\Vector

Linear vector model (LDM): linear clutter vector data describes plane

distribution and space relationship of linear clutters, including speedway,

street and river.

The following is an example of Projection file.The following is an example of Projection file.

The contents of HeightsThe contents of Heights\\projection.txt are shown below:projection.txt are shown below:

Krasovsky Krasovsky -- 19401940

5050

Gauss Gauss -- KrugerKruger

0.0 117.0 500000 0.00.0 117.0 500000 0.0

Four parameters are: Four parameters are:

Elliptical modelElliptical model------regard the earth as an elliptical modelregard the earth as an elliptical model

Projection band IDProjection band ID------the ID of one of sixty projection band globally of the the ID of one of sixty projection band globally of the EE--mapmap

Projection modeProjection mode------main mode includes UTM, and TM (Gaussmain mode includes UTM, and TM (Gauss--Kruger)Kruger)

Latitude and longitude coordinate of projection band center and Latitude and longitude coordinate of projection band center and coordinate coordinate in the grid coordinate systemin the grid coordinate system

The following is an example of index file.The following is an example of index file.

The contents of HeightsThe contents of Heights\\index.txt are shown below:index.txt are shown below:

demo.bin 480000.000000 495000.000000 4234000.000000 demo.bin 480000.000000 495000.000000 4234000.000000 4249000.000000 20.0000004249000.000000 20.000000

The parameters are:The parameters are:

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Selecting coordinate system

Selecting coordinate system

• Primary coordinate system: It is a coordinate system of

geographical database

• Display coordinate system: it is a coordinate system for

display and data-input. All the geographical coordinates are

displayed and input according to this system. If the

projection coordinate system and the display coordinate

system do not match with each other, U-Net will adjust them.

U-Net works with the following two coordinate systems at the same time:

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9

Antenna Data and Lobe PatternAntenna Data and Lobe Pattern

Input antenna type, manufacturer

and antenna gain in [General].

Import the corresponding

attenuation table at each angle of

the antenna in [Horizontal pattern ]

and [Vertical pattern].

Input Beamwidth, FMax, FMin or

other user-defined parameters in

[Other properties ].

Right click “Antennas－>Properties”

in the “Browse-Data” window to

open antenna attributes box.

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Data ImportingData Importing

Sites information: refer to BTS equipment type and channel element data Include the following parameters: BTS name, longitude and latitude, height above sea level, and whether to lock BTS location.

Transmitter TMA, feeder and BTS equipment:

Include the following parameters: Active，transmitted and received total loss (including actual loss and calculated loss), total noise coefficient (including actual one and calculated one), BTS equipment selection, antenna model, mounted height, direction angle, and downtilt.

CELL information:

Include the following parameters: carrier wave of each cell in this sector, active set threshold value, maximum transmit power, pilot channel power, synchronization channel power, other common channel power, total transmit power, UL load, and neighbor cell.

Microsoft Excel 工作表

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Introduction to Propagation ModelsIntroduction to Propagation Models

Okumura-Hata model

Cost231-Hata model

Typical models are from repeated CW tests.

Lp =69.55+26.16logloglogf−13.82loglogloghb+(44.9−6.55loglogloghb)logloglogd−SR−Ahm

Lp =46.3+33.9logloglogf−13.82loglogloghb+(44.9−6.55loglogloghb)logloglogd−SR−Ahm+Cm

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Coverage PredictionCoverage Prediction

There are ten analog predictions in all, but only the first three can be performed at the current stage because simulation results are unavailable.

A “Coverage bytransmitter” analog prediction is the precondition for simulation.

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Setting the following parameters:

Signal level threshold value: defaulted as -110dBm and the

maximum value has no upper limit.

All and Best signal level: usually select Best signal level so as to be

convenient to observe the coverage of the best cell.

Signal level margin of the best cell: defaulted as 0

Reliability: 50% is usually set.

Carrier wave: it is usually set to “All carrier waves” for coverage area

computation.

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Drawing a computation area

Select “Draw” from “Computation zone” in the “Tools” menu in the Atoll

software. And then draw a polygon with the mouse on the zone to be

researched. The computation zone is within the red line.

Shadowing margins

Compute shadowing margins in each type of landform by inputting

the standard variance of each clutter and improving Reliability Level.

Reliability level is 50% Calculate or Calculate all by default.

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Traffic ModelingTraffic Modeling

Traffic data involved in traffic modeling includes service

type, terminals, mobility type, user profile, environment

and traffic map.

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Service TypeService Type

Service type

Speech service 1X RTT data service 1X EVDO data service

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TerminalsTerminals

Terminals

RC1 RC2 RC3 RC4 RC5 EVDO_HAT

RC1 and RC2 are used for speech service.

RC3, RC4 and RC5 are used for 1X RTT data service.

EVDO_HAT is used for EVDO data service.

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Mobility TypeMobility Type

Mobility Type

50km/h 90km/h Pedestrian

Different mobility types have different settings.

Tadd, T_Drop, Min Ec/Nt, Max rate=f(C/I)

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User ProfileUser Profile

Urban User

Rural User

Communication profile in different areas differs.

Services：voice Or Data

Terminal：RC1、、RC5？

Calls/hour：

Duration：

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EnvironmentEnvironment

Environment

Business center City Rural

The following differ in different types of traffic environment:

User

Mobility

Density

Clutter Weighting

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Creating a Traffic MapCreating a Traffic Map

Based on Environments (raster): refer to the raster map based on traffic model

Based on User profiles (vector): refer to the vector map based on user profile

Based on Transmitters and Services (throughput): refer to throughput map based on

sector and service type

Based on Transmitters and Services (#users): refer to users map based on sector and

service type

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Monte Carlo SimulationMonte Carlo Simulation

The process of Monte-Carlo simulation is as follows:

Perform Monte-Carlo simulation based on traffic map. Atoll randomly

distribute user location and user profile on the traffic map based on the

number of users and density.

Perform uplink/downlink power simulation based on results from step 1.

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Static SimulationStatic Simulation

1. Generate a certain quantity of network instantaneous state—“Snapshot”

Here, some MSs or terminals are distributed based on a certain rule (such as random even distribution) at each “Snapshot”.

2. Acquire connection capability between terminals and networks by incremental operation.

Here, it is required to consider the possibility of multiple connection failure (uplink/downlink traffic channel maximum transmit power,unavailable channels, low Ec/Io and uplink/downlink interference).

3. Measure and analyze results of multiple “Snapshots” to have a overall understanding of network performance.

Monte Carlo simulation is one type of static simulation.

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100%100% 100%100%20%20% 60%60%

0%0% 75%75% 40%40%60%60%

100%100% 100%100%20%20% 60%60%

0%0% 75%75% 40%40%60%60%

Monte Carlo Simulation－Coverage ProbabilityMonte Carlo Simulation－Coverage Probability

The following takes coverage probability for an example to further

understand how Monte Carlo simulation is performed.

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Monte Carlo SimulationMonte Carlo Simulation

The overlay measurement results of multiple Snapshots

should be consistent with traffic model.

500mErl

300mErl

1200mErl

1000mErl

50％

30％

120％

100％

X

X

X

X

XX

X

X

XX

X

X

XX

X

X

X

X

XX

X

X

X

XXX

X

X1

1

1

4

44

43

3

3

2

2 5

5

5

X

X

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Static simulation has its own disadvantages, including

Lack of time continuity. In this case, low-end users

cannot be accessed when there are a great number of

users.

Failure to simulate 1X dynamic threshold. The reason

is that the 1X system introduced soft handoff dynamic

threshold but static simulation lacks time continuity. In

this sense, static simulation is more seriously restricted

in the 1X system than in the 95 system.

Disadvantages of Static Simulation

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Initialisation

2nd step : Mi active set determination

3rd step : Uplink power control

1st step : Mi best server determination

For each mobile Mi

4th step : Downlink power control

5th step : Uplink and downlink interference update

Congestion and radio resource control

Convergence study

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Atoll completes calculation on each user within the network by the following five steps:

Step 1: Determine the best cell. The possible reasons for cells failing to become the best cells

may be: deficient pilot strength and UL load exceeding the rated value

Step 2: Determine cells entering the Active set of the terminal. The possible reasons for cells

failing to enter the Active set may be: Ec/Io value is lower than Tdrop in Mobility type.

Step 3: Control uplink power (namely the power of the terminal). In this step, the following

case may occur: The terminal is refused due to its deficient transmit power.

Step 4: Control downlink power (namely traffic channel power). In this step, the following case

may occur: The MS fails to access this cell due to deficient downlink traffic channel power.

Step 5: Update uplink/downlink interference in each cell.

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UL load control

— CE control

— Walsh code control

— Cell total power control

Check congestion and radio resource control after a repetition.

Check whether uplinks and downlinks are converged. If they are, terminate this simulation. If not, calculate one by one all terminals in the network again.

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Convergence 下的为收敛的条件：Convergence 下的为收敛的条件：

Max num of interations：the maximum repeated calculations. That is to say, the

simulation is over although the result of the last repetition is not converged. A repetition is

the process of calculating all users during the simualtion. One simulation can contain

multiple repetitions.

UL convergence threshold：uplink convergenece threshold. When the difference

between the result of the current repetition and that of the previous repetition reaches this

threshold, the simulation is over even though repetitions do not reach the maximum

times.

DL convergence threshold：downlink convergence threshold. When the difference

between the result of the current repetition and that of the previous repetition reaches this

threshold, the simulation is over even though repetitions do not reach the maximum

times.

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Simulation ReportSimulation Report

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Analysis Report on Simulation ResultsAnalysis Report on Simulation Results

Statistics In the Request is total users accessed into the network, uplink/downlink total

volume required by the network, and details classification of each type of

service.

In the Result is refused users and relevant causes, users successfully

accessed, actual volume of the network, and details classification of each

type of service.

Sites Include BTS rated maximum channel elements, FCH and SCH channel

elements actually used for uplinks and downlinks, channel elements of

uplink/downlink overhead channels for soft handoff, speech/data volume of

uplink/downlink FCH and SCH channels.

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Analysis Report on Simulation ResultsAnalysis Report on Simulation Results

The following initial conditions must be satisfied:

Setting global parameters of the transmitter

Setting original parameters of this simulation

Setting parameters related to landform, such as the orthogonal factor and standard variance of each type of landform

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