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CCAP: A Strategic Tool forCCAP: A Strategic Tool for

Managing Capacity of CDMAManaging Capacity of CDMA

NetworksNetworks

Teleware Co. Ltd.

in cooperation with

Washington University, Saint Louis,

Missouri, USA

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What is CCAPWhat is CCAP

Graphical interactive tool for CDMA

Calculates coverage area

Calculates call capacity of a CDMA

network

Calculates subscriber network

performance

Optimizes capacity

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Unique Capabilities of CCAPUnique Capabilities of CCAP

Capacity calculation for non-uniform cells

Capacity calculation for non-uniform

loading

Explicit analysis of intra and inter cell

interference

Soft Handoff analysis

Network performance analysis

Power control analysis

Capacity optimization

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Development of CCAPDevelopment of CCAP

Project began 1995

Algorithm tested in Louisiana trial

Used for PCS auction in Korea in 1996

Algorithm updated in 1996 at Washington

University

Joint tool development by WashingtonUniversity and Teleware

Version 1.0 completed Q1 1998

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Scope of CCAPScope of CCAP

User definable inputs

Elevation information

Antenna attributes (height, gain, )

Path loss characteristics (Hata, COST-231, )

Shadow fading

Rayleigh fading

Imperfect power control

Sectorization

Voice activity detection

Unequal cell sizes

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Scope of CCAP (cont.)Scope of CCAP (cont.)

Calculate capacity taking into account

Hard handoff reception

Soft handoff reception

Different number of users in cells

Network subscriber performance (Erlang

blocking probability)

Engineering and optimization of capacity

by power tuning

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CDMA Capacity IssuesCDMA Capacity Issues

Soft capacity based on code division

multiple access

Cell size

Loading

Forward and reverse power

Adjustable capacity by

Voice activity detection

Sectorization

Power control

Handoff threshold

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CDMA Capacity Issues (cont.)CDMA Capacity Issues (cont.)

Power control: transmitted signal power of

mobiles are received at the base station

with the same value

Open loop: Input from the base station is

measured at the mobile

Closed loop: Power of the mobile user as

received at the base station is measured. The

mobile is told to increase or decrease the

transmitted power and by how much.

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CDMA Capacity Issues (cont.)CDMA Capacity Issues (cont.)

Shadow fading: is modeled by a log

normal distribution

Rayleigh fading: fast-fluctuations around

those resulting from perturbations caused

by shadow fading

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A

B

Cell I

Cell J

CDMA Capacity Issues (cont.)CDMA Capacity Issues (cont.) Power Compensation

Factor (PCF)

User A will cause an

extremely high

interference to user B.

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CDMA Capacity Issues (cont.)CDMA Capacity Issues (cont.)

Power Compensation

Fine tune the nominal power of the users

PCF defined for each cell

Optimal PCFs maximize the capacity of the

entire network

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Base Station DatabaseBase Station Database

Base Station

Base Station Id

Easting and Northing

Number of antennas or sectors

Antenna

Direction and beamwidth

Forward power

Power compensation factor

Demand Estimator

Height and gain

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Define Area of ServiceDefine Area of Service

Parameters needed:

Base Station Database

Eps: Receiver sensitivity [-120 dBm]

Fc: Carrier Frequency [1800 MHz]

Hte: Base Station antenna height [30 m]

Hre: Mobile antenna height [1.5 m]

dx: Horizontal grid size [300 m]

dy: Vertical grid size [300 m]

(all user controlled)

Area is divided into grids

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InterInter--Cell InterferenceCell Interference Parameters needed:

m: Path Loss Exponent [4]

sigma_s: Standard deviationfor the shadow fading [6 dB]

Rayleigh: [0] for off [1] for on

Alpha: Total number of users

in a cell divided by the

minimum number of users in

every cell.

Fij: interference of cell Ion

cell J is obtained.Cell

CellRj

Ri

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Calculation of CapacityCalculation of Capacity

Parameters needed:

W/R: Total bandwidth / User data rate [19.31 dB]

Eb/Io: Bit energy / Interference [7 dB]

rho: Voice activity factor [3/8]

sigma_c: Standard deviation for the imperfect

power control random variable [2.5 dB]

Beta: Power compensation factor [1 1 1 1] Target_Pout: Log10 (Blocking Probability) [-2]

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Calculation of Capacity (cont.)Calculation of Capacity (cont.)

Call capacity is calculated for each cell.

Smallestvalue defines the capacity of the

network.

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Subscriber PerformanceSubscriber Performance

Parameters needed:

erl_user: user load in Erlangs [0.025]

N is the number of trunks or channels [1]

B is the blocking probability [0.01]

Maximum sustainable subscribers per cell

Subscriber network performance

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Optimizing CapacityOptimizing Capacity

Parameters needed:

Initial Power Control Factor

Same inputs as for capacity calculation

The gradient descent algorithm is used.

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Considerations for FadingConsiderations for Fading The inter cell interference - shadow fading

and Rayleigh fading

Power control overcomes both large scale

path loss and shadow fading but not

Rayleigh fading

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Soft HandoffSoft Handoff User is permitted to be in soft handoff to

its two nearest cells.

Better frame received by either base

station is accepted by the network.

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Soft Handoff (cont.)Soft Handoff (cont.) Soft handoff region

for cell 0: six pointed

star

Propagation loss to

neighbor is less than

to the zeroth base

station

Within So, interference

into the zeroth base

station

1

3

4

2

5

6

0

So

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Power Compensation FactorPower Compensation Factor Initial default value is 1 for every cell

Optimize capacity by optimizing the PCF

New PCF is the factor that the nominal

power needs to be increased by for every

cell

Each PCF is used by its Base Station in

the Closed Loop Power Control

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CCAP ReportCCAP Report Interference pattern

Call capacity

Optimal power control factors

Optimal capacity

Subscriber network performance