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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