WCDMA RNP Link Budget.ppt

8/14/2019 WCDMA RNP Link Budget.ppt

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WCDMA RNP Link Budget

3 November 2013

WCDMA RNP Link Budget


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Link Budget in WCDMA

The link budget is used to calculate the maxi

path loss to maintain a link between the transmi

and the receiver on a specific environment. Thucorresponding cell range can be derived from t

loss with a propagation model.


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Contents

Introduction

Parameters of Link Budget

Example of Link Budget


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Introduction

Link Budget

Forward link :

Difficult to assess: depends on the cell edge level of interference on

the location of the mobile

Reverse link:

Easy to assess

Largely used in RND / RNO


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Introduction

Interference

WCDMA is intrinsically Interference limited system

Coverage and capacity depend on the interference experimented bythe receiver


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Introduction

Interference on the Forward link

Primary source of interference: typically power broadcasted by

surrounding cells

Secondary source of Interference: other links in the same cell

serving other UE


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Introduction

Interference on the Reverse link

Primary source of interference: other UE in the same cell

Secondary source of Interference: other UE outside the

cell. These UE are not under the power control of the cell.


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Introduction

Interference reduction during RNP

critical

Need of thorough guidelines in order to:

Reduce co-channel interference

Reduce adjacent frequencies interference

own network

Network of Competitors


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Contents

Introduction




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Link Budget Parameters

Analysis Scenarios

Maximum Transmission Power of DCH

Cable Loss & Body Loss

Antenna Gain

EIRP(Equivalent isotropic Radiation Power)

Noise Figure

Required Eb/No

Sensitivity of receiver


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Link Budget Parameters

Interference margin

Margin of Background Noise

Fast Fading Margin

Minimum Required Signal Strength

Penetration Loss

slow Fading Margin

Soft Handover Gain

Propagation Model


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Analysis Scenarios

Morphology

Generally, there are 5 types of planning area:

Dense Urban

Urban

Suburban Rural Area

Highway

The type of area impacts:

Mean penetration loss

Standard deviation of slow fading

Propagation Model & the factor of path loss


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Analysis Scenarios

Morphology (Cont.)

Various planning strategies are applied according to the type of area.

It is necessary to configure following parameters:

Channel model

Sectorization

Indoor coverage

Target service (seamless coverage)

TMA and Diversity mode

Cell loading

Average antenna height

Cable loss


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Analysis Scenarios

Channel model

The channel model defines the number of signal path, relative path

loss and delay variance to abstract the wireless channel.

According to specifications of 3GPP R4(TR25.943 V4.0.0), typical

channel models are used as following:

Static: no multipath

TU3: typical urban area, pedestrian, 3km/h

TU50: typical urban area, vehicle, 50km/h

TU120: typical urban area, vehicle, 120km/h

RA120: rural area, vehicle, 120km/h

RA250: rural area, vehicle, 250km/h

HT120: high terrain, vehicle, 120km/h


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Analysis Scenarios

Channel model (Cont.)

Values of some parameters vary with the channel in the wireless

environment. The variances are acquired generally by the link

simulation.

Link performance: required EbNo in both channels

Downlink interference margin: due to the variance of orthogonal

factor in different channel environments

Fast fading margin (Power control headroom): due to different link

performance

Soft handover gain over fast fading margin: due to different linkperformance


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Analysis Scenarios

Sectorization

Three types of sectorization are commonly used:

Omni

3-sector

6-sector

The item cause changes:

Antenna gain: the antenna type is different with the sectorization.

Cell loading: the area of cell coverage and thus soft handover

overhead vary with sectorization.


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Analysis Scenarios

Bearer Type

This is the bit rate that the user service requires.

Generally in UMTS the following options are supported:

4.75 kb/s

5.15 kb/s 5.9 kb/s

6.7 kb/s

The requirements of EbNo are different with bearers or services.

7.4 kb/s

7.95 kb/s

10.2 kb/s

12.2 kb/s

(AMR Voice Codec)

64 kb/s LCD&UDD

144 kb/s LCD&UDD

384 kb/s LCD&UDD


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Analysis Scenarios

Diversity mode

The diversity in Node B

Uplink receive diversity

two-antenna

four-antenna Downlink transmit diversity

None

STTD (Space Time Transmit Diversity)

Closedloop-Mode1

Closedloop-mode2

The link performance, required EbNo, is improved by the diversity.


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Analysis Scenarios

Tower Mounted Amplifier (TMA)

TMA will boost signal strength to overcome the effect of noise in

the first amplifier on the receiver.

It can be very useful when the feeder loss is so large.

The noise figure of the receiver will be improved if TMA is used.


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Analysis Scenarios

Indoor coverage

Whether indoor coverage is available depends on the intention of

the operator.

The penetration loss and the standard deviation of slow fading are

subject to the requirement for indoor coverage.


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Maximum Transmission Power of TCH

Uplink TX Power

For a UE, the maximum transmission power of DCH is the same as

its nominal maximum output power.

The UE is assumed to transmit the maximum power in the link

budget. According to 3GPP TS 25.101 V3.7.0, four classes ofoutput power are specified for UE:

Power Class Nominal maximum

output power

Tolerance

1 +33 dBm +1/-3 dB

2 +27 dBm +1/-3 dB

3 +24 dBm +1/-3 dB

4 +21 dBm 2 dB


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Maximum Transmission Power of TCH

Downlink TX Power

The maximum transmission power for a TCH in the downlink is

determined by the RNC and varies with the service.

In the link budget, it can be configured according to the service

type, capacity requirement and concern of link balance.


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Cable Loss

The cable between the cabinet and the antenna or TMA often

introduces loss of signal power.

The cable loss impacts:

Noise Figure of the receiver in the uplink

EIRP in the downlink

For the 7/8 cable, the loss is about to be 6dB per hundred- meterlength in 2G frequency band. Besides, the loss of jumper andconnector should be included.


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Body Loss

Introduces the effect of the human being handling theterminal in the link budget.

And depends on the operational conditions.

Typical values are about 3dB for voice service and 0dB for

data service.


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Antenna Gain

Accounts for the gain at the antennas of the mobile terminaland Base Station

Typical values for the Mobile station are 0dBi .

Base station antennas gains are dependant on

configuration.


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EIRP

Equivalent Isotropic Radiation Power (EIRP) is defined asfollows in Link Budget:

)()()(

)()(

dBnnaGainOfAntedBBodyLossdBCableLoss

dBmowerOfDCHnsmissionPMaximumTradBmEIRP


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Noise Figure

UE

Typical value for UE receiver is 7dB

BS

Define the cable connector of the antenna as the reference point for

NF calculation to accommodate the cases of with and without TMA

In the case of without TMA and 3 dB for cable loss, according tothe following diagram and the formula of NF calculation,

the noise figure can be calculated as follows:

Cable NodeB

NF

Gain

XdB NF at this port:2.72 dB

-XdB

72.5)10

11010lg(10

13.0

272.03.0

Cable

CabinetTopCable

G

NFNFNF


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Noise Figure

BS (Cont.)

In the case of with TMA and 3dB for cable loss,

similarly the noise figure can be calculated as follows:

Cable NodeB

NF

Gain

XdB

-XdB

TMAJumper

before TMA

2.0dB

12dB

0.5dB

-0.5dB

NF at this port is Channel Gainrelated, See Table Below

CableTMAJumper

CabinetTop

TMAJumper

Cable

Jumper

TMAJumper

GGG

NF

GG

NF

G

NFNFNF

1

11

Note: the NFCabinetTop is a variable parameter because of gain adjustment

to compensate gain variance and maintain a constant RF channel gain.


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Required EbNo

Needed by the user service to maintain the link withacceptable quality.

Output from Link-level Simulation according to the following

factors: Channel type

Mobile speed

QoS

Receiver implementation


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Sensitivity of the Receiver

Minimum signal power on the cable connector of antenna needed

by the receiver to demodulate signal with specific BER or BLERtarget.

In the Link Budget, the sensitivity of receiver is determined by

performance of BS or UE itself and required Eb/No.

Diversity, service and channel-related impacts on the sensitivity of

receiver are included in the relevant required Eb/No

)(log)(log

)/(log)(log

10010

10010

bb

bb

RNENFKT

RWNENFKTWS

K: Koltzmann constantT: temperatures in degrees Kelvin

W: receiver bandwidth

NF: Noise Figure of the receiver on the cable connector of antenna

EbNo: required demodulation threshold

Rb: bit rate of service


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Sensitivity of the Receiver

Note that the concept of sensitivity of the receiver is

different from that defined in the specification of 3GPPTS25.104 V3.7.0 in the following aspects:

Reference point: it is the cable connector of the antenna whether a

TMA is available in the link budget; comparatively in the protocol

it is defined as where the figure indicates:

Diversity mode: it is assumed a receiver with available diversity in

the link budget; but none for the requirements in the protocol.

Channel model: only static channel is assumed in the specification

requirements.

BS

cabinet

Test ort A Test ort B

External

diplexer

or

RX filter

(if any)

External

LNA

(if any)

From

antenna connector


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Uplink Loading

The loading factor can be defined as:

Where Rjis the bit rate of the j-th link in the cell

jis the user activity factor

i is the other to own cell interference ratio

EbN0is the target for the j-th link in the cell

W is the chip rate

N

j

jjjb

UL

vR

W

NE

i1

0

1

)/(

11

11


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Uplink Interference Margin

The uplink interference margin should be equal to themaximum planned noise rise in BS receiver:

UL

UL NoiseRiseIM

1

1


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Downlink Interference Margin

The downlink interference margin should be equal to the

planned maximum noise rise in the receiver of UE on cell

edge. For a user j on cell edge:

DL

N

n j

n

n

nbn

Nj

CCH

jj

N

jTXBSjj

N

OCSCN

N

Totalj

CL

CL

RW

NEv

PCL

P

i

P

CLPi

P

IIPP

jINoiseRise

1

]/

)/([

)(1

/)(

1

)(

1

0

_


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Where jis the orthogonality factor in the downlink

Rjis the bit rate of the j-th link in the cell

jis the user activity factor

ijis the other to own cell interference ratio

Eb/N0is the target for the j-th link in the cellW is the chip rate

PCCH is the common channel power transmitted by the BS

PN is the noise floor of UE

CLj is the coupling loss, which is the loss between the antenna

connectors of BS cabinet and UE receiver for j-th link

CableLossennaeGainsOfAntnLossPenetratioBodyLossPathLossCL


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CLSIRNCL

RW

NEvENCL

RW

NEv n

n

nbnn

N

n n

nbn

]}

/

)/({]

/

)/([ 0

1

0

)()]}1(/

)/({[

)]1(/

)/([)1(

1

)/(

11

1

0

1

0

1

0

iSIRNiRW

NEvEN

iRW

NEvi

vR

W

NE

jj

j

jb

n

N

jjj

j

jb

n

N

jjj

jjjb

DL

Assuming there are enough users in the cell and demodulationperformance is irrelevant to location, such approximation can be

supposed:


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So the downlink interference margin can be written as:

)/(1

)(1

1

]/

)/([

)(1

}

1

]/

)/([

)(1{

1

0

1

0

j

DL

N

jCCH

DL

jj

DL

N

n j

n

n

nbn

Nj

CCH

jj

DL

N

n j

n

n

nbn

Nj

CCH

jj

jDL

CLCL

iPCLPi

CL

CL

RW

NEv

PCL

P

i

CL

CL

RW

NEv

PCL

P

iE

NoiseRiseIM

Note: mean values without subscript j refer to averaging over all users in the cell;

mean values with subscript j refer to averaging over users on the cell edge.


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Interference Margin (IM) vs. Load Factor

An example of downlink interference margin vs. downlink

loading with balanced links is depicted as:


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Interference Margin vs. Load Factor

It indicates a nonlinear relationship between downlinkinterference margin and load factor.

While downlink load factor approaches unit, the system

reaches its pole capacity and the noise rise over thermal

goes to infinity.Because of common channel power, the noise rise over

thermal is a non-zero value while no user accesses to the

cell. It is different from that of uplink.


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Total Transmission Power vs. Load Factor

In the downlink, it is important to estimate the total amountof BS transmission power required.


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Total Transmission Power vs. Load Factor

Starting from the same point where load factor is zero,

power requirements reach the maximum limited by thepower amplifier in different rates, and with different

downlink loading.

And the figure also presents that the larger the cell range,the faster the increase rate and the less load factor while

hitting the limit.

It means that for a large cell, the BS should allocate more

power for compensating path loss instead of more links

than the BS of a small cell does.


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Optimal Design with PA and Capacity

Generally, the larger maximum transmission power , the

more available capacity. But regarding the issue of cost-performance ratio, there is a optimal design with capacity

and maximum transmission power, which determines the

cost of the power amplifier, the most valuable component of

BS hardware.


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Another Definition of DL Load & IM

Due to the limit of transmission power in downlink, theloading can be estimated by:

Accordingly, the interference margin in downlink is:

MAX

jDCH

MAX

CCH

MAX

TXBS

DL

P

jP

P

P

P

P

)(

_

jN

DLMAXjj

jN

DLMAX

jj

jDL

CLP

Pi

CLP

P

iE

NoiseRiseIM

)(1

])(1[

Note that mean values of j, ijand CLjare caculated by

averaging over users on the cell edge.


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Another Definition of DL Load & IM

With givenj, ij, CLj and maximum transmission power, theinterference margin changes linearly with the load in the DL.

Due to an intuitive linear relationship, together with the

concern of the link between transmission power and

capacity in the downlink, this definition of DL load andinterference margin is applied in the link budget.


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Margin of Background Noise

Accounts for the environmental noise above the thermal noise ofthe receiver.

The background noise is introduced by other systems, human

beings and so on.

A non-zero margin of background noise means:

Reduced cell range of the network

Reduced capacity of the network

)())()(()( dBmXdBmYdBmXdBMGN


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Fast Fading Margin

In the link budget, the required EbNo is estimated by the

link-level simulation with the assumption of perfect powercontrol.

The assumption will be invalid If a terminal transmits with

maximum power on the cell edge and subsequently suffers

from fast fading. It is because the terminal cannot respond

to the power increase command issued by power controlalgorithm from RNC.

The fast fading margin, or PC headroom, is included to

account for the additional headroom needed in the mobile

station transmission power to maintain adequate power.Consequently, fast fading margin can be calculated as:

perfectPCEbNonoPCEbNoheadroomPC ___


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Penetration Loss

If indoor coverage is guaranteed, penetration loss should

be included in the link budget.Angles of incidence, building structures and material are

among the factors determining penetration loss.

It is assumed that penetration loss is log-normal distributed

and described with standard deviation and mean value. In the link budget, the standard deviation of penetration

loss combine with that of path loss to calculate the standard

deviation of indoor loss according to the following formula:

nLossPenetratio2

PathLoss2

TOT


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Slow Fading Margin

If the Transmitter cannot increase its output power andcompensate the path loss to ensure minimum required

signal strength on the Receiver, the link will be failed and

outage occurs.

In order to ensure the coverage probability, or keep a

certain link outage probability, the Slow Fading Margin

must be considered.

Slow Fading Margin is relative to the coverage probability,

slop of path loss and Std Dev of slow fading.


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Slow Fading Margin

The outage probability is:

It is obvious that when a UE is located on the cell edge, it isof most possibility for a outage to occurs.

)}(Pr{})(Pr{

})(Pr{

})(Pr{

})(Pr{)(Pr_

minmax_

minmax_

minmax_

dd

dPLSP

SdPLP

SdPLPdoutage

UE

UE

UE

Where , it represents the difference

between maximum permitted path loss and average path loss at a location

with the distance of r.

)()()( maxminmax_ rPLPLrPLSPr UE


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Slow Fading Margin

With given standard variation of slow fading and maximum

outage probability on the cell edge, the cell range can bededuced by following diagram:

slow fading margin and reserved in the calculation of path

loss to ensure the coverage reliability.

More common than outage probability, minimum edge

coverage probability or area coverage probability are used

in the target of network planning.

RRPLRoutage R )()(Pr_1 2 3

1 )]([Pr_Q-1

RoutageR

2 )()( minmax_ RSPLRPL UE

3Reverse path loss function specified by Propagation Model


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Slow Fading Margin

Considering the following expression:

It is assumed Smin is unrelated to the location. It is true for the uplink.

Because the interference margin in the downlink is subject to thelocation, the assumption is somewhat invalid.

But for the purpose of simplification, the slow fading margin in

both directions are supposed to be the same.

)()()( maxminmax_ rPLPLrPLSPr UE

S f G i


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Soft Handover Gain

Soft handover gain accounts for the diversity gain achievedduring soft handover conditions .

In link Budget, we divide it into two parts as follows:

SHO gain over fast fading (Macro Diversity Combining Gain) Reduce the requirement for EbNo on the cell edge

Estimated in different circumstances by the link-level simulation

S f H d G i


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Soft Handover Gain

SHO gain over slow fading (Multicell Gain)

More uncorrelated paths available to reduce the outage probability The outage probability on the cell edge in SHO area is estimated by:

The gain can be resulted from:

db

aQeR

SHOR

OutageSHO

2_ )]([2

1)(Pr

2

SHORSingleRG __

P i M d l


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Propagation Model

With the path loss calculated in the link budget, the cellrange for the specific analysis scenario can be figured out

by using propagation model

COST231-Hata, Asset standard macrocell,

COST231-Hata model:

P ti M d l


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Propagation Model

Asset Standard Macro model is specified as following:

C t t


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Contents

Introduction



S i f Li k B d t


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Scenario of Link Budget

Receiver Sensitivity

PDCH_Max Minimum Required Signal Strength

EiRP

PUE_Max

Slow Fading Margin

Penetration Loss

TX RX

Duplexer

Antenna

UE

PL_DL

PL_UL

Body Loss

Interference Margin

Fast Fading Margin

Margin for Background

Noise

TX RX

Duplexer

Cable

Antenna

Node B

Interference Margin

Fast Fading Margin

Margin for Background

Noise

Soft Handover

Area

SHO Gain

U li k B d t


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Uplink Budget

PL_UL: maximum Path Loss in uplink

Pout_UE: maximum transmission power for traffic channel of UE

Lc_BS: cable loss in BS

Lf_BS: feeder loss in BS

Ga_BS: antenna gain in BS

Ga_UE: antenna gain in UE

Mf: margin of fast fading (TPC headroom)

G_Mf: SHO gain over fast fading

Ms: margin of slow fading (slow fading)

G_Ms: SHO gain over slow fading

MI_UL: margin of interference in uplink

MBn: margin of background noise

Lp: mean value of penetration loss

Lb: body loss

S_BS: sensitivity of BS receiver

BSSLbLpMBnULMIMsGMsMfGMf

BSLfBSLcUEGaBSGaUEPoutULPL

____

______

D li k B d t


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Downlink Budget

PL_DL: maximum Path Loss in downlink

Pout_BS: maximum transmission power for traffic channel of BS

Lc_BS: cable loss in BS

Lf_BS: feeder loss in BS

Ga_BS: antenna gain in BS

Ga_UE: antenna gain in UE

Mf: margin of fast fading (TPC headroom)

G_Mf: SHO gain over fast fading

Ms: margin of slow fading (slow fading)

G_Ms: SHO gain over slow fading

MI_DL: margin of interference

MBn: margin of background noise

Lp: mean value of penetration loss

Lb: body loss

S_UE: sensitivity of UE receiver

UESLbLpMBnDLMIMsGMsMfGMf

UEGaBSGaBSLfBSLcBSPoutDLPL

____

______

E l f Li k B d t


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E ample of Link B dget


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Cell Coverage Calculation


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Cell Coverage Calculation

The coverage area for one site is a hexagonal configuration,which is estimated from

2^*RKSS: coverage area

K: constant accounting for sector configurationr: maximum cell range

Site configurati Omni 2-sectored 3-sectored 6-sectored

Value of K 2.6 1.3 1.95 2.6


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WCDMA RNP Link Budget.ppt