w(Level2) Wcdma Rnp Link Budget 20050526 a 1[1].0

WCDMA RNP Link Budget WCDMA RNP Link Budget

April 11, 2023April 11, 2023

WCDMA RNP Link Budget

Link Budget in WCDMALink Budget in WCDMA

The link budget is used to calculate the maximum The link budget is used to calculate the maximum path loss to maintain a link between the transmitter path loss to maintain a link between the transmitter and the receiver on a specific environment. Thus the and the receiver on a specific environment. Thus the corresponding cell range can be derived from the path corresponding cell range can be derived from the path loss with a propagation model.loss with a propagation model.

Contents Contents

Introduction

Parameters of Link Budget

Example of Link Budget

Introduction 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

IntroductionIntroduction

Interference

― WCDMA is intrinsically Interference limited system

― Coverage and capacity depend on the interference experimented by the receiver


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


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.


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

Contents Contents

Introduction



Link Budget ParametersLink 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

Link Budget ParametersLink 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

Analysis ScenariosAnalysis 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


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


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


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 link performance


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.


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


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.


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.


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.

Maximum Transmission Power of TCHMaximum 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 of output power are specified for UE:

Power Class Nominal maximumoutput 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

Maximum Transmission Power of TCHMaximum 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.

Cable LossCable 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- meter length in 2G frequency band. Besides, the loss of jumper and connector should be included.

Body LossBody Loss

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

And depends on the operational conditions.

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

Antenna GainAntenna Gain

Accounts for the gain at the antennas of the mobile terminal and Base Station

Typical values for the Mobile station are 0dBi .

Base station antennas gains are dependant on configuration.

EIRPEIRP

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

)()()(

)()(

dBnnaGainOfAntedBBodyLossdBCableLoss

dBmowerOfDCHnsmissionPMaximumTradBmEIRP

Noise FigureNoise 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 to the

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

Noise FigureNoise 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

TMAJ umper

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

111

Note: the NFCabinetTop is a variable parameter because of gain adjustment to compensate gain variance and maintain a constant RF channel gain.

Required EbNoRequired EbNo

Needed by the user service to maintain the link with acceptable quality.

Output from Link-level Simulation according to the following factors:― Channel type ― Mobile speed― QoS― Receiver implementation

Sensitivity of the ReceiverSensitivity of the Receiver

Minimum signal power on the cable connector of antenna needed by the receiver to demodulate signal with specific BER or BLER target.― 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 constant• T: 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

Sensitivity of the ReceiverSensitivity of the Receiver

Note that the concept of sensitivity of the receiver is different from that defined in the specification of 3GPP TS25.104 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.

BScabinet

Test port A Test port B

Externaldiplexer

orRX filter

(if any)

ExternalLNA

(if any)

Fromantenna connector

Interference MarginInterference Margin

The interference margin is used to account for the increase in the interference level within the cell due to other users.

It introduces in the Link Budget a way for accounting for the loading of the cell.

The more loading is allowed the larger margin is needed.

Typical values for the interference margin are between 1-3dB corresponding to 20%-50% loading in the uplink.

Uplink LoadingUplink Loading

The loading factor can be defined as:

Where Rj is the bit rate of the j-th link in the cell

j is the user activity factor

i is the other to own cell interference ratio

EbN0 is the target for the j-th link in the cell

W is the chip rate

N

j

jjjb

UL

vRW

NE

i1

0

1)/(

11

11

Uplink Interference MarginUplink Interference Margin

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

ULUL NoiseRiseIM

1

1

Downlink LoadingDownlink Loading

In the Downlink the loading factor can be expressed as

Where j is the orthogonality factor in the downlink

Rj is the bit rate of the j-th link in the cell


ij is the other to own cell interference ratio of j-th link

Eb/N0 is the target for the j-th link in the cell

W is the chip rate

N

jjj

jjjb

DL i

vRW

NE1

0

)1(1

)/(1

1

1

Downlink Interference MarginDownlink 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

IIP

P

jINoiseRise

1

]/

)/([

)(1

/)(1

)(

1

0

_


Where j is the orthogonality factor in the downlink

Rj is the bit rate of the j-th link in the cell


ij is the other to own cell interference ratio

Eb/N0 is the target for the j-th link in the cell

W 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 linkCableLossennaeGainsOfAntnLossPenetratioBodyLossPathLossCL


CLSIRNCLRW

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

vRW

NE

jjj

jbn

N

jjj

j

jbn

N

jjj

jjjb

DL

Assuming there are enough users in the cell and demodulation performance is irrelevant to location, such approximation can be supposed:


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

CL

CL

iP

CLPi

CL

CL

RW

NEv

PCL

P

i

CLCL

RWNE

vPCL

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.

Interference Margin (IM) vs. Load FactorInterference Margin (IM) vs. Load Factor

An example of downlink interference margin vs. downlink loading with balanced links is depicted as:

Interference Margin vs. Load FactorInterference Margin vs. Load Factor

It indicates a nonlinear relationship between downlink interference 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.

IM vs. Load Factor vs. Coupling LossIM vs. Load Factor vs. Coupling Loss

According to the following figure, it should be noticed that the variation of coupling loss on the cell edge will impact the noise rise of UE there.

Total Transmission Power vs. Load Factor Total Transmission Power vs. Load Factor

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

Total Transmission Power vs. Load Factor Total Transmission Power vs. Load Factor

Starting from the same point where load factor is zero, power requirements reach the maximum limited by the power 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.

Optimal Design with PA and CapacityOptimal 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.

Another Definition of DL Load & IMAnother Definition of DL Load & IM

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

Accordingly, the interference margin in downlink is:

MAX

jDCH

MAX

CCH

MAX

TXBSDL P

jP

P

P

P

P

)(_

jN

DLMAXjj

jN

DLMAXjj

jDL

CLP

Pi

CLP

PiE

NoiseRiseIM

)(1

])(1[

Note that mean values of j, ij and CLj are caculated by averaging over users on the cell edge.

Another Definition of DL Load & IMAnother Definition of DL Load & IM

With given j, ij, CLj and maximum transmission power, the interference 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 and interference margin is applied in the link budget.

Margin of Background NoiseMargin of Background Noise

Accounts for the environmental noise above the thermal noise of the 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

Fast Fading MarginFast Fading Margin

In the link budget, the required EbNo is estimated by the link-level simulation with the assumption of perfect power control.

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 control algorithm 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 ___

Minimum Required Signal StrengthMinimum Required Signal Strength

On the base of sensitivity of the receiver, together with gains, losses and margins, the minimum signal strength required for achieving link quality can be estimated by:― For the uplink

― For the downlink

Noise Background for Margin

Fading Fast over Gain SHO

MarginFading Fast MarginceInterferen

Gain Anetnna - Receiver ofy Sensitivit Strength SignalRequired Minimum

Noise Background for Margin

Fading Fast over Gain SHO MarginFading Fast

MarginceInterferenLossBody Loss Cable

Gain Anetnna - Receiver ofy Sensitivit Strength SignalRequired Minimum

Penetration LossPenetration 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

Slow Fading MarginSlow Fading Margin

If the Transmitter cannot increase its output power and compensate 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.


The outage probability is:

It is obvious that when a UE is located on the cell edge, it is of 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


With given standard variation of slow fading and maximum outage probability on the cell edge, the cell range can be deduced 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

3 Reverse path loss function specified by Propagation Model


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 the location, 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

Soft Handover GainSoft Handover Gain

Soft handover gain accounts for the diversity gain achieved during 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

Soft Handover GainSoft 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

OutageSHO2_ )]([

2

1)(Pr

2

SHORSingleRG __

Propagation ModelPropagation Model

With the path loss calculated in the link budget, the cell range for the specific analysis scenario can be figured out by using propagation model― COST231-Hata, Asset standard macrocell,…

COST231-Hata model:

Propagation ModelPropagation Model

Asset Standard Macro model is specified as following:

Contents Contents

Introduction



Scenario of Link BudgetScenario 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

Uplink BudgetUplink 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

____

______

Downlink BudgetDownlink 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

____

______

Example of Link BudgetExample of Link Budget



Cell Coverage CalculationCell Coverage Calculation

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

2^*RKS S: coverage areaK: constant accounting for sector configurationr: maximum cell range

Site configuration Omni 2-sectored 3-sectored 6-sectoredValue of K 2. 6 1. 3 1. 95 2. 6

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w(Level2) Wcdma Rnp Link Budget 20050526 a 1[1].0