3) Link Budget Designing

8/10/2019 3) Link Budget Designing

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MobileCommProfessionals, Inc.The Cell Planning Process

Step 5:Implementation

System Growth Initial Planning

Step 2: NominalCell Plan

Step 1: Traffic &Coverage Analysis

Step 4: SystemDesign

Step 6: SystemTuning

Step 3:Surveys


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MobileCommProfessionals, Inc.Must Know


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MobileCommProfessionals, Inc.

The ratio of two signals with powers P1 and P2 is expressed in dBas:

10 log P1/P2 [dB]

and in dBm it is given by:

10 log P1/1 mW [dBm]

deciBel


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dB = 10 * log10(P1/P2)

deciBel

dB is a relative unit of measurement used to describe powergain or loss.

The dB value is calculated by taking the log of the ratio of themeasured or calculated power (P2) with respect to a reference

power (P1). This result is then multiplied by 10 to obtain thevalue in dB.

The powers P1 ad P2 must be in the same units. If the unitsare not compatible, then they should be transformed.

Equal power corresponds to 0dB.

A factor of 2 corresponds to 3dB

deciBel


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Decibel is a relative comparison between numbers...whatever the numbers are!

Absolute comparison in decibel between numbers...

whatever the numbers are!

AP

P(dB) 10 log10

1

2

AP

P(dBunity) 10 log10

unity

dBm = dBW + 30

A P

(dBW) 10 log10 1 Watt A

P(dBm) 10 log10

1 milliWatt

Warming-up: The decibel definition


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Calculations in dB (deciBel)

Logarithmic scale

Always with respect to a reference

dBW = dB above Watt

dBm = dB above mWatt

dBi = dB above isotropic

dBd = dB above dipole

dBmV/m= dB above mV/m

Rule-of-thumb: +3dB =factor 2

+7 dB =factor 5

+10 dB = factor 10

-30 dBm = 1 mW

-20 dBm = 10 mW

-10 dBm = 100 mW

-7 dBm = 200 mW

-3 dBm = 500 mW

0 dBm = 1 mW+3 dBm = 2 mW

+7 dBm = 5 mW

+10 dBm = 10 mW

+13 dBm = 20 mW

+20 dBm = 100mW

+30 dBm = 1 W

+40 dBm = 10W

+50 dBm = 100W

deciBel Conversion


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dBm

where dBm = Power in dB referenced to 1 milliwatt

P = Power in watts

If power level is 1 milliwatt:

Power(dBm) = 10 log (0.001 watt/1 mW)

= 10 log (1)

= 10 (0)

= 0Thus a power level of 1 milliwatt is 0 dBm.

If the power level is 1 watt

1 watt Power in dBm = 10 log (1 watt/1 mW)

= 10 (3)= 30 dBm

Calculations

dBm = 10 log P/1 mW


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dBm

The dBm can also be negative value.

If power level is 1 microwattPower in dBm = 10 log (1 x 10E-6 watt) (1000 mW/watt)

= -30 dBm

Since the dBm has a defined reference it can be converted back towatts if desired.

Since it is in logarithmic form it may also be conveniently combinedwith other dB terms.

Calculations

dBm = 10 log (P) (1000 mW/watt)


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Power absolute

linear scale13 dBm+ 3dB = 16 dBm dBm + dB dBm

1 mW

20 mW

40 mW

0 dBm

13 dBm

16 dBm

Power absolute

logarithmic scale

3dB

3dB

Decibel operations

16 dBm- 3dB = 13 dBm dBm - dB dBm

16 dBm- 13dBm = 3 dB dBm - dBm dB

13 dBm+ 16dBm = 29 dBm dBm + dBm

794 mW

18 dBm

Undefined!

20 mW + 40 mW = 60 mW

The mystery of deciBel


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- 74 dBm

- 74 dBm - 86 dBm -(74 dBm + 86 dBm )

Undefined!10-74/10

0.000000039 mW

10-86/100.0000000025 mW

- 86 dBm

Linear scale

+

0.0000000415 mW

Power - absolute

logarithmic scale

- 90 dBm

- 80 dBm

- 70 dBm

+

-

10 log (0.0000000415) = -73.8 dBm

Logarithm scale

Struggling against deciBel


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Radio Waves


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MobileCommProfessionals, Inc.Free Space Propagation

Friis Formula

Propagation Loss

The square term is the propagation exponent. It is greater than 2when obstructions exist.

Propagation Loss in dB:

f = MHz

d = km

Pt

GtGr

PrLp

d

Pr = Pt GtGr2

(4d)2

L p = 32.44 + 20Log(d) +20Log(f)

Lp = 10log [4d / ]2


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Radio Wave Propagation And The

Pathloss Concept

transmitter/

emitter

(receiver)

receiver

(transmitter/

emitter)

transmission loss!!!

Factors that affect the wave propagation...

absorption

refractionreflection

diffraction

scattering effect

Real Scenario


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MobileCommProfessionals, Inc.Propagation Mechanisms

Reflection

Occurs when a wave impinges upon a smooth surface. Dimensions of the surface are large relative to .

Reflections occur from the surface of the earth and from buildings and walls.

Diffraction (Shadowing)

Occurs when the path is blocked by an object with large dimensions relative toand sharp irregularities (edges).

Secondary waveletspropagate into the shadowed region.

Diffraction gives rise to bending of waves around the obstacle.

Scattering

Occurs when a wave impinges upon an object with dimensions on the order of or less, causing the reflected energy to spread out orscatter in manydirections.

Small objects such as street lights, signs, & leaves cause scattering


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MobileCommProfessionals, Inc.Multipath Propagation

Different radio paths have different properties

Distance: Delay/Time Direction: Angle

Direction & Receiver/Transmitter Movement: Frequency


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MobileCommProfessionals, Inc.Multipath

Multiple Waves Create Multipath

Due to propagation mechanisms, multiple waves arrive at the receiver Sometimes this includes a direct Line-of-Sight (LOS) signal


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Antenna


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MobileCommProfessionals, Inc.Antennas

Antennas form a essential part of any radio communication

system. Antenna is that part of a transmitting or receiving system which

is designed to radiate or to receive electromagnetic waves.

An antenna can also be viewed as a transitional structurebetween free-space and a transmission line (such as a coaxial

line). An important property of an antenna is the ability to focus and

shape the radiated power in space e.g.: it enhances the powerin some wanted directions and suppresses the power in otherdirections.

Many different types and mechanical forms of antennas exist.

Each type is specifically designed for special purposes.


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Directional antenna

These antennas are mostly used in mobile cellular systems to gethigher gain compared to omnidirectional antenna and to minimiseinterference effects in the network.

In the vertical plane these antennas radiate uniformly across allazimuth angles and have a main beam with upper and lower side

lobes. In these type of antennas, the radiation is directed at a specific angle

instead of uniformly across all azimuth angles in case of omniantennas.

Antennas Types


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MobileCommProfessionals, Inc.Antenna Characteristics

Radiation Pattern


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Antenna Gain

Antenna gain is a measure for antennas efficiency.

Gain is the ratio of the maximum radiation in a given directionto that of a reference antenna for equal input power.

Generally the reference antenna is a isotropic antenna.

Gain is measured generally in decibelsabove isotropic(dBi)ordecibelsabove a dipole(dBd).

An isotropic radiator is an ideal antenna which radiates powerwith unit gain uniformly in all directions. dBi = dBd + 2.14

Antenna gain depends on the mechanical size, the effective

aperature area, the frequency band and the antennaconfiguration.

Antennas for GSM1800 can achieve some 5 to 6 dB more gainthan antennas for GSM900 while maintaining the samemechanical size.


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Main Lobe Axis Power Beamwidth

Side Lobe

Back Lobe

First Null


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Antenna Lobes

Main lobe is the radiation lobe containing the direction of maximumradiation.

Side lobes

Half-power beam width

The half power beam width (HPBW) is the angle between the pointson the main lobe that are 3dB lower in gain compared to themaximum.

Narrow angles mean good focusing of radiated power.

Polarisation

Polarisation is the propagation of the electric field vector .

Antennas used in cellular communications are usually verticallypolarised or cross polarised.

Antenna Characteristics


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antenna lobe

maximum gain-3 dB

maximum gain-3 dB

main directionBEAMWIDTH

Beam Width

Beam width, B, is defined as the opening angle between the pointswhere the radiated power is 3 dB lower than in the main direction.

Both the horizontal and the vertical beam width are found usingthe 3 dB down points, alternatively referred to as the half-power

points.


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MobileCommProfessionals, Inc.Antenna Downtilting

Antenna down tilting is the downward tilt of the vertical patterntowards the ground by a fixed angle measured w.r.t the horizon.

There are two methods of down tilting

Mechanical down tilting

Electrical down tilting


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MobileCommProfessionals, Inc.Mechanical Downtilting

Mechanical down tilting consists of physically rotating anantenna downward about an axis from its vertical position.


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MobileCommProfessionals, Inc.Mechanical Downtilting

M h i l D tilti


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Vertical antenna pattern at 0

Vertical antenna pattern at 15downtilt

Backlobe shoots over the horizon

Mechanical Downtilting


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MobileCommProfessionals, Inc.Electrical Downtilt

Electrical down tilt uses a phase taper in the antenna array to

angle the pattern downwards. This allows the antenna to be mounted vertically.

Electrical down tilt is the only practical way to achieve patterndown tilting with Omni directional antennas.

Electrical down tilt affects both front and back lobes.

If the front lobe is down tilted the back lobe is also down tiltedby equal amount.

Electrical down tilting also reduces the gain equally at all angleson the horizon. The that adjusted down tilt angle is constant

over the whole azimuth range.

Variable electrical down tilt antennas are very costly.

l l l


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El i l D il


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Horizontal and vertical pattern for allgon 7144 antenna

Horizontal Beamwidth = 90

Vertical Beamwidth = 16

Electrical Downtilt = 16

N k C l


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MobileCommProfessionals, Inc.Network Cycle


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CW and Model Tuning

b l f lP ti M d l T i Fl


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MobileCommProfessionals, Inc.Propagation Model Tuning Flow


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M bil C P f i l ISite Selection


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MobileCommProfessionals, Inc.Site Selection

Principles of site selection

Number of sites: It is usually agreed that aminimum of 5 sites should be tested in large and

dense city, but one site is enough in normal city,

which mainly depends on antenna height and EIRP.

Representation:Site selection should aim to cover

all types of clutter (from the digital map) in thecoverage zone.

Multiple models: Define the corresponding zone of

each model if the test environment requires

multiple models to describe its propagation

characteristics. Overlap:Increase measurement overlap area

between each site as

much as possible. But reasonable inter-site

distance should be ensured.


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MobileComm Professionals IncPropagation Model Tuning


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MobileCommProfessionals, Inc.Propagation Model Tuning

Map correction

GPS locating in CW test usually adopts WGS84 and UTM projection.Correct digital maps if CW test data does not correspond to them.

Correction method:

Correct four parameters on rectangular coordinates in a digital

map to realize the optimal match with the test data.


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calculated

values for the

variable

ERROR (measurement prediction)

Regression line



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Analysis of correction results

Analyze correctness of the acquired model aftercorrection.

Evaluate the correctness of the model with Std Dev,which refer to the binding degree of the acquired modeland actual test environment.

Make Std Dev less than 8 as much as possible in actualmodel tuning, which indicates that the tuned model andactual test environment are well bound.

MobileComm Professionals, Inc.Propagation Models


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MobileCommProfessionals, Inc.Propagation Models

Empirical

Deterministic

Semi-empirical

An equation based on extensive empiricalmeasurements is created. Those models can be usedonly in the environments similar to the examined one.The small changes in the environment characteristic cancause enormous errors in the prediction of wavepropagation.

Combination of empiricaland deterministic models(e.g. empirical COST Hata canbe combined with thetheoretical knife edgemodel).

Wave propagation is described by means of rays travelling betweentransmitted and receiving antenna and coming in to reflections,scattering, diffractions, etc . Those methods, generally based on rayoptical techniques, give a very accurate description of the wavepropagation but require a large computation time.

MobileComm Professionals, Inc.Radio Propagation Model


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MobileCommProfessionals, Inc.Radio Propagation Model

Propagation model is used to predict the effect of

terrain, obstacle and artificial environment on the

path loss.

Okumura/Hata model

COST231-Hata model

COST231 Walfish-Ikegami model

Ray Tracing

Common Propagation Models


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MobileCommProfessionals, Inc.Ray Tracing Models


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,Ray Tracing Models

Ray tracing is a deterministic modeling approach based on

geometrical optics. Ray tracing techniques were originallyintroduced in computer graphics applications to create photo-

realistic pictures of 3-dimensional sceneries.

Wall


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Propagation Mechanism

MobileCommProfessionals, Inc.Fast Fading


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Fast Fading

Different signal paths interfere and affect the received signal

Rice Fadingthe dominant (usually LOS) path exist

RayleighFadingno dominant path exist

MobileCommProfessionals, Inc.Fast Fading Rayleigh Distribution


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Fast Fading Rayleigh Distribution

It can be theoretically shown that fast fading follows Rayleigh

Distribution when there is no single dominant multipath component Applicable to fast fading in obstructed paths

Valid for signal level in linear scale (e.g. mW, W)

+10

0

-10

-20

-30

0 1 2 3 4 5 m

level dB)

920 MHz

v = 20 km/h

MobileCommProfessionals, Inc.Fast FadingRician Distribution


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g

Fast fading follows Rician distribution when there is a

dominant multipath component, for example line-of-sightcomponent combined with in-direct components

Sliding transition between Gaussian and Rayleigh

Rice-factor K = r/A: direct / indirect signal energy

K = 0 RayleighK >>1 Gaussian

K = 0

(Rayleigh)

K = 1

K = 5

MobileCommProfessionals, Inc.Fast Fading Margin


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0.14 0.145 0.15 0.155 0.16 0.165 0.17

-15

-10

-5

0

5

transmit power

90 km/hr Rayleigh Channel

Time

Fast Fading Margin

MobileCommProfessionals, Inc.Slow Fading


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Slow Fading

Slow Fading

This is due to shadowing by terrain structures and large obstacles.It is in the order of 10s of wavelengths.

The slow fading can be described mathematically by the Gaussian

distribution.

MobileCommProfessionals, Inc.Slow FadingGaussian Distribution


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g

Measurement campaigns have shown that slow fading

follows Gaussian distributionReceived signal strength in dB scale (e.g. dBm, dBW)

Gaussian distribution is described by mean value m, standard

deviation

68% of values are within m 95% of values are within m 2

Gaussian distribution used in planning margin calculations

MobileCommProfessionals, Inc.Slow Fading


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g

d

Normal / Gaussian Distr ibution

Standard Deviation, = 7 dB

0.00000

0.01000

0.02000

0.03000

0.04000

0.05000

0.06000

0.07000

-25 -20 -15 -10 -5 0 5 10 15 20 25

Normal / Gaussian Distribution

22

1

MobileCommProfessionals, Inc.Coverage Probability


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Coverage Probability

If the transmit power of a UE hits the maximum threshold, but still cannotovercome the path loss to guaranty the lowest receive level, the radio link will

drop or the UE will fail to access

If the designed signal level at the edge of the cell equals to the Minimum SignalStrength Required, the actual measurement result will obey the normaldistribution.

This means there is a 50% probability that the UE cannot access the network

MobileCommProfessionals, Inc.Required Eb/No


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q /

When Eb/N0is selected, it has to be known in whichconditions it is defined:

Service and bearer Radio channel

Receiver/connection configuration

Soft handover gain

Power control gain

Fast fading margin

Eb/Nois classically defined as the ratio of Energy per Bit (Eb) to

the Spectral Noise Density (No).

It is measured at the input to the receiver and is used as the

basic measure of how strong the signal is.



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q /

When Eb/N0is selected, it has to be known in which conditions it is definedService and Bearer

Bit rate, BER requirement, channel codingRadio Channel

Doppler spread (Mobile speed, frequency)

Multipath, delay spread

Propagation Environments

3GPP models, Case 1-5

COST 259 models, Typical urban (TU),

Rural area (RA), Hilly terrain (HT)

ITU models, Indoor A/B, Pedestrian A/B, Vehicular A/B

Receiver/Connection Configuration

Handover situation

Fast power control status

Diversity configuration (antenna diversity, 2-port, 4-port)

Corrections

Soft handover gain

Power control gain

Fast fading margin

MobileCommProfessionals, Inc.Noise Figure


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g

Noise figure (NF) is used to measure the noise performance of

an amplifier. It refers to the ratio of the input SNR to the outputSNR of the antenna

NF = SNRi/ SNRo

= (Si/ Ni) / (So/ No)

Thermal Noise is caused by the random movement of atoms inmaterial and its spectrum is white.

= -174 (dBm/Hz) + 10lg(3.84MHz / 1Hz) + NF(dB)

= -108 (dBm/3.84MHz) + NF (dB)

Where, KBoltzmann constant, 1.3810-23 J/K

TKelvin temperature, normal temperature: 290 K

WSignal bandwidth, WCDMA signal bandwidth 3.84MHz

MobileCommProfessionals, Inc.Penetration Loss


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Indoor signals depend on penetration loss of building.

Signals are different at the indoor window and in the middleof room.

Building materials have great effect on penetration loss.

The reference angle of electromagnetic wave have greateffect on penetration loss.

T

RPenetration loss


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Link Budget

MobileCommProfessionals, Inc.Path-Loss


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Path-loss includes all of the lossy effects associated with

distance and the interaction of the propagating wave with the

objects in the environment between the antennas.

MobileCommProfessionals, Inc.Why Link Budget


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Target of coverage dimensioning is to give estimate of sitecoverage area (site count for given area)

Coverage dimensioning requires multiple inputs

Service type

Target service probability

Initial site configurationEquipment performance

Propagation environment

Link budget calculations are used for calculation of the sitecoverage area with the given inputs

MobileCommProfessionals, Inc.Link budget


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The target of the link budget calculation is

to estimate the maximum allowed pathloss (R) on radio path from transmit

antenna to receive antenna

The minimum Eb/N0(and BER/BLER)

requirement is achieved with themaximum allowed path loss and transmit

power both in UL & DL

The maximum path loss can be used to

calculate cell range R

Lpmax_DLLpmax_UL

R

MobileCommProfessionals, Inc.Free Space Models


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The free-space path loss model treats the region between the

transmit and receive antennas as being free of all objects that

might absorb or reflect radio frequency (RF) energy.

The path loss expressed as the ratio of the received power to the

transmitted power in linear scale is given by;

Where,

Gtand Gr are the transmitter and receiver

antenna gains,

lis the signal wavelength, and

d is the distance between the transmitter and

the receiver.

MobileCommProfessionals, Inc.Propagation Model Overview


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Propagation models provide a forecast of

Average signal and Variations around the average

Path Loss

Models must give a forecast as close aspossible to real scenarios, so that they can be usedas reliable tools to plan cellular networks

MobileCommProfessionals, Inc.Link Budget Parameter


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MSMaximum output power [dBm]

Feeder loss [dB]

Antenna gain [dBi]

EIRP [dBm]

Receiver sensitivity [dBm]

BTS

Rx-diversity gain [dB]Antenna gain [dB]

Head amplifier gain [dB]

Jumper, feeder, connector losses [dB]

Duplexer losses [dB]

Receiver sensitivity [dBm]

EnvironmentBody loss [dB]

Building (indoor) penetration loss [dB]

Path loss [dB]

Fading margin (lognormal and Rayleigh) [dB]

Interference margin [dB]

Frequency hopping gain [dB]

MobileCommProfessionals, Inc.Link budget types


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R99 DCH link budgetUplink

Can be based on many different PS and CS servicesDownlink

Can be based on many different PS and CS servicesHSDPA link budget

UplinkHSDPA associated UL DPCH link budget is used which can be 16, 64 ,128 or 384

kbpsPeak HS-DPCCH overhead is included to the R99 DCH Eb/No (this overheadoften appears in the transmitter section of the link budget)

DownlinkCan be based on defined cell edge throughput conditions

HSUPA link budgetUplink

Can be based on defined cell edge throughput conditionsPeak HS-DPCCH overhead is included to the HSUPA Eb/NoBLER need to be considered

DownlinkCan be based on defined cell edge throughput conditions


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MobileCommProfessionals, Inc.R99 UL Link Budget


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The calculation is done for each

service (bit rate) separatelyBit rate depends on service,

which can vary in speechservice bit rates (e.g. 4.75, 5.9,7.95, 12.2 kbps) to packet

service bit rates (e.g. 8, 16, 32,64, 128 and 384 kbps) as wellas video service (e.g. 64 kbps)

Coverage limiting service can be

defined based on customer inputsor lowest path loss based oncalculations



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Transmitter - Handset

Transmission power classes

Power Class 4 most commonat the moment (note 2 dBtolerance)

Power Class 3 most commonin new mobiles and data cards(+1/-3dB tolerance)

Antenna TX/RX gainTypically assumed to be 02

dBi

For data card 2 dBi can beassumed

Body Loss

For CS voice service body lossof 3 dB is assumed as themobile is near head.

EIRP represents the effectiveisotropic radiated power from thetransmit antenna.

LossBody-GainAntennaTransmitPowerTransmitUEEIRPUplink


R99 UL Link Budget


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ReceiverNode B

Node B noise figure

Depends on Node B

Depends on Frequency

Thermal Noise

= 108dBm k = Boltzmanns constant, 1.43 E-23

Ws/K T = Receiver temperature, 293 K

B = Bandwidth, 3 840 000 Hz

Uplink Load

Definition of UL load can bebased on traffic inputs or

estimated Interference margin

Interference margin is calculatedbased on UL load

BTkDensityNoiseThermal

ce_margininterferenfigurenoiseBNodenoisehermal_I Tfloorenterferenc

MobileCommProfessionals, Inc.Interference Margin


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Interference margin is calculated from the UL loading () value

From set maximum planned load

"sensitivity" is decreased due to the network load (subscribers in the network) & in UL indicatesthe loss in link budget due to load.

dBLog 11010

IMargin=

1.25

3

20

10

6

25% 50% 75% 99%

IMargin[dB]

Load factor


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When Eb/N0is selected, it has to be known in which conditions it is definedService and Bearer

Bit rate, BER requirement, channel codingRadio Channel

Doppler spread (Mobile speed, frequency)

Multipath, delay spread

Propagation Environments

3GPP models, Case 1-5

COST 259 models, Typical urban (TU),Rural area (RA), Hilly terrain (HT)

ITU models, Indoor A/B, Pedestrian A/B, Vehicular A/B

Receiver/Connection Configuration

Handover situation

Fast power control status

Diversity configuration (antenna diversity, 2-port, 4-port)

Corrections

Soft handover gain

Power control gain

Fast fading margin



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ReceiverNode B

RX Antenna Gain

Is different for different frequencies

Gain and size varies

Cable Loss

MHA

MHA can be used to compensate thecable loss as well as lower the systemnoise figure

MobileCommProfessionals, Inc.Cable loss


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Cable loss is the sum of all signal

losses caused by the antenna line

outside the base station cabinet

Jumper losses

Feeder cable loss

MHA insertion loss in DL when

MHA is used Typical 0.5 dB

Feeder losses decrease when

frequency is lower

7/8 loss at 900 MHz is about 3.7dB/100 m

MobileCommProfessionals, Inc.Benefit of using MHA


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MHA can be used to improve the base station system noise

figure in UL

The benefit achieved by using MHA equals to the noise figure

improvement

Calculated with MHA (G = 12 dB, NF = 2 dB)

Note MHAinsertion loss forDL

MHA Gain



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ReceiverNode B

UL fast fade margin

SHO gain (old MDC gain)

Gain against shadowing

MobileCommProfessionals, Inc.Fast fading Margin


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Fast fading margin is used as a correction factor for Eb/No at the

cell edge, when the used Eb/No is defined with fast power

control

At the cell edge the UE does not have enough power to

follow the fast fading dips

In DL fast fading margin is not usually applied due to Lower

Power Control dynamic range

Fast fading margin = (average received Eb/N0)without fast PC - (average received Eb/N0)with fast PC


Fast Fading Margin


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0 0.5 1 1.5 2 2.5 3 3.5 410

15

20

25

dB

0 0.5 1 1.5 2 2.5 3 3.5 4-10

0

10

20

dBm

0 0.5 1 1.5 2 2.5 3 3.5 4-0.5

0

0.5

1

1.5

0 0.5 1 1.5 2 2.5 3 3.5 45

10

15

dB

Seconds

Mobile transmission

power starts hitting

its maximum value

Eb/No target

increases fast

Received qualitydegrades, more

frame errors

MS moving towards the cell edge

Some headroom is needed in the mobile station TX power formaintaining adequate fast power control

This is needed at cell edge for UEs to be able to compensatefast fading

Typical values are from 2 to 5 dB for slow-moving mobiles(according to WCDMA for UMTS)

MobileCommProfessionals, Inc.Soft Handover (MDC) GainUL


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SHO gain (Macro Diversity Combining) gives the Eb/No

improvement in soft handover situation compared to single

link connection

At cell edge the SHO gain can be around 1.5 dB,

An average over the cell in UL is commonly 0 dB, this is due to

the fact that:

Significant amount of diversity already exist2-port UL antenna diversity, multipath diversity (Rake)

MobileCommProfessionals, Inc.Soft Handover (MDC) GainUL


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Soft HOCombining(including softer combininggain for the other branch)Softer HO

Combining


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MobileCommProfessionals, Inc.Planning Margins


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Output of the link budget calculation is a maximum

path loss estimate from transmit antenna to thereceived antenna

In coverage planning additional planning marginsare introduced to take into account

Signal shadowing due to obstructions (buildings, treesetc.) on the radio pathSlow fading

Signal attenuation by buildingstructures for indoorusers

Attenuation to the signal caused by phone user Body loss

MobileCommProfessionals, Inc.Slow Fading margin


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Slow fading is caused by signal

shadowing due to obstructionson the radio path

A cell with a range predictedfrom maximum path loss willhave a Coverage Probabilityof about 75 %

Lot of coverage holes due toshadowing

Slow fading margin (SFM) is

required in order to achievehigher coverage quality,Coverage Probability

Smaller cell, less coverage holesover cell area ........max RSFMLRf

Max pathlossfrom link

budget

Pathlossprediction

model

Cell Range

Coverageprobability =

75 % outdoors

Max pathlossfrom link

budget

Pathlossprediction

model

Cell Range

Coverageprobability >75 % outdoor

- Slow fadingmargin

MobileCommProfessionals, Inc.Coverage Probability


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Location Probability over Cell Area

Coverage Probability = Area Location Probability over Cell Area

In dimensioning, the Area Location Probability of a single cell is defined insteadof Point Location Probability at Cell Edge.

Area Location Probability over Cell Areameans the probability that theaverage received field strength is better than the minimum needed receivedsignal strength (in order to make a successful phone call) within the cell.

The difference between Point & Area location probability is illustrated below :

MobileCommProfessionals, Inc.Point Location Probability at Cell Edge


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As shown previously, the Slow Fading (log-normal fading) is

normal distributed with the distribution function

22

1

2

12

1

0

2

)(

2

0

2

2

0

m

x

rr

x

rxerf

rdep

m

Refer to Cellular Radio Performance Engineering, Chapter 2, e.g. 2.9 Page 29

Jakes, W.C.Jr. Microwave Mobile Communications. USA 1974, John Wiley & Sons. 473 p

The probability, Pxo that r exceeds some threshold, xo at a given

point inside the cell is called the Point Location Probability. Thepoint location probability can be written as the upper tail probabilityof the above equation :

2

2

2

)(

22

1)(

mrr

erp

Slow FadingMargin, SFM


Formula


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FR

p dAu x

1

2 0

Area Location Probability

Point Location Probabilities

px0

F erf a e erf a b

bu

a b

b

1

21 1

12 1

2

( )

2)( 00

Pxa

2

log10

eb

P0 field strength threshold value at cell edge path loss slope

Slow Fading

Margin,SFM

StandardDeviation,

From Point Location Probability to Area Location Probability

MobileCommProfessionals, Inc.Slow Fading Margin


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Slow Fading Margin

SFM [dB] (xo-Po)

Point Location

Probability,

Pxo

a bArea Location

Probability, Fu

-5.00 26.60% -0.4419 1.2964 56.00%-4.50 28.69% -0.3977 1.2964 58.00%

-4.00 30.85% -0.3536 1.2964 59.99%

-3.50 33.09% -0.3094 1.2964 61.97%

-3.00 35.38% -0.2652 1.2964 63.93%

-2.50 37.73% -0.2210 1.2964 65.86%

-2.00 40.13% -0.1768 1.2964 67.76%

-1.50 42.56% -0.1326 1.2964 69.63%

-1.00 45.03% -0.0884 1.2964 71.45%

-0.50 47.51% -0.0442 1.2964 73.23%

0.00 50.00% 0.0000 1.2964 74.96%

0.50 52.49% 0.0442 1.2964 76.63%

1.00 54.97% 0.0884 1.2964 78.25%

1.50 57.44% 0.1326 1.2964 79.81%

2.00 59.87% 0.1768 1.2964 81.30%

2.50 62.27% 0.2210 1.2964 82.73%

3.00 64.62% 0.2652 1.2964 84.09%

3.50 66.91% 0.3094 1.2964 85.38%

4.00 69.15% 0.3536 1.2964 86.61%

4.50 71.31% 0.3977 1.2964 87.76%5.00 73.40% 0.4419 1.2964 88.85%

5.50 75.41% 0.4861 1.2964 89.87%

6.00 77.34% 0.5303 1.2964 90.82%

6.50 79.17% 0.5745 1.2964 91.71%

7.00 80.92% 0.6187 1.2964 92.53%

7.50 82.57% 0.6629 1.2964 93.29%

8.00 84.13% 0.7071 1.2964 93.99%

8.50 85.60% 0.7513 1.2964 94.64%

8.80 86.43% 0.7777 1.2964 95.00%

9.50 88.25% 0.8397 1.2964 95.77%10.00 89.44% 0.8839 1.2964 96.25%

Slow fading margin valuespresented for the

different Point Location

and Area Location

Probability values

Standard Deviation, s= 8dB

SFM = 0 Point Location Probability = 50 %

Area Location Probability = 75 %

MobileCommProfessionals, Inc.Jakes Curve


102/142

MobileCommProfessionals, Inc.Distribution Table


103/142

MobileCommProfessionals, Inc.Building Penetration Loss


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Signal levels from outdoor base stations into buildings are

estimated by applying a Building Penetration Loss (BPL)

margin

Slow fading standard deviation is higher inside buildings due

to shadowing by building structures

There are big differences between rooms with window

and deep indoor (10 ..15 dB)

Pref= 0 dB

Pindoor= -3 ...-15 dB

Pindoor= -7 ...-18 dB

-15 ...-25 dB no coverage

rear side :

-18 ...-30 dB

signal level increases withfloor number :~1,5 dB/floor(for 1st ..10th floor)



105/142

marginfadeslowBPLgainULSHO-marginfadefastULgainMHA-

losscableainRxAntennaGysensitivitReceiverrequiredpowerotropicI

s

Isotropic power required

Required signal power is

calculated to take intoaccount the building

penetration loss and indoor

standard deviation as well as

receiver sensitivity and

additional margins.

Allowed propagation loss

requiredpowerIsotropic-EIRP. losspAllowedpro


106/142

R99 Downlink Link

Budget

MobileCommProfessionals, Inc.R99 DL Link Budget


107/142

The calculation is done for each

service (bit rate) separatelyBit rate depends on service,

which can vary in speech

service bit rates (e.g. 4.75,

5.9, 7.95, 12.2 kbps) to packet

service bit rates (e.g. 8, 16,32, 64, 128 and 384 kbps) as

well as video service (e.g. 64

kbps)

Coverage limiting service can be

defined based on customer inputsor lowest path loss based on

calculations



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TransmitterNode B

Max Tx Power (total)

Max Tx power is based on selected equipment,e.g. 20 W = 43 dBm and 40 W = 46 dBm. Thisdepends on Node B type and configuration.

This parameter is used in definition of Max Txpower per radio link.

TX power per user

Tx power per user is depended on DL load used in

link budget calculation (it is used to define howmuch power is used per user)

This parameter notifies the average user locationsuch as 6 dB which correspond to average userlocation.

MHA insertion loss

In DL the insertion loss needs to be noticed.Commonly 0.5 assumed.

Other margins

Cable loss, Tx antenna gain noticed as earlier

GainAntennaTransmitonlossMHAinserti-lossCabler)TxPowerUseower,MIN(MaxTxPEIRPDownlink

MobileCommProfessionals, Inc.Max Tx power per radio link


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The maximum allowed downlink transmit power for each connectionis defined by the RNC admission control functionality

Vendor specific

Maximum DL power depends on

Connection bit rate

Service Eb/N0requirement (internal RNC info)CPICH transmit power and group of other RNC parameters

Actual available DL power per user depends on maximum total BTSTX power, DL traffic amount and distribution over the cell (All usersshare same amplifier)



110/142

Receiver - Handset

Handset Noise Figure

Handset NF varies between

frequency and can vary

between different models

Interference margin

Interference margin isdefined based on downlink

load and interference

Thermal noise

As defined in Uplink

Interference floor

marginceinterferenfigurenoiseHandsetnoisehermal_I Tfloorenterferenc

MobileCommProfessionals, Inc.Handset Noise Figure


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Handset noise figure varies between frequencies as well as

between models 3GPP Specification defines certain limits for UE performance

for different frequencies

For higher frequencies (e.g. 2 GHz) specification defines 9

dB requirement for UEFor lower frequencies (e.g. 900 MHz) 11 dB requirement is

specified



112/142

Service Eb/No

Related to the selectedservice in DL

Channel model

BLER targets etc,

Refer to Uplink part

Service Processing gain

Related to the service

bit rate

Receiver Sensitivity

As defined in UL

GainProcessingEb/NoRequirede_floornterferencySensitivitReceiver I



113/142

RX antenna gain

Commonly in data cards some antenna gain

is defined, commonly this is just 2 dBi.Assumption needs to be as defined in UL

Body loss

Similarly as in uplink the DL needs toconsider the body loss if defined e.g. forvoice service in UL

DL Fast fading margin

No fast fading margin noticed in DL as wasnoted in UL. In DL fast fading margin is notusually applied due to lower power controldynamic range.

SHO gain

In SHO gain 1 dB advantage can be noticed

compared to the UL.Gain against shadowing

This is harmonized between UL/DL as theselection of better cell can happen in eitherdirection independently.

MobileCommProfessionals, Inc.Soft Handover (MDC) GainDL


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At Cell Edge, 34 dB SHO gain can be seen on required DL

Eb/No in SHO situations compared to single link reception

Combination of 23 signals

Commonly in dimensioning the DL SHO gain is assumed

to be 2.5 dB

In DLthere is also some combining gain (about 1.2 dB) as an

average over the cell this is due to UE maximal ratio

combining

soft and softer handovers included

MobileCommProfessionals, Inc.Soft Handover (MDC) GainDL


115/142

Soft HO

Softer HO



116/142

marginfadeslowBPLgainDLSHO-marginfadefastDL

losscableainRxAntennaGysensitivitReceiverrequiredpowerotropicI

s

The rest of the calculation are as

shown in Uplink link budget

Building penetration loss asdefined for UL

Location probability and

standard deviation as

defined for UL

Isotropic calculation and allowed

propagation loss are calculated

almost as earlier with few

differences (no MHA gain, DL

gains and factors)

requiredpowerIsotropic-EIRP. losspAllowedpro

MobileCommProfessionals, Inc.Must Know


117/142

The main parameters used to calculate Link Budget are:

Noise figure

Transmit power

Feeder loss

Antenna gain


118/142

R5 Uplink Link Budget

MobileCommProfessionals, Inc.Uplink Link Budget for HSDPA


119/142

Overall same approach asnormal R99 uplink link budget

except the requirement toinclude a peak overhead for theHS-DPCCH

HS-DPCCH Overhead isdependent upon the selectedassociated DCH

(16/64/128/384).

Rest of the link budget is thesame as for a conventionalUplink link budget

The soft handover gain has

effect on the cell radius and sitecoverage


120/142

R5 Downlink LinkBudget


121/142

MobileCommProfessionals, Inc.HS-PDSCH Link Budget


122/142

Max Tx poweris the allocated power forHS-PDSCH which depends on the CCCHand in shared carrier also on the requiredDCH power

41 dBm in 20 W dedicated HSDPA carrier

SINR Requirementdepends on therequired cell edge throughput

Spreading gainis calculated from theused spreading factor 16

Soft handover gainis 0 dB because noSHO on HS-PDSCH

Cell edge throughputaffects the requiredSINR


Th HSDPA d

HS-PDSCH LINK BUDGET


123/142

The HSDPA power corresponds tothe total transmit power assigned

to the HS-PDSCH and HS-SCCH.Thus in dimensioning the HS-SCCHpower have to noticed from thetotal HSDPA power.

C/I requirement computed fromSINR rather than Eb/No like in R99

R99

HSDPA

HS-PDSCH SINR should correspondto the targeted cell edgethroughput

C/I Requirement = Eb/NoProcessingGain

C/I Requirement = SINRSpreadingGain

MobileCommProfessionals, Inc.HS-PDSCH LINK BUDGET


124/142

Relationship between SINR andRLC throughput can be validatedas part of a practicalinvestigation

No fast fade margin because noinner loop power control

HS-PDSCH does not enter softhandover

Other differences:

UE antenna gain can beassumed to be 2 dBi or 0 dBi

No body lossNo soft ho gain

Gain against shadowing 2.5 dB,referring to macro cellenvironment best cell selection

MobileCommProfessionals, Inc.HSDPA signal quality SINR


125/142

Total TransmitPower

SpreadingFactor

Orthogonally

factor

TransmittedHS-PDSCHpower


126/142

MobileCommProfessionals, Inc.HS-SCCH LINK BUDGET


127/142

HS-SCCH makes use of power control based uponHS-DPCCH CQI and ACK/NACK

Usual to assume 500 mW of transmit poweralthough a greater power can be assigned for UE atcell edge

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

040

80

120

160

200

240

280

320

360

400

440

480

520

560

600

640

680

720

760

800

HS-SCCH Transmit Power (mW)

Occurances

HSDPA Tx Power = 30 dBm



HS-SCCH does not enter soft handover

MobileCommProfessionals, Inc.HSDPA ThroughputOrthogonality


128/142

Close to the BTS the own cell

interference dominates and

SINR depends only on HSDPA

power share of total cell power

and orthogonality

Even in these optimal

conditions high throughput

requires high orthogonality

Orthogonality of higherthan 0.9 can be achieved in

isolated environment

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

Throughput, kbps

Ort

hogonality

10% BTS power for HSDPA 50% BTS power for HSDPA

80% BTS power f or HSDPA

116 tot

PDSCHHS

P

P

SFSINR


129/142

R6 Uplink Link Budget


130/142

MobileCommProfessionals, Inc.HSUPA Uplink Link Budget


131/142

Eb/No look-up tables

Cell Edge Throughput

Target BLER

Propagation Channel

used to index the Eb/Nolook-up table and

determine an appropriateEb/No figure as well ascalculate processing gain

Eb/No values are included for

Bit rates 32 kbps to 1920 kbpsTarget BLER 1, 5 and 10 %

Propagation channels Vehicular A 30 km/hr and PedestrianA 3 km/hr

Eb/No values include E-DPDCH, E-DPCCH and DPCCH


132/142

MobileCommProfessionals, Inc.HSUPA Uplink Link Budget


133/142

The receiver sensitivity calculation is the same as that fora R99 DCH link budget

Receiver Sensitivity =Interference floor + Eb/No -Processing Gain

Receiver RF parameters, gains and margins are thesame as for a R99 DCH link budget

same fast fade margin due to same inner looppower control

No differences in calculations


134/142

CPICH Link Budget

MobileCommProfessionals, Inc.CPICH Link Budget


135/142

CPICH reception is required for cellaccess and synchronisation

The CPICH link budget is similar to thedownlink service link budget

The CPICH transmit power is defined byRNC parameter

The CPICH link budget is calculatedbased on C/I requirement (Ec/Io) of -15dB

CPICH reception does not benefit fromsoft handover

Channel CPICH

Service Pilot

Transmitter - Node B

Pilot Tx Power 33.00 dBmCable Loss 0.5 dBi

MHA Insertion Loss 0.0 dB

Tx Antenna Gain 18 dB

EIRP 50.5 dBm

Receiver - Handset

Handset Noise Figure 7 dB

Thermal Noise -108 dBm

Downlink Load 80 dBInterference Margin 6.99 dB

Interference Floor -94.0 dBm

Required Ec/Io -15.0 dB

Receiver Sensitivity -109.0 dBm

Rx Antenna Gain 0 dB

Body Loss 3 dB

DL Fast Fade Margin 0 dB

SHO gain 0 dB

Gain against shadowing 2.5 dB

Building Penetration Loss 12 dB

Indoor Location Prob. 90 %

Indoor Standard Dev. 10 dB

Shadowing Margin 7.8 dB

Isotropic Power Required -88.7 dB

Allowed Prop. Loss 139.2 dB


When cell radius is known the cell area can be calculated

Cell Type and Cell Area


136/142

When cell radius is known, the cell area can be calculated

Often traditional hexagon model is considered

R

Omni

A = 2.6 R2

Bi-sector

A = 1.73 R2

Tri-sector

A = 1.95 R2

R

R

MobileCommProfessionals, Inc.Coverage AreaHexagons vs. Cells


137/142

Three hexagons Three cells

MobileCommProfessionals, Inc.Coverage Dimensioning


138/142

Planned area and the environment features

Coverage probability

Indoor coverage

Cell load

System parameters

Equipment performance

Propagation model

Create link budget

Max cell radius

Calculate site area

Site quantity

Maximumpath loss

Total coveragearea

Analyze the customers request

Area per site = 1.95*R2

Site quantity = planned area / site

coverage area

MobileCommProfessionals, Inc.Compare UMTS and GSM Planning

I GSM t th f i f h llWCDMA th d t t h l


139/142

In GSM system, the frequencies for each cell are

planned in order to control the co-frequency and

adjacent-frequency interference.

If the interference requirement is met, the

number of supported subscribers can be

calculated based on the number of carriers and

the number of timeslots.

The coverage of the GSM system depends on the

transmit power of the transmitter and the

demodulation performance of the receiver.

GSM system mainly offers voice service, and the

GoS and design objective are correspondingly

simple.

f1

f1

f2

f2

f3

f1

f1

f2

f2

f3

f3f1

f2f1

f3

f1

WCDMA uses the spread spectrum technology,

11 frequency multiplexing without frequency

planning.

The capacity of each carrier in WCDMA is "soft"

because it is related to factors such as environment

and adjacent-cell interference.

The coverage of the WCDMA system is related to

the system load. If the system load increases, the

coverage/quality will decrease.

The WCDMA system supports services with

different rate and QoS, including voice service, and

their coverage capability is different. In the network

planning, the system performance shall be

optimized through reasonable planning and radio

resource management.

f1

f1

f1

f1

f1

f1

f1

f1

f1

f1

f1f1

f1f1

f1

f1

MobileCommProfessionals, Inc.Planning Constraints


140/142

Planning should meet current standards and demands andalso comply with future requirements.

Uncertainty of future traffic growth and service needs.

High bit rate services require knowledge of coverage and

capacity enhancements methods.

Real constraints

Network planning depends not only on the coverage but

also on load.

MobileCommProfessionals, Inc.Summary

WCDMA Planning Process Overview


141/142

WCDMA Planning Process Overview

CW Test Purpose

Model Tuning

Parameters


WCDMA Link Budget R99

R4

R5

R6

CPICH Link Budget Criterion

Cell Area Calculation




142/142

HAPPY LEARNING

MobileCommProfessionals, Inc.www.mcpsinc.com

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Documents

3) Link Budget Designing