dBm

dBm =Decibel unit in reference toa power unit which is 1mW. x = 10 log10 ( P / 1mW )

where:x is in dBm

0 dBm [ 1mW / 1mW ]

10 dBm [ 10mW / 1mW ]

20 dBm [ 0.1W / 1mW ]

- 3 dBm [ 0.5mW / 1mW ]

3 dBm [ 2mW / 1mW ]

30 dBm [ 1W / 1mW ]

- 50 dBm [ W / 1mW ]

- 75 dBm [ 0.032nW / 1mW ]

- 110 dBm [ 0.01pW / 1mW ]


dBi vs dBd

dBi is a unit to measure antenna gainin reference to an isotropic antenna.An isotropic antenna has a power gain of unity; i.e., O dBi.

dBd is a unit to measure antenna gain inreference to a lossless half-wave dipole antenna. A lossless half-wave dipole antenna has a power gain of 0 dBd.

CONVERSION FACTOR:

dBi = dBd + 2.15 dB

id


EFFECTIVE RADIATED POWERERP vs EiRP

ERP (Effective Radiated Power): is the radiated power (transmit power times antenna gain) with respect to a dipole antenna within a given geographic area.EiRP (Effective Isotropic Radiated Power): is the radiated power from an isotropic antenna.

EiRP = ERP + 2.15 (dB)

EiRPLp

SSdesign


OBJECTIVES OF

LINK BUDGET ANALYSIS

to estimate the maximum allowable path loss to compute the required BS transmitter power

for a balanced path to estimate the coverage design threshold to evaluate technology performance

Tx Combiner Feeder

Feeder

RxTx

RxReceiverDivider

Feeder

FeederGdBTS

LcBTS LfBTS

GaBTS Lp

Lp

GaMS

LfMS

PinBTS

PoutBTS

LfBTS

GaBTS

PoutMS PinMS

RF PATH

WHY BALANCED PATH?

BS does nothear the MS

MS hears the BS

Strong SignalWeak Signal

UPLINK LIMITED:

DOWNLINK LIMITED:

BS hears the MSMS does nothear the BS

Weak SignalStrong Signal

HOW TO BALANCE PATH?

Coverage in a two-way radio communication system is decidedby the weakest transmission direction.

AssumeUplink Limited

Balance Path Compute BSTx Power Output

Path Loss in Uplink = Path Loss in Downlink

Balanced Path:

LINK BUDGET ANALYSIS

LBA ProcessorEngineer

INPUT OUTPUT

Rx SensitivityMS Max. Power

CoverageThresholdReliability

Equipment /Technology

Maximum Path Loss

CoverageThreshold

BS TX PowerOutput - Balanced

Path

Gain Loss

AntennaPA

Diversity

CombinerFeeder

Connectoretc

Cell Radiusand Count

INPUT TO LBA





Gain Loss

AntennaPA

Diversity

CombinerFeeder

Connectoretc


MS RX SENSITIVITY and BTS RX SENSITIVITY

Sensitivity

GSM900 MS RX SENSITIVITY

MS TYPE Sensitivity ValueEricsson MS - 104 dBmGSM900 Recommendation - 102 dBm

GSM900 BTS RX SENSITIVITY

BTS TYPE Sensitivity ValueEricsson RBS 2000/2301/200 - 107 dBmGSM900 Recommendation - 104 dBm

NokiaLCC


MS RX SENSITIVITY and BTS RX SENSITIVITY

V to dBm

Sensitivity

In the conversion of V to dBm, a terminal impedance should be known.

EXAMPLE:A receiver has a sensitivity of 0.1 V. What is the equivalent level in decibels above 1 mW if the terminal impedance is 50?

(x) dBW = 10 log [ (V2/R) / 1 W ](x) dBW (y) dBm


MS POWER CLASSES

GSM900 MS Power Classes and CorrespondingMaximum Power Levels:

POWER CLASS Maximum Power Level

1 (20 Watts)

2 39 dBm (8 Watts)

3 37 dBm (5 Watts)

4 (handheld) 33 dBm (2 Watts)

5 (handheld) 29 dBm (0.8 Watt)

Originalpower &is noweliminated.

Class 4

33 dBm / 2 Watts

Power Control Level Peak Output Power (dBm)0 -1 -2 393 374 355 336 317 298 279 2510 2311 2112 1913 1714 1515 1316 1117 918 719 5


GSM900 MS POWER CONTROL LEVEL


CELL COVERAGE

MSSENS + MARGINS

Indoor In-Car Outdoor


MARGINSIndependentof theEnvironment

EnvironmentDependent

RayleighFadingMargin

InterferenceMargin

BodyLoss

Outdoor Log Normal Fading Margin

Outdoor + Indoor Log NormalFading Margin

Car Penetration Loss

Mean Building Penetration Loss




InterferenceMargin

BodyLoss

REQUIRED SIGNAL STRENGTH, SSreq

SSreq = MSsens + RFmarg + IFmarg + BL

where MSsens = MS SensitivityRFmarg = Rayleigh Fading MarginIFmarg = Interference MarginBL = Body Loss




InterferenceMargin

BodyLoss

RAYLEIGH FADING MARGIN

RFmarg = 3 dB* (slow MSs, no FH)RFmarg = 0 dB* (with FH)

*based on Ericsson GSM900 RF Guidelines FH = Frequency Hopping




InterferenceMargin

BodyLoss

INTERFERENCE MARGIN

IFmarg = 2 dB*

*based on Ericsson GSM900 RF Guidelines

Nokia and LCC define this as Interference Degradation Margin. LCC uses about 3 dB.




InterferenceMargin

BodyLoss

BODY LOSS

BL = 5 dB*

*based on Ericsson GSM900 RF Guidelines

LCC values for Body Loss = 2 - 4 dBETSI recommended value is 3 dB


MARGINSEnvironmentDependent

DESIGN LEVEL, SSdesign

SSdesign = SSreq + LNFmarg(o) -MS outdoorSSdesign = SSreq + LNFmarg(o) + CPL -MS in-carSSdesign = SSreq + LNFmarg(o+i) + BPLmean -MS indoor

where SSreq = Required signal strengthLNFmarg(o) = Outdoor log normal fading marginLNFmarg(o+i) = Outdoor + indoor log normal fading marginCPL = Car penetration lossBPLmean = Mean building penetration loss







>THRESHOLD

LOG NORMAL FADING MARGIN

% AREA COVERAGE

% BORDER COVERAGE

JAKE’SFORMULAS


LOG NORMAL FADING MARGINS

90% AREA COVERAGE

50% BORDERCOVERAGE

threshold+ 4.5 dB

LNF Marginat 7 dB

standarddeviation

75% BORDERCOVERAGE

In order to plan for morethan 50% probability of signalstrength above a threshold, alog normal fading margin isadded to the threshold duringthe design process. (Ericsson)

(Nokia)


LOG NORMAL FADING MARGINS

Log NormalFading Marginin a Multi-CellEnvironment

Jakes’ formula does nottake the effect of manyservers into account.The presence of many serversat the cell borders will reducethe required log normal fadingmargin. (Ericsson)


OUTDOOR LOG NORMAL FADING MARGINS

% AREA COVERAGE

LNF(o) (dB) 75 85 90 95 99

6 -3 -1 1 3 7

8 -3 0 2 5 10

10 -3 0 3 6 12

12 -3 1 4 8 15

14 -3 1 4 9 17

Outdoor Log Normal Fading Margins (LNFmarg(o) ) in dB for different environments (LNF(o) ).

Suburban/Rural

Urban

Dense Urban


OUTDOOR + INDOORLOG NORMAL FADING MARGINS

% AREA COVERAGE

LNF(o+i) (dB) 75 85 90 95 99

10 -3 1 3 7 13

12 -3 1 4 8 15

14 -3 1 4 9 17

Outdoor + Indoor Log Normal Fading Margins(LNFmarg(o+i) ) in dB for differentenvironments (LNF(o+i) ).

Suburban

Urban

Dense Urban







CAR PENETRATION LOSS

CPL = 6 dB*

*based on Ericsson GSM900 RF GuidelinesLCC value is 4 to 10 dB CPL (portable)







BUILDING PENETRATION LOSS

BPLmean (dB)*

Dense Urban 18Urban 18Suburban 12

* based on Ericsson GSM900 RF GuidelinesLCC value is 10 - 20 dB


BASE STATION RF COMPONENTS

LNA

PA RX1 RX2

Duplexer

Power AmpifierReceiver withsensitivity

ReceiverMulticoupler

Combiner

Bottom Jumper Cables

Main CableFeeder

Connector

Lightning Arrestor

Top JumperCables

RX1 TX/RX2


RF COMPONENTS

GAINS LOSSES

MS BS MS BS

Antenna Antenna Feeder Main Cable/FeederPower Amp Power Amp Duplexer

Diversity CombinerLNA Jumper Cable

ConnectorLightning Arrestor

Gains

Losses


BASE STATION ANTENNAS

Gains

OmniAntenna7- 11 dBi

DirectionalAntenna11- 17 dBi

Antenna gain plays avery important role inthe maximum allowablepath loss.


MOBILE AND PORTABLE ANTENNAS

Gains

Portable antennastypically haveno gain

0 dBi

Mobile antenna gain1 - 4 dBi


AMPLIFIERSTX Power Amplifier & Low Noise Amplifier

Gains

LNA

RX1 TX/RX2

TX PowerAmplifier

Low Noise Amplifiertypical gain up to 20 dB

TX Power Amplifier

System PA Output RangeGSM 2.5 - 32 WattsTACS 0.5 - 100 Watts


DIVERSITY

Gains

LNA

RX1 TX/RX2

RX RX


DIVERSITY SCHEMES

Gains

LNA

RX1 TX/RX2

•SPACE DIVERSITYd = 10 minimum according to LCCd = 12to 18 according to Ericsson

Smart uses 4 meters RX separation for GSM900/ETACS

•POLARIZATION DIVERSITY

For Ericsson, both schemes will give a gain of 3 to 6 dB.

For Nokia, the practical range is 0 to 5 dBdepending on environment and antennainstallation (separation). When BTS RX diversity is used,the default value is 4 dB for urban areas.

d


DIVERSITY COMBINERS

Gains

RX RX

RXSelectiveCombining

SwitchedCombining

usually used in Mobiles

RX RX

+Maximal-RatioCombining

RX RX

+

Equal-GainCombining

commonlyused in BS’s

(S/N)ii=1

M

(Envelope)ii=1

M


DIVERSITY GAIN TABLE

Gains

LNA

RX1 TX/RX2

Manufacturer Diversity Combining Diversity(Technology) Scheme Method Gain

Nokia MaximumGSM/DCS1800 Space Ratio 3.0 dB

Ericsson MaximumGSM/DCS1800 Space Ratio 3.0 dB


another DIVERSITY SCHEMEFREQUENCY HOPPING for

Frequency Diversity

Gains

0.5 to 2.5 dB FH Gain


CABLE LOSSES (BS)

Losses

LNA

RX1 TX/RX2Jumper CablesLDF4-501/2 inch Heliax Foam2.160 dB loss per 100 ft at 900 MHz

Main Cable / Feeder CableLDF5-507/8 inch Heliax Foam1.210 dB loss per 100 ft at 900 MHzrecommended use < 55 meters


CONNECTOR LOSS (BS)

Losses

LNA

RX1 TX/RX2

Connectors connect RFcomponents and typicallyhave a loss of 0.1 dB each.


LIGHTNING ARRESTOR LOSS (BS)

Losses

LNA

RX1 TX/RX2

LightningArrestor

Loss = 0.1 dB


COMBINER LOSS (BS)

Losses

PA RX1 RX2

Duplexer

Characteristic Cavity Hybrid

Frequency Range 806-960 806-1000(MHz)

Continuous Input 150 150Power (Watts)

Insertion Loss (dB) 2 to 4.8 3.8 to 7.4

Maximum VSWR 1.5 : 1 1.5 : 1

Combiners


DUPLEXER LOSS (BS & MS)

Losses

PA RX1 RX2

Duplexer

Duplexer Characteristic Value

Isolation (across all 3 ports, with >60 dBunused ports terminated at 50

Insertion Loss (across all ports) 0.5 dB

Power handling 500 W

Maximum Input VSWR 1.5 : 1

OUTPUT OF LBA


Maximum Path Loss

CoverageThreshold


Path


Maximum Path Loss

MAXIMUM ALLOWABLE PATH LOSS (MAPL)

Uplink Path Loss

Uplink Path Loss = MAPLfor uplink limited system

Maximum Path Loss

UPLINK PATH LOSS

RxReceiverDivider

Feeder

FeederGdBTS

PinBTS = BTSSENS LfBTS

GaBTS

Feeder

RxTx

GaMS

LfMS

PoutMS PinMS

PLUP + FM

LdupMS

BTSSENS = PoutMS - LdupMS - LfMS + GaMS - PLUP

+ GaBTS - LfBTS + GdBTS - FM - others

PLUP = PoutMS - BTSSENS - LdupMS - LfMS + GaMS

+ GaBTS - LfBTS + GdBTS - FM - others

Maximum Path Loss

DOWNLINK PATH LOSS

Feeder

RxTx

GaMS

LfMS

PoutMS PinMS = MSSENS

PLDOWN + FM

LdupMSMSSENS = PoutBTS - LcBTS - LfBTS + GaBTS - PLDOWN

+ GaMS - LfMS - LdupMS - FM - others

PLDOWN = PoutBTS - MSSENS - LcBTS - LfBTS + GaBTS

+ GaMS - LfMS - LdupMS - FM - others

Tx Combiner Feeder

LcBTS LfBTS

GaBTS

PoutBTS

Maximum Path Loss

MAXIMUM ALLOWABLE PATH LOSS (MAPL)

UPLINK PATH LOSSPLUP = PoutMS - BTSSENS - LdupMS - LfMS + GaMS + GaBTS - LfBTS + GdBTS - FM - others

Note common parameters!!!

DOWNLINK PATH LOSSPLDOWN = PoutBTS -MSSENS - LcBTS - LfBTS + GaBTS+ GaMS - LfMS - LdupMS - FM -others

MAPL = PLUP


Path

BS TX POWER OUTPUT

UPLINK PATH LOSSPLUP = PoutMS - BTSSENS - LdupMS - LfMS + GaMS + GaBTS - LfBTS + GdBTS - FM - others

Note common parameters!!!

DOWNLINK PATH LOSSPLDOWN = PoutBTS -MSSENS - LcBTS - LfBTS + GaBTS+ GaMS - LfMS - LdupMS - FM -others

PLUP = PLDOWN = MAPL

PoutBTS = PoutMS + GdBTS + LcBTS + (MSSENS - BTSSENS)

Balanced Equation

CoverageThreshold

COVERAGE THRESHOLD

EiRP(balanced)

PenetrationLoss

MAPL

COVERAGETH

CoverageThreshold

COVERAGE THRESHOLD

COVERAGETH

Feeder

RxTx

GaMS

LfMS

PoutMS PinMS = MSSENS

LdupMSCOVERAGETH = PinMS + LdupMS + LfMS - GaMS + FM + other

COVERAGETH = EiRP(balanced) - MAPL

EiRP(balanced) = PoutBTS - LcBTS - LfBTS + GaBTS

COVERAGETH = SSDESIGN

CoverageThreshold

COVERAGE ENVIRONMENTS with GSM900 Coverage Thresholds

On StreetPortable- 95 dBm

In Car Portable- 85 dBm

Vehicle MountedMobile- 95 to -100 dBm

In Building Portable - 75 dBm

LBA DATA SHEET


INPUT OUTPUT




Maximum Path Loss

CoverageThreshold


Path

Gain Loss

AntennaPA

Diversity

CombinerFeeder

Connectoretc


CELL SIZE ESTIMATION

CellRadius

Estimate

MAPLPropagationLoss Model

Required Input

d

R

PROPAGATION LOSS MODEL

OKUMURA-HATA MODEL

Lp(urban) = 69.55+ 26.16logf - 13.82loghb + (44.9 - 6.55loghb)logR - a(hm)

whereLp = Path Loss in dBa(hm) = (1.1logf - 0.7)hm - (1.56logf - 0.8)f = carrier frequency in MHz (150-1000 MHz)hb = the base station antenna height in meter (30-200m)R = distance in km from the base station (1-20 km)hm = mobile antenna height in meter above ground (1-10m)



CELL RADIUS ESTIMATEBASED ON OKUMURA-HATA MODEL

d

R

MAPL - 69.55 - 26.16logf + 13.82loghb + a(hm)

44.9 - 6.55loghb

log R =

* urban area


CELL COUNT ESTIMATION

CellCount

Estimate

TechnologyLBA

MAPLMobile TypeEnvironment

Area BoundariesType of Coverage

DemographicsTraffic Assumptions

ReUse Pattern

Required Input

d

R


CRUDE CELL COUNT ESTIMATION

R

A

2.6 R2

Cell Count =

Cell Radius, R, from Okumura-Hata’s FormulaA = Market Area


CONCLUSION1. What is receiver sensitivity?2. What is Fade Margin/Log-Normal Margin?3. Why do we care about coverage reliability?4. What is diversity?5. How many different kinds of diversity exist?6. Why balanced path?7. How does the environment affect LBA?

link budget analysis1

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