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1Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

SMS4DC training seminar27 November – 1 December 2006

SMS4DC training seminar27 November – 1 December 2006

Point – to – pointRadiocommunication

Point – to – pointRadiocommunication

2Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

ContentContent

• Technical overview• SMS4DC Software link calculation• Exercise

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3Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Point-to-point Radiocommunication LinkPoint-to-point Radiocommunication Link

Propagationloss

Receiver

Filters,feeder, etc.

Isotropic antenna

Transmitter

RX antennacable lose

Receivingantenna gain

Filters,feeder, etc.

TX antennacable lose

Transmittingantenna gain

Isotropicantenna

f1 f2 fnrepeater repeater

Hop 1 Hop 2Terminal Terminal

A Radio Link

A Hop

4Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

• Point-to-point communicationRadiocommunication between specified fixed stations

• FadingFluctuation of signal level respect to stable condition for number of reasons

• Path ProfileA vertical cut of terrain along propagationpath between transmitter and receiver

• NFDDiscrimination gained because of TXemission and RX reception masks

• PolarizationThe locus of electric field vector fluctuation

• SWRStanding Wave Ratio ([1+|Г|]/[1-|Г|])

DefinitionDefinition

Minimum acceptable signal level

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5Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Link BudgetLink Budget• Total Loss = [Free Space Loss]

+ [Atmospheric Gaseous Loss]+ [Rain Attenuation]+ [Clear Air Fading]+ [Diffraction Loss]+ [NFD]

• Flat Receive Level = PT + GT– [Free Space Loss]– [Atmospheric Gaseous Loss]– [Diffraction Loss]– GR– [Receiver Insertion Loss]

• Fade Margin = [Flat Receive Level] – [Receiver Threshold]• Insertion Loss= [Cable Loss]+[Branching Loss]+[Mismatch Loss]

24

Loss

Space

Free

λπ=d

6Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

YdB (usually Y = 6dB to noise floor)

noise floorspectrum floor

Occupied bandwidth

%2

β%

2

β

frequency1f 2f3f 4f

2|)(| fX

Normally ββββ = 0.5 %

Power Spectral Density of x(t) :

∫=4

3

2)( |)(|

f

f

tx dffXP = Area of yellow color

)(22

200|)(||)(|

4

2

1

3

tx

f

f

f

f

PdffXdffXβ== ∫∫

RF Signal SpectrumRF Signal Spectrum

Out of band emission

Necessarybandwidth

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7Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Transmitting and Receiving MasksTransmitting and Receiving Masks

• The power spectral density (PSD)

• Normally each TX has identical corresponding RX receiving masks

• Mismatched TX & RX masks cause additional loss (NFD)

RF Signalxc(t)

Assigned Frequency

Necessary bandwidth

Spurious emissions

Spectrum floor

0 dB

Transmitter emission mask

Noise floor

~6 dB

8Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Propagation EffectsPropagation Effects

• Diffraction fading due to obstruction of the path;• Attenuation due to atmospheric gases;• Fading due to atmospheric multipath or beam spreading

(commonly referred to as defocusing) associated with abnormal refractive layers;

• Fading due to multipath arising from surface reflection;• Attenuation due to precipitation or solid particles in the

atmosphere;• Variation of the angle-of-arrival at the receiver terminal and

angle-of-launch at the transmitter terminal due to refraction;• Reduction in cross-polarization discrimination (XPD) in

multipath or precipitation conditions;• Signal distortion due to frequency selective fading and delay

during multipath propagation.

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9Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Propagation LossPropagation Loss

• Attenuation due to atmospheric gases,• Diffraction fading due to obstruction or partial

obstruction of the path,• Fading due to multipath, beam spreading and

scintillation,• Attenuation due to variation of the angle-of-

arrival/launch,• Attenuation due to precipitation,• Attenuation due to sand and dust storms

10Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Gaseous Attenuation (ITU-R P.676)Gaseous Attenuation (ITU-R P.676)

• Considerable lossabove 10 GHz

• High attenuation frequencies havespecial usages

H O2

H O2

102

10

10– 1

10– 2

1

10– 3

2

5

5

2

5

2

5

2

5

2

Spe

cific

atte

nua

tion

(dB

/km

)

3.552 52 2102

101

Dry airDry airTotal

Frequency, f (GHz)

Pressure: 1 013 hPaTemperature: 15° CWater vapour: 7.5 g/m3

dBdA aa γ=

6

11Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

k-factork-factor

• Electromagnetic wave bends while passing through non-homogenous medium,

• Vertical profile of atmosphere is non-homogeneous,

• Median effective Earth radius factor :• Effective radius of Earth in km:

• See ITU-R P.453 for ∆N (vertical refractivity gradient),

k > 1 k < 1

ee ka ×= 6371]157/[15750 Nk ∆−=

Actual Modified Actual Modified

12Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Propagation by Diffraction (ITU-R P.526)Propagation by Diffraction (ITU-R P.526)

• Diffraction over a sphericalearth for trans-horizon paths

• Diffraction by obstaclesinside Fresnel zone

• Consideration of diffraction from round, wedge and sharp obstacles, single and multiple (in P.452 propagation model)

shadow

LOS is possible

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13Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

• More than 90% of power, propagates inside first ellipsoid• For Line – of – Sight (LOS) communication first Fresnel

ellipsoid should be enough clear

Fresnel ellipsoidsFresnel ellipsoidsn =1 n =2Fresnel Ellipsoids

M

2AB MBAM

λn+=+

Wavelength

A B

14Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Fresnel zoneFresnel zone

nR

2/1

21

21

)(550

+=

fdd

ddnRn

Radius of nth Fresnel zone

2d1d

f is frequency in MHz and all distances are in km

nR

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15Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Diffraction FadingObstruction of the Path

Diffraction FadingObstruction of the Path

• No LOSpath

• ObstructioninsideFresnel zone

16Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

• 0.6 F1 clearance is necessaryfor tropical climate

Diffraction loss and clearanceDiffraction loss and clearance

40

30

20

10

0

– 10

B

D

Ad

– 1 0 1– 1.5 – 0.5 0.5

Diff

ract

ion

loss

re

lativ

e t

o fr

ee

spa

ce (

dB

)

Normalized clearance h/F1

B: theoretical knife-edge loss curve

D: theoretical smooth spherical Earth loss curve,at 6.5 GHz and k = 4/3

A: empirical diffraction loss for intermediate terrain

h: amount by which the radio path clears the Earth’s surfaceF: radius of the first Fresnel zone

Obstruct

1st Fresnel zone

Negative h

Positive h h

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17Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Antenna Height Determination(Single Antenna in tropical climate)

Antenna Height Determination(Single Antenna in tropical climate)

• Step 1: Determine antenna heights for 1.0F1 clearance in median k- factor (k50 = (157/(157-∆N)) or k =4/3)

• Step 2: Determine antenna heights for 0.6F1 using effective k-factor from the following figure

• Step 3: Select the larger antenna heights

• In temperate climatestep 2 will be down using0.0F1 for single isolated obstruction or 0.3F1 for obstruction is extendedalong a portion of the map

10210252

1

1.1

0.9

0.8

0.7

0.6

0.5

0.4

0.3

Path length (km)

ek

18Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Multipath FadingMultipath Fading

Beam Spreading(defocusing)

Antenna Decoupling(governs the minimum beamwidth)

surface Multipathatmospheric Multipath

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19Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Multipath Fading ElementsMultipath Fading Elements

• Multipath fading depends on:– Refractivity gradient in the lowest 65m of atmosphere – Area terrain roughness– Path inclination– Exceedance time percentage– Frequency– Altitude of antennas

• Calculation method explained in ITU-R P.530

20Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Hydrometer AttenuationHydrometer Attenuation

• Can be ignored in frequencies below 5 GHz• ITU gathered rain statistics during 15 year (ITU-

R P.837),

• Specific attenuation γR depends on polarization and frequency,

• Rain attenuation exceedance can be estimated within 0.001% to 1% of the time

dBα=γ kRR

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21Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

XPD Degradation(XPD: Cross-polarization discrimination)

XPD Degradation(XPD: Cross-polarization discrimination)

• XPD defined in ITU-R P.310• A measure of polarization diversification

• Multipath occurrence and precipitation degrade XPD

TX RX

H H

V

TX RX

H

V

V

XPolR

CoPolR

P

PXPD

,

,=

22Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Techniques to Reduce Multipath FadingTechniques to Reduce Multipath Fading

• Using inclined path to reduce flat fading due to atmospheric mechanisms (beam spreading, antenna decoupling, and atmospheric multipath);

• Reducing the occurrence of significant surface reflections;– Using terrain shielding,– Moving reflection point to poorer location

• Using vertical polarization over water• Prevention of larger value of clearance• Using diversities

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23Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Diversity TechniqueDiversity Technique

• Space diversity– To combat specular surface reflection– To combat surface multipath fading

• Angle diversity (two antennas indifferent orientation, in same ordifferent heights)

• Frequency diversity, more than one frequency used for transmission

24Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Interference MechanismsInterference Mechanisms

• Long-term mechanisms• Short-term mechanisms

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25Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Long-term Interference Propagation Mechanisms (P.452)

Long-term Interference Propagation Mechanisms (P.452)

0452-01155471

FIGURE 1

Long-term interference propagation mechanisms

Tropospheric scatter

Diffraction

Line-of-sight

26Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Short-term Interference Propagation Mechanisms (P.452)

Short-term Interference Propagation Mechanisms (P.452)

0452-02155471

FIGURE 2

Anomalous (short-term) interference propagation mechanisms

Hydrometeor scatter

Elevated layerreflection/refraction

Ducting

Line-of-sight withmultipath enhancements

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27Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Exercising SMS4DCExercising SMS4DC

28Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Types of RF Channel Arrangements

Types of RF Channel Arrangements

• Homogeneous channel arrangement

• Uniform channel arrangement

• Non-uniform channel arrangement• References:

– ITU-R Recommendations, F series,– CEPT Recommendations,

,....2,1,0,MHz0 =⋅++= nXSnfff offsetn

,....2,1,0,MHz0 =⋅+= nXSnffn

,....2,1,0,MHz0 =⋅+′+=′ nXSnfff offsetn

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29Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Homogeneous RF Channel Arrangements (F.746)

Homogeneous RF Channel Arrangements (F.746)

1 3

2 4XS

XS2

XS

H(V)

V(H)

A

YSN N

1 3

2 4ZS

B

YS

Alternated patternMain frequencies

Channel numberPo

lari

zatio

n(A)

H(V)

V(H)

21 3 4

2r1r 3r 4r

N

Nr

21 3 4

2r1r 3r 4r

DS

N

Nr Channel numberZSYS

A B

XS

Band re-use in theco-channel mode

Main frequency pattern

(B)

A: “go” channels B: “return” channels

H(V)

V(H)

21 3 4

2r1r 3r 4r

N

Nr

21 3 4

2r1r 3r 4r

N

Nr Channel numberZSYS

A B

XS

Band re-use in theinterleaded mode

Main frequency pattern

XS

XS2

(C)

Alte

rnat

ed

RF

cha

nnel

A

rran

gem

ent

Co-

chan

nel

RF

cha

nnel

A

rran

gem

ent

Inte

rleav

ed

RF

cha

nnel

A

rran

gem

ent

Po

lari

zatio

nP

ola

riza

tion

30Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Uniform Channel ArrangementUniform Channel Arrangement

• Suitable for Simplex operation mode• More common in the bands shared

between Fixed and Mobile• The only choice for TDD transmission

– Transmitting and receiving will be down in different time slots

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31Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Exercising SMS4DC software (1)Exercising SMS4DC software (1)

• Link Calculation provided for following models in the menu of Propagation Model:– ITU-R P.370– ITU-R P.1546– ITU-R P.526– ITU-R P.452, and– ITU-R P.530

• Step 1: Lunch the SMS4DC software• Step 2: Lunch the DEM view using toolbar push

button

32Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Exercising SMS4DC software (2)Exercising SMS4DC software (2)

• Step 3: Establish Fixed station A using set the frequency to 890 MHz

• Step 4: Choose antenna “ant_ALE8603_806.ant” and check the antenna pattern

• Step 5: Establish an other Fixed station B using set the frequency to 880 MHz

• Step 6: Choose antenna “ant_ALE8603_806.ant” and check the antenna pattern

• Step 7: Open the administrative part from “Database->Licensing”

• Step 8: Select “Anonymous Station” and find station B,

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33Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Exercising SMS4DC software (3)Exercising SMS4DC software (3)

• Step 9: Open Antenna Information Table of station B• Step 10: Push the “Modify” button,• Step 11: Change the field “Class of Antenna” from “T” to “R”• Step 12: Push the “Save” button,• Step 13: Find the station A and go to the level of

“Frequency”• Step 14: Push the “Add Receiver” button top of the

“Frequency Information” table of station A. The “Add Receiver” dialog box will appear.

• Step 15: Select the “Point” Radio button. All the selectable receivers will be displayed in relevant spreadsheet

34Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Exercising SMS4DC software (4)Exercising SMS4DC software (4)

• Step 16: Choose the station B from table under POINT section and push ok

• Step 17: Close Administrative dialog box• Step 18: Open the “Database” menu and select “Display

Link”.• Step 19: Select the record of new established hop• Step 20: Push OK button to display stations of selected

hop on map

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35Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Exercising SMS4DC software (5)Exercising SMS4DC software (5)

• Step 21: Open the menu “Propagation Model” and select Link item under the ITU-R P.370 propagation model

Values with colored background can be tried respect to the editable values

Changing direction of calculation

Push button to save profile

36Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Exercising SMS4DC software (6)Exercising SMS4DC software (6)

• Step 21: Repeat step 21 for P.452 and P.526 propagation model. See the different calculated results

• Step 22: Repeat step 21 for P.530 propagation model. See the different calculated results

• Step 23: Use mouse drag to change antenna height and manage reflection points

• Step 24: Push “Reflection Points”button to see spreadsheet of reflection points Profile data

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37Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

Exercising SMS4DC software (6)Exercising SMS4DC software (6)

• Step 25: Push “Availability”button to see the availability calculation result

38Caribbean Seminar for Training of the Trainers in Sp ectrum Management System for Developing Countries (S MS4DC)St John’s, Antigua and Barbuda, 27 November – 1 Decem ber 2006

EndEnd