005 - Introduction to Microwave Links (Asiacell Telecom Platform Course)

Introduction to Microwave Links

Asiacell Telecom Platform Course 1


By [email protected] Engineer Specialist



Micro...wave... link?



Introduction toMicrowave

Links



To describe microwave link architectures.

To define wavelength.

To define polarizations.

To describe propagation in free space.

To list propagation problems.

To list the characteristics of an antenna.

To identify the types of modulation.

To list parameters for preparing a frequency plan.

To prepare a simplified link budget.

To describe the configurations of a transceiver.

Objectives



Microwave link architectures

Signals to be transmitted

Definition

Architectures

Radio waves

Definition

Polarization

Propagation in free space

Propagation problems

Antennas

Gain

Radiation pattern

Aperture angle

Modulation

Frequency plan

Organizations

Plan

Link budget

Transceiver hardware configurations

Course content





Definition

Architectures

Radio waves

Definition

Polarization



Antennas

Gain

Radiation pattern

Aperture angle

Modulation

Frequency plan

Organizations

Plan

Link budget


Course content



Optical fibre

Copper wire

Microwave link architecturesSignals to be transmitted



MicrowaveLink




Diagram of a microwave link

TxRx

TxRx

0110111

0110111

1011101

1011101

F

F ’

Tx : transmitter

Rx : receiver

F : transmission frequency




Point-to-point radio

Point-to-multipoint radio




Offices

Hospitals

Universities

Nodal point

Offices

Offices




Central office

Heavy traffic customers

Offices






Definition

Architectures

Radio waves

Definition

Polarization



Antennas

Gain

Radiation pattern

Aperture angle

Modulation

Frequency plan

Organizations

Plan

Link budget


Course content



λ = C * T = C / F

λ : wavelength in metres,C : speed of light in metres per second,F : frequency in Hertz,T : period in seconds.

F in GHz λ in mm2 1507 42.8613 23.0823 13.0438 7.89

Radio wavesDefinition



Polarizations

Radio waves

VERTICAL POLARIZATION

HORIZONTAL POLARIZATION

CIRCULAR POLARIZATION

PROP

AGAT

ION

DIRE

CTIO

N

PROP

AGAT

ION

DIRE

CTIO

N

PROP

AGAT

ION

DIRE

CTIO

N



Polarizations

E

E

Earth horizontal

Rectangular waveguide section

Radio waves

E : electric field



Radio waves

Waveguides with different flanges

Polarizations

≅ 30 dB !



≅


Free space = no solar effects

no effects induced by atmospheric conditions

Clearance of the first Fresnel ellipsoid

Radio waves



First Fresnel ellipsoid

d

r

AM + MB = AB + (n*λ/2)

n = 1, first Fresnel ellipsoid

d : axis of radio wave path,

r : radius of first ellipsoid

Radio wavesPropagation in free space



Maximum radius of first Fresnel ellipsoid

0

5

10

15

20

25

30

35

40

0 5 10 15 20 25 30 35 40

distance in km

radi

us in

m

F (GHz)2 GHz7 GHz13 GHz23 GHz38 GHz

Radius of first Fresnel ellipsoid: rmax = 0.5*√λ*d

Propagation in free spaceRadio waves



Path Length (65.00 km)0 5 10 15 20 25 30 35 40 45 50 55 60

Elev

atio

n(m

etre

s)

0

20

40

60

80

100

120

140

160

180

200

220

240

260

Radiofrequency propagation pathFirst Fresnel ellipsoid

Radio wavesPropagation in free space




Part of the transmitted energy that is picked up by the receive antenna

Pe

Pr

d

Sr: receive antenna

equivalent surface area

Pr = Pe * Sr / (4*π*d2) , where Sr = λ2 / (4*π)

Pr = Pe * (λ / 4 * π * d)2

α = 20 log (4 * π * d / λ)

Part of the sphereof radiated isotropic power

Radio waves



Telegraphists’ equation:Propagation in free space

α = Pe / Pr = 20 log (4πD / λ)Free space losses

90

100

110

120

130

140

150

160

170

1 10 100 1000Distance in km

Loss

es in

dB

F (GHz)2 GHz 7 GHz 13 GHz 23 GHz 38 GHz

5020

Radio waves



Losses in free space and absorption losses

Refraction, multiple paths

Losses due to obstruction

Losses due to rainfall

Losses in Fresnel area

Multiple paths

Radio wavesPropagation problems



021000 21

Rddh

××

×=

COLOMBIAPROYECTO RIC chapmari.pl3

Date 09-08-99 By DO

ALCATEL

CHAPARRALLatitude 003 43 40.00 NLongitude 075 29 47.00 WAzimuth 61.13 degElevation 895 m ASLAntenna CL 0.0 m AGL

LA MARIALatitude 004 14 25.00 NLongitude 074 34 10.00 WAzimuth 241.20 degElevation 1586 m ASLAntenna CL 0.0 m AGL

Frequency = 1440.0 MHzK = 1.00

%F1 = 100.00

Path Length (117.50 km)0 10 20 30 40 50 60 70 80 90 100 110

Elev

atio

n (m

etre

s)

200300400500600700800900

100011001200130014001500160017001800

The bulging of the earth at a point on the profile is:

Radio wavesPropagation problems : correction for the roundness of the earth



Propagation problems :Effect of atmospheric refraction

Gases in the atmosphere such as water vapour and oxygen create additional attenuation over and above that produced during propagation in free space.

13 GHz 18 GHz 23 GHz 38 GHz

0.03 dB/km 0.08 dB/km 0.19 dB/km 0.12 dB/km

Radio waves




According to vertical variations in the atmospheric refractive index, microwave signals do not propagate in astraight line between antennas, but on a curved path whichchanges over time.

“Standard” conditions = 50% of the time, and the path curves towards the earth;

Unfavourable conditions = 0.1% of the time, and the path curves towards the sky.

Radio waves




kmax = 4/3, R0 = 8504 km

the radiofrequency horizonis further away and theearth seems flatter.

kmin = 2/3, R0 = 4252 km

the radiofrequency horizon is closer and the earth seems rounder.

R0 kmax R0

R0 = 6378 km

kmin R0 R0

Radio waves



60% OF RADIUS CLEARED (K=4/3)0% OF RADIUS CLEARED (K MIN) pldemo_1.pl2

Date 09-22-99 By LBT

ALCATEL

WESTONVILLELatitude 049 15 12.00 NLongitude 122 34 14.00 WAzimuth 47.41 degElevation 120 m ASLAntenna CL 36.7 m AGL

BAKER LAKELatitude 049 38 49.00 NLongitude 121 54 29.00 WAzimuth 227.91 degElevation 150 m ASLAntenna CL 53.2 m AGL

Frequency = 2000.0 MHzK = 1.33, 0.85%F1 = 100.00

Path Length (65.00 km)0 5 10 15 20 25 30 35 40 45 50 55 60

Elev

atio

n (m

etre

s)

0

20

40

60

80

100

120

140

160

180

200

220

240

Radio waves



60% OF RADIUS CLEARED (K=4/3)0% OF RADIUS CLEARED (K MIN) pldemo_1.pl2

Date 09-22-99 By LBT

ALCATEL

WESTONVILLELatitude 049 15 12.00 NLongitude 122 34 14.00 WAzimuth 47.41 degElevation 120 m ASLAntenna CL 36.7 m AGL

BAKER LAKELatitude 049 38 49.00 NLongitude 121 54 29.00 WAzimuth 227.91 degElevation 150 m ASLAntenna CL 53.2 m AGL

Frequency = 2000.0 MHzK = 1.33, 0.85%F1 = 100.00

Path Length (65.00 km)0 5 10 15 20 25 30 35 40 45 50 55 60

Elev

atio

n (m

etre

s)

0

20

40

60

80

100

120

140

160

180

200

220

240

Radio waves



Diffraction Algorithm PathlossMultiple Knife Edge Method Deygout

Maximum Number of Obstacles 2Obstacle Radius Method All obstacles

Foreground Loss Method Not Included

WESTONVILLE BAKER LAKE

Antenna Height (m) 36.66 53.15Distance (km) 65.00

Frequency (MHz) 2000.00K 0.85

Polarization VerticalTree Type Dry bare trees

Ground Type Average

1 Knife edgeProfile Segment (km) 0.00 65.00

Location (km) 38.47Clearance / F1 0.00

Loss (dB) 6.02

Diffraction loss (dB) 6.02Free Space Loss (dB) 134.75

Total Loss (dB) 140.77




WESTONVILLE BAKER LAKE



Polarization VerticalTree Type Dry bare trees

Ground Type Average

1 Knife edgeProfile Segment (km) 0.00 65.00

Location (km) 38.47Clearance / F1 0.70

Loss (dB) 0.00



Radio waves



Propagation problems:

Attenuation due to hydrometeors

Attenuation, in dB per kilometre6 GHz 10 GHz 20 GHz 40 GHz

Fine rain 0.013 0.07Downpour 0.012 0.08 0.45 1.5Storm 0.22 1.2 5.5 13Heavy storm 1.2 5.5 18 27

Radio waves



Propagation problems:


Radio waves

Per cent of Tim

e Gradient



Radio wavesPropagation problems:


Per cent of Tim

e Gradient





Definition

Architectures

Radio waves

Definition

Polarization



Antennas

Gain

Radiation pattern

Aperture angle

Modulation

Frequency plan

Organizations

Plan

Link budget


Course content



Antennas



Antennas



HornG SdB = 10 4

2logη πλ

S: projected surface areaη: antenna gain, from 50% to 70%

Frequency 2 GHz 4 GHz 8 GHz 13 GHz 23 GHz 38 GHzEfficiency 50% 50% 60% 60% 70% 70%Diameter 3.7 m 32 dB 38 dB 45 dBDiameter 2.4 m 28 dB 34 dB 42 dB 46 dBDiameter 1.2 m 28 dB 36 dB 40 dB 46 dBDiameter 0.6 m 34 dB 40 dB 44 dBDiameter 0.3 m 34 dB 38 dB

GainAntennas



Radiation patternsAntennas



Aperture angle at 3 dB

θλ

− ≈370

dB d.

Frequency 2 GHz 4 GHz 8 GHz 13 GHz 23 GHz 38 GHzDiameter 3.7 m 2.8° 1.4° 0.7°Diameter 2.4 m 4.4° 2.2° 1.1° 0.7°Diameter 1.2 m 2.2° 1.3° 0.8°Diameter 0.6 m 2.7° 1.5° 0.9°Diameter 0.3 m 3° 1.8°

Antennas





Definition

Architectures

Radio waves

Definition

Polarization



Antennas

Gain

Radiation pattern

Aperture angle

Modulation

Frequency plan

Organizations

Plan

Link budget


Course content



Modulation

Ρ Ρ

Ρ Ρ

Ρ Ρ

Ρ Ρ

Ρ Ρ

Ρ Ρ

Ρ Ρ

Ρ Ρ

Ρ Ρ

Ρ Ρ

Ρ Ρ



BPSK

Modulation

S ( t )

O.L.

Frequency F0

A ( t ) xMixer

Modulator

-1

0

1

0 1 2 3 4 5

-1

0

1

0 1 2 3 4 5

-1

0

1

0 1 2 3 4 5



X

X

OL

++π/2

Q sin ω0t

P cos ω0t

cos ω0t

P

H

A(t)

Q

F0

S(t)sin ω0t

4QAM Modulator

H/2

H/2

-1

-0,5

0

0,5

1

0 1 2 3 4 5 6 7 8 9 10

-1

-0,5

0

0,5

1

0 1 2 3 4 5 6 7 8 9 10

4QAM

-1,5

-1

-0,5

0

0,5

1

1,5

0 1 2 3 4 5 6 7 8 9 10

Modulation

-1

-0,5

0

0,5

1

0 1 2 3 4 5 6 7 8 9 10

-1

0

1

0 1 2 3 4 5



The basic duration of a symbol cannot be indefinitely reduced, but the number of bits per symbol can be increased:

2n signal states = n bits transmitted for a symbol.

The Nyquist criterion defines the Nyquist band: minimumbandwidth of a transmission channel.

Modulation Nyquist band Theoretical peak power BER

BPSK B P 10-n

4QAM B/2 P 10-n

16QAM B/4 P+6.5 dB 10-n

Modulation





Definition

Architectures

Radio waves

Definition

Polarization



Antennas

Gain

Radiation pattern

Aperture angle

Modulation

Frequency plan

Organizations

Plan

Link budget


Course content



Frequency plan

ITU: International Telecommunications Union

CEPT: European Conference on Posts andTelecommunications

FCC: Federal Communication Commission (≈ CEPT)

Organizations



Duplex separation = ⏐Fn - F ’⏐

F4

F3

F2

F1 Fn

F'4

F'3

F'2

F'1 F'nVerticalpolarization

Horizontalpolarization

CEPT T/R 13-02 Duplex separation = 1008 MHz

Fn (MHz) = F0 (MHz) + 798 + 28n

F ’n (MHz) = F0 (MHz) + 1806 + 28n

where F0 = 21,196 MHz and n =1,…,20

Frequency plan



Frequency plan

1, 3, 5 V

1 ’, 3 ’, 5 ’ V 2, 4 V

2 ’, 4 ’ V

1, 3, 5 H1 ’, 3 ’, 5 ’ H





Definition

Architectures

Radio waves

Definition

Polarization



Antennas

Gain

Radiation pattern

Aperture angle

Modulation

Frequency plan

Organizations

Plan

Link budget


Course content






BONNY LNG AMENAM



Polarization HorizontalTree Type Dry bare trees

Ground Type Average

1 Isolated obstacleProfile Segment (km) 0.00 51.16

Location (km) 25.94Radius (km) 8337.06

Clearance / F1 0.87Loss (dB) 0.00






BONNY LNG AMENAM



Polarization HorizontalTree Type Dry bare trees

Ground Type Average

1 Isolated obstacleProfile Segment (km) 0.00 51.16

Location (km) 25.94Radius (km) 11719.56

Clearance / F1 0.30Loss (dB) 5.70







Definition

Architectures

Radio waves

Definition

Polarization



Antennas

Gain

Radiation pattern

Aperture angle

Modulation

Frequency plan

Organizations

Plan

Link budget


Course content



Simplified link budgetFrequency = 23 GHzDistance = 10 kmBit rate = 2 tributariesAntenna diameter = 0.6 m

Transmittedpower

dBm

Transmitantenna gain

Received power

Free spacelosses

Threshold 10-6

≅ -87dBm

Threshold 10-3

≅ -90dBm

Threshold 10-8

≅ -85dBm

Qualitythreshold

Receive antennagain

Marginrelative toDCP : 40 dB

PTx = 12 dBm

PN = - 50 dBm

DCA

DC

DCP

Propagationalarm

DCA PRx

- 75 dBm

- 80 dBm

Connectionlosses

ConnectionlossesTx Rxα

Free space losses = - 140 dB

Tx connection losses = - 1 dBTx antenna gain = 40 dB

Rx antenna gain = 40 dBRx connection losses = - 1 dBTotal losses = -62 dB



1+0 Configuration

TxRx

TxRx

01101110

01101110

1011101

1011101

F

F ’

Hardware configurations



1+1 HSB Configuration

1011101

F ’Rx 1

1011101

FTx 101101110

Tx x

Rx xoo

Rx 1

F Tx 1 01101110

Tx x

Rx xoo




Frequency Diversity Configuration

TxRx

TxRx

F2

F2’

TxRx

TxRx

F1

F1’1100101 101010

011010

1101101




Space Diversity Configuration

TxRx

01101110

TxRx

01101110

1011101

1011101

F

F ’

TxRx

F




Microwavelink!

By [email protected] Engineer Specialist

005 - Introduction to Microwave Links (Asiacell Telecom Platform Course)

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Transcript of 005 - Introduction to Microwave Links (Asiacell Telecom Platform Course)