Transmission Planning Mod 1

Network Planning 1.1 Introduction to Network Planning

3FL 42104 AAAA WBZZA Edition 2 - July 2005

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Objectives Network Planning - Introduction to Network Planning

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3

To be able to describe concepts such as: •Polarization •Frequency plans •Antenna parameters •Free space loss

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Table of Contents Network Planning - Introduction to Network Planning

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5

Page

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7 1 Electromagnetic waves Electromagnetic waves 8 Exercise 9 Blank Page 10 2 Polarization 11 Polarization 12 Exercise 13 Blank Page 14 3 Electromagnetic spectrum 15 Electromagnetic spectrum 16 4 Radio spectrum 17 Radio spectrum 18 5 Use of the spectrum 19 Use of the spectrum 21 Blank Page 22 6 General characteristics on the ITU-R recommended frequency plans 23 General characteristics on the ITU-R recommended frequency plans 26 7 Antenna System 27 Antenna System 36 Exercise 37 Blank Page 38 8 Field strength and related parameters 39 Field strength and related parameters 41 Blank Page 42 9 Free space loss 43 - RADIO NETWORK PLANNING All rights reserved © 2005, Alcatel Free space loss 44 Exercise 45 Blank Page 46 10 Radio Network Design procedure 47 Radio Network Design procedure 48 Radio Network Design procedure 49 End of Module 50

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Table of Contents [cont.] Network Planning - Introduction to Network Planning

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1 Electromagnetic waves

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1 Electromagnetic waves

Electromagnetic waves 1-1-8

Network Planning - Introduction to Network Planning

TEM Wave

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Electromagnetic Waves An electromagnetic wave is a simultaneous interaction between an electrostatic (E) field and a magnetic (H) field. Radiated energy from an antenna, once a distance from the source, forms E and H fields, which are perpendicular to each other and to the direction of propagation and are hence referred to as Transverse Electro-Magnetic (TEM) waves. Frequency, Wavelength and Velocity Wavelength is the distance in meters between any two “similar” points on the wave. This portion of the wave is referred to as one complete cycle. Wavelength is given symbol “ ”. Frequency “f” is the number of complete cycles passing a fixed point in one second. If one cycle passes a fixed point in one second this corresponds to a frequency of 1 Hertz (Hz). In free space the velocity of an EM wave is approximately 3 x 108 ms-1. This is the speed of light (since light is an EM wave) and is usually given symbol “c”. The relationship between “c” (velocity), “f” (frequency) and “ ” (wavelength) of an EM wave is given by the equation: c=f where

c f

= velocity of propagation in ms-1 (3 x 108 ms-1) = Frequency in Hertz (Hz) = Wavelength in meters (m)

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1 Electromagnetic waves

Exercise

Network Planning - Introduction to Network Planning

1-1-9

Exercise - Wavelenght Calculate the wavelength of a 10 GHz signal.

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Network Planning - Introduction to Network Planning

2 Polarization

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2 Polarization

Polarization 1 - 1 - 12

Network Planning - Introduction to Network Planning

E

Vertical Polarization H EARTH

H

Horizontal Polarization E EARTH

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The plane of polarization is defined in terms of the orientation of the E field with respect to the earth. Vertical polarization and horizontal polarization are common forms of plane polarization.

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2 Polarization

Exercise Network Planning - Introduction to Network Planning

1 - 1 - 13

In the vertical polarization is: field E vertical to the ground? field M vertical to the ground?

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3 Electromagnetic spectrum

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3 Electromagnetic spectrum

Electromagnetic spectrum 1 - 1 - 16

Network Planning - Introduction to Network Planning

Visible Light

X-rays Radio Systems

10 0 300 000km

10 3 300km

Infra-red

10 6

10 9

10 12

300m

0.3m

300µm

Ultra-violet

10 15 0.3 µm

10 18 300pm

c= f x

Where c = 3 x 108 ms

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The Figure illustrates the electromagnetic spectrum and indicates the portion occupied by radio systems. Radio systems are identified by their frequency or wavelength of operation. The Figure shows the relationship between frequency and wavelength (Example: f = 10 GHz =3 cm.)

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Network Planning - Introduction to Network Planning

4 Radio spectrum

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4 Radio spectrum

Radio spectrum 1 - 1 - 18

Network Planning - Introduction to Network Planning

Band VLF LF MF HF VHF UHF SHF

Frequency up to 30 kHz 30 – 300 kHz 300 – 3000 kHz 3 – 30 MHz 30 – 300 MHz 300 – 3000 MHz 3 – 30 GHz

EHF

>30 GHz

Typical Use Navigation systems Long-range broadcast, navigation systems Medium wave broadcast and communications Long-range commercial and military communications Mobile communications Mobile communications Point-to-point microwave links, including satellite communications Point-to-point microwave links (Experimental systems)

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The radio spectrum is sub-divided into a number of bands. The Figure lists these bands and the typical use of each band. Factors influencing the use of a particular frequency band for a given application include: Propagation mechanism - choice of Surface, Sky or Space wave depending on desired range. Antenna size - consideration of particular antenna construction for given applications. Capacity - ability of a small carrier deviation to deliver the required bandwidth and hence bit rate.

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5 Use of the spectrum

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5 Use of the spectrum

Use of the spectrum [cont.] 1 - 1 - 20

Network Planning - Introduction to Network Planning

Radio frequency channel arrangements for radio-relay systems in frequency bands below about 17 GHz Band

Frequency range

Rec. ITU-R

Channel spacing

Band

Frequency range

Rec. ITU-R

Channel spacing

(GHz) 1.4

(GHz) 1.35 – 1.53

F-Series Rec. [Doc. 9/12]

(MHz) 0.25; 0.5; 1; 2; 3.5

(GHz) 8

(GHz) 8.2 – 8.5 7.725 – 8.275 7.725 – 8.275 8.275 – 8.5 10.3 – 10.68 10.5 – 10.68 10.55 – 10.68 10.7 – 11.7 10.7 – 11.7 10.7 – 11.7 10.7 – 11.7 11.7 - 12.5 12.2 – 12.7

F-Series 386 386, Annex 1 386, Annex 2 386, Annex 3 746, Annex 3 747, Annex 1 747, Annex 2 387, Annex 1 and 2 387, Annex 3 387, Annex 4 387, Annex 5 746, Annex 4, § 3 746, Annex 4, § 2

(MHz) 11.662 29.65 40.74 14; 7 20; 5; 2 7; 3.5 (patterns) 5; 2.5; 1.25 (pattern) 40 67 60 80 19.18 20 (pattern)

12.75 – 13.25 12.75 – 13.25 12.7 – 13.25 14.25 – 14.5 14.25 – 14.5

497 497, Annex 1 746, Annex 4, § 1 746, Annex 5 746, Annex 6

28; 7; 3.5 35 25; 12.5 28; 14; 7; 3.5 20

14.4 – 15.35 14.5 – 15.35 14.5 – 15.35

636 636, Annex 1 636, Annex 2

28; 14; 7; 3.5 2.5 (pattern) 2.5

2

4 5

6L 6U 7

1.427 – 2.69 701 0.5 (pattern) 1.7 – 2.1; 1.9 – 2.3 382 29 1.7 – 2.3 283 14 1.9 – 2.3 1098 3.5; 2.5 (patterns) 1.9 – 2.3 1098, Annexes 1 and 2 14 1.9 – 2.3 1098, Annex 3 10 2.3 – 2.5 746, Annex 1 1; 2; 4; 14; 28 2.29 – 2.26 Rec. [Doc. 9/13] 0.25; 0.5; 1; 1.75; 2; 3.5; 7; 14; 2.5 (pattern) 2.5 – 2.7 283 14 3.8 – 4.2 382 29 3.6 – 4.2 635 10 (pattern) 3.6 – 4.2 635, Annex 1 90; 80; 60; 40 4.4 – 5.0 746, Annex 2 28 4.4 – 5.0 1099 10 (pattern) 4.4 – 5.0 1099, Annex 1 40; 60; 80 4.54 – 4.9 1099, Annex 2 40; 20 5.925 – 6.425 383 29.65 5.85 – 6.425 383, Annex 1 90; 80; 60 6.425 – 7.11 6.425 – 7.11 7.425 – 7.725 7.425 – 7.725 7.435 – 7.75 7.11 – 7.75

384 384, Annex 1 385 385, Annex 1 385, Annex 2 385, Annex 3

10 11

12 13 14

15

40; 20 80 7 28 5 28

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5 Use of the spectrum

Use of the spectrum 1 - 1 - 21

Network Planning - Introduction to Network Planning

Radio frequency channel arrangements for radio-relay systems in frequency bands above about 17 GHz Band

Frequency range

Rec. ITU-R

Channel spacing

(GHz) 18

(GHz) 17.7 – 19.7 17.7 – 21.2 17.7 – 19.7 17.7 – 19.7 17.7 – 19.7 21.2 – 23.6 21.2 – 23.6 21.2 – 23.6 21.2 – 23.6 21.2 – 23.6 21.2 – 23.6 22.0 – 23.6 24.25 – 25.25 24.25 – 25.25 25.25 – 27.5 25.25 – 27.5 27.5 – 29.5 27.5 – 29.5 27.5 – 29.5 31.0 – 31.3 36.0 – 40.5 36.0 – 37.0 54.25 – 58.2 54.25 – 57.2 57.2 – 58.2

F-Series 595 595, Annex 1 595, Annex 2 595, Annex 3 595, Annex 4 637 637, Annex 1 637, Annex 2 637, Annex 3 637, Annex 4 637, Annex 5 637, Annex 1 748 748, Annex 3 748 748, Annex 1 748 748, Annex 2 748, Annex 3 746, Annex 7 749 749, Annex 3 1100 1100, Annex 1 1100, Annex 2

(MHz) 220; 110; 55: 27.5 160 220; 80; 40; 20; 10; 6 3.5 13.75; 27.5 3.5; 2.5 (patterns) 112 to 3.5 28; 3.5 28; 14; 7; 3.5 50 112 to 3.5 112 to 3.5 3.5; 2.5 (patterns) 56; 28 3.5; 2.5 (patterns) 112 to 3.5 3.5; 2.5 (patterns) 112 to 3.5 112; 56; 28 25; 50 3.5; 2.5 (patterns) 112 to 3.5 3.5; 2.5 (patterns) 140; 56; 28; 14 100

23

27

31 38 55

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6 General characteristics on the ITU-R recommended frequency plans

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6 General characteristics on the ITU-R recommended frequency plans

General characteristics on the ITU-R recommended frequency plans [cont.] 1 - 1 - 24

Network Planning - Introduction to Network Planning

Separate sub-bands for Tx and Rx channels, with a central guard band. Constant channel spacing between co-polarized channels. Two types of channel arrangements:

Interleaved Co-Channel

Criteria followed by ITU- R: Below 12 GHz: Compatibility of channel arrangements in the transition from Analog to Digital systems. Above 12 GHz: Channel arrangements optimized for Digital systems.

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6 General characteristics on the ITU-R recommended frequency plans

General characteristics on the ITU-R recommended frequency plans [cont.] 1 - 1 - 25

Network Planning - Introduction to Network Planning

INTERLEAVED CHANNEL ARRANGEMENT

GO CHANNELS x

Pol.

3

1

...

H(V)

RETURN CHANNELS

N-1

1’

3’

...

N-1’ F

V(H) z

2

4

N

y

2’

4’

N’ z

x/2 x/2

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x = Co-polar channel spacing y = Central guard band z = Edge guard band

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6 General characteristics on the ITU-R recommended frequency plans

General characteristics on the ITU-R recommended frequency plans 1 - 1 - 26

Network Planning - Introduction to Network Planning

CO-CHANNEL ARRANGEMENT

GO CHANNELS

Pol. z x 1 H(V)

RETURN CHANNELS y z 1’

3

...

3’

...

F

V(H) 2

4

N

2’

4’

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N’

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x = Co-polar channel spacing y = Central guard band z = Edge guard band

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Network Planning - Introduction to Network Planning

7 Antenna System

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7 Antenna System

Antenna System [cont.] 1 - 1 - 28

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Ideal Isotropic Radiator

Theoretical Half-Wave Dipole

Pratical Antenna Main Lobe RX

Boresight

2.15 dBi Practical Antenna Side Lobes

0 dBi Antenna Gain dBi

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Isotropic radiator An isotropic radiator radiates the energy evenly in all directions. Its radiation diagram is thus circular in both vertical and horizontal planes. Though a truly isotropic source is unrealizable it is easy to describe mathematically and is a useful reference. Antenna gain Antenna gain is the result of the focusing action of a practical antenna, radiating more energy in one direction and less in others. The axis along which maximum energy or field strength is radiated is termed the boresight and may be readily identified from a polar diagram of field strength in a given plane (see the next figure). The antenna gain is the ratio of the field strength along the boresight compared to that which be produced by an isotropic radiator radiating the same total power. Gain = 10 log (F antenna /F iso) dBi Note: dBi means the use of the isotropic antenna as reference The dipole is only loosely directional perpendicular to the plane containing its axis and, due to symmetry, not directional in the other plane (this property is called omni-directional). The dipole is also easy to analyze mathematically. Its gain compared to an isotropic source is 2.15 dBi. EIRP (Effective Isotropic Radiated Power) EIRP of an antenna is: Input power to the transmission line feed – feeder losses + antenna gain in dBi

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7 Antenna System

Antenna System [cont.] 1 - 1 - 29

Network Planning - Introduction to Network Planning

Max. gain -3 dB

Antenna lobe (Main)

Beam width to half Power point 3dB

Boresight (Max. gain)

Antenna Max. gain -3 dB

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Antenna beamwidth Antenna beamwidth is the angular distance between the half power (-3 dB points) on the polar diagram (see the next Figure). Though this is the angle normally used to asses what an antenna will “see”, radiation and reception does occur outside of the beamwidth in the mean beam and in the sidelobes, when present as this a potential source of interference. Antenna bandwidth Most antennas are designed at some center frequency. As the operating frequency is moved away from this the dimensions of the antenna in terms of wavelength will vary and will be consequential changes in radiation pattern (gain and beamwidth), antenna impedance and hence VSWR in the antenna feed, etc. Any of this parameters could be a practical limit on the range of frequencies used for a given antenna. Front to Back ratio The Front to Back ratio is a measure of how well the antenna discriminates from a signal entering along the boresight compared to the reverse direction and is a factor in reducing interference Cross-Polar Discrimination Antennas (or their feed arrangements) are designed to operate in one plane of polarization. This is useful for frequency re-use as it is possible to have two links operating at the same frequency, but with different polarization. To prevent mutual interference between the two systems their antennas should not receive the incorrect polarization. Cross-polar discrimination is the measure of how successful this is and the ratio of the wanted to unwanted signals received in dB.

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7 Antenna System

Antenna System [cont.] 1 - 1 - 30

Network Planning - Introduction to Network Planning

1 2 3

1 2 3

3 2 2 3 1 1

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Radiation Patterns determine an antenna’s ability to perform under conditions of radio congestion and also limit the route capacity. Radiation patterns are dependent on antenna series and size. An RPE comparison of various antenna series is illustrated below.

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7 Antenna System

Antenna System [cont.] Network Planning - Introduction to Network Planning

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HH VV

VH HV

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Parallel and cross-polar response are represented for both horizontal an vertical polarizations. The curves are identified as follows: HH - Response of a horizontally polarized port to a horizontally polarized signal HV - Response of a horizontally polarized port to a vertically polarized signal VV - Response of a vertically polarized port to a vertically polarized signal VH - Response of a vertically polarized port to a horizontally polarized signal

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7 Antenna System

Antenna System [cont.] 1 - 1 - 32

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Wavefront X Z

A X

B

Antenna

The Parabolic antenna surface focuses the arriving plane on the antenna. ie RAX = RBX

Parabolic antenna

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Parabolic antenna This antenna consists of a large reflecting surface (geometry is parabolic), this creates a focal point from which energy can be fed to illuminate the dish: when receiving signals the parabolic dish concentrates the energy onto the focal point. The next figure illustrates the importance of the antenna geometry, energy illuminating the reflector from the focal point will create a parallel wavefront in front of the dish. The parabolic antenna is highly directional with a gain typically of 40-50 dBi. The gain is related to the dimensions of the reflector relative to the signal wavelength. The antenna concentrates most radiation into the main lobe, which typically has a 3 dB beamwidth of a few degrees. The antenna does produce a number of undesired side lobes which are in the order of 25 dB down on the main lobe.

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7 Antenna System

Antenna System [cont.] 1 - 1 - 33

Network Planning - Introduction to Network Planning

Antenna gain The gain of a parabolic antenna is:

G=

D

2

where: D = antenna diameter (m) = signal wavelength (m) = antenna efficiency (usually is from 0.55 to 0.65) The efficiency is related to the irregularities in the antenna and illumination.

Another approximation of gain is: G (dBi) = 20 log F + 20 log D + 18.2 + 0.5 (depending on ) where: F = signal frequency (GHz) D = antenna diameter (m)

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7 Antenna System

Antenna System [cont.] 1 - 1 - 34

Network Planning - Introduction to Network Planning

Antenna beamwidth The 3 dB beamwidth of a parabolic antenna is: Beamwidth (3 dB) = where:

70 (degrees) D

= wavelength (m) D = antenna diameter (m)

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7 Antenna System

Antenna System [cont.] 1 - 1 - 35

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(a) Parabolic Dish

(b) Offset Horn

Typical Microwave Antennas

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Feeder The parabolic antenna can be fed in different ways, as shown in the Figure. Center fed antennas can cause blocking of the aperture and reduced efficiency. This may be overcome by offsetting the feed, but the feed point needs rigid support and such antennas, although more efficient, are bulkier. A single feed point may be orientated to produce the desired polarization. Twin feeds may be used to produce a dual polarization from a single dish. Note:

With circular waveguide it is possible to have V and H polarization in same feeder. With elliptical waveguide it is possible only one polarization (Elliptical cross section is really rectangular).

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7 Antenna System

Antenna System 1 - 1 - 36

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a) f/D ratio

b) Antenna Shrouds

D

f

Antenna

Focal Point

Shroud

Overspill Radiation

c) Tapered Illumination

Parabolic Reflector

Illumination Intensity

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Front to Back ratio The parabolic antenna has a relatively high front to back ratio (30 to 40 dB approx.). However some energy from the focal point feed overspills the reflector (as shown in Figure a). With diffraction effects the overspill can produce significant radiation at the rear side of the antenna. This is especially true of antennas with a small aperture diameter (D) compared to focal length (f), i.e. a large f/D ratio. Decreasing f/D ratio by making the dish deeper reduces spillover, but degrades the radiation pattern, as the illumination is more uneven. The antenna is also larger and heavier. If front-to-back ratio is critical, another option is to use a conducting shroud (as shown in Figure b) attached to the front of the antenna to eliminate the overspill, but this again may have an adverse effect on the gain and radiation pattern. Very often shrouds can be confused with antenna radomes. A radome offers physical protection to the antenna from the effects of the environment and is made from material transparent to microwaves. An alternative techniques is to concentrate the illumination of energy at the center of the reflector and decrease the illumination at the periphery. This tapered illumination is shown in Figure c. Amplitude tapering reduces the gain and increase the beamwidth, as the full aperture is not being fully used.

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7 Antenna System

Exercise

Network Planning - Introduction to Network Planning

1 - 1 - 37

Exercise 1 - Front to back ratio What is the front to back ratio in a parabolic antenna? Exercise 2 - Antenna gain Calculate the gain of a 1 m parabolic antenna at 6 GHz. Exercise 3 - Antenna gain Calculate the gain of a 1 m parabolic antenna at 24 GHz. Exercise 4 - Antenna beamwidth Calculate the 3 dB beamwidth of a 2 m parabolic antenna at 10 GHz.

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8 Field strength and related parameters

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3FL 42104 AAAA WBZZA Edition 2 - July 2005 Section 1 - Module 1 - Page 39

A model which can be used to approximate the propagation loss between two points is the Free Space model. As its name implies here should be no significant obstructions or surfaces adjacent to the path. It also assumes isotropic characteristics at the transmitter and receiver and that propagation is through a vacuum. Isotropic Radiation If a transmit power, Pt (Watts), is fed into an isotropic source, then the power will radiate evenly in all directions causing an even Power Flux, Fiso, measured in Wm-2. As the power is evenly distributed over the surface of an expanding sphere the power flux is given by:

where

Pt = Power transmitted in Watts d = range of measurement in metres

as shown in next Figure power Flux thus falls according to the square of distance - the inverse square law.

8 Field strength and related parameters

Field strength and related parameters [cont.] 1 - 1 - 40

Network Planning - Introduction to Network Planning

Fiso =

Isotropic Radiator

Pt Fiso = 4 d2

Pt 4 d2

Pt 1m

(Wm ) 2

1m

Power Flux per square meter at distance d

d

Isotropic Radiator

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8 Field strength and related parameters

Field strength and related parameters

ISOTROPIC RECEIVER

The abilityPlanning of a receiving antenna to Planning receive power from an incident power flux is determined by its apparent or Network - Introduction to Network 1 - 1 - 41 effective aperture, (Ae) in m2. This is a function of the antennas construction and for an isotropic antenna is given by: 2

Pr =

where

Pt Pt x Ae = x 2 4 d 4 d2 4

= wavelength in meters

Power Received Power received may be expressed by: Pt Isotropic Radiator

Ae

Free-space Propagation Loss

Pr

Effective Aperture in m2

Free-space Propagation loss may be expressed as: d

Isotropic Receiver

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2

Ae = Pt Pr = 4 d2

Pt A fsl = = Pr

4

2

x

(Watts)

4

4 d

2

=

4 df c

2

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(m ) 2

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9 Free space loss

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9 Free space loss

Free space loss 1 - 1 - 44

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The free space loss, expressed in dB, is a function of distance and frequency. The free space loss equation may then be expressed as:

4 d (km) x 103 x F(GHz) x 109 A fsl (dB) = 10 log 3 x 108 i.e.

2

Afsl (dB) = 92.4 + 20 log F (GHz) + 20 log d (km)

where F = frequency in GHz d = distance in km

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9 Free space loss

Exercise

Network Planning - Introduction to Network Planning

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Exercise - Free-space loss attenuation Calculate the free-space loss attenuation of a 50 km link operating at 8 GHz.

- RADIO NETWORK PLANNING

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10 Radio Network Design procedure

- RADIO NETWORK PLANNING

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10 Radio Network Design procedure

Radio Network Design procedure Network Planning - Introduction to Network Planning

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Step 1: By starting with the simplest (low cost) configuration (1+0), calculate the PRx nom level by using the Power link budget formula (Section 1, Module 2, Chapter 1) Step 2: Calculate the clearance of the hop (Section 1, Module 2, Chapter 2 & 3) Step 3: Calculate the PRx threshold (Section 1, Module 2, Chapter 4) Step 4: Calculate the FM=PRx nom – PRx threshold Step 5: By using the FM of Step 4 calculate the outage probability due to the rain (Section 1, Module 2, Chapter 5) Step 6: Calculate the outage probability due to the fading (Section 1, Module 2, Chapter 6) Step 7: Calculate the objectives according to the ITU-T and ITU-R reccomandations (Section 1, Module 2, Chapter 7)

- RADIO NETWORK PLANNING

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10 Radio Network Design procedure

Radio Network Design procedure Network Planning - Introduction to Network Planning

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Step 8: If the outages of the link (calculated in Chapter 5 & 6) meet the objective, go to Step 10 Step 9: Change the PRx nom level or use the Fading countermeasures (Section 1, Module 2, Chapter 8) in order to meet the objective Step 10: Consider all the possible interferences (Section 1, Module 2, Chapter 9, 10 & 11) and calculate the new FM Step 11: If, with the new FM, the objectives are always met, the radio planning procedure is over. Otherwise go back to Step 9.

- RADIO NETWORK PLANNING

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Network Planning - Introduction to Network Planning

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