Determining Microwave channels : Frequency plan

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Determining Microwave channels Frequency
plan G.N. THON, Nicolas.thon_at_esmt.sn


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• Overview
• 1.    Micro wave link and the need of a frequency
  plan
• Generalites
• Bilateral transmission
• Jamming
• Frequency plan
• a) objectives
• b) Organisation
• c) ITU-R Recommandations
• d) Example of frequency plan

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1.    Micro wave link and the need of a frequency
plan

• Principle of Radio transmission

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1.    Micro wave link and the need of a frequency
plan (a) Generalities spectruum distribution
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1.    Micro wave link and the need of a frequency
plan b) billateral transmission

• 1 1

Info S. élec
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Adaptation support
Station A
MIDIUM
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S. élec S. élec
Adaptation support
Info S. élec

Adaptation support
S. Élec S élec
Station B
Adaptation support
Info S. élec
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1.    Micro wave link and the need of a frequency
plan b) billateral transmission

• Example Transmission midia and interfacing

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1.    Micro wave link and the need of a frequency
plan b) billateral transmission

• Microwave Radio-raley Meaning of a channel

Channel dir 1 dir 2 in a double-sideband
transmission
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1.    Micro wave link and the need of a
frequency plan b) billateral transmission

• Microwave Transmission Midium
• the space

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1.    Micro wave link and the need of a frequency
plan b) billateral transmission

• Microwave midium interface

Tx
Microwave frame
Modulation

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1.    Micro wave link and the need of a frequency
plan b) billateral transmission

• Microwave example of medium interface

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1.    Micro wave link and the need of a frequency
plan b) billateral transmission

• Implementing a Radio-relay link Transmitted
  signal

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1.    Micro wave link and the need of a frequency
plan b) billateral transmission

• Implementing a microwave link What to take
  into account ?
• The layout (link mapping)
• The channels choice (frequencies)
• The Possible jammings
• The Power budget

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1.    Micro wave link and the need of a frequency
plan b) billateral transmission

• Implementing a microwave link The channels
• 2 frequencies (carriers) per channel
• F-Tx (fn)
• F-Rx (fn)
• The difference between fn and fn must be large
  to facilitate the séparation of the 2 ways
• The polarisation
• Vertical Polarisation
• Horizontal Polarisation
• Coupling between Tx and et Rx signals with the
  same polarisation

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1.    Micro wave link and the need of a frequency
plan b) billateral transmission

• High data rate links
• Several polarisations can be used on the same
  antenna

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1.    Micro wave link and the need of a frequency
plan b) billateral transmission
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1.    Micro wave link and the need of a frequency
plan b) billateral transmission

• Implementing a microwave link The link
• terminal stations
• and relays stations depending on the distance the
  terminal stations the geographic configuration

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1.    Micro wave link and the need of a frequency
plan c) Jammings

• They must be avoided (CEM)
• Origine
• Internal jamming
• External jamming

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1.    Micro wave link and the need of a frequency
plan c) Jammings

• Internal jammings
• Type 1 jamming
• The emission of station 1 (F1) jams the reception
  of station 4 (F1)
• It happens when both antennas are in direct
  visibility allignement
• To avoid misalign the antennas

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1.    Micro wave link and the need of a frequency
plan c) Jammings

• Internal jamming
• Type 1 jammings (suite)
• To avoid misalign the antennas

2
4
3
5
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1.    Micro wave link and the need of a frequency
plan c) Jammings

• Internal jammings
• Type 2 jamming

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1. Microwave transmission midia-Frequency Plan
c) Jammings

• Type 2 jamming
• Its a coupling between Tx and Rx signals on the
  same antenna.
• A part of the emitted energy is reintroduced in
  the reception path.
• To avoid
• A good connectin g systemt (cirulator, wave
  guide)
• A good spacing between Tx and Rx frequencies
• Good Rx filters

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1.    Micro wave link and the need of a frequency
plan c) Jammings

• Internal jammings
• Type 3 jamming

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1.    Micro wave link and the need of a frequency
plan c) Jammings

• Internal jammings
• Type 3 jamming
• It is the perturbation on the received signal on
  station 2 (F1 received from station 3) by
  received at station 2 coming from station 1
• Part of the backward radiation in direction of
  station 1 ends up on station
• To avoid
• Use directionnal antennas

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1.    Micro wave link and the need of a frequency
plan c) Jammings

• Internal jammings)
• Type 4 jamming

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1.    Micro wave link and the need of a frequency
plan c) Jammings

• Internal jamming
• Type 4 jamming
• It is the perturbation of the received signal at
  station 1 by the backward radiation toward
  station 3.
• To avoid
• Uses directionnal antennas
• Misalign bonds

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1.    Micro wave link and the need of a frequency
plan c) Jammings

• Jamming and quality
• Effects Quality degradation
• -         reduction of C/N ratio
• -         reduction of receving power maging
• -         increment of erronned second
• -         reduction of the availability
• Analysis
• It takes into account
• -         the spectrum frequency of the
  interfering factor
• -         the power of the disturbing signal
• -         the probability of this occurrence

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2 Frequency plana) Objectives

• The goal is essentialy to optimise the spectrum
• -         transmitting the maximum information
  with the minimal wave band
• -         avoid the jamming of the spactrum by
  unnecessary an undiserable signals
  (interferences, disturbancies)

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2 Frequency planb) organisation

• Each ½ band is divided into channels (the same
  number on both sides)
• A central frequency that specifies the band Two
  half-bands
• ½ Lower band
• ½ Upper band

½ Lower band
½ Upper band
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2 Frequency planb) organisation
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2 - Frequency planb) organisation

• Elementary rules to choose a channel
• The channel
• A frequency f n  (emission or reception)
• A frequency  fn  emission or reception
• Spacing between adjacent channels of the same
  link
• Cross Polarization One time the space between 2
  channels
• Co polarization 2 times the space between deux
  channels
• In a relay station
• East and West emission same frequency Fn or Fn
• East or West reception same frequency Fn or Fn
• Take account of interferencies

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2 Frequency planb) organisation

•  

Fn
Fn
Fn
Fn
½ lower band
½ upper band
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c) UIT-R Recommandations
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2 Frequency pland) Examples of frequency plans

• Example of frequency plans use

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2 - Frequency pland) Examples of frequency plan

• Plan at 2 GHz
• ITU-R RECOMMENDATION F.283
• Recommended for 
• -         digital systems at 34 Mbit/S
• -         analog systems at 960 circuits
  (maximum)
• Frequencies 
• -       f0 centered between 1808 2000 2203
  MHz
• -         fn within the lower half band
• -         fn within the upper half band
• -         fréquency expressions
• Lower half band fn f0 108.5 14 n,
• Upper half band fn f0 10.5 14 n,
• with n 1, 2, 3, 4, 5 or 6

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frequency plan at 2 GHz
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2 - Frequency pland) Examples of frequency plan

• Plan at 13 GHz
• ITU-R RECOMMENDATION F.497-6
• Recommended for 
• -         Digital systems at 34 Mbit/S
• -         Analog systems at 960 circuits
• Frequencies 
• -       f0 centered at 12.75 et 13.25 GHz
• -         fn within the lower haf band
• -         fn within the upper haf band
• -         fréquency expressions
• o       lower haf band fn f0 - 259 28
  n MHz
• o       upper haf band fn f0 7 28 n
  MHz
• with n 1, 2, 3, 4, 5, 6, 7 or 8

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3 - frequency plan
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2 - Frequency pland) Examples frequency plan

• Another example

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• Bibliography
• Manuel Gestion nationale du spectre (BR UIT6R)
• Les Faisceaux Hertziens Analogiques et Numériques
  (J.M. Mathieu
• et E. Fernadez Edition Dunod)
• UIT R Recommandations série F
• Documents de cours Faisceaux Hertziens (CNAM,
  ESMT)
• Propagation des ondes radioélectriques dans
  lenvironnement
• Terrestre (L. Boithias)