Satellite Link Design
• Transponder bandwidth is usually the most
expensive resource in a satellite communications
link.
• For maximum efficienc...
 Traditionally, you could reduce Bandwidth or Power,
but not both without significantly increasing the
expenditure.
 Red...
 Reduce bandwidth by 50%.
 Increase data throughput by a factor of 2.
 Reduce antenna size by 30%.
 Reduce transmitter...
Allocated BW PEB
Portion of transponder BW actually used. Fraction of transponder power required to
close link.
Linear fun...
 Allocated Bandwidth :
Bandwidth, Allocated Bandwidth or Occupied Bandwidth is
the frequency space required by a carrier ...
 Power Equivalent Bandwidth :
Power Equivalent Bandwidth (PEB) is the transponder power
used by a carrier, represented as...
• Antenna Gain
• Power of Amplifier
Uplink
• Path Loss
• Rain Attenuation
Satellite
• G/T
• EIRP (Equivalent Isotropic Radiated Power)
• SFD (Saturated Flux Density)
• Amplifier Characteristic
Dow...
Receiving Earth Station
• Antenna Gain
• LNA /LNB Noise Temperature
• Other Equipment
EIRP :
Is the effective radiated power from the
transmitting side and is the product of the
antenna gain and the transmitt...
Signal Power (Pr) :
Pr = EIRP – Path Loss + Gr (sat) [dB]
Where,
Path Loss = (4ΠD / λ) 2
D is the Slant Range (m)
Satellite link design
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Satellite link design

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Satellite link design

  1. 1. Satellite Link Design
  2. 2. • Transponder bandwidth is usually the most expensive resource in a satellite communications link. • For maximum efficiency, a satellite link should be engineered to balance bandwidth and power. • Traditionally, it involved playing with modulation and coding to get the right balance for fixed satellite and earth station parameters.
  3. 3.  Traditionally, you could reduce Bandwidth or Power, but not both without significantly increasing the expenditure.  Reduce Occupied Bandwidth :  Use Higher Order Modulation • Increases Transponder Power Utilization • Increases HPA Size and/or Antenna Size.  Reduce Transponder Power Utilization :  Use Lower Order Modulation or more powerful FEC • Increases Occupied Bandwidth • Reduces HPA Size and/or Antenna Size  Without Using Lower Order Modulation • Increase Antenna Size antenna size
  4. 4.  Reduce bandwidth by 50%.  Increase data throughput by a factor of 2.  Reduce antenna size by 30%.  Reduce transmitter power by a factor of 2.  Provide 3dB more link margin.
  5. 5. Allocated BW PEB Portion of transponder BW actually used. Fraction of transponder power required to close link. Linear function of modulation and FEC. Complicated function of hub antenna, remote antenna and satellite specifics along with required Eb/No. Decreases with higher order modulation. Increases with powerful FEC. “Bandwidth Limited” links have greater allocated than PEB. “Power Limited” links have greater PEB than Allocated.
  6. 6.  Allocated Bandwidth : Bandwidth, Allocated Bandwidth or Occupied Bandwidth is the frequency space required by a carrier on a transponder. E.g. : a duplex E1 (2.048 Mbps) circuit with 8-PSK modulation, FEC rate 3/4 and 1.4 spacing requires: 2.048 / (3 * 0.75) * 1.4 * 2 = 2.548 MHz For a 36 MHz transponder, 2.548 MHz corresponds to 7.078% bandwidth utilization.
  7. 7.  Power Equivalent Bandwidth : Power Equivalent Bandwidth (PEB) is the transponder power used by a carrier, represented as bandwidth equivalent. PEB calculation example: •Transponder EIRP = 37 dBW •Output Backoff (OBO) = 4 dB •Available EIRP = 37 – 4 = 33 dBW = 10^3.3= 1995.26 Watts •Transponder Bandwidth = 36 MHz •Power Available / MHz = 1955.26 / 36 = 55.424 W •If a carrier uses 24 dBW, then PEB = Power used by your carrier/transponder saturated power PEB = 10^2.4/ 55.424 = 4.532 MHz This corresponds to 12.59% of available transponder power.
  8. 8. • Antenna Gain • Power of Amplifier Uplink • Path Loss • Rain Attenuation
  9. 9. Satellite • G/T • EIRP (Equivalent Isotropic Radiated Power) • SFD (Saturated Flux Density) • Amplifier Characteristic Downlink : • Path Loss • Rain Attenuation
  10. 10. Receiving Earth Station • Antenna Gain • LNA /LNB Noise Temperature • Other Equipment
  11. 11. EIRP : Is the effective radiated power from the transmitting side and is the product of the antenna gain and the transmitting power, expressed as EIRP = Gt + Pt –Lf [dB] Where, Lf is the Feed Losses
  12. 12. Signal Power (Pr) : Pr = EIRP – Path Loss + Gr (sat) [dB] Where, Path Loss = (4ΠD / λ) 2 D is the Slant Range (m)

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