Satellite Network Coordination

1WRAP 0974B

Satellite Network Coordination

• Available satellite calculations in WRAP– Satellite ground coverage – in Coverage– Earth station coverage of space orbit – in Coverage– Interference between space stations, terrestrial stations

and earth stations – in Interference– Specific tool for Satellite Network Coordination in

accordance with the ITU Radio Regulations Appendix 8

• Full spherical geometry calculations• Specific Space-to-Earth propagation model P.619

(Free-space, P.526 can also be used)• Space – to – Space propagation: Free-space with

line-of-sight check

2WRAP 0974B

Satellite networks

• Satellite networks can be defined:– Earth A Space A/Space B Earth B– A satellite comprises one or more stations

(transponders)

3WRAP 0974B

Creating a satellite network

4WRAP 0974B

– Enter earth stations EA and EB

– Enter satellite S as a group of stations SA, SB

– Form links • EA SA• SB EB

– Calculate transmission gain

Space – Earth propagation• ITU-R Rec. P.619-1 accounts for

– Free-space loss– Attenuation due to atmospheric gases (P.618-6)– Beam spreading (P.618-6)– Amplitude scintillations (2.4.1 of P.618-6)

• Identification of whether the space station is visible from the point on earth

• Consideration to refraction to calculate the apparent elevation angle (P.834)

• ITU-R Rec P.526 (diffraction) extended to valid spherical geometry for space – earth paths

5WRAP 0974B

Note that propagation for AP8 is just free-space with line-of-sight check

Coverage

6WRAP 0974B

Example of coverage– Footprints on

ground from four space stations

– Power flux density contours

– All features of the Coverage tool are available also for space-earth paths

ITU Radio Regulations Appendix 8

• Calculates the equivalent noise increase in receivers in satellite networks due to interference from other satellite networks

• Result expressed as a percentage “T/T” T: Noise increase in degrees due to interference– T: Noise temperature of receiver, including all noise sources

except from the interfering transmissions

• Free-space propagation– With line-of-sight check– Correction for refraction to give apparent elevation angle

• Result above a certain value (normally 6%) indicates need for coordination

7WRAP 0974B

Example of AP8 result

8WRAP 0974B

– Noise increases are shown for all receivers

– Sources of interference can be identified

– The total result is referred to the earth station receivers in this example (simple frequency-changing transponders)

– Result referred to space station receivers for other types of transponders

Interference calculations

T/T calculations of AP8 do not consider specific spectral shapes of transmissions or receiver selective properties.

• Detailed signal-to-interference calculations(S/I; C/I) are performed in the Interference tool.

9WRAP 0974B

WRAP space service applications

• Ground coverage for satellites• Space coverage for earth stations• Interference between satellite networks• Interference between space services and

terrestrial services• Calculation of coordination contours (often power

flux density) for satellite emissions• Interference in space from terrestrial stations (for

instance along the geo-stationary orbit)• Calculation of coordination values for T/T in

accordance with ITU RR Appendix 8

10WRAP 0974B