Specifications

82 Network Design and Engineering Guide 2010-10-26

Outdoor Unit and Satellite Link Design

Considerations for SkyWAN

Link Budget Calculations

Figure 3-8 Power Conditions with Uplink Power Control

Note that a further reduction to the minimum power requirement for clear sky conditions X

possible but unnecessary.

This functionality is generally called “Uplink Power Control (UPC)” and is implemented in Sky-

WAN

networks as the built-in automatic Transmission Power Control (TPC). Generally the

power requirement for the satellite transponder including rain margin is given by:

With UPC: EIRP

= EIRP

S,clear Sky

+ Downlink rain fade

Without UPC: EIRP

= EIRP

S,clear Sky

+ Downlink rain fade + Uplink rain fade

Note that the power requirement for the transmitting earth station is not affected by UPC, but

is always given by:

EIRP

= EIRP

T,clear Sky

+ Downlink rain fade + Uplink rain fade

3.4 Considerations for SkyWAN

Link Budget Calcu-

lations

3.4.1 Network Topology

So far we have considered satellite links which include a transmitting and a receiving earth sta-

tion using a specific satellite transponder. Most widely used link budget tools actually are de-

signed for such point-to-point links, where each station uses a dedicated carrier to reach

another station. In SkyWAN

networks however, we have to take into account the following

specific points:

-A SkyWAN

station in a meshed network communicates not only with one remote station

but with up to 509 remote stations.

-A SkyWAN

carrier is typically not only used by a single station but by a whole group of

stations.

-A SkyWAN

station may use not only one carrier but different carriers which may be locat-

ed on different transponders on a satellite.

To calculate the power requirement for a SkyWAN

earth station, the individual power require-