ND SatCom SKYWAN IDU 7000, Manual

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48 Network Design and Engineering Guide 2010-10-26
General Carrier Design
Network Traffic Estimation
Figure 2-30 Traffic Calculation Example - Carrier Configuration Worksheet
Note that a general restriction is that master stations must be assigned to carrier 1. In star to-
pology networks the hub station must be assigned to a different carrier than the star terminals.
In many cases the optimal station distribution for a multi carrier solution is generating carriers
with almost equal data rate requirements. Since the power requirement for a station is deter-
mined by the largest carrier, such a solution minimizes the transmitter power class or antenna
size of a station. However, other considerations like traffic flows, satellite footprint variations or
restrictions on possible antenna sizes for some stations (e.g. mobile stations) might lead to a
solution with different carrier sizes. The latter consideration could be the result of a link budget
analysis, which will be discussed in a later section of this guide.
In the example presented in the screenshot the multi carrier solutions were designed under the
following assumptions:
-
For administrative reasons the master stations must be located at the head offices. There-
fore both stations of type 1 must be assigned to carrier 1.
- To create a 2 carrier solution with almost equally sized carriers, only the head offices (one
big and one medium size office) are assigned to carrier 1 and all other stations to carrier 2.
- For the 3 carrier solution the assignment for carrier 1 cannot be changed as these are the
master stations. The other stations are distributed evenly among carrier 2 and 3 to make
at least these carriers equally sized.
As mentioned before real-time traffic requirements may be defined per station or for the whole
network. In the latter case, distributing stations on carriers will not automatically take into ac-
count the real-time bandwidth. Instead the real-time bandwidth has to be assigned manually to
one or multiple carriers using the row ’per network RT data rate’ in the carrier configuration
sheet.
In the example presented before, it was assumed that the 42 small sites should support 2 si-
multaneous video sessions each with 256 kbps. Since the sessions are not linked to individual
small sites, the required real-time data rate of 512 kbps was assigned to the whole network. In
a multicarrier network this data rate has to be assigned to individual carriers. An example is
displayed in the following picture figure 2-31.