ND SatCom SKYWAN IDU 7000, Manual

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70 Network Design and Engineering Guide 2010-10-26
General Carrier Design
From Capacity Estimation to TDMA Structure
supported range of maximal allowed slots on Sky WAN
®
. Although this smaller slot size
will result in a smaller numerical efficiency due to an increased TDMA overhead, the over-
all network efficiency is typically higher. The reason for this is that stations, which require
e.g. on a specific carrier just the capacity of 1 voice call must always request one full time
slot, which will be much more than actually needed in the case of big time slots. If this
extra capacity cannot be used for additional traffic on this carrier, it will be wasted.
3. Since the same optimization criterion 2 voice calls per slot has been selected for all chan-
nels, the ’TDMA Calculator’ uses a data slot length factor of 2 for the small carriers to cre-
ate slots which can also carry 2 voice calls for these carriers. If we want an even finer
capacity allocation granularity on these carriers, we could have specified 1 call per slot on
channel 2 and 3, leading to a solution which uses a data slot length of 1 also on these car-
riers.
The optimized 3 carrier solution is presented in figure 2-44:
Figure 2-44 TDMA Calculator Output for Optimized 3 Carrier Solution