Conclusion

Satellite-based communications has the significant advantage of not being constrained by the range-capacity-mobility trade-off that restricts all other communications systems. That is, satellite-based systems can provide communications over long ranges with high capacities to mobile terminals. This great advantage has seen satellite communications systems become ubiquitous for both military and commercial applications.

Despite their overwhelming utility, however, satellite systems are vulnerable to space weather and space warfare. A wise military would therefore assume that, for one or more reasons, there will be periods during which satellite communications systems will not be available.

Absent the ability to use satellite-based systems, communications planners must fall back to an alternate means (HF sky wave, troposcatter and airborne platforms), each of which is best suited to a particular range: namely, airborne platforms and troposcatter are suitable out to 1,000 kilometers and only HF sky wave is available beyond that. The use of airborne platforms will deliver capacities not dissimilar to satellite-based systems so, when employed as a back-up system, little performance would be lost.

For ranges beyond 1,000 kilometers, HF sky wave is the only viable solution, although the capacity available is a mere trickle compared to satellite-based systems or, for that matter, the alternative back-up means of airborne platforms and troposcatter. Consequently, in satellite degraded/denied environments, long-range communications beyond 1,000 kilometers can only support the bare minimum capacity required for the command and control of deployed assets. Still, regardless of the sparse capacity available as a result, the ADF must continue to maintain a significant HF capability—there is no other viable option in a satellite denied/degraded environment for communications to force elements deployed beyond 1,000 kilometers.