When designing a waveform for packet radio usage, it'd be helpful to know a few things, mainly
- distribution of coherency bandwidths
- distribution of coherency times
Whilst such statistics are reasonably possible to generate for higher frequencies based on own measurements, for terrestrial HF propagation, due to the large distances involved and the low useable bandwidths, a sufficient measurement campaign would be infeasible.
HF propagation models are very light on details or vary wildly when it comes to the relevant aspects that would allow for simulation of the same (that being delay spread and doppler spread). Mostly, they're early cold war studies that care only about amplitude attenuation.
- Are there more modern channel models for HF propagation?
- Alternatively, statistics over the coherency properties?