>The approximately 11-year solar cycle causes variations in sunspot activity, resulting in changes to the levels of solar electromagnetic radiation that reach Earth. This, in turn, causes fluctuations in the altitude of the ionosphere at different times of day and from year-to-year. In addition, electromagnetic frequency noise in the 2-25 MHz Band is quite high as compared to other spectrum bands

Shortwave broadcasters have been dealing with this forever. Data sources will have to use multiple frequencies which will be receivable depending on which bands work the best at a particular time of day. Just take one look at the US Coast Guard's HF broadcasts and you'll see not one but many frequencies for broadcasting the same info. That's just the nature of the beast.

As far as combating RFI, that's partially up to the receiver of the broadcast. Ask SW listeners and Ham Radio enthusiasts about it, there are a variety of ways to improve reception. It's going to be interesting to see what allotments they are allowed. Hopefully new bands will be designated for this, if it occurs.