First, when I read this, I thought ITU wants to use short waves, which naturally propagate beyond line of site, only they are very tricky to use reliably. Plus very narrow band don't allow much data to be sent.
But actually they are dedicating 1087.7-1092.3 MHz for satellite service. I wonder if we already have satellite constellation up there that is able to receive that frequency band?
1090 MHz is the frequency that is used by the transponders to reply to radar & TCAS interrogations and is also used for transmission of ADS-B messages.
Aireon is currently deploying satellite based ADS-B receivers on the next generation of Iridium satellites. Global coverage is expected in a couple of years.