Sounds like a scheme to free-up space for mobile phones, so that more people can ring more people and shout. "I'm on the train".
You're not wrong there.
"There is an increasing demand for the use of the electromagnetic spectrum and it is likely that the current frequency allocations for PSR, in both the L- and S- bands, will come under threat, with MSPSR offering the potential to provide improved coverage and performance for a smaller frequency allocation."