wrote:
It seems to me that the astronaut and cosmonaut on ISS only have
little time for experiments.

Would it be possible to mount a sort of Comsat on the backbone of the
station and then control a number of experiments from a control room on
the ground.

There are experiments on ISS which are controlled from the ground.
Rokviss
http://www.energia.ru/english/energia/iss/researches/works-10.html is
one example.

ISS has enough communications infrastructure that nothing needs to be
added to control experiments from the ground.

That said, much of the research done on ISS centers around humans
themselves, or things that would be hard to do without human
intervention. That is, after all, the point of having a manned station.
(whether the research being done or planned is worthwhile is an
entirely different topic...)