Bandwidth - bandwidth again:-

While most of the bands that you mentioned as examples, involves the space service, and the satellite service are by in large DAMA systems that have flexible bandwidth use (as per transmission requirements), most of the time the bandwidths that are assigned are much larger than the necessary bandwidth of the actual transmission, the authority that recommends the bands and the amount of spectrum per channels are the ITU-R, they provide the recommendations on spectrum use,and its coordination between different regions of the world, this more pronounced in practice specially in the space services assignments.