  We explore the effect of cosmic radiative feedback from the sources of
reionization on the thermal evolution of the intergalactic medium. We find that
different prescriptions for this feedback predict quite different thermal and
reionization histories. In spite of this, current data can not discriminate
among different reionization scenarios. We find that future observations both
from 21-cm and CMB experiments can be used to break the degeneracy among model
parameters provided that we will be able to remove the foreground signal at the
percent (or better) level.
