  Loop quantum cosmology provides an efficient framework to study the evolution
of the Universe beyond the classical Big Bang paradigm. Because of holonomy
corrections, the singularity is replaced by a "bounce". The dynamics of the
background is investigated into the details, as a function of the parameters of
the model. In particular, the conditions required for inflation to occur are
carefully considered and are shown to be generically met. The propagation of
gravitational waves is then investigated in this framework. By both numerical
and analytical approaches, the primordial tensor power spectrum is computed for
a wide range of parameters. Several interesting features could be
observationally probed.
