  The inverse Compton process by which soft photons are up-scattered by hot
electrons in a corona plays a fundamental role in shaping the X-ray spectra of
black-hole (BH) low-mass X-ray binaries (LMXBs), particularly in the hard and
hard-intermediate states. In these states, the power-density spectra of these
sources typically show Type-C low-frequency quasi-periodic oscillations (QPOs).
Although several models have been proposed to explain the dynamical origin of
their frequency, only a few of those models predict the spectral-timing
radiative properties of the QPOs. Here we study the physical and geometrical
properties of the corona of the BH-LMXB GRS 1915+105 based on a large sample of
observations available in the RXTE archive. We use a recently-developed
spectral-timing Comptonisation model to fit simultaneously the energy-dependent
fractional rms amplitude and phase-lag spectra of the Type-C QPO in 398
observations. For this, we include spectral information gathered from fitting a
Comptonisation model to the corresponding time-averaged spectra. We analyse the
dependence of the physical and geometrical properties of the corona upon the
QPO frequency and spectral state of the source, the latter characterised by the
hardness ratio. We find consistent trends in the evolution of the corona size,
temperature, and feedback (the fraction of the corona photons that impinge back
onto the disc) that persist for roughly 15~years. By correlating our
observations with simultaneous radio-monitoring of the source at 15 GHz, we
propose a scenario in which the disc-corona interactions connect with the
launching mechanism of the radio jet in this source.
