  X-ray binaries (XRBs) often exhibit a high energy power-law tail (X-ray) and
these tails can be generated by the bulk Comptonization (BMC) process with a
free-fall bulk region onto the compact object. We frequently observe a radio
emission (which is generated by a synchrotron-emitting outflowing electrons)
from the XRBs. We aim to study the high energy power-law tail in BMC process by
an outflowing medium. We mainly consider a collimated and conical (of opening
angle $\theta_b$ with axis perpendicular to the accretion disk) outflow for a
BMC process. We simulate the bulk Comptonized spectra by using a Monte Carlo
scheme. Out of two possible conical outflow directions i) along the surface of
the cone, ii) inside the conic region, we find that a) the randomness of
outflow directions increases with $\theta_b$, b) the emergent spectra have
power-law tail (of photon index $\Gamma$ $>$ 2 and with high energy cut-off
$E_{c}$ $>$ 200 keV) only for $\theta_b$ greater than $\sim$30 degree, while
for a collimated or a conical outflow ($\theta_b$ $<$ 30degree) these power-law
tail can be only generated when it is also found in thermal Comptonized spectra
(i.e., at sufficiently high medium temperature). We compare the GRS 1915+105
spectra for two classes $\chi$ and $\gamma$, for this the outflow speed is
highly relativistic and the relevancy of wind parameters suggest that wind must
be occurred at inner region of the accretion disk, so consistent with inner
disk radio emission.
