  A possible method for linking the optical Gaia Celestial Reference Frame
(GCRF) to the VLBI-based International Celestial Reference Frame (ICRF) is to
use radio stars in a manner similar to that in the linking of the Hipparcos
Celestial Reference Frame (HCRF) to ICRF. In this work, an obtainable accuracy
of the orientation angles between GCRF and ICRF frames was estimated by Monte
Carlo simulation. If the uncertainties in the radio star positions obtained by
VLBI are in the range of 0.1-4 mas and those obtained by Gaia are in the range
of 0.005-0.4 mas, the orientation angle uncertainties are 0.018-0.72 mas if 46
radio stars are used, 0.013-0.51 mas if 92 radio stars are used, and
0.010-0.41~mas if 138 radio stars are used. The general conclusion from this
study is that a properly organized VLBI programme for radio star observation
with a reasonable load on the VLBI network can allow for the realization of
GCRF-ICRF link with an error of about 0.1 mas.
