  Future direct imaging missions such as HabEx and LUVOIR aim to catalog and
characterize Earth-mass analogs around nearby stars. The exoplanet yield of
these missions will be dependent on the frequency of Earth-like planets, and
potentially the a priori knowledge of which stars specifically host suitable
planetary systems. Ground or space based radial velocity surveys can
potentially perform the pre-selection of targets and assist in the optimization
of observation times, as opposed to an uninformed direct imaging survey. In
this paper, we present our framework for simulating future radial velocity
surveys of nearby stars in support of direct imaging missions. We generate
lists of exposure times, observation time-series, and radial velocity
time-series given a direct imaging target list. We generate simulated surveys
for a proposed set of telescopes and precise radial velocity spectrographs
spanning a set of plausible global-network architectures that may be considered
for next generation extremely precise radial velocity surveys. We also develop
figures of merit for observation frequency and planet detection sensitivity,
and compare these across architectures. From these, we draw conclusions, given
our stated assumptions and caveats, to optimize the yield of future radial
velocity surveys in support of direct imaging missions. We find that all of our
considered surveys obtain sufficient numbers of precise observations to meet
the minimum theoretical white noise detection sensitivity for Earth-mass
habitable zone planets, with margin to explore systematic effects due to
stellar activity and correlated noise.
