  The two binary black-hole (BBH) coalescences detected by LIGO, GW150914 and
GW151226, were relatively nearby sources, with a redshift of ~0.1. As the
sensitivity of Advanced LIGO and Virgo increases in the next few years, they
will eventually detect stellar-mass BBHs up to redshifts of ~1. However, these
are still relatively small distances compared with the size of the Universe, or
with those encountered in most areas of astrophysics. In order to study BBH
during the epoch of reionization, or black holes born from population III
stars, more sensitive instruments are needed. Third-generation
gravitational-wave detectors, such as the Einstein Telescope or the Cosmic
Explorer are already in an advanced R&D stage. These detectors will be roughly
a factor of 10 more sensitive in strain than the current generation, and be
able to detect BBH mergers beyond a redshift of 20. In this paper we quantify
the precision with which these new facilities will be able to estimate the
parameters of stellar-mass, heavy, and intermediate-mass BBH as a function of
their redshifts and the number of detectors. We show that having only two
detectors would result in relatively poor estimates of black hole intrinsic
masses; a situation improved with three or four instruments. Larger
improvements are visible for the sky localization, although it is not yet clear
whether BBHs are luminous in the electromagnetic or neutrino band. The
measurement of the spin parameters, on the other hand, do not improve
significantly as more detectors are added to the network since redshift
information are not required to measure spin.
