  The design luminosity for the future linear colliders is very demanding and
challenging. Beam-based feedback systems will be required to achieve the
necessary beam-beam stability and steer the two beams into collision. In
particular we have studied the luminosity performance improvement by
intra-train beam-based feedback systems for position and angle corrections at
the interaction point. We have set up a simulation model which introduces
different machine imperfections and can be applied to both the International
Linear Collider (ILC) and the Compact Linear Collider (CLIC).
