  We investigate the stability conditions for remote state estimation of
multiple linear time-invariant (LTI) systems over multiple wireless
time-varying communication channels. We answer the following open problem: what
is the fundamental requirement on the multi-sensor-multi-channel system to
guarantee the existence of a sensor scheduling policy that can stabilize the
remote estimation system? We propose a novel policy construction and analytical
framework and derive the necessary-and-sufficient stability condition in terms
of the LTI system parameters and the channel statistics.
