  Time-triggered and event-triggered control strategies for stabilization of an
unstable plant over a rate-limited communication channel subject to unknown,
bounded delay are studied and compared. Event triggering carries implicit
information, revealing the state of the plant. However, the delay in the
communication channel causes information loss, as it makes the state
information out of date. There is a critical delay value, when the loss of
information due to the communication delay perfectly compensates the implicit
information carried by the triggering events. This occurs when the maximum
delay equals the inverse of the entropy rate of the plant. In this context,
extensions of our previous results for event triggering strategies are
presented for vector systems and are compared with the data-rate theorem for
time-triggered control, that is extended here to a setting with unknown delay.
