  For delay-limited communication over block-fading channels, the difference
between the ergodic capacity and the maximum achievable expected rate for
coding over a finite number of coherent blocks represents a fundamental measure
of the penalty incurred by the delay constraint. This paper introduces a notion
of worst-case expected-capacity loss. Focusing on the slow-fading scenario
(one-block delay), the worst-case additive and multiplicative expected-capacity
losses are precisely characterized for the point-to-point fading channel.
Extension to the problem of writing on fading paper is also considered, where
both the ergodic capacity and the additive expected-capacity loss over
one-block delay are characterized to within one bit per channel use.
