Channels with cost constraints: Strong converse and dispersion

This paper shows the strong converse and the dispersion of memoryless channels with cost constraints. The analysis is based on a new non-asymptotic converse bound expressed in terms of the distribution of a random variable termed the b-tilted information density, which plays a role similar to that of the information density in channel coding without cost constraints. We also analyze the fundamental limits of lossy joint-source-channel coding over channels with cost constraints.