Capacity of Finite-State Two-Way Channels

This paper addresses the capacity problem for a class of finite-state two-way channels (FS-TWCs). Specifically, inner and outer bounds for the channel capacity of FS-TWCs are derived, and they are combined to characterize the capacity region in a limiting expression for some special FS-TWCs. Although such an expression is often incomputable, it is illustrated via an example that a reduction to single-letter form is possible as long as the system variables exhibit stationarity and the associated "average channel" satisfies certain symmetry properties.