An Upper Bound on the Capacity of the Causal Dirty-Paper Channel

A bound on the capacity of the causal dirty-paper channel with arbitrary interference and general independent identically distributed additive noise is derived. In particular, it is shown that for the case of Gaussian noise, the capacity is upper bounded by log₂(1+SNR/e) bits per real dimension. This bound is useful for SNR ≤ e(e-2) .