Abstract

Flash helping has recently been shown to be an effective technique for describing additive noise to a decoder. It is shown here to be effective also in assisting the encoder: it achieves the helper capacity on the single-user Gaussian channel, on the multiple-access Gaussian channel, on the Exponential channel, and on the discrete modulo-additive noise channel. Most of the results hold irrespective of whether the helper observes the noise causally or noncausally.