  Information transmission over channels with transceiver distortion is
investigated via generalized mutual information (GMI) under Gaussian input
distribution and nearest-neighbor decoding. A canonical transceiver structure
in which the channel output is processed by a minimum mean-squared error
estimator before decoding is established to maximize the GMI, and the
well-known Bussgang's decomposition is shown to be a heuristic that is
consistent with the GMI under linear output processing.
