  In this paper, a novel unified analytical expression for average bit error
rates (ABER) and average channel capacity (ACC) is presented for the
${\kappa}-{\mu}$ shadowed fading model. This new shadowed fading model has
shown to be suitable for underwater wireless channel modeling for the
measurements conducted by the Naval Research Laboratory, and is not so well
covered in the public literature. Deploying the Maximal Ratio Combining (MRC)
receiver, a new simple analytical expression for the probability density
function (PDF) of the receiver output signal to noise ratio is presented. Based
on this new PDF, the novel unified ABER and ACC expression derived. To further
generalize the error rate analysis, the additive white generalized Gaussian
noise model is assumed that models the different noise environments. The new
unified expression is accurate, simple and generic, and is suitable for MRC
analysis in this generalized shadowed fading and noise environment. Numerical
techniques and published results from the technical literature corroborate the
generality and accuracy of our analysis under the different test scenarios.
