On the single-user capacity of some multiple access channels

We consider an additive multiple-access channel where single-user decoding is performed at the receiver and study the Shannon capacity when the interference is modeled as impulsive alpha-stable and the additive noise as Gaussian distributed. We investigate scenarios whereby the input is possibly non-linearly distorted, and consider generic cost functions on the input. We prove that the optimal input is compactly supported´ and that it is generally discrete with finite number of mass points provided that the cost function and the channel distortion function are analytically extendable.