Compound multiple access channels with conferencing decoders

A two-user discrete memoryless compound multiple access channel with a common message and conferencing decoders is considered. The capacity region is characterized in the special cases of physically degraded channels and unidirectional cooperation, while achievable rate regions are provided for the general case. The results are then extended to the corresponding Gaussian model. In the Gaussian setup, the provided achievable rates are shown to lie within a fraction of one bit from the boundary of the capacity region in several special cases. Numerical results are also provided to obtain insights about the potential gains of decoder cooperation in the underlying model.