Capacity of a class of overlay cognitive MAC radios

This paper considers a class of overlay cognitive radios with three messages, referred to as overlay cognitive MAC radios. The system consists of two transmitters and receivers but three independent messages, two of which are to be decoded at one receiver while the third is destined for the other receiver. An achievable region and an outer bound for the “weak” and “strong” interference cases are presented for this channel, which are ultimately shown to match for the special class of “weak” Gaussian overlay cognitive MAC radios.