The sum-capacity of different K-user cognitive interference channels in strong interference

This work considers different K-user extensions of the two-user cognitive interference channel model. The models differ by the cognitive abilities of the transmitters. In particular, the primary message sharing model, in which only one user is cognitive and knows all messages, and the cumulative message sharing model, in which a user knows the messages of all users with lesser index, are analyzed. The central contribution is the characterization of the sum-capacity of both models under a strong interference condition, which amounts to having one receiver in the network that can decode all transmitted signals without loss of optimality. The sum-capacity is evaluated for the Gaussian noise channel, as well as the conditions on the channel gains that grant strong interference.