Abstract
In this paper, we study the Gaussian Cognitive Zinterference channel (GCZIC) and its multiuser extension the Gaussian Cognitive Z-broadcast interference channel (GBZIC). We review some known capacity results and bounds for the GCZIC for various levels of interference. We derive a new improved inner bound for the CZIC under conditions which intersect with those for which the capacity is not known. Then we derive the capacity results and bounds for the CBZIC when the broadcast component of the channel is a degraded broadcast channel.