Cognitive channels with oblivion constraints

The paper considers a network with two coexisting Gaussian point-to-point links where one link, termed the secondary link, is permitted to transmit if it does not significantly degrade the communication of the other link, termed the primary link. The capacity of the secondary link is upper and lower bounded under different models for the cognition/knowledge the secondary system has about the primary system. The primary system is assumed to be oblivious of the presence of the secondary system (to support legacy systems). Upper bounds are obtained by relaxing the oblivion constraint for the primary link. Lower bounds are derived by suitably modifying known achievable regions without oblivion constraint so that the oblivion constraint for the primary link is met. For certain models of cognition and for certain parameter ranges upper and lower bounds meet.