On the capacity of partially cognitive radios

This paper considers the problem of cognitive radios with partial message information. Here, an interference channel setting is considered where one transmitter (the ldquocognitiverdquo one) knows the message of the other (ldquolegitimaterdquo user) partially. An outer bound on the capacity region of this channel is found for the ldquoweakrdquo interference case (where the interference from the cognitive transmitter to the legitimate receiver is weak). This outer bound is shown for both the discrete-memoryless and the Gaussian channel cases. An achievable region is subsequently determined for a Gaussian partially cognitive-radio channel. The achievable strategy described in this paper is a combination of superposition and dirty paper coding.