Achievable rate regions of cognitive radio channels with a confidential message

This paper investigates cognitive radio channels with a confidential message (CRC-CM) from an information-theoretic perspective. It is assumed that the secondary user (SU) transmitter has perfect and a priori knowledge on the message being transmitted by the primary user (PU) and the message of the SU is confidential to the PU receiver. An achievable rate region of the CRC-CM in the discrete memoryless (DM) case is derived. Two achievable rate regions are obtained by extending the DM rate result to a multi-antenna Gaussian CRC-CM case with two transmission strategies. A numerical example in the multi-antenna Gaussian case is provided.