Power Allocation and Outage Analysis for Cognitive Radio with Jamming Signal under Primary Secrecy Outage Constraint

In this paper, an optimal power allocation between information and jamming signals at a secondary user (SU) in cognitive radio is investigated. The power allocation is achieved to minimize SU's outage probability while keeping a secrecy requirement at a primary user (PU). By sending jamming signals, SU contributes to improving PU's secrecy outage, which in turn enables SU to find a vacant room of radio spectrum for transmitting its own information signal. The jamming signal is assumed to be known to PU in advance. But we investigate both of two cases regarding whether SU's receiver knows the jamming signal or not. SU's outage probability is derived as a function of the power allocation for the respective cases and is optimized with the primary secrecy constraint. Numerical results are provided to verify the analysis and to give insights on the outage performance of SU.