Performance Analysis of Scheduled Cognitive Radio Systems With MIMO Transmission

In this paper, we investigate the performance analysis of cognitive radio (CR) multiple-input-multiple-output (MIMO) systems, including the scheduled transmit antenna selection (TAS) with maximal ratio combining (MRC) and the scheduled space-time block coding (STBC). Here, the scheduled MIMO systems transmit data of a user to provide the maximum instantaneous postprocessing signal-to-noise ratio (SNR) at the CR receiver. For the closed-form performance analysis, we derive approximated probability density functions (pdfs) of the instantaneous postprocessing SNR at the receiver for the scheduled TAS with MRC and the scheduled STBC systems, respectively. Based on the results, we derive the approximated closed-form expressions of the average postprocessing SNR and ergodic capacity for the scheduled CR systems with MIMO transmission. Through the analysis, we provide the achievable average postprocessing SNR and ergodic capacity of the proposed scheduled systems as a function of the peak interference power constraint. In addition, we present the impact of imperfect channel state information (CSI) on the ergodic capacity for the scheduled TAS with MRC and the scheduled STBC systems through arbitrary order statistics, respectively.