Analysis of SIR for spectrum sharing system with OSTBC in Nakagami fading

This paper analyzes spectrum sharing cognitive radio system where orthogonal space time block codes (OSTBCs) are applied at the secondary user (SU) link. The influence of primary user's (PU) interference on the performances of the SU are studied in Nakagami fading environment. We derive exact closed-form expressions for probability density function and moments of the SIR (signal-to-interference ratio) of SU. Ergodic capacity is evaluated for different system parameters. The accuracy of the analytical expressions is verified using Monte Carlo simulation method.