Spatial Modulation in MIMO Limited-Feedback Spectrum-Sharing Systems With Mutual Interference and Channel Estimation Errors

This letter investigates spatial modulation (SM) in multiple-input multiple-output (MIMO) spectrum-sharing systems in an effort to improve the overall spectral efficiency. Specifically, we study the secondary system performance adopting the SM technique under mutual primary-secondary interferences and channel estimation errors (CEEs). With limited feedback from the primary receiver, a closed-form expression for the average pairwise error probability, a tight upper bounded average bit error rate expression, and an approximate simple, yet accurate expression are derived over Rayleigh fading channels. Simulation results, which corroborate the numerical ones, show the importance of SM in improving the overall secondary performance and its robustness to CEEs.