تجزیه و تحلیل عملکرد سیستم های رله شناختی با دخالت طیف به اشتراک گذاری تحت محدودیت احتمال قطع اولیه

This paper investigates the performance of an underlay cognitive relay system where secondary users (SUs) suffer from a primary outage probability constraint and spectrum-sharing interference imposed by a primary user (PU). In particular, we consider a secondary multi-relay network operating in the selection decode-and-forward (SDF) mode and propose a best-relay selection criterion which takes into account the spectrum-sharing constraint and interference. Based on these assumptions, the closed-form expression of the outage probability of secondary transmissions is derived. We find that a floor of the outage probability occurs in high signal-to-noise ratio (SNR) regions due to the joint effect of the constraint and the interference from the PU. In addition, we propose a generalized definition of the diversity gain for such systems and show that a full diversity order is achieved. Simulation results verify our theoretical solutions.