BER analysis of underlay relay cognitive networks with imperfect Nakagami-m fading channel information

This paper studies the effect of imperfect Nakagami-m fading channel information on the bit error rate (BER) performance of underlay relay cognitive networks (URCNs) with arbitrary number of hops, taking into account both maximum transmit power constraint (MTPC) and interference power constraint (IPC). To eliminate time-consuming simulations, we propose an exact closed-form BER expression. Various results demonstrate its validity and show the performance saturation of URCNs. Additionally, channel information imperfection (CII), the order of locating secondary users of different maximum transmit power (MTP) levels, and optimum positions of secondary relays dramatically affect their performance.