BER analysis of proactive relay selection in underlay cognitive networks

This paper proposes a BER (bit error rate) analysis framework for proactive relay selection (PRS) in underlay cognitive networks with channel information imperfection (CII), maximum transmit power constraint, interference power constraint, independent non-identical (i.n.i) Rayleigh fading distributions, and arbitrary modulation level. The analysis provides exact and asymptotic BER expressions, which facilitate in promptly evaluating system performance without time-consuming simulations and providing important performance metrics such as diversity order. Numerous results illustrate that CII considerably increases the BER of the PRS and completely eliminates its diversity order. However, the effect of CII can be significantly mitigated by increasing the number of relays.