On the impact of transceiver impairments to cognitive DF relay networks

The impairments of hardware in physical transceivers are proven to degrade the performance of wireless systems severely; however, their effects on cognitive relaying networks have not been investigated yet. In this paper, the impacts of hardware impairments in cognitive decode-and-forward (DF) network are quantified. More specifically, the exact signal to noise-and-distortion ratio (SNDR) of the relay link at the relay node and destination node of the cognitive DF network are attained. The SNDRs are used to deduced the exact outage performance (OP) of the network. Furthermore, numerical simulations are provided to corroborate the accuracy of our analysis in compared to the simulation results. It is proved that impairment levels of transceiver hardware degrade the performance of cognitive DF system dramatically. The impacts of this factor are nonlinear and more severe in high signal-to-noise regime. As such, there is a remarkable performance loss of around 4 dB in signal-to-noise (SNR) ratio when the impairment level of transceivers of relay and destination node are changed from 0 to 0.2.