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This paper focuses on the first-order and second-order performance of dual-hop underlay cognitive radio systems with opportunistic relaying(UCR-OR) over independent and non-identically distributed(i.ni.d)Rayleigh fading channels.For the UCR-OR systems,the tolerable maximum interference power(TMIP) Q at primary users(PUs) and the allowable maximum transmission power limit(AMTP) P_(max) at secondary users(SUs)are considered,simultaneously.We first obtain the closed-form solutions to the first-order performance such as outage probability,average symbol error ratio(SER),and ergodic capacity(EC).Secondly,we investigate the second-order statistical performance,i.e.,average outage rate(AOR) and average outage duration(AOD).With the consideration that in practice implementation the receiver performance is primarily influenced by the signalto-noise ratio(SNR)(not the signal envelope),the second-order statistical performance is investigated based on the equivalent instantaneous end-to-end SNR.Finally,we present the detailed performance comparison analysis of UCR-OR systems by defining a random variable μ=P_(max)/Q.The results show that the effect of μ on the first-order and second-order performances is different greatly.For the first-order performance,the performance gap is negligible when the value of μ is relatively large.However,for the second-order one,the gap is distinct.
This paper focuses on the first-order and second-order performance of dual-hop underlay cognitive radio systems with opportunistic relaying (UCR-OR) over independent and non-identically distributed (i.ni.d) Rayleigh fading channels. For the UCR -OR systems, the tolerable maximum interference power (TMIP) Q at primary users (PUs) and the allowable maximum transmission power limit (AMTP) P_ (max) at secondary users (SUs) are considered, form solutions to the first-order performance such as outage probability, average symbol error ratio (SER), and ergodic capacity (EC) .Secondly, we investigate the second-order statistical performance, ie, average outage rate (AOR) and average outage duration (AOD) .With the consideration that in practice implementation the receiver performance is absorbed by the signalto-noise ratio (SNR) (not the signal envelope), the second-order statistical performance is investigated based on the equivalent instantaneous end- to -end SNR.Fi nally, we present the detailed performance comparison analysis of UCR-OR systems by defining a random variable μ = P max / Q. The results show that the effect of μ on the first-order and second-order performances are different greatly. For the first-order performance, the performance gap is negligible when the value of μ is relatively large. However for the second-order one, the gap is distinct.