This paper provides an analytic performance evaluation of dual-hop cognitive amplify-and-forward (AF) relaying networks over independent nonidentically distributed (i.n.i.d.) fading channels. Two different transmit po...This paper provides an analytic performance evaluation of dual-hop cognitive amplify-and-forward (AF) relaying networks over independent nonidentically distributed (i.n.i.d.) fading channels. Two different transmit power constraint strategies at the secondary network are proposed to investigate the performance of the secondary network. In the case of combined power constraint,the maximum tolerable interference power on the primary network and the maximum transmit power at the secondary network are considered. Closed-form lower bound and its asymptotic expression for the outage probability (OP) are achieved. Utilizing the above results,average symbol error probability (ABEP) at high signal-to-noise ratios (SNRs) are also derived. In order to further study the performance of dual-hop cognitive AF relaying networks,the Closed-form lower bounds and asymptotic expressions for OP with single power constraint of the tolerable interference on the primary network is also obtained. Both analytical and simulation are employed to validate the accuracy of the theoretical analysis. The results show that the secondary network obtains a better performance when higher power constraint is employed.展开更多
A Cognitive radio communication link is possible to be interrupted easily when its physical channel suffers severe fading. Relay technology is an effective way to mitigate the fading effect of wireless channels in a n...A Cognitive radio communication link is possible to be interrupted easily when its physical channel suffers severe fading. Relay technology is an effective way to mitigate the fading effect of wireless channels in a network. Based on the highest achievable rate of the relay channels, this paper considers a cognitive radio relay network where the secondary transmitter communicates with the receiver through the best relay node under the peak power constraint of a primary receiver. Intuitively, the secondary transmission can benefit from an intermediate relay node chosen from N possible nodes. To quantify this benefit, outage probability of cognitive radio relay networks is derived and also the closed-form expressions for outage capacity and ergodic capacity of cognitive radio relay networks are obtained in Rayleigh fading channels. Numerical simulation results are provided to show that the outage capacity and ergodic capacity benefit tremendously by properly increasing the number of relaying nodes.展开更多
The optimization of the network throughput and transmission range is one of the most important issues in cognitive relay networks （CRNs）. Existing research has focused on the dual-hop network, which cannot be extend...The optimization of the network throughput and transmission range is one of the most important issues in cognitive relay networks （CRNs）. Existing research has focused on the dual-hop network, which cannot be extended to a triple-hop network due to its shortcomings, including the limited transmission range and one-way communication. In this paper, a novel, triple-hop relay scheme is proposed to implement time-division duplex （TDD） transmission among secondary users （SUs） in a three-phase transmission. Moreover, a superposition coding （SC） method is adopted for handling two-receiver cases in triple-hop networks with a cognitive relay. We studied a joint optimization of time and power allocation in all three phases, which is formulated as a nonlinear and concave problem. Both analytical and numerical results show that the proposed scheme is able to improve the throughput of SUs, and enlarge the transmission range of primary users （PUs） without increasing the number of hops.展开更多
基金National Natural Science Foundation of China(No.61461024)
文摘This paper provides an analytic performance evaluation of dual-hop cognitive amplify-and-forward (AF) relaying networks over independent nonidentically distributed (i.n.i.d.) fading channels. Two different transmit power constraint strategies at the secondary network are proposed to investigate the performance of the secondary network. In the case of combined power constraint,the maximum tolerable interference power on the primary network and the maximum transmit power at the secondary network are considered. Closed-form lower bound and its asymptotic expression for the outage probability (OP) are achieved. Utilizing the above results,average symbol error probability (ABEP) at high signal-to-noise ratios (SNRs) are also derived. In order to further study the performance of dual-hop cognitive AF relaying networks,the Closed-form lower bounds and asymptotic expressions for OP with single power constraint of the tolerable interference on the primary network is also obtained. Both analytical and simulation are employed to validate the accuracy of the theoretical analysis. The results show that the secondary network obtains a better performance when higher power constraint is employed.
文摘A Cognitive radio communication link is possible to be interrupted easily when its physical channel suffers severe fading. Relay technology is an effective way to mitigate the fading effect of wireless channels in a network. Based on the highest achievable rate of the relay channels, this paper considers a cognitive radio relay network where the secondary transmitter communicates with the receiver through the best relay node under the peak power constraint of a primary receiver. Intuitively, the secondary transmission can benefit from an intermediate relay node chosen from N possible nodes. To quantify this benefit, outage probability of cognitive radio relay networks is derived and also the closed-form expressions for outage capacity and ergodic capacity of cognitive radio relay networks are obtained in Rayleigh fading channels. Numerical simulation results are provided to show that the outage capacity and ergodic capacity benefit tremendously by properly increasing the number of relaying nodes.
基金Project supported by the Zhejiang Provincial National Natural Science Foundation （No. LQ14F020005）, the National Natural Science Foundation of China （Nos. 61379123 and 61402414）, and the Research Program of the Educational Commission of Zhej iang Province, China （No. Y201431815）
文摘The optimization of the network throughput and transmission range is one of the most important issues in cognitive relay networks （CRNs）. Existing research has focused on the dual-hop network, which cannot be extended to a triple-hop network due to its shortcomings, including the limited transmission range and one-way communication. In this paper, a novel, triple-hop relay scheme is proposed to implement time-division duplex （TDD） transmission among secondary users （SUs） in a three-phase transmission. Moreover, a superposition coding （SC） method is adopted for handling two-receiver cases in triple-hop networks with a cognitive relay. We studied a joint optimization of time and power allocation in all three phases, which is formulated as a nonlinear and concave problem. Both analytical and numerical results show that the proposed scheme is able to improve the throughput of SUs, and enlarge the transmission range of primary users （PUs） without increasing the number of hops.
