Research On Cognitive Cooperative Relay Technology Oriented To End-to-end Performance Analysis

As wireless communication technology and Mobile Internet are developed more and more rapidly,the conflict emerges more clearly between the request on wireless spectrum and the limit spectrum resource.Therefore,more and more scare spectrum resource has been one of the key factors that limit the development of wireless communication technology.Based on the background,cognitive radio and cognitive wireless network have been put forward to improve the spectrum utilization efficiency.Cognitive relay networks which introduce relay to cognitive wireless networks improve not only the spectrum utilization efficiency but also the performance of networks.Initially,cooperative relay technology is introduced in this paper.We investigate the relay forward protocols and compare the different protocols.Based on these researches,the key technologies of cognitive cooperative relay are introduced,and the research status of cognitive cooperative relay is also summarized.In addition,cognitive cooperative relay based on dynamic spectrum leasing is discussed in this paper.Under the constraint of the predefined transmission rate of primary users,three relay selection schemes are proposed to research the performance of primary and secondary networks in the scenario that secondary users cooperate with primary users to transmit primary data.By derivations and simulations,the schemes in this paper improve the performance of networks significantly,and secondary users are proved to have more chances to access the licensed spectrum in this scenario.What's more,cognitive cooperative relay based on average interference power constraint of primary users are also investigated in this paper.Under the tolerable interference power constraint of primary users,two relay selection schemes are proposed to analyze the performance of networks based on spectarum-sharing scenario.The transmit power of secondary transmitter and relay nodes is optimized by the tolerable interference of primary users in order to avoid having influence on communications of licensed users.Based on the power allocation and relay selection,the performance of secondary networks is also analyzed in this paper.The simulations indicate that proposed schemes can improve the spectrum efficiency and the coverage of secondary network.Finally,we conclude the paper and give some suggestions on future work.