| With the rapid development of wireless communication networks technology and the rapid increase of its services,the problem of spectrum resources and energy efficiency(EE)is becoming a bottleneck restricting the rapid development of the next-generation of wireless communication networks.Future technologies must simultaneously address the problem of low spectrum efficiency and high energy consumption.Cognitive radio(CR)is a new type of intelligent radio technology that is expected to alleviate contradiction between shortage of wireless spectrum resources and low utilization of licensed spectrum and has received extensive attention from industry and academia.In this paper,cognitive wireless communication system is the research object for the problem of how to improve spectrum efficiency(SE)and energy efficiency faced by resource allocation technology of cognitive wireless communication system.Researches on key issues such as optimizing spectrum allocation,improving spectrum efficiency and network energy efficiency,and proposing corresponding energy-efficient transmission mechanisms and resource allocation strategies provides certain theoretical basis and technical support for promoting resource optimization and high energy-efficient transmission of cognitive radio networks.The main research contents are as follows:1.We study the problem of spectrum resources allocation in one-hop cognitive radio network.Aiming at the network benefit in spectrum allocation and the time-effectiveness requirements of spectrum allocation algorithm,an improved quantum genetic algorithm(IQGA)is proposed.The algorithm dynamically adjusts the quantum rotation angle,sets the mutation threshold to chromosome variation,and establishes new interference constraint rules in the spectrum allocation process,which can speed up the convergence of the algorithm,reduce the interference between secondary users,and achieve efficient utilization of idle resources shared.The simulation shows that the proposed algorithm can reduce the time cost effectively,improve the average income of cognitive radio networks,and achieve efficient allocation of spectrum.2.The problem of high-efficiency resource allocation in multiple-hop cognitive radio networks is studied.Aiming at the problem of low spectrum utilization of licensed spectrum in multiple-hop links,a multiple-hop link can be used to multiplex the same primary user idle spectrum for data transmission.At the same time,considering the spectrum and power allocation,a successive multiple-step convex(SMCA)approximation is proposed.According to the non-convex complexity of the model,an equivalent convex approximation conversion method is designed to transform the model problem into a successive convex problem.Combined with the Dinkelbach fractional programming scheme,the sub-optimal solution of the model problem is obtained.From the theoretical computational complexity and simulation analysis,it is shown that compared with the exhaustive search method,SMCA can not only obtain the approximately lower bound of the optimal solution of the SE model problem,but also has lower computational complexity.3.The problem of high energy efficiency transmission in multiple-hop cognitive radio networks is studied.Aiming at the problem of low energy efficiency in multi-hop cognitive radio networks transmission,an energy-efficient multiple-hop transmission mechanism is designed.The spectrum sensing phases in the multiple-hop cognitive network are analyzed,and the problem of system average energy efficiency maximization is modeled with the constraint of secondary transmission outage probability.According to the non-convex complexity of the model,the sub-optimal solution of the sensing time and power allocation is obtained by using the coordinate ascent method and the Charnes–Cooper Transformation(CCT).At the same time,the convergence of the algorithm is analyzed.Simulation results show that this scheme can improve the energy efficiency of the secondary system. |
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