The Research On Resource Allocation Method Of Cognitive Radio Network

Spectrum sharing cognitive radio network is a kind of network which consists of primary users and secondary users.Compared with traditional wireless communication network,spectrum sharing cognitive radio network has higher spectrum efficiency and has been widely applied in recent years.With the development of next generation of wireless communication technology,how to improve the network energy efficiency is of great significance in the case of the slow development of battery technology.In multicarrier modulation technology,filter bank multicarrier technology has the advantage of insensitivity to carrier frequency offset,high spectral efficiency and high energy efficiency,which is used as one of the key technologies of next generation wireless communication network.Therefore,this paper focuses on energy efficiency optimization,the spectrum sharing cognitive radio network and the resource allocation problem based on filter bank multicarrier modulation technology.Power allocation problem and subcarrier allocation problem are studied in this paper respectively.Firstly,a power allocation problem in multiuser spectrum sharing cognitive radio network is considered and a power allocation method in order to suppress the interference is proposed.Cross layer interference limit is introduced to protect secondary users from excessive interference,while virtual queue is introduced to transform the extra packet delay caused by the contention of the channel to the queuing delay in virtual queue corresponding to the channel.Taking the energy efficiency as the objective function,a nonlinear programming problem with nonlinear constraints is proposed under the constraints of time delay and transmission power.Firstly,the fractional objective function is transformed into polynomial form,and then the global optimal solution is obtained by iteration after reducing the computational complexity.In addition,a suboptimal algorithm is developed to reduce computational complexity while reduces some performance.The simulation results show that the optimal algorithm has higher performance while the suboptimal algorithm has a lower computational complexity.Both two algorithms have some certain practical importance.Secondly,we consider evolution game method to optimize subcarrier allocation because subcarriers don't need to be orthogonal so that there is a characteristic of competition between subcarriers in filter bank multicarrier technology.Introducing channel state matrix to display the quality of current subcarrier and taking the energy efficiency as the objective function,a nonlinear programming problem with multi-constraints is proposed under the constraints of total power consumption,power consumption in single subcarrier,total time delay,interference temperature limit and number of secondary users in single subcarrier.The evolution game operator is designed to establish utility function of each secondary user.When the utility function becomes optimal,the evolution game reaches Nash equilibrium point,thus the policy combination is considered as the best resource allocation.Through experimental simulation and comparison,the energy efficiency of the method proposed in this paper is optimal and gives the most reasonable subcarrier scheme which allocates more subcarriers for subcarriers which have better channel state.