Research On Spectrum Resource Management For 5G Ultra Dense Heterogeneous Networks

With the rapid development of mobile communication technology and intelligent terminals,today's world is slowly moving towards the era of great connectivity of all things,the number of networking equipment and mobile data traffic in the field of communication are also experiencing explosive growth,as a result,the demand for spectrum resources is increasing rapidly,and the contradiction between scarce spectrum resources and low effective utilization rate of spectrum is becoming increasingly prominent.As a key technology of the fifth generation mobile communication system(5G),ultra dense networks can effectively improve the system capacity and realize seamless network connection.However,this ultra-dense,multi-level and heterogeneous networks deployment will easily lead to further aggravation of users' competition for spectrum resources and expansion of energy consumption,therefore,the traditional spectrum resource management scheme can no longer adapt to future complex network systems,it is the general trend to propose a spectrum resource management scheme for 5G ultra dense heterogeneous networks environment.As an important way to dynamically manage and utilize spectrum resources,cognitive radio(CR)technology can effectively improve the utilization rate of spectrum and solve the problem of shortage of spectrum resources,at the same time,CR has the ability to learn and reset,can adaptively adjust its working parameters,and control the transmit power on the basis of ensuring the service quality of users,so as to reduce interference and the energy consumption of network systems.This paper proposes a spectrum resource management scheme based on ultra dense cognitive networks,based on the research on spectrum resource management and CR technology by many scholars at home and abroad,and the following main researches are carried out to solve the above mentioned important problems that need to be solved urgently:1.In order to solve the problem of spectrum resource shortage and low utilization in ultra dense heterogeneous networks,this paper by comprehensively considering the uncertainty of noise power,multipath fading and shadowing effect,the influence of malicious secondary users on the spectrum sensing performance of the system,and the relationship between cognitive network throughput and perception time,a dynamic dual threshold semi-soft fusion cooperative spectrum sensing algorithm based on reputation value transfer is proposed to maximize the spectral efficiency of cognitive users.At the same time,based on the noise power uncertainty factor,this paper obtains a dynamic dual detection threshold from the optimal single detection threshold under the optimal spectrum efficiency,thus inhibiting the influence of the noise power uncertainty on the perception result,through updating the cognitive user's reputation value based on the spectrum perception result of the previous cycle,the local perception information located in the reliable area is sent to the fusion center for semi-soft fusion cooperative detection,thus realizing the screening of malicious secondary users and further improving the spectrum perception performance.Simulation results and comparative analysis show that the algorithm can be suitable for complex and changeable channel environment,reduce the impact of noise power uncertainty on spectrum sensing performance,and can better resist the spectrum sensing data falsification attacks of malicious secondary users on the sensing system,thus ensuring the security of the spectrum sharing system,ultimately effectively improving the utilization rate of spectrum resources in cognitive networks,expanding the system capacity,and easing the competition of users for the use of spectrum resources.2.Based on the better spectrum sensing performance of cognitive network system,in order to solve the interference and energy consumption in ultra dense heterogeneous networks,firstly,based on the dynamic spectrum access technology,a hybrid spectrum access mechanism combining Overlay and Underlay sharing modes in this paper is proposed to make full use of blank spectrum resources,and to maximize the spectrum efficiency of cognitive users to a certain extent.Secondly,the power control and interference suppression management strategies for users under imperfect spectrum sensing are studied,this paper based on the above hybrid spectrum sharing mode,considering the limitation of spectrum sensing technology,by modeling the power control process as a non-cooperative Stackelberg game,and cognitive users allocate power to maximize their energy efficiency after considering their own business needs,interference to primary users and the price they need to pay.The energy efficiency optimization power allocation problem is modeled to obtain a nonlinear fractional programming problem,and the original optimization problem is equivalently converted into an optimization problem in the form of parameter subtraction,based on the Lagrange multiplier method and Lagrange duality property,Dinkelbachs algorithm and subgradient method are finally adopted to obtain the optimal transmission power allocation strategy for secondary users.Simulation results show the convergence and effectiveness of the proposed power control strategy,the numerical analysis shows that the scheme can not only fully suppress the interference of cognitive users to primary users,but maximize the energy efficiency and spectrum efficiency of cognitive users to a certain extent.