Research On Admission Control Algorithms For Heterogeneous Cognitive Wireless Networks

Accompanying to the race evolution of wireless communication technology and the diversification of its bearer services,and which increasingly make the demand for wireless communication resources.Owing to the openness and shared nature of wireless communication channels have led to the increasingly scarce radio spectrum resources available when users access to wireless networks.How to efficiently improve the utilization rate of radio spectrum resources,and to achieve precise service to users' demands for different types of services and terminals have become one of the key issues urgently to be solved in mobile wireless communications in the present and future.Simultaneously,with the wireless communication systems facing the explosive growth of multi-user business types,it has been putted forward higher requirements to the quality of service of mobile terminal services.The single service type of the traditional network can no longer meet the multi-dimensional and diversified development process and decision-making standards.The emergence of a variety of different radio access technology networks solves the shortcomings of the traditional network and makes up for own shortcomings.But,the contradiction between limited spectrum resources and the ever-increasing users service requirements is becoming increasingly.How to use cognitive radio technology to effectively solve the serious supply and demand contradiction of spectrum resource shortage has become a hot spot of research now.Secondly,how to use QoS as the main optimization goal has become the main research of admission control direction for users.In response to the above problems,this dissertation mainly proposes admission control algorithm under three different system models,and analyzes the performance of the algorithm.The main work and research results of this dissertation are as follows:Firstly,aiming at the competition and cooperation between newly arrived services and handover services,operators and operators,as well as users and operators,an admission control algorithm based on population competition is proposed.This dissertation analyzes the distributed network architecture model where multiple RATs overlap and the network attracts secondary users,using the relationship between the number of users and the growth of business volume as a competitive relationship.The analysis show that the introduction of the population competition relationship is conducive to balancing the relationship between the number of users and the growth of business volume.This relationship can maximize the number of users be accepted,and the distributed architecture can flexibly change the equilibrium relationship.However,the main problem of the algorithm is that when the competitive relationship reaches a balanced state,the balance state will be affected by the new arrival and switching services.While the balance is reached again,the users' QoS will be affected.Secondly,aiming at the same frequency band in the same time,which doesn't affect the primary user as well as can optimize the QoS of secondary users,and to solve the NP problem in admission control take a joint power admission control algorithm is proposed.Using Benders decomposition theory to decompose it into two problems: power control and users acceptance,and optimize the indicators in the system.Through the simulation analysis of the two indicators of throughput and interruption rate,according to the constraints that three different secondary users removal criteria are proposed which ensures the number of secondary users to access the network while ensuring the QoS of the secondary users to maximize and reaching ideal value.Finally,in view of the overlapping coverage area of macro base stations and micro base stations,how to optimally access newly arrived services and handover services to the network,an admission control algorithm based on semi-Markov decision process is proposed.Through MATLAB,the admission control algorithm for population competition,the admission control algorithm for joint power,and the admission control algorithm based on semi-Markov decision process are analyzed.The simulation results show that the admission control algorithm based on semi-Markov decision process can solve both it solves the problem of the impact on users' QoS under population competition,and solves the problem of congestion that caused by the removal of secondary users in the admission control algorithm of joint power.After the algorithm is improved,the expected goals are achieved in both energy efficiency and network revenue.