Restarch On Spectrum Allocation Strategy And Performance Optimization In Multiple-Channel Cognitive Radio Networks

In recent years,wireless communication technology has entered a rapid development period.Since the development trend of business requirements on the user side becomes more and more complex and diversified trend,the problem of wireless spectrum shortage becomes increasingly acute.As a new technology in effectively solving the spectrum shortage problem,Cognitive Radio Networks(CRNs)become a hot research topic.In a CRN,there are usually two types of users,Primary Users(PUs)and Secondary Users(SUs),which have different priorities.In this thesis,based the admission control and transmission control for user data,considering different network requirements,the dynamic spectrum allocation strategies for CRNs consisted of multiple channels are proposed.Then,the mathematical modeling and system optimization for the proposed spectrum allocation strategies are presented by fusing stochastic theory,economic elementary theory,game theory and swarm intelligence optimization theory.Firstly,a multiple channels spectrum allocation strategy with the energy detection threshold is proposed and optimized.In order to effectively control sharing spectrum interference caused by mistaken detection and false alarm of SUs,the energy detection method is introduced to control the admission of SUs.A priority queueing model with interference caused by sharing multiple service counters is built to describe the stochastic actions of two types of users.The system performance measures are established,and then the influences of energy detection threshold on the system performance are also evaluated.The system cost function is constructed by trading off the different system performance.By using the logistic chaos to initialize population,the teaching-learning-based optimization(TLBO)algorithm is improved,and then the optimal energy detection threshold is given ultimately.Secondly,a multiple channels spectrum allocation strategy with dynamically reserving the spectrum is proposed and optimized.With purpose of balancing the response performance of two types of users,a dynamic method for setting the aside spectrum ratio is presented,and the channel open threshold mechanism is presented to control the transmission of SUs.A priority queueing model with adjustable service rate is built to describe the stochastic actions of two types of users.The system performance measures are established,and then the influences of adaptive control factor and channel open threshold on the performance are also evaluated.The system cost function is presented by trading off the different system performance.At last,by blending the improved TLBO algorithm and traversing method,the optimal combination of adaptive control factor and channel open threshold is suggested.Thirdly,a multiple channels spectrum allocation strategy with periodic sleep is proposed and optimized.In order to save the energy consumption in a CRN,a multiple sleep mode is introduced to control the transmission of SUs.A priority queueing model with multiple working vacations is built to describe the actions of two types of users.The system performance measures are established,and then the influences of channel service rate and sleep parameter on the system performance are also evaluated.The system cost function is constructed by trading off the different system performance.By a decreasing method with exponential form to balance the global exploration and local exploitation ability of TLBO algorithm,the TLBO algorithm is improved,and then the optimal combination of service rate and sleep parameter is given ultimately.Fourthly,a multiple channels spectrum allocation strategy with stopping threshold and periodic sleep is proposed and optimized.With purpose of saving system energy consumption,and alleviating network congestion,the stopping threshold mechanism is introduced to control the admission of SUs.A priority queueing model with limited capacity and multiple working vacations is presented to describe the stochastic actions of two types of users.The system performance measures are established,and then the influences of the sleep parameter and stopping threshold on the system performance are evaluated.The game analysis for the access actions of the SUs is conducted,and a pricing scheme is presented to maximize social benefit at last.Finally,a new multiple channels spectrum allocation strategy with awaken threshold and periodic sleep is proposed and optimized.With purpose of saving system energy consumption,and increasing throughput of SU,the awaken threshold mechanism is introduced to control the transmission of SU.A priority queueing model with N-strategy and multiple working vacations is bulit to describe the stochastic actions of two types of users.The system performance measures are established,and then the influences of sleep parameter and awaken threshold on the system performance are evaluated.The access actions of the SUs are analyzed by combining game theroy,and a pricing scheme is presented to maximize social benefit ultimately.