Dynamic Spectrum Access Technology Research Based On QoS Guarantee In The Cognitive Wireless Network

In all of the resources,the radio spectrum resources is an important non-renewable resources,it occupies a strategic position.In recent years,on the one hand,the rapid development of wireless technology presents an explosion,the application of wireless technology increases,the grim fact that the spectrum resource is out of use is more prominent.On the other hand,at this stage,the spectrum resource is used in a fixed allocation approach internationally,which greatly hindered the increase of spectrum utilization.Since the cognitive radio technology appears,spectrum resources shortage problem has been appropriately mitigated,new ideas have been produced to achieve dynamic spectrum allocation,and thus improve the utilization of the spectrum with new solutions,cognitive radio opens up a new road for all of these problems.Cognitive wireless network uses cognitive radio technology,the network dynamically adjusts the parameters and protocols to achieve the purpose of adaptive learning,it is possible to optimize the results of the final decision by adaptive learning,thus to achieve the goal of improving network performance.Dynamic spectrum access technology is an important technology for cognitive radio network,it can make use of the spectrum holes in a flexible way,and can effectively alleviate the spectrum shortage dilemma.It has become a hot research topic in recent years.However,the current study focus on predicting and guiding the secondary user behavior by the primary user activity tracks,and then control the secondary user behavior when they access the network.This paper starts from the secondary user's perspective,using queuing theory to simulate the secondary user's activity when they access the network,using Markov state transition to analyze the state of the channel which is available to the secondary users.This paper calculates the user's delay parameters?switching probability and transition probabilities based on mathematical formulas,based on these parameters,this paper presents an admission control algorithm which is from secondary user's point of view to guarantee secondary user's access quality,and then meet the secondary user's QoS.The basic idea is:First accept the secondary user's new request for accessing into the network according to the system parameters and system preferences algorithm,then compare the new parameters with the theoretical parameters,if the result meets the conditions,the secondary users will be accepted into the real network,on the contrary,they will be rejected.Specific studies are as follows:Admission control algorithm based on secondary user's QoS guarantees under an independent network scenario and Admission control algorithm based on secondary user's QoS guarantees under multiple networks coexist scenario.