Research On Joint Spectrum Sensing And Spectrum Access Optimization Technology In Cognitive Radio

With the explosive growth of wireless applications,the shortage of spectrum resources is becoming extraordinary severe.The current fixed spectrum resource allocation scheme makes low utilization of a large amount of spectrum resource,and has been a bottleneck in the current development of wireless networks.As a non-renewable resource,spectrum resources are very limited.Only by improving the management schemes of spectrum resource can we effectively solve the problem of insufficient spectrum resources.Cognitive radio technology gradually become one of the most eye-catching technologies for solving the problem of spectrum scarcity,for that it can intelligently sense the surrounding electromagnetic environment,adaptively adjust operating parameters,and dynamically access the idle authorized channel without causing serious interference to the transmission of the primary user.This thesis first introduces the research background and significance of cognitive radio networks,and then focuses on the definition of cognitive radio networks and the key technologies involved in cognitive radio.Spectrum sensing and spectrum access are important parts in cognitive radio technology.Researchers have done a lot of work for spectrum sensing and spectrum access optimization.This thesis investigates the spectrum prediction techniques commonly used to optimize spectrum sensing,and focuses on latest research results in spectrum sensing and access optimization.On this basis,this thesis aims to improving the average throughput of cognitive users,make a further optimization of spectrum sensing and spectrum access.This thesis makes the following contributions:1.Considering the limited transmission power of low-cost equipment in the actual working environment,we redesigned the transmission frame structure of cognitive users,and proposed an optimal spectrum sensing stopping rule.The spectrum sensing process is stopped in time,and multiple idle channels are aggregated for data transmission,which can significantly improve the average throughput of cognitive users.2.When the distribution of cognitive users is relatively concentrated,cognitive users face the same electromagnetic environment.A spectrum sensing optimization allgorithm based on base station sensing is proposed,transfer the spectrum sensing function to the base station.The base station know well the global information of all authorized channel states,and can narrow the channel sensing range only to the candidate channel,which saves the sensing time overhead and ultimately improves the average throughput of multiple cognitive user node pairs in the system.