Research On Cognitive Radio Technology Based On Software Radio Platform

In recent years,with the development of wireless networks and the exponential growth of information flow,the demand for spectrum resources in wireless communication systems has been increasing.However,scarce spectrum resources are increasingly difficult to meet wireless communication needs.The traditional spectrum resource allocation algorithm is mainly to allocate dedicated frequency bands for specific users.This inflexible allocation method is the main reason for the lack of spectrum resources.Cognitive users with cognitive capabilities in cognitive radio,perceive the surrounding environment and find spectrum holes,under the premise of not disturbing the use of authorized users,dynamically access the frequency band of licensed users,this method is currently recognized as an effective solution to the lack of spectrum resources.Software radio is a new wireless communication architecture based on the combination of software and hardware and supported by microelectronics technology.It is the preferred platform for the realization of cognitive radio technology.This paper studies from three perspectives: Wireless environment detection,channel information detection and wireless resource management in cognitive radio,this paper has conducted theoretical analysis and algorithm design in the fields of spectrum sensing,cognitive radio channel estimation and cognitive cellular network spectrum resource management,using software radio to build a cognitive radio system for simulation verification,solved many problems from perception of authorized user spectrum to cognitive user spectrum resource reuse in cognitive radio networks.The main research contents and contributions of this article are as follows:(1)The waste of spectrum sensing information in the double threshold energy detection algorithm caused by the energy detection result falling into the confusion area and making no decision,therefore,this paper proposes spectrum sensing algorithm based on improved double threshold energy detection,the improved algorithm increases the refinement threshold in the confusion area,refines the energy detection results in the confusion area,performs fusion judgment in the fusion center to obtain spectrum hole information.Compared with the traditional algorithm,the proposed algorithm can obtain a higher detection probability.At the same time,the error probability of the proposed algorithm is lower than the traditional algorithm under low SNR scenarios.(2)This paper analyzes the impact of channel estimation on the realization of cognitive radio,uses an improved dynamic autoregressive model to model wireless channel estimation,dynamically estimates changes in channel statistics.This paper proposes an adaptive channel estimation algorithm based on an improved dynamic autoregressive model and extended Kalman filtering,based on the first-order autoregressive model,the proposed algorithm adds original equations to estimate the channel statistical characteristics and noise parameter changes caused by channel environment changes,estimate the noise matrix in real time and use the extended Kalman filtering to recursively update the channel parameters,reduced channel estimation complexity.Simulation results show that the adaptive channel estimation algorithm obtains higher estimation accuracy than traditional algorithm.(3)In view of the current situation of low spectrum utilization in cellular networks,this paper discusses the dynamic spectrum multiplexing method in cognitive cellular networks,proposes an improved spectrum resource management method in cognitive cellular networks,the proposed algorithm takes into account resource allocation errors caused by incomplete spectrum sensing,provides different users with spectrum resources to meet their needs,ensure that every user in the network gets a satisfactory communication experience.Simulation results show that the proposed algorithm can perform dynamic spectrum reuse under the premise of ensuring that authorized users are not disturbed,ensure reasonable allocation of spectrum resources while possessing the fairness of spectrum resource allocation.