Research On Maximum Throughput Algorithm Of Congnitive Radio Opportunistic Spectrum Access

In order to resolve the current tension in wireless spectrum resource,cognitiveradio technology has come into being, and because of the feature of the using ofwireless spectrum of cognitive radio systems, it’s introduced the concept ofopportunistic spectrum access (OSA). Nowdays, the research on cognitive radioOSA technology is very hot. And the most typical is the POMDP-based model ofcognitive radio OSA technology. This thesis aims to study the OSA problem whichis based on POMDP model, in order to maximize the thoughtput of cognitive radiousers maintining the requirements on the primary users interference. This paper hasimportant theoretical significance, and enven can be used to OSA in the actualcognitive sysetems.Firstly this paper studied deeply the basic principles of cognitive radio and theOSA, according to the idea of reinforcement learning, it’s introduced the theory ofPOMDP in cognitive radio OSA. Then it research the OSA problem with nospectrum sensing error when cognitive radio users perform spectrum sensing, andthis also a problem based on no constrained-POMDP model. In this case this paperstudy the channel selection strategy and get the optimal channel selection. Althoughthe optimal strategy can get the optimal performance, there is huge computationalcomplexity. So we seek to the improve algirthm, and by simualtion it can be see thatthis improve algirthm has good performance of spectrum access. It can make thecognitive radio users achieve ideal access throughput and also simplify thecaculation.In additon, this paper focused on how to improve the proposed opportunisiticspectrum access algorithm in special scenarios. Firstly when the cognitive radiousers has sensing error when they perform spectrum sensing, we give the channelselection strategy. In this algorithm taking into account the cognitive radio users’sensing error as well as the transmission synchronization problems on both send andreceive ends, we combine the confidence vector updates with specturm sensing, thusthe constrained POMDP problem was converted into no constrained POMDPproblem, which simplify the problem. The simulation results show that thisalgorithm can make sure the cognitive radio users achive ideal throughput whenensure the interference requirements on primary user. Then this paper research theOSA algorithm thinking about the channel fading, and by simulation, we verify thefeasibility of the proposed algorithm. Finally this paper give out the design details ofthe MAC protocol in the distributed OSA networks. The analysis shows that thisprotocol can ensure the synchronous transmission during spectrum access process, and can effectively avoid the hidden terminal and exposed terminal problems intraditional communications.