Collaboration In The Cognitive Radio Spectrum Perception Technology

The core idear of cognitive radio is that to avoid causing to primary users or theinterference under the level. The cognitive radio allows the secondary users toopportunistic access the primary’s spectrum in order to maximize the spectrumutilization. So spectrum sensing technology is the key and basis of the CR, in order toenhance the probabity of spectrum sensing, the collabarity spcectrum sensing caneffectively overcome the limitations of signle-node specteum sensing by using largenumber of cognitive nodes,so as to achieve the the purpose of detection.This dissertation mainly investigates the cooperative spectrum sensing technique.According to the different research direction, it can be divided into three parts:Firsrly, the dissertation will introduce the basis of cooperative spectrumsensing-signle-node spectrum sensing, and introduce the signle-node spectrum sensingalgorithms. Then introduce the cooperative spectrum sensing algorithms because of thetransmission between the local detection and the judgment center, there exit thecontradiction between the detection performance and system overhead. To solve thisproblem this dissertation presents two algorithms-a lower-bit data transfer algorithmsand iterative spectrum detection algorithm. the former focused on the local harddecision information fusion, local cognitive judgment information storage, the formerfocused on the local hard decision information fusion, through the decision storage inthe local secondary users, if this moment local decision are the same as the fomer thennothing will upload, otherwise upload the local decision. Thelatter focused on theconsumption of energy and bandwidth increase with the number of collaborativespectrum sensing increased. If in the fomer decetion time the secondary didn’t detect theexit of primary user, the current moment the other one detect the primary user. Throughtwo secondary users’ mutual iterative detection to reduce system overhead, thensimulation and description of the algorithm is given.Secondly, this dissertation describes the clustering cooperative spectrum sensingalgorithm, analysis the proposed of clustering algorithm and its problems. Thenaccording to the probability requirements of detection in cognitive radio, an improved algorithm based on traditional clustering algorithm is proposed. This algorithm ismainly solve the low detection probability because that the judgement center treat allthe secondary users’ local detection information equally in the traditional hardcombination. This algorithm used the soft-weighted decision within the cluster, thehard-weighted decision in the judgment center. The simulation results show thesuperiority of this algorithm.In the end, this dissertation introduces double threshold spectrum sensingtechnology. According to the contradiction between the system overhead and thedetection probability, the cooperative spectrum sensing based on the serial and parallelmodel was proposed. Simulation results showed that the proposed algorithm couldeffectively improved the accuracy of the detection probability and decreased thebandwidth for reporting the cognitive user’s sensing results to the cognitive base station...