Research And Application Of Spectrum Sensing For Cognitive Radio

With the development of wireless communication technology and the current wireless applications continuing to expand, the lack of spectrum resources becomes an urgent problem in the process of research in wireless applications. However, some studies suggest that the large number of precious spectrum resources has not been fully utilized currently, and even in many cases is idle. In order to effectively address the problem of scarce spectrum resources, a new spectrum usage pattern---Cognitive Radio (CR) are gradually being people's attention.The research of this paper is spectrum sensing in cognitive radio.Firstly, local spectrum sengsing methods including energy method, match filtering spectrum sensing and Cyclostationary spectrum sensing are analyzed。The main objective of spectrum sensing is to provide more spectrum access opportunities to cognitive radio users without interfering with the operations of the primary network. Hence, recent research has been focused on the interference avoidance problem. To coexist with the primary user (PU) in the same frequency band, the secondary user (SU) has to adopt strict interference control rules to avoid interference towards primary users. A scheme based on forward modification and multi-step-ahead prediction (FMFAP) for cognitive radio is proposed to modify the sensing result and predict the interference time ratio (ITR) satisfying the strict interference constraint of primary networks in order to control the ITR so that it does not exceed a predefined threshold.Sensing/monitoring of spectrum-availability has been identified as a key requirement for dynamic spectrum allocation in cognitive radio networks (CRNs). An important issue associated with MAC-layer sensing in CRNs is how often to sense the availability of licensed channels and in which order to sense those channels. To resolve this issue, we develop a sensing-period optimization mechanism and an optimal channel-sequencing algorithm, as well as an environmentadaptive channel-usage pattern estimation method.