| Cognitive radio (CR), which is a new wireless network design model, is put forward to improve the spectrum efficiency. It is the core idea that to avoid causing interference to the licensed users or make the interference under some level and allow the secondary users to opportunistic approach to maximize the spectrum utilization by accessing the spectrum. Spectrum sensing is the key issues for CR technology, which can solve the opportunistic access and avoid interference to the primary users.In this paper, signal detection in CR, blind detection and recognition of primary users' signals in CR and the optimal spectrum sensing framework (framework period) are researched. The main research mainly includes three parts:Firstly, the paper discusses the classification of spectrum sensing technology and the challenges, including signal detection, signal recognition and sensing framework optimization, and then give the present algorithms about these issues. GSM signals detection algorithms are researched in the CR contexts. We analyse the proposed GSM detection algorithms and compare them with the existing algorithms. A software about the signal detection algorithms is designed based on DMB-TH and GSM signals.Subsequently, this paper proposed a blind detection and recognition algorithm of OFDM signals in CR contexts. With none prior information, the SU can blindly detect the OFDM signals from the various environments and the SU can correctly recognition the OFDM parameters. Simulation results validate the proposed algorithm.Because of the contradictions between the detection time and transmission time, the throughput and the interference, it is difficult to design an optimal spectrum sensing framework. In this paper, we design an optimal framework model, which maximize the throughput and subject to the detection probability, the false alarm probability, and the interference. What's more, we take the time length distributions of the PU's activity. Simulations validate the proposed the framework. |
PDF Full Text Request