| The rapid development of wireless communications technology, leading to a sharp increase in the number of wireless users, making the limited spectrum resources is becoming increasingly strained, thereby increasing the utilization of the wireless spectrum has become a key problem to be solved. Cognitive Radio (CR) technology is widely seen as an effective way to improve the radio spectrum utilization. It continuously detects the spectrum hole of the primary user (PU), the idle frequency bands in the PU communications are carried out, thus the detection and track of the weak PU signals has to be reliable and necessary. However, in the Cognitive Radio Network (CRN), due to channel fading and shadow effect, a single CU can not capture the instantaneously idle frequency bands information in a accurately and timely manner, so multi- CU spectral detection techniques has been continuously researched, the focus of this study is the technology for multi- CU spectrum detection and its application in wireless radio standard.In the second chapter of this paper, the single-node spectrum detection techniques have been done a certain amount of analysis, the advantages and disadvantages of various basic detection methods have been compared in the aspects of computational complexity, relevance and so on. For the multi- CU spectral detection technology, strive to design an effective testing program to make the best performance of signal detection with the reasonable bandwidth and power needs. Distributed detection transports the observation data with a certain degree pretreatment in the local CUs through the channels, and this means of communication transfers a smaller amount of data through the channels, has a reasonable bandwidth requirements and its detection performance meets the needs, so it is very practical. Therefore, for the distributed detection programs, in the third chapter of the text, does a detailed analysis on solving the test statistics under different fusion systems for various local CU and has got the specific expression with different basic detection methods. In the fourth chapter, start from the traditional signal detection, do a certain amount of research on the specific fusion algorithm for all the test statistics in the Fusion Center (FC) of the CRN, and has done a specific analysis on its implementation process and characteristics.Through previous research, in this paper, in the absence of a priori knowledge (only know the local CU noise variance), an optimized linear-weighted detection schemes based on the NP criterion is proposed. In this program, the solution of the weight coefficient is transformed into the solution of the most value problem of the constraint multi-variable convex function mathematically at a constant false alarm probability in the FC, to make the probability of signal detection greatest. Finally, on the conditions of AWGN channel with different SNR, the effectiveness of the testing program has been verified with Matlab simulation.Papers finally, a certain studies on the application of the spectrum detection technology in radio have been done. Firstly, introduces the main considerations in the application of spectrum sensing; followed, has analyzed exactly the application of this technology in radio standards such as the IEEE802.11k, Bluetooth, IEEE802.22, and focus on the detection of the two main signals: ATSC DTV signal, Part74 signal in Wireless Regional Area Network based on IEEE802.22 standard; at last, under different SNR conditions, has got the simulation diagram of the two kinds of modulation signals. |
PDF Full Text Request