The Research Of Spectrum Sensing Methods In Cognitive Ultra Wideband

:Cognitive radio technology was proposed in1999by Dr. Mitola. Through spectrum sensing technology, cognitive radio system can detect spectrum holes, and enable the unauthorized user to occupy these spectrum holes without affecting the main user. Thus, cognitive radio technology can greatly improve the utilization of wireless spectrum. Because of the limited the wireless spectrum resources as well as the applications of broadband wireless communications, cognitive radio technology has become one of the key technologies to solve the problem of spectrum resources, and has been widely recognized in industry field. In recent years, ultra-wideband (UWB) technology has become one of the focuses of the short-range wireless communications technology. The UWB system has a high transfer rate, low power consumption, strong anti-interference ability and safe transmission; however, because of its wide transmission bandwidth, it is easy to interfere with other wireless communication systems. In order to overcome the interference, cognitive ultra-wideband technology (CUWB) attracts people’s attention. CUWB system can sense the current wireless environment and adjust its transmission parameters to avoid interference with other wireless communication systems. In this paper, we improve the current spectrum sensing scheme. In addition, this article presents a new kind of adaptive-threshold energy detection method, which is suitable for the background noise environment. Because of the wide distribution range of noise, we can calculate the noise energy value in adjustment band and use it to amend the detection threshold. In addition, the energy value of primary user signals can be approximately neglected in the adjustment band, since the selected adjustment band is much larger than narrow-band primary user signal bandwidth. Therefore, this new method does not impact on the detection performance. Theoretical analysis and simulation results show that this new method can significantly reduce the probability of false alarm under the condition of the noise interference.The first chapter introduces the concept of cognitive radio technology, research background, research status and main purposes, and clarifies the current conditions of limited radio spectrum resources as well as the significance of the application of cognitive radio technology. The second chapter elaborates the CUWB system in detail. The third chapter describes the existing spectrum sensing schemes. Besides the principle introduction of matched filter detection, energy detection, cyclostationary feature detection, local oscillator leak detection, interference temperature monitoring and joint detection, it is also focus on their strengths and weaknesses and the applicable environment. In the forth chapter, taking the global interoperability for microwave access (WIMAX) as the primary user, we elaborate the specific detection scheme of CUWB system. The fifth chapter indicates the defect of the current detection scheme in the background noise environment. This paper presents a new adaptive threshold energy detection method to improve the defect. I have demonstrated this new method by theoretical analysis and simulation (based on the principle of Monte Carlo). Simulation results also verify the key role of the new method in the noise environment. In the conclusion, I summarize the full text and propose the prospect for future research work.