The Research Of Spectrum Detection Based On Signal Sample Autocorrelation

Nowadays, with the rapid development of wireless communication technology and the rapid growth of wireless users, the using shortages of the radio spectrum resources become noticeable. Obviously, spectrum is a kind of non-renewable resources. Its allocation at present all countries in the world adopt static (fixed) pattern, thus improving the already allocated spectrum resources utilization is one of the effective ways to solve the spectrum allocation shortages. Cognitive Radio (CR) is considered to be a potential solution technique to improve the use of radio spectrum efficiency. The IEEE 802.22 Working Group is aimed at using CR techniques to allow sharing of time or space domain unused spectrum which allocated to the Television Broadcast Service. Considering that spectrum detection is the primary job and the key technology in CR, this thesis mainly researches this technology. The structures of the thesis are organized as follows:The background of CR technology and related concepts are introduced in the first chapter, there also analysis the latest status of the IEEE 802.22 Working Group, including the developing situation of spectrum sensing algorithm in domestic and aboard.In Chapter 2, the strengths and weaknesses of different detection algorithms are discussed and analyzed in detail. Due to the detection the single node detection algorithms existing differences in principles, some algorithms have application limitations, therefore, we present a detection algorithm based on the sample covariance matrix of received signals in Chapter 3, and then we concretely apply this algorithm to the actual urban wireless communication environment. We described traditional energy detection, and compared with the presented algorithms. Theoretical analysis for the presented algorithm and the detection threshold based on false-alarm probability in Rayleigh Fading Channel are also given in this Chapter. In order to accurately get the detection performance under Rayleigh fading channel, an improved method of simulation Rayleigh Fading Channel is proposed in Chapter 4. There are some simulation results about Rayleigh Fading Channel. In view of the facts of IEEE 802.22 wireless regional area networks (WRAN) operates on the 54-862MHz VHF/UHF bands, simulation results of spectrum detection based on captured digital television (DTV) signals and random Binary Phase Shift Keying (BPSK) signals are listed in Chapter 5 to verify the algorithms. Moreover, because of the difference of Primary Users signals, there proposed over-sampling method to increase the relativity of the signal itself, thus improving the detection performance of spectrum detection. Taking into account the fading signal instability, we also proposed a multi-antenna signals detection mode in this thesis, and analyzed robustness of the detection method.