Research On Carrier Estimation Of Digital Communication Signal And Interference

With the rapid development of digital communication, the digital signal based communication systems are widely used. The non-cooperative communication becomes a research hotspot, receiving more and more attention. Signal parameter estimation and signal interference as an important part of which has been highly valued. In this thsis, the carrier estimation of commonly used digital signal and interference are the keys to research.This thsis first introduces the model of commonly used digital signal and its frequency spectrum characteristics. On the basis of the model and the characteristics, the carrier estimation of several kinds of digital communication signal is studied. Second, for the OFDM signal, the carrier estimation algorithm is derived and simulated. Finally, the interference for OFDM technology is studied.The specific work is as follows:(1) We analyze three carrier estimation methods which are nonlinear carrier estimation, autocorrelation carrier estimation and cyclic cumulants estimation. After verifying their authenticity, we campare their respective advantages and applicability.(2) We study the subcarrier estimation of OFDM signals. Estimation the subcarrier of OFDM signal which is by PSK or QAM modulation based on the high-order cyclic cumulants method. By computer simulation, we get the curve of correct estimation probability which are respectively under the condition of flat fading channel and frequency selective fading channle. So we have the conclusion that the subcarrier estimation depending on high-order cyclic cumulants is also applicable to frequency selective fading channel with enough signal-to-noise ratio.(3) We study the audio interference of OFDM signal. We analyze the influence of audio interference when the receiver do synchronization and frequency offset estimation by ML synchronization algorithm. After respectively doing audio jamming under the frequency aiming at and without, we compare the interference effect, and conclude the frequency values range of interference signal.