Anti-interference Technology With Adaptive Antennas

The spread spectrum communication with an aperiodic PN code and under strong man-made jammers has an important significance in military communications. Adaptive antenna is the front-end research field of anti-jammer. Thus, this dissertation investigates the implementation and application of adaptive array based on MMSE criteria. The new contributions of the dissertation are as follows.Firstly, the dissertation reveals at length the procedure of reference signal generating of adaptive array for the first time and presents the premise of adaptive array transforming from a transient state to a stable state and introduces a concept, threshold signal-to-interference noise ratio, SINRth. Based on these, it improves the method of reference signal generating.Secondly, the dissertation presents a 3-dimensional searching method with AFC and PN code synchronization and adaptive array convergence in order to accurately estimate the frequency difference between the received signal and the local oscillator. And it presents an estimation method for frequency difference by means of data synchronization selecting the time window of AFC frequency difference estimation hi order to solve the problem that data symbol transition induces an enormous error of frequency difference estimation. It also evaluates the performance of frequency difference estimation of AFC.Thirdly, the dissertation presents an anti-interference technology of adaptive array for non-spread spectrum signal using a pilot signal, by which a non-spread spectrum system can use the decoupled 2-D RAKE receiver and the original non-spread spectrum system need not be modified. And it analyses the performance of the anti-interference method.Lastly, the dissertation designs a rank-reduced blind space-time 2-D RAKE receiver using time extraction which has not only the capability of space-time equilibrium but also reduces the convergence time of adaptive array and the rank of correlated matrix of the received data. And it analyses the performance of the 2-D RAKE receiver and the method of reference signal generating.