| Smart antenna is one of the key techniques in 3G mobile communication, its development is very fast, and it is for the moment the hotspot of research. Adopting the suitable adaptive algorithm, smart antenna may obtain the maximum processing gain in the direction of the desired signal and null the strong interferer, so can enhance the performance of the system. Up to date, many problems need to be resolved in the implement of the smart antenna; these problems include primarily two categories. First, the existing algorithms about smart antenna are applicable to the perfect case. The obtained results are based on the computer simulation, but there are many errors in the real system and those errors influence the performance of the system to some enormous extant. Second, smart antenna signal processing is multi-dimensional signal processing, hence, the computation effort is very large, and need the higher speed DSP device. The researchers are actively studying the fast algorithm; on the other hand, they are studying how to increase the robustness of the algorithm. In fact, these two cases are presently the difficulty and the hotspot.This thesis analyzes the smart antenna and the channel model, and studies the uniform linear array and uniform circular array respectively, in the end, presents several new DOA estimation algorithm by constructing felicitously the second order statistics. Those algorithms reduce efficiently the computation effort of the estimation.Above all, the thesis analyzes the smart antenna and the vector channel model, derives detailedly various parameter of the model aiming at GSBCM and GSBEM, describes the sense of the DOA estimation about these model, prepare for the expansion of the thesis.Aiming at the shortcoming that need to perform SVD decomposition about ULA DOA estimation, the thesis presents the closed-form solution of the DOA estimation by constructing second order statistics in the arbitrary adjacent threeelements and perfoming mathematical operator. When SNR is very low, this closed-form solution can work perfectly in the presence of the spatial white noise and reduce the computation effort.Because the circular array is planar array, it has many advantages. For example the pattern of the circular array does not change as the direction of main lobe change and can estimate the two-dimensional DOA just to name a few. The thesis presents a novel two-dimensional DOA algorithm and obtains the closed-form solution of the azimuth and elevation angle of the desired signal. Theory analysis illustrates the method can operate perfectly, when SNR is very low. The computation effort is very small. The thesis specifies the applicable scenario of the method.The thesis derives the two-dimension DOA estimation algorithm based on variance matrix in the uniform circular array and resolves the problem in the two-dimension DOA estimation using variance matrix by constructing second-order statistics. The computer simulation verifies the efficiency of the method proposed by this thesis.
|
PDF Full Text Request