| Summary: | 碩士 === 國立海洋大學 === 電機工程學系 === 91 === In wireless communications, channel estimation is one of important research topics. Through a known signal’s transmission and reflecting or scattering of channel, the received signal in antenna array will include various parameters such as directions-of-arrival (DOA) and time delay in each path. If these parameters can be effectively estimated, it would be helpful in the design of beamformer and equalizer as well as the application of mobile unit localization.
In the thesis, we investigate the characteristics of 2-D signal subspace algorithms, JADE-MUSIC and JADE-WSF, in time-varing Rayleigh fading channel. When the path’s coefficients do not change in time, we propose a two-stage scheme for DOA and time delay estimation, which is able to significantly reduce the computational load. This method employs ROOT-MUSIC algorithm to estimate DOA and then modifies the maximum likelihood method proposed by Wax to estimate time delay. Compared with JADE-MUSIC and JADE-WSF, the proposed method has mush lower computational load, but the path number must be less than the number of the antennas. Finally, computer simulations are executed in order to evaluate the proposed scheme as well as compare it with the Wax’s iterative maximum likelihood method and Cramer-Rao bound.
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