| Summary: | 碩士 === 國立交通大學 === 電子研究所 === 106 === In this thesis, we study downlink channel estimation based on the IEEE 802.11p system designed for vehicular communications. We investigate the performance of subspace-tracking channel estimation method in a IEEE 802.11p downlink system. And we simulate the channel estimation method with MATLAB.
We use subspace-tracking channel estimation method as an intermediate step after obtaining the least-squares (LS) estimate over the pilot subcarriers, whose purpose is to increase the accuracy of the estimate over the pilot subcarriers. And this preliminary estimate is interpolated/smoothed over the entire frequency-time grid to obtain the channel estimate of the corresponding symbol. In subspace-tracking channel estimator, we parameterize the channel frequency response into the multiplication of delay matrix and amplitude vector. Since the temporal variation characteristic of these two parameters are different, we use subspace-tracking and least mean square (LMS) methods to estimate them respectively. We show the performance of subspace-tracking estimator in additive white Gaussian noise (AWGN) channel and Rayleigh fading channel for IEEE 802.11p system.
In this thesis, we first introduce the system structure of IEEE 802.11p standard. Then we describe the channel estimation method we use. Next, we introduce the common channel estimators for IEEE 802.11p system. Finally, we do the simulation and discuss the performance in each transmission condition.
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