具相位雜訊正交分頻多工系統之改良接受技術研究

• Main Authors: Hsiao-Min Chen, 陳曉旻
• Other Authors: Chi-Chao Chao
• Format: Others
• Language: en_US
• Online Access: http://ndltd.ncl.edu.tw/handle/08699965054630936817

碩士 === 國立清華大學 === 通訊工程研究所 === 96 === Applications of multi-carrier systems have increased extensively in recent years to cope with the need of high-data-rate transmissions. Orthogonal frequency-division multiplexing (OFDM) is a modulation technique wildly employed in wireless communication systems due to its advantages such as high spectra efficiency, robustness against inter-symbol interference (ISI) and multipath interference, etc. However, OFDM is extremely sensitive to time-varying effects. In particular, phase noise, coming from unavoidable oscillator jitters, is a random perturbation that would result in two unwanted effects: common phase error (CPE) and inter-carrier interference (ICI). There were quite a number of research works in the literature that have been proposed to deal with the problem; yet, the assumptions of those methods, such as the requirement of full knowledge on the channel and/or the transmitted signals or the need of preambles, may be impractical for certain situations. Therefore, the purpose of this thesis is to propose an algorithm that can compensate the CPE caused by phase noise and estimate the unknown channel response jointly by using pilots only. The key step toward this feature is to exploit the channel stationarity within a reasonable time duration and to perform joint estimation over several OFDM symbols. Improvements on the coded performance can be realized by incorporating the frequency-selective ICI-plus-noise energy profile in de-mapping. Several practical considerations of algorithm implementation are also addressed. Finally, simulation results are provided to demonstrate the performance of the proposed algorithm.